JP3631698B2 - OFDM signal transmission system, OFDM signal transmitter and OFDM signal receiver - Google Patents

Description

ここで、ＨはＭ×Ｎのマトリクスであり、その要素（ｉ，ｊ）はｉ番目の送信アンテナとｊ番目の受信アンテナとの間の伝達関数である。また、ＩはＭ×Ｎの固有値行列、ρは平均ＳＮＲである。また、ｄｅｔはｄｅｔｅｒｍｉｎａｔｉｏｎ、＊は複素共役を示す。Ｍ＝Ｎの時、容量の下限は次式で与えられる。
【数２】

ここで、χ^２ _２ｋはｋ次のダイバーシチの効果を示す。すなわち、ＭＩＭＯチャネルでは、容量は単一チャネルのＮ倍になる。このように、ＭＩＭＯチャネルにおいて理想的に干渉キャンセルができれば、広帯域移動通信において大容量・高速伝送を実現できる。
このＭＩＭＯチャネルにおける従来の送受信装置の構成例を図１２に示す。これはＮ個の送信アンテナ１１０−１〜１１０−ＮとＮ個の受信アンテナ１１１−１〜１１１−Ｎを用いた時空等化を行う送受信装置の構成例であって、送信側では、送信情報は符号器１０１−１〜１０１−Ｎにおいて符号化され、インタリーバ１０２−１〜１０２−Ｎでインタリーブされ、Ｎ個の変調器１０３−１〜１０３−Ｎに分配された後、送信される。
【０００５】
一方、受信側にはＮ個の干渉キャンセラ１１４−１〜１１４−ＮとＮ個の等化器１１５−１〜１１５−Ｎとが配置されている。受信アンテナ１１１−１の受信信号は、まず等化器１１５−１で等化された後、デインタリーバ１１６−１でデインタリーブされ、復号器１１８−１に入力される。復号器１１８−１では、符号器１０１−１での符号化に対応した復号が行われる。
【０００６】
復号器１１８−１の出力とデインタリーバ１１６−１の出力との差分をとることにより、干渉成分が抽出される。この干渉成分は、インタリーバ１１７−１に入力され、その出力は等化器１１５−１に制御情報としてフィードバックされる。一方、等化器１１５−１の出力に対し、インタリーバ１１７−１の出力である干渉成分が差し引かれ、再度デインタリーバ１１６−１に入力される。
【０００７】
ここでの繰り返し処理により、復号器１１８−１の出力の信頼度が高められる。受信アンテナ１１１−１では、送信アンテナ１１０−１〜１１０−ＮからのＮ個の送信信号がすべて合成されて受信される。干渉キャンセラ１１４−１において、Ｎ個の送信信号がすべて合成された受信アンテナ１１１−１の受信信号より、復号器１１８−１の出力が差し引かれる。
【０００８】
これにより、送信アンテナ１１０−１で送信された信号は、受信アンテナ１１１−１で受信された信号から除去され、送信アンテナ１１０−２〜１１０−Ｎの（Ｎ−１）個の送信信号が合成された信号となる。この信号は、次の等化器１１５−２に入力される。等化器１１５−２では、等化器１１５−１の系統での処理と同様に、等化器１１５−２で等化された後、デインタリーバ１１６−２でデインタリーブされ、復号器１１８−２に入力される。
【０００９】
復号器１１８−２では、符号器１０１−２での符号化に対応した復号が行われる。復号器１１８−２の出力とデインタリーバ１１６−２の出力との差分をとることにより、干渉成分が抽出される。この干渉成分は、インタリーバ１１７−２に入力され、その出力は等化器１１５−２に制御情報としてフィードバックされる。一方、等化器１１５−２の出力に対し、インタリーバ１１７−２の出力である干渉成分が差し引かれ、再度デインタリーバ１１６−２に入力される。
【００１０】
ここでの繰り返し処理により、復号器１１８−２の出力の信頼度が高められる。干渉キャンセラ１１４−２において、復号器１１８−１からの入力より、復号器１１８−２の出力を差し引く。これにより、さらに、送信アンテナ１１０−２で送信された信号が除去され、送信アンテナ１１０−３〜１１０−Ｎの（Ｎ−１）個の送信信号が合成された信号となる。
【００１１】
この信号は、次の等化器１１５−３に入力される。このようにして、干渉キャンセラ１１４で順次、復号器１１８で復号した干渉信号が除去され、干渉キャンセラ１１４−（Ｎ−１）の出力は最終的に送信アンテナ１１０−Ｎの送信信号となり、等化器１１５−Ｎで等化され、デインタリーバ１１６−Ｎ、復号器１１８−Ｎで復号される。この操作を受信アンテナ１１１−２，１１１−３，・・・，１１１−Ｎについて行う。
【００１２】
各復号器１１８−１〜１１８Ｎからの復号結果は一連の処理を繰り返し、最終的なＮ個の復号器の出力は変換器１１９に送られ、シリアルの受信データに変換される。これは、すなわち、送信アンテナ１１０−ｉと受信アンテナ１１１−ｊとの間の各経路における伝達関数を等化器により推定し、これをもとに干渉キャンセルを行うことと等価である。
【００１３】
したがって、等化器の動作としては、Ｎ×Ｎの経路の等化を行うとともに、その結果をもとに（Ｎ−１）×Ｎの干渉キャンセルを行う必要がある。
【００１４】
【発明が解決しようとする課題】
図１２のような従来のＭＩＭＯチャネルにおける送受信装置では、受信装置の受信アンテナに対応した各受信系統毎に、Ｎ個の等化器が必要になる。また、厳しいマルチパスフェージング環境において広帯域伝送を行う場合、周波数選択性フェージングが発生し、各系統毎に極めて短時間で高精度にフェージングによって発生する振幅・位相の周波数特性を同定する必要がある。
【００１５】
しかし、現実のフェージング環境においては、到来する遅延波の数や強度、いわゆる遅延プロフィールは様々であり、このようなすべての環境に対して有効な等化器の実現は極めて困難である。このため、ＭＩＭＯチャネルにおける送受信装置は、固定通信のようなガウスチャネルに近い環境では実現可能性があるものの、厳しいマルチパスフェージングが生じるＭＩＭＯチャネルでは、極めて大きな信号処理能力が必要となるため、ＭＩＭＯチャネルにおける送受信装置の実現は困難であった。
【００１６】
また、図１２のような従来のＭＩＭＯチャネルにおける送受信装置では、復号器１１８−１の出力に対し、フェージング伝搬路での多重波フェージングにより歪んだ振幅・位相周波数特性を推定して差し引くことにより干渉キャンセルを行うことになる。この場合、各等化器には振幅・位相の周波数特性について高い推定精度が要求される。等化精度が達成できない場合には、干渉キャンセラでの干渉除去が十分できず、残留干渉雑音となるからである。
【００１７】
しかし、等化器では精度の高い振幅・位相の周波数特性についての等化が困難であるため、信号対干渉雑音比が劣化しやすいという問題があった。
更に、固定された基地局と移動端末との間で無線通信するシステムを想定する場合には、移動端末側に複雑な処理機能を設けると、移動端末におけるハードウェア規模の増大や消費電力の増大につながるので移動端末の小型化及び低コスト化の点で問題が生じる。
【００１８】
本発明は、上述の事情に鑑み、広帯域移動体通信等に用いられるＯＦＤＭ信号伝送システムにおいて、厳しい周波数選択性フェージング環境下で安定な動作を達成し、高品質化を図ることを目的とする。
【００１９】
【課題を解決するための手段】
上述した課題は、特許請求の範囲記載の発明により解決される。
【００２１】
請求項１は複数Ｎ個の送信アンテナと、複数Ｎ個の受信アンテナを含んでなるシステムであって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段を有する少なくとも１つのＯＦＤＭ信号送信装置と、上記ＯＦＤＭ信号送信装置に係るＯＦＤＭ変調器の全てに共通のＯＦＤＭシンボルタイミングを供給する手段と、上記ＯＦＤＭ信号送信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段を有する少なくとも１つのＯＦＤＭ信号受信装置と、上記ＯＦＤＭ信号受信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、上記ＯＦＤＭ信号受信装置に係る各ＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号発生手段により構成されることを特徴とする。
【００２２】
請求項２は、請求項１記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段を有する。
【００２３】
請求項３は、請求項１記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段を有する。
【００２４】
請求項４は、請求項１記載のＯＦＤＭ信号伝送システムにおいて、送信アンテナとして互いに直交する偏波を用いる２本の送信アンテナと、受信アンテナとして互いに直交する偏波を用いる２つの受信アンテナを使用する。
請求項５は、請求項４記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段を有する。
【００２５】
請求項６は、請求項４記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段を有する。
【００２６】
請求項７は、複数Ｎ個の送信アンテナと、複数Ｎ個の受信アンテナを含んでなるシステムであって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正機の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインタリーブを行うインタリーバを有する少なくとも１つのＯＦＤＭ信号送信装置と、上記ＯＦＤＭ信号送信装置に係るＯＦＤＭ変調器の全てに共通のＯＦＤＭシンボルタイミングを供給する手段と、上記ＯＦＤＭ信号送信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変操器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバと及び上記誤り訂正符号を復号する誤り訂正復号器を有する少なくとも１つのＯＦＤＭ信号受信装置と、上記ＯＦＤＭ信号受信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、上記ＯＦＤＭ信号受信装置に係る各ＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号発生手段により構成されることを特徴とする。
【００２７】
請求項８は、請求項８記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正機の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインタリーブを行うインタリーバを有する。
【００２８】
請求項９は、請求項７記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバと上記誤り訂正符号を復号する誤り訂正復号器を有する。
【００２９】
請求項１０は、請求項７記載のＯＦＤＭ信号伝送システムにおいて、送信アンテナとして互いに直交する偏波を用いる２つの送信アンテナと、受信アンテナとして互いに直交する偏波を用いる２つの受信アンテナを使用する。
請求項１１は、請求項１０記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接統され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正機の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインタリーブを行うインタリーバを有する。
【００３０】
請求項１２は、請求項１０記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバと及び上記誤り訂正符号を復号する誤り訂正復号器を有する。
【００３１】
請求項１３は、複数Ｎ個の送信アンテナと、複数Ｎ個の受信アンテナを含んでなるシステムであって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び送信情報信号を直並列変換した信号又は同一の送信情報信号を切り替えて送出する切替器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正機の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインターリーブを行うインタリーバを有する少なくとも１つのＯＦＤＭ信号送信装置と、上記ＯＦＤＭ信号送信装置に係るＯＦＤＭ変調器の全てに共通のＯＦＤＭシンボルタイミングを供給する手段と、上記ＯＦＤＭ信号送信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバ及び上記誤り訂正符号を復号する誤り訂正復号器及び送信ＯＦＤＭ信号の任意のサブキャリアに係るサブキャリア復調手段の出力の受信品質を測定する手段及び送信側において送信情報信号を直並列変換した信号を送出する場合にはサブキャリア復調出力を出力し、同一の送信情報信号を送出する場合にはサブキャリア復調出力を加算する又はサブキャリア復調出力のうち受信レベルの大きい方を出力する切替器を有する少なくとも１つのＯＦＤＭ信号受信装置と、上記ＯＦＤＭ信号受信装置に係る周波数変換器の全てに共通の局部発振信号を供給する局部発振器と、上記ＯＦＤＭ信号受信装置に係る各ＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号発生手段により構成されることを特徴とする。
【００３２】
請求項１４は、請求項１３記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び送信情報信号を直並列変換した信号又は同一の送信情報信号を切り替えて送出する切替器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正器の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインタリーブを行うインタリーバを有する。
【００３３】
請求項１５は、請求項１３記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバ及び上記誤り訂正符号を復号する誤り訂正復号器及び送信ＯＦＤＭ信号の任意のサブキャリアに係るサブキャリア復調手段の出力の受信品質を測定する手段及び送信側において送信情報信号を直並列変換した信号を送出する場合にはサブキャリア復調出力を出力し、同一の送信情報信号を送出する場合にはサブキャリア復調出力を加算する又はサブキャリア復調出力のうち受信レベルの大きい方を出力する切替器を有する。
【００３４】
請求項１６は、請求項１３記載のＯＦＤＭ信号伝送システムにおいて、送信アンテナとして互いに直交する偏波を用いる２本の送信アンテナと、受信アンテナとして互いに直交する偏波を用いる２つの受信アンテナを使用する。
請求項１７は、請求項１６記載のＯＦＤＭ信号伝送システムにおいて用いる送信装置であって、各送信アンテナ毎に接続され、同一の無線周波数が使用され、シンボルタイミングに基づいて動作するＯＦＤＭ変調器及び送信アンテナに接続され該ＯＦＤＭ変調器の出力を局部発信周波数を用いて無線周波数に変換する周波数変換器及び送信情報信号を直並列変換した信号又は同一の送信情報信号を切り替えて送出する切替器及び該各ＯＦＤＭ変調器に対応して既知のパイロット信号を発生する手段及び該各ＯＦＤＭ変調器に接続され送信情報信号と該パイロット信号とを多重化する手段及び送信情報に対して誤り訂正符号化を行う誤り訂正符号器及び誤り訂正器の出力をＯＦＤＭ変調器とサブキャリアの組み合わせによってインタリーブを行うインタリーバを有する。
【００３５】
請求項１８は、請求項１６記載のＯＦＤＭ信号伝送システムにおいて用いる受信装置であって、各受信アンテナ毎に接続され、局部発振周波数を用いて無線周波数の受信信号を復調に適した周波数に周波数変換する周波数変換器及び該周波数変換器にそれぞれ接続されＯＦＤＭ変調器毎に対応して送出されるパイロット信号を受信アンテナで受信するためのタイミング信号に基づき動作する高速フーリエ変換器及び送信アンテナと受信アンテナの全ての組み合わせについて、パイロット信号の受信振幅と位相を既知のパイロット信号振幅・位相で正規化して伝達係数を測定し、各サブキャリアに係る行列に対する逆行列を計算して記憶する逆行列演算手段及び高速フーリエ変換器の出力たる各受信ＯＦＤＭ信号であって任意のサブキャリアに係るものと前記逆行列の積をとり、各送信ＯＦＤＭ信号の該サブキャリアの振幅・位相を出力するサブキャリア復調手段及びサブキャリア復調手段の復調出力を入力としインタリーバと逆の操作を行うデインタリーバと及び上記誤り訂正符号を復号する誤り訂正復号器及び送信ＯＦＤＭ信号の任意のサブキャリアに係るサブキャリア復調手段の出力の受信品質を測定する手段及び送信側において送信情報信号を直並列変換した信号を送出する揚合にはサブキャリア復調出力を出力し、同一の送信情報信号を送出する場合にはサブキャリア復調出力を加算する又はサブキャリア復調出力のうち受信レベルの大きい方を出力する切替器を有する。
【００３６】
請求項１９は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムであって、前記ＯＦＤＭ信号送信装置には、前記Ｎ個の送信アンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出される逆行列の情報を受信する逆行列受信手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列受信手段の取得した逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力するＮ系統の信号のそれぞれに、前記パイロット信号発生手段の出力するＮ種類のパイロット信号を多重化するＮ個の多重化手段と、前記Ｎ個の多重化手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記Ｎ個の高速逆フーリエ変換手段の全てに共通のＯＦＤＭシンボルタイミングを与えるシンボルタイミング発生手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段の全てに共通の局部発振信号を与える送信用局部発振手段とを設けるとともに、前記ＯＦＤＭ信号受信装置には、前記Ｎ個の受信アンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段の全てに共通の局部発振信号を与える受信用局部発振手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信アンテナのそれぞれを介して送信されたＮ個のパイロット信号を受信信号から抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力に現れる受信されたＮ個のパイロット信号からその振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて前記Ｎ個の送信アンテナ及びＮ個の受信アンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記逆行列演算手段の求めた逆行列の情報を前記ＯＦＤＭ信号送信装置に対して送信する逆行列情報送信手段とを設けたことを特徴とする。
【００３７】
請求項２０は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムに用いられるＯＦＤＭ信号送信装置であって、前記Ｎ個の送信アンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出される逆行列の情報を受信する逆行列受信手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列受信手段の取得した逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力するＮ系統の信号のそれぞれに、前記パイロット信号発生手段の出力するＮ種類のパイロット信号を多重化するＮ個の多重化手段と、前記Ｎ個の多重化手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記Ｎ個の高速逆フーリエ変換手段の全てに共通のＯＦＤＭシンボルタイミングを与えるシンボルタイミング発生手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段の全てに共通の局部発振信号を与える送信用局部発振手段とを設けたことを特徴とする。
【００３８】
請求項２１は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムに用いるＯＦＤＭ信号受信装置であって、前記Ｎ個の受信アンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段の全てに共通の局部発振信号を与える受信用局部発振手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信アンテナのそれぞれを介して送信されたＮ個のパイロット信号を受信信号から抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力に現れる受信されたＮ個のパイロット信号からその振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて前記Ｎ個の送信アンテナ及びＮ個の受信アンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記逆行列演算手段の求めた逆行列の情報を前記ＯＦＤＭ信号送信装置に対して送信する逆行列情報送信手段とを設けたことを特徴とする。
【００３９】
請求項２２は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムであって、前記ＯＦＤＭ信号送信装置には、前記Ｎ個の送信アンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出されるパイロット信号の受信情報を受信する情報受信手段と、前記情報受信手段の受信した情報に基づいて、前記ＯＦＤＭ信号受信装置が受信したＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて前記Ｎ個の送信アンテナ及びＮ個の受信アンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列演算手段の求めた逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力するＮ系統の信号のそれぞれに、前記パイロット信号発生手段の出力するＮ種類のパイロット信号を多重化するＮ個の多重化手段と、前記Ｎ個の多重化手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記Ｎ個の高速逆フーリエ変換手段の全てに共通のＯＦＤＭシンボルタイミングを与えるシンボルタイミング発生手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段の全てに共通の局部発振信号を与える送信用局部発振手段とを設けるとともに、前記ＯＦＤＭ信号受信装置には、前記Ｎ個の受信アンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段の全てに共通の局部発振信号を与える受信用局部発振手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信アンテナのそれぞれを介して送信されたＮ個のパイロット信号を受信信号から抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力から、受信したＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出した情報を前記ＯＦＤＭ信号送信装置に対して送信する情報送信手段とを設けたことを特徴とする。
【００４０】
請求項２３は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムに用いるＯＦＤＭ信号送信装置であって、前記Ｎ個の送信アンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出されるパイロット信号の受信情報を受信する情報受信手段と、前記情報受信手段の受信した情報に基づいて、前記ＯＦＤＭ信号受信装置が受信したＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて前記Ｎ個の送信アンテナ及びＮ個の受信アンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列演算手段の求めた逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力するＮ系統の信号のそれぞれに、前記パイロット信号発生手段の出力するＮ種類のパイロット信号を多重化するＮ個の多重化手段と、前記Ｎ個の多重化手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記Ｎ個の高速逆フーリエ変換手段の全てに共通のＯＦＤＭシンボルタイミングを与えるシンボルタイミング発生手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段の全てに共通の局部発振信号を与える送信用局部発振手段とを設けたことを特徴とする。
【００４１】
請求項２４は、複数のＮ個の送信アンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の受信アンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の送信アンテナから送信するＯＦＤＭ信号伝送システムに用いるＯＦＤＭ信号受信装置であって、前記Ｎ個の受信アンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段の全てに共通の局部発振信号を与える受信用局部発振手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信アンテナのそれぞれを介して送信されたＮ個のパイロット信号を受信信号から抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力から、受信したＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出した情報を前記ＯＦＤＭ信号送信装置に対して送信する情報送信手段とを設けたことを特徴とする。
【００４２】
請求項２５は、請求項１９又は請求項２２のＯＦＤＭ信号伝送システムにおいて、前記ＯＦＤＭ信号受信装置には、少なくとも１つの情報送信用アンテナを更に設け、前記ＯＦＤＭ信号送信装置には、少なくとも１つの情報受信用アンテナを更に設けたことを特徴とする。
請求項２７は、複数のＮ個の第１組のアンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の第２組のアンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の第１組のアンテナから送信するＯＦＤＭ信号伝送システムであって、前記ＯＦＤＭ信号受信装置には、前記第１組のアンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、前記パイロット信号発生手段が出力するＮ種類のパイロット信号に対して逆高速フーリエ変換を施すＮ個の逆高速フーリエ変換手段と、前記逆高速フーリエ変換手段から出力される信号を送信のために無線周波数に変換するＮ個の送信用周波数変換手段と、前記第２組のアンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信用周波数変換手段及びＮ個の受信用周波数変換手段の全てに共通の信号を与える局部発振手段と、前記Ｎ個の第２組のアンテナについて送信と受信とを切り替える送受信切替スイッチ手段とを設けるとともに、前記ＯＦＤＭ信号送信装置には、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出され前記第１組のアンテナで受信された無線周波数のパイロット信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記受信用周波数変換手段の出力する信号に対してフーリエ変換を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段の出力する受信信号から、前記第２組のアンテナを介して送信されたＮ個のパイロット信号のそれぞれを抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力から抽出された信号に基づいて、前記ＯＦＤＭ信号送信装置から送信されたＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて、前記Ｎ個の第１組のアンテナ及びＮ個の第２組のアンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列演算手段の求めた逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段及びＮ個の受信用周波数変換手段の全てに共通の局部発振信号を与える局部発振手段と、前記Ｎ個の第１組のアンテナについて送信と受信とを切り替える送受信切替スイッチ手段とを設けたことを特徴とする。
【００４３】
請求項２７は、複数のＮ個の第１組のアンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の第２組のアンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の第１組のアンテナから送信するＯＦＤＭ信号伝送システムに用いるＯＦＤＭ信号受信装置であって、前記第１組のアンテナのそれぞれに対応した既知のＮ種類のパイロット信号を発生するパイロット信号発生手段と、前記パイロット信号発生手段が出力するＮ種類のパイロット信号に対して逆高速フーリエ変換を施すＮ個の逆高速フーリエ変換手段と、前記逆高速フーリエ変換手段から出力される信号を送信のために無線周波数に変換するＮ個の送信用周波数変換手段と、前記第２組のアンテナが受信した無線周波数の受信信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記Ｎ個の受信用周波数変換手段が出力するＮ系統の受信信号の各々に対してフーリエ変換処理を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段から出力されるＯＦＤＭシンボルをビット列に変換するＮ個の復調手段と、前記Ｎ個の送信用周波数変換手段及びＮ個の受信用周波数変換手段の全てに共通の信号を与える局部発振手段と、前記Ｎ個の第２組のアンテナについて送信と受信とを切り替える送受信切替スイッチ手段とを設けたことを特徴とする。
【００４４】
請求項２８は、複数のＮ個の第１組のアンテナを含むＯＦＤＭ信号送信装置と、複数のＮ個の第２組のアンテナを含むＯＦＤＭ信号受信装置とを備え、前記ＯＦＤＭ信号送信装置が同一の無線周波数のＯＦＤＭ信号を前記Ｎ個の第１組のアンテナから送信するＯＦＤＭ信号伝送システムに用いるＯＦＤＭ信号送信装置であって、入力されるＮ系統の送信データのそれぞれをＯＦＤＭシンボルに変換するＮ個のデータ変換手段と、前記ＯＦＤＭ信号受信装置から送出され前記第１組のアンテナで受信された無線周波数のパイロット信号を復調に適した周波数に変換するＮ個の受信用周波数変換手段と、前記受信用周波数変換手段の出力する信号に対してフーリエ変換を施すＮ個の高速フーリエ変換手段と、前記高速フーリエ変換手段の出力する受信信号から、前記第２組のアンテナを介して送信されたＮ個のパイロット信号のそれぞれを抽出するのに必要なタイミング信号を生成するタイミング信号発生手段と、前記高速フーリエ変換手段の出力から抽出された信号に基づいて、前記ＯＦＤＭ信号送信装置から送信されたＮ個のパイロット信号の振幅及び位相をサブキャリア毎に検出し、検出された振幅及び位相に基づいて、前記Ｎ個の第１組のアンテナ及びＮ個の第２組のアンテナの各々の組み合わせに対応するＮ×Ｎ個の要素の伝達係数で構成される行列の逆行列を演算する逆行列演算手段と、前記データ変換手段の生成した各ＯＦＤＭシンボルの各サブキャリアに対して、前記逆行列演算手段の求めた逆行列の乗算を行う前置干渉キャンセル手段と、前記前置干渉キャンセル手段の出力する信号に対して逆フーリエ変換を施すＮ個の高速逆フーリエ変換手段と、前記高速逆フーリエ変換手段の出力する信号の周波数を無線周波数に変換するＮ個の送信用周波数変換手段と、前記Ｎ個の送信用周波数変換手段及びＮ個の受信用周波数変換手段の全てに共通の局部発振信号を与える局部発振手段と、前記Ｎ個の第１組のアンテナについて送信と受信とを切り替える送受信切替スイッチ手段とを設けたことを特徴とする。
【００４５】
（作用）
本発明では、等化器を用いることなくＭＩＭＯチャネルでの信号伝送システムを実現すべくＯＦＤＭ方式を用いる。そして、等化器による時間軸での伝達関数の推定ではなく、例えばパイロット信号を用いてサブキャリア毎の伝達係数（振幅・位相）を直接測定し、サブキャリア毎にＯＦＤＭ信号間の干渉キャンセルのための伝達係数を取得する。
【００４６】
従って、サブキャリア毎に干渉キャンセルを行うため、容易に、かつ、精度の高い干渉キャンセルが可能となる、また、このシステムによれば、等化器を用いる場合のようにフィードバック制御を行う必要がなく、フィードフォワード処理ができるため、厳しい周波数選択性フェージング環境下においても安定な動作を達成できる。
【００４７】
なお、請求項１〜請求項１８では、逆行列演算手段及び干渉キャンセル手段をＯＦＤＭ信号受信装置側に配置する態様を想定している。
【００４８】
しかしながら、逆行列演算手段及び干渉キャンセル手段については処理が複雑であるので、それらの機能を備えると装置のハードウェア規模が増大し、消費電力も増大する。従って、逆行列演算手段及び干渉キャンセル手段を移動端末に搭載するのは望ましくない。
請求項１９〜請求項２８においては、逆行列演算手段及び干渉キャンセル手段の少なくとも一方をＯＦＤＭ信号送信装置側に搭載することを想定している。例えば、ＯＦＤＭ信号送信装置については複数の移動端末を管理する基地局に対応付けて考えればよく、ＯＦＤＭ信号受信装置については各移動端末に対応付けて考えればよい。従って、移動端末の小型化や電力消費の低減などの課題を克服できる。
【００４９】
【発明の実施の形態】
（第１の実施の形態）
請求項１に係る発明の１つの実施形態を図１に示す。この実施形態では、ＯＦＤＭ信号伝送システムは、２以上のＮ個の送信アンテナを備えアンテナ毎に接続され同一の無線周波数を使用するＮ個のＯＦＤＭ信号送信装置と、Ｎ個の受信アンテナを備え、アンテナ毎に接続され同一の無線周波数を利用するＮ個のＯＦＤＭ信号受信装置とで構成される。
受信された信号は、周波数変換器９−１〜９−Ｎで復調に適した周波数に周波数変換され、高速フーリエ変換器１１−１〜１１−Ｎにおいてフーリエ変換される。ここで、フーリエ変換されるＯＦＤＭ信号のＯＦＤＭシンボルタイミングは、ＯＦＤＭシンボルタイミング再生手段９から供給され、全て共通になっている。
ＯＦＤＭシンボルタイミング再生手段９の実現方法については、シンボルタイミング再生用の特別なプリアンブルを別途送出してＯＦＤＭシンボルタイミングを再生するなど種々の方法があげられる。送信アンテナ５−１〜５−Ｎから送信されるＯＦＤＭ変調信号の例を図２に示す。図２の例では、簡単のためパイロット信号Ｐ₁，Ｐ₂，・・・，Ｐ_Nは時間軸上で互いに重ならないように送信される。
【００５０】
図１記載の実施形態の構成と動作について詳細に説明する。本実施形態では、Ｎ個の送信アンテナ５−１〜５−Ｎに対応してＮ個のＯＦＤＭ変調器１−１〜１−Ｎが配置される。ＯＦＤＭ変調器１−１〜１−Ｎでは、サブキャリアの変調および逆フーリエ変換を行う。これらのＯＦＤＭ変調器１−１〜１−Ｎには、共通のＯＦＤＭシンボルタイミングがＯＦＤＭシンボルタイミング制御回路２から供給される。
【００５１】
送信情報信号Ｔ_１〜Ｔ_Ｎは、各ＯＦＤＭ変調器１−１〜１−Ｎに対応して既知のパイロット信号Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎを発生するパイロット信号発生手段６−１〜６−Ｎから入力されるパイロット信号Ｐ_１〜Ｐ_Ｎと、多重化手段７−１〜７−Ｎによってそれぞれ時間軸上において多重化される。この多重化された信号は、それぞれ各ＯＦＤＭ変調器１−１〜１−Ｎに入力される。
【００５２】
パイロット信号Ｐ_ｉは、送信アンテナ５−ｉと、受信アンテナ８−１〜８−Ｎの間の伝達係数を測定するのに用いられる。これらのパイロット信号と送信情報信号とが多重化され、それぞれＮ個のＯＦＤＭ変調器１−１〜１−Ｎに入力される。これらのＯＦＤＭ変調器１−１〜１−Ｎは、全て共通のＯＦＤＭシンボルタイミングで動作する必要があるため、ＯＦＤＭ変調器１−１〜１−Ｎの全てに共通のＯＦＤＭシンボルタイミングがＯＦＤＭシンボルタイミング制御回路２から供給される。
【００５３】
ＯＦＤＭ変調器１−１〜１−Ｎの変調出力は、無線周波数に変換するためＮ個の周波数変換器３−１〜３−Ｎに入力される。これらの周波数変換器３−１〜３−Ｎには、局部発振器４より共通の局部発振信号が供給される。これにより、送信アンテナ５−１〜５−Ｎより送信されるＯＦＤＭ信号の位相雑音や周波数変動は全て同一になる。
【００５４】
一方、ＯＦＤＭ信号受信装置においても、周波数変換器９−１〜９−Ｎには局部発振器１０から共通の局部発振信号が供給されるため、受信されるＯＦＤＭ信号の位相雑音や周波数変動は全て同一になる。このため、各送信ＯＦＤＭ信号は共通の周波数変動をもつことになるから、各サブキャリア間の干渉キャンセル及び同期検波を容易にすることができる。
【００５５】
周波数変換器３−１〜３−Ｎで周波数変換されたＯＦＤＭ信号は、それぞれ送信アンテナ５−１〜５−Ｎに入力され、ＯＦＤＭ信号受信装置に向けて送信される。ＯＦＤＭ信号受信装置においては、送信アンテナ５−１〜５−Ｎから送信されたＮ個のＯＦＤＭ信号が空間において加算された信号として各受信アンテナ８−１〜８−Ｎでそれぞれ受信される。
【００５６】
受信された信号は、周波数変換器９−１〜９−Ｎで復調に適した周波数に周波数変換され、高速フーリエ変換器１１−１〜１１−Ｎにおいてフーリエ変換される。ここで、フーリエ変換されるＯＦＤＭ信号のＯＦＤＭシンボルタイミングは、ＯＦＤＭシンボルタイミング再生手段９から供給され、全て共通になっている。
ＯＦＤＭシンボルタイミング再生手段９の実現方法については、シンボルタイミング再生用の特別なプリアンブルを別途送出してＯＦＤＭシンボルタイミングを再生するなど種々の方法があげられる。送信アンテナ５−１〜５−Ｎから送信されるＯＦＤＭ変調信号の例を図２に示す。図２の例では、簡単のためパイロット信号Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎは時間軸上で互いに重ならないように送信される。
【００５７】
一方、送信情報信号Ｔ_１〜Ｔ_Ｎで変調されたＯＦＤＭ信号は、時間軸上において重ねて送信される。パイロット信号Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎは、送信アンテナ５−ｉから受信アンテナ８−ｊへの伝達関数を知るために用いられる。パイロット信号Ｐ_１〜Ｐ_Ｎとしては、一般には各サブキャリアの振幅をすべて同一とすると、サブキャリア毎、受信アンテナの系統毎に同一の処理でよいため、信号処理を容易にすることができる。
【００５８】
このパイロット信号を用いると、ＯＦＤＭ信号の各サブキャリアは、ＯＦＤＭシンボル内では一定振幅で一定位相の信号であるから、送信アンテナ５−１から受信アンテナ８−ｉへの伝達関数は、以下のようにして求められる。
送信アンテナ５−１から送信されたパイロット信号Ｐｉは、受信アンテナ８−１〜８−Ｎで受信される。この受信されたパイロット信号は、周波数変換器９−１〜９−Ｎにおいて周波数変換された後、Ｎ個の高速フーリエ変換器１１−１〜１１−Ｎに送られる。
【００５９】
高速フーリエ変換器１１−１〜１１−Ｎにおいて、受信パイロット信号は各サブキャリア毎に分離される。この各受信サブキャリア信号の振幅及び位相を検出することにより、サブキャリア毎の伝達関数を複素数として測定できる。
送信アンテナ５−ｉから送信され、受信アンテナ８−ｊで受信されたサブキャリアの伝達関数は複素数ｓ_ｉ，_ｊとして得られる。ここで、このサブキャリア毎の伝達関数である複素数ｓ_ｉ，_ｊを伝達係数と呼ぶ。
【００６０】
ＯＦＤＭ信号のサブキャリア数をＭとすると、送信アンテナ５−ｉから受信アンテナ８−ｊへの伝達関数は、サブキャリア毎の複素数ｓ_ｉ，_ｊの組、すなわちＭ個の複素数ｓ_ｉ，_ｊによって表される。この伝達関数は、送信アンテナの数Ｎと受信アンテナの数Ｎとの積（Ｎ×Ｎ）だけ得られる。
すなわち、（Ｍ×Ｎ×Ｎ）個の複素数により、すべての送信アンテナ５−１〜５−Ｎと受信アンチナ８−１〜８−Ｎとの組み合わせの伝達関数が得られることになる。
【００６１】
ここで、ある１つのサブキャリアに着目して、送信アンテナ５−１〜５−Ｎからの送信信号を（ｔ_１，ｔ_２，・・・，ｔ_Ｎ）、受信アンテナ８−１〜８−Ｎで受信される受信信号を（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）で表す。
ｉ番目のサブキャリアの伝達係数を送信アンテナ５−１〜５−Ｎと受信アンテナ８−１〜８−Ｎとの組み合わせに応じて行列式Ｓ_ｉで表すと、（Ｎ×Ｎ）要素の行列式として表すことができる。この行列式Ｓ_ｉは次式で与えられる。
【数３】

ｉ番目のサブキャリアに着目すると、受信アンテナ８−１〜８−Ｎで受信される受信信号（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）は、送信アンテナ５−１〜５−Ｎで送信される送信信号（ｔ_１，ｔ_２，・・・，ｔ_Ｎ）と行列式Ｓ_ｉを用いて次式で表される。
【数４】

受信アンテナ８−１〜８−Ｎでは、送信アンテナ５−１〜５−Ｎから送信されたＯＦＤＭ信号が重畳して受信されるので、これらを復調するためには、受信信号（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）から、もとの送信信号（ｔ_１，ｔ_２，・・・，ｔ_Ｎ）を復元する必要がある。受信信号（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）から送信信号（ｔ_１，ｔ_２，・・・，ｔ_Ｎ）を復元するためには、サブキャリア毎にＳ_ｉの逆行列Ｓ_ｉ ^−１を計算し、サブキャリア毎に下式の演算を行えばよい。
【数５】

逆行列演算手段１３では、このように、Ｎ個の送信アンテナ５−１〜５−ＮとＮ個の受信アンテナ８−１〜８−Ｎの各組み合わせについて、受信パイロット信号の受信振幅及び位相を既知のパイロット信号の振幅・位相で正規化し、ｉ番目のサブキャリア毎に伝達係数である複素数を要素とする（Ｎ×Ｎ）の行列式Ｓ_ｉを測定により求め、その逆行列Ｓ_ｉ ^−１を計算して記憶する。
【００６２】
このｉ番目のサブキャリア毎に得られた逆行列Ｓ_ｉ ^−１を用いて、サブキャリア復調手段１４では、Ｎ個の高速フーリエ変換器１１−１〜１１−Ｎの出力である各受信ＯＦＤＭ信号のｉ番目のサブキャリアである（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）に対して（（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）×Ｓ_ｉ ^−１）の演算を行う。これにより、振幅・位相の基準となるパイロット信号をもとにした振幅・位相出力が得られるが、これはとりもなおさず、サブキャリア毎に同期検波された復調出力となる。
【００６３】
このように、（（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）×Ｓ_ｉ ^−１）の演算を行うことにより、各送信ＯＦＤＭ信号のｉ番目のサブキャリアである（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）の復調出力を得ることができる。この演算を、全てのサブキャリアについて行うことにより、送信情報信号（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）を復調することができる。
このように、パイロット信号を用いてサブキャリア毎の振幅・位相を測定することにより、受信信号（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）から送信信号（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）を復元するための伝達関数Ｓ_ｉが得られ、その逆行列Ｓ_ｉ ^−１を計算し、（（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）×Ｓ_ｉ ^−１）の演算を行うことにより、送信信号（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）を復元し、復調出力を得ることができる。
【００６４】
このように、本発明によれば、サブキャリア毎に干渉キャンセルのための伝達係数Ｓ^ｉが得られ、（（ｒ_ｉ１，ｒ_ｉ２，・・・，ｒ_ｉＮ）×Ｓ_ｉ ^−１）の演算だけで、チャネル間の干渉をキャンセルし、送信信号（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）を復元すると共に、復調が可能となる。
また、ここで説明したように、本発明では等化器における複雑な信号処理を行う必要がなく、フィードバック制御を行わない、いわゆるフィードフォワード制御になっているため、厳しいマルチパスフェージング環境においても、安定な動作が期待できる。
【００６５】
（第２の実施の形態）
次に、請求項１に係る発明のもう１つの実施形態について図３を用いて説明する。フェージングに対する特性を改善するため、一般にＯＦＤＭは誤り訂正及びインタリーブと組み合わせて用いられる。誤り訂正及びインタリーブを組み合わせた実施の形態が図３に示されている。
【００６６】
図３において、送信情報信号（ｔ_ｉ１，ｔ_ｉ２，・・・，ｔ_ｉＮ）は、誤り訂正符号器１５−１〜１５−Ｎにおいて誤り訂正符号化が行われた後、インタリーバ１６−１〜１６−Ｎにおいてサブキャリア方向、すなわち周波数軸方向においてインタリーブが行われる。これは、ある周波数近傍におけるレベルの落ち込み（ノッチ）に対して連続誤りを避け、高い誤り訂正符号化利得を得るために行われる。
【００６７】
受信側においては、復調出力は、デインタリーバ１７−１〜１７−Ｎにおいて送信側のインタリーブと逆の操作であるデインタリーブが行われ、その後、誤り訂正復号器１８−１〜１８−Ｎで復号される。
本実施形態は第１の実施の形態の変形例であり、第１の実施の形態と同一の構成要素を含んでいる。上記以外の構成要素については、第１の実施の形態と同一なので説明は省略する。
【００６８】
（第３の実施の形態）
図３の構成では、比較的長遅延のフェージングの場合は、連続誤りが生じないため良好な特性が得られるが、短遅延のフェージングの場合、図４のように周波数軸上でのフェージング周期が長くなるため、ノッチが広くなり、この部分において連続誤りが生じやすくなり、誤り訂正利得が小さくなるという問題がある。
【００６９】
請求項７に係る発明について、図５を参照して説明する。この発明は、上記のような誤り訂正利得の低下を改善するための発明である。
送信情報信号（ｔ_i1，ｔ_i2，・・・，ｔ_iN）は、図５に示す誤り訂正符号器１５−１〜１５−Ｎにおいて誤り訂正符号化が行われた後、インタリーバ１６においてサブキャリア方向（周波数軸方向）及び送信アンテナ方向（空間方向）において、複合してインタリーブを行う。
【００７０】
受信側では、復調出力は、デインタリーバ１７において送信側のインタリーブと逆の操作であるデインタリーブが行われ、その後、誤り訂正復号器１８−１〜１８−Ｎで復号される。
このようにすることにより、アンテナ方向と周波数軸方向とを組み合わせてインタリーブを行うことになるため、周波数ダイバーシチ効果に加えてアンテナ（空間）ダイバーシチ効果も得られる。このため、短遅延のフェージングにおいても連続誤りの発生が軽減され、誤り訂正符号化利得の低下を小さくすることができ、高品質化を図ることができる。
【００７１】
なお、１つの誤り訂正符号器の出力を、インタリーバ１６においてサブキャリア方向及び送信アンテナ方向に複合してインタリーブを行い、受信側ではデインタリーバ１７においてデインタリーブを行い、１つの誤り訂正復号器で復号する場合も同じ効果が得られる。
（第４の実施の形態）
次に、請求項４及び請求項１０に係る発明の１つの実施形態について、図６を参照して説明する。図６に示すように、この発明では送信アンテナ数が２であり、受信アンテナ数も２になっている。
【００７２】
送信側では、送信アンテナ５−１Ａと送信アンテナ５−２Ａとの偏波を異なる偏波、例えば垂直偏波と水平偏波とし、さらに受信側においては、受信アンテナ８−１Ａと受信アンテナ８−２Ａとを、同様に異なる偏波、例えばそれぞれ垂直偏波と水平偏波とする。
これにより、例えば送信アンテナ５−１Ａと受信アンテナ８−１Ａとの間の経路と、送信アンテナ５−２Ａと受信アンテナ８−２Ａとの間の経路とを送受信アンテナの偏波識別度により分離することができる。ここで、ｉ番目のサブキャリアの伝達関数Ｓ_ｉは（２×２）の要素の行列式として、次式で与えられる。
【数６】

この行列式において、送受信アンテナの偏波識別度により分離することができることは、Ｓ_１１，Ｓ_２２の絶対値はＳ_１２，Ｓ_２１の絶対値に比べて十分大きいことを意味する。従って、Ｓ_ｉに対する逆行列Ｓ_ｉ ^−１を計算する場合、逆行列演算において行列式の分母が０にならないようにすることができるため、各アンテナ毎に受信されるＯＦＤＭ信号Ｒ_１，Ｒ_２のｉ番目のサブキャリアの組である（ｒ_１，ｒ_２）に対して、（ｒ_１，ｒ_２）×Ｓ_ｉ ^−１の演算が発散しにくくなる。
【００７３】
したがって、送信信号（ｔ_１，ｔ_２）の受信側における分離度を大きくでき、安定な通信が可能になる。また、本装置を用いてセルラー構成による展開を考えた場合、偏波が異なるセルに対しては、干渉を偏波識別度分だけ軽減できる。
したがって、電力を２倍に増加して伝送容量を増加させても、干渉電力は異なる偏波に対しては偏波識別度分だけ小さくできるため、偏波毎にみると干渉電力は増加しない。このため、セルラー構成による展開においても、干渉電力が増加しないことから、同一偏波を用いる場合に比べ、本発明によればシステムの面的な容量を約２倍にすることができる。
【００７４】
（第５の実施の形態）
次に請求項４及び請求項１０に係る発明のもう１つの実施形態を、図７を参照して説明する。図７に示すように、この発明では送信アンテナ数が２であり、受信アンテナ数も２になっている。
【００７５】
送信側では、送信アンテナ５−１Ａと送信アンテナ５−２Ａとの偏波を異なる偏波、例えば垂直偏波と水平偏波とし、さらに受信側においては、受信アンテナ８−１Ａと受信アンテナ８−２Ａとを、同様に異なる偏波、例えばそれぞれ垂直偏波と水平偏波とする。
これにより、例えば送信アンテナ５−１Ａと受信アンテナ８−１Ａとの間の経路と、送信アンテナ５−２Ａと受信アンテナ８−２Ａとの間の経路とを送受信アンテナの偏波識別度により分離することができる。
【００７６】
本発明によれば、送信信号（ｔ_１，ｔ_２）の受信側における分離度を大きくできると共に、偏波が異なるため、図５の実施形態の場合と同様に比較的短遅延のフェージングの場合においても、ＯＦＤＭに特有の周波数ダイバーシチ効果に加えて、アンテナ（空間）と偏波とによるダイバーシチの相関係数を小さくすることができる。したがって、大きなダイバーシチ効果が得られ、連続誤りの発生が軽減され、誤り訂正符号化利得の低下を小さくすることができ、高品質化を図ることができる。
【００７７】
（第６の実施の形態）
次に、請求項１６に係る発明の実施形態について、図８を用いて説明する。この形態では、図６の実施形態と同様に送信アンテナ数が２、受信アンテナ数が２であり、送信側においては送信アンテナ５−１Ａと送信アンテナ５−２Ａとの偏波を異なる偏波、例えば垂直偏波と水平偏波とし、さらに受信側においては、受信アンテナ８−１Ａと受信アンテナ８−２Ａとを同様に異なる偏波、例えばそれぞれ垂直偏波と水平偏波とする。
【００７８】
これによれば、異なる偏波を用いているために偏波ダイバーシチの効果が期待でき、通信品質の改善をはかることができる。本発明では、送信情報信号を分配して同じ送信情報信号をＯＦＤＭ変調器１−１，１−２に対して入力する場合と、直並列変換した送信情報信号Ｔ_１，Ｔ_２を入力する場合とで切り替えが行われる。ここで、直並列変換した送信情報信号を送る場合は、同じ送信情報信号を送る場合に比べて、情報伝送速度は２倍になる。
【００７９】
一方、同一の送信情報信号を送出する場合には、受信側では２つのサブキャリア復調出力を加算するか又は２つのサブキャリア復調出力のうち受信レベルの大きい方を出力するため、ダイバーシチ効果を得ることができ、高品質化を図ることができる。
本発明では、受信品質を測定する通信品質測定手段２２において受信品質を測定し、第１の切替器２０において、切替判定のための閾値に対して受信品質が低ければ同じ送信情報信号を、高ければ直並列変換した送信情報信号Ｔ_１，Ｔ_２をＯＦＤＭ変調器１−１，１−２に送出する。
【００８０】
一方、受信側では、第２の切替器２１において、切替判定のための閾値に対して受信品質が低ければ２つのサブキャリア復調出力を加算する、または２つのサブキャリア復調出力のうち受信レベルの大きい方を出力する。閾値より高ければ復調出力をそのまま出力する。この第１の切替器２０と第２の切替器２１の切替制御は通信品質測定手段２２の測定結果をもとに行われる。
【００８１】
これにより、伝送速度は１／２になるものの、２つのＯＦＤＭ変調器により同一の送信情報信号を送信すれぱ、偏波ダイバーシチ効果が得られるため高品質化が図れる。一方、伝搬環境がよい場合には、図６の実施形態と同様に、偏波の異なるＯＦＤＭ信号を分離できるため、異なる送信情報を送信することができ、２倍の伝送容量を、必要とする周波数を増加させることなく伝送できる。このように、品質及び伝送容量を伝搬環境や受信品質に応じて適応的に制御することが可能になる。
【００８２】
以上の実施の形態では、送信装置においては、各ＯＦＤＭ変調器の送信ＯＦＤＭシンボルタイミングおよび周波数変換器の局部発振器を共通とし、送受信アンテナ間の伝達係数を推定するためにパイロットを送出する。さらに受信装置においては、周波数変換器の局部発振器を共通にすると共に、高速フーリエ変換器の出力に対して、前記のパイロット信号を用いて、送受信アンテナのＮ×Ｎの組み合わせについて、各サブキャリア毎のパイロット信号の受信振幅と位相を検出して伝達係数を測定する。
【００８３】
これをもとにし、サブキャリア毎にＮ×Ｎの行列Ｓｉに対する逆行列Ｓ_ｉ ^−１を計算し、高速フーリ手変換器の出力に対して、サブキャリア毎に、受信信号（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）に対して（（ｒ_１，ｒ_２，・・・，ｒ_Ｎ）×Ｓ_ｉ ^−１）の演算を行うことにより、送信ＯＦＤＭ信号のｉ番目のサブキャリアである（ｔ_１，ｔ_２，・・・，ｔ_Ｎ）の振幅・位相を推定することができる。したがって、等化器を用いることなくＯＦＤＭ方式によりＭＩＭＯチャネルでの信号伝送装置が実現される。
【００８４】
（第７の実施の形態）
次に、本発明のもう１つの実施の形態について、図９を参照しながら説明する。この形態は、請求項１９〜請求項２１及び請求項２５に対応する。図９はこの態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
この形態では、請求項１９の送信アンテナ，ＯＦＤＭ信号送信装置，受信アンテナ，ＯＦＤＭ信号受信装置は、それぞれアンテナ３７，ＯＦＤＭ信号送信装置３０，アンテナ５１，ＯＦＤＭ信号受信装置５０に対応する。
【００８５】
また、請求項１９におけるＯＦＤＭ信号送信装置のパイロット信号発生手段，データ変換手段，逆行列受信手段，前置干渉キャンセル手段，多重化手段，高速逆フーリエ変換手段，シンボルタイミング発生手段，送信用周波数変換手段及び送信用局部発振手段はそれぞれパイロット信号発生器３４，データ変換器３１，受信機４１，前置干渉キャンセラ３２，多重化回路３３，高速逆フーリエ変換器３５，タイミング信号発生器３８，周波数変換器３６及び局部発振器３９に対応し、ＯＦＤＭ信号受信装置の受信用周波数変換手段，受信用局部発振手段，高速フーリエ変換手段，復調手段，タイミング信号発生手段，逆行列演算手段及び逆行列情報送信手段はそれぞれ周波数変換器５２，局部発振器５５，高速フーリエ変換器５３，復調器５４，タイミング信号発生器５６，逆行列演算器５７及び送信機５８に対応する。
【００８６】
また、請求項２５の情報送信用アンテナ及び情報受信用アンテナは、それぞれ送信アンテナ５９及び受信アンテナ４０に対応する。
図９に示すＯＦＤＭ信号伝送システムは、ＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０で構成されている。なお、このＯＦＤＭ信号伝送システムを移動体通信などに適用する場合には、ＯＦＤＭ信号送信装置３０を基地局側に搭載し、ＯＦＤＭ信号受信装置５０を利用者側の移動端末に搭載するのが望ましい。
【００８７】
図９に示すように、ＯＦＤＭ信号送信装置３０には、データ変換器３１，前置干渉キャンセラ３２，多重化回路３３，パイロット信号発生器３４，高速逆フーリエ変換器３５，周波数変換器３６，アンテナ３７，タイミング信号発生器３８，局部発振器３９，受信アンテナ４０及び受信機４１が備わっている。
また、データ変換器３１，多重化回路３３，パイロット信号発生器３４，高速逆フーリエ変換器３５，周波数変換器３６及びアンテナ３７は、それぞれＮ個（複数）が備わっている。
【００８８】
一方、ＯＦＤＭ信号受信装置５０にはアンテナ５１，周波数変換器５２，高速フーリエ変換器５３，復調器５４，局部発振器５５，タイミング信号発生器５６，逆行列演算器５７，送信機５８及び送信アンテナ５９が備わっている。
また、アンテナ５１，周波数変換器５２，高速フーリエ変換器５３及び復調器５４は、それぞれＮ個（複数）が備わっている。
【００８９】
ＯＦＤＭ信号送信装置３０における構成要素数ＮとＯＦＤＭ信号受信装置５０における構成要素数Ｎとは同一である。すなわち、後述する逆行列を求めるためには送信側のアンテナ数Ｎと受信側のアンテナ数Ｎとを同一にする必要がある。
【００９０】
データ変換器３１（１）〜３１（Ｎ）は、それぞれ入力される送信データＴ_１〜Ｔ_ＮをＯＦＤＭシンボルに変換する。各データ変換器３１は、シリアル信号として入力されるデータ列を各々シンボルに変調するための変調器（例えばＢＰＳＫ，ＱＰＳＫ，ＡＳＫなどの変調器）とシンボルをパラレル信号に変換する直並列変換器とを内蔵している。すなわち、入力された送信データに対応するシンボルがパラレル信号形式でデータ変換器３１から出力される。
【００９１】
受信機４１は、ＯＦＤＭ信号受信装置５０から送信される逆行列の情報を受信アンテナ４０を介して受信し逆行列を取得する。
前置干渉キャンセラ３２は、受信機４１で取得された逆行列を用いて干渉キャンセルのための前置処理を行う。具体的には、送信データＴ_１〜Ｔ_Ｎに対してデータ変換器３１（１）〜３１（Ｎ）が出力するＯＦＤＭシンボル（Ｍ_１，Ｍ_２，・・・，Ｍ_Ｎ）の各々のサブキャリア成分（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）の全てについて前記逆行列を乗算する。
【００９２】
Ｎ個のパイロット信号発生器３４（１）〜３４（Ｎ）は、それぞれ互いに異なる既知のパイロット信号を出力する。
多重化回路３３（１）〜３３（Ｎ）のそれぞれは、前置干渉キャンセラ３２から出力されるＯＦＤＭシンボルと、パイロット信号発生器３４（１）〜３４（Ｎ）から出力されるパイロット信号とを時間軸上で多重化した信号を出力する。
【００９３】
高速逆フーリエ変換器３５（１）〜３５（Ｎ）のそれぞれは、多重化回路３３（１）〜３３（Ｎ）から出力される信号に対して高速逆フーリエ変換（ＩＦＦＴ）処理を施す。Ｎ個の高速逆フーリエ変換器３５（１）〜３５（Ｎ）には、タイミング信号発生器３８から共通のシンボルタイミング信号が供給される。
高速逆フーリエ変換器３５（１）〜３５（Ｎ）のそれぞれが出力するＯＦＤＭ信号は、周波数変換器３６（１）〜３６（Ｎ）で無線周波数に周波数変換される。Ｎ個の周波数変換器３６（１）〜３６（Ｎ）には、局部発振器３９から共通の局部発振信号が供給される。
【００９４】
従って、周波数変換器３６（１）〜３６（Ｎ）の出力と接続されたＮ個のアンテナ３７（１）〜３７（Ｎ）からは、同一の無線周波数のＯＦＤＭ信号が電波として同時に送信される。
アンテナ３７（１）〜３７（Ｎ）から送信されたＮ個のＯＦＤＭ信号は、空間上で加算され、ＯＦＤＭ信号受信装置５０側の互いに異なる位置に配置されたＮ個のアンテナ５１（１）〜５１（Ｎ）でそれぞれ受信される。
【００９５】
アンテナ５１（１）〜５１（Ｎ）で受信されたＯＦＤＭ信号は、それぞれ周波数変換器５２（１）〜５２（Ｎ）を通って信号処理に適した比較的低い周波数のＯＦＤＭ信号に周波数変換される。周波数変換器５２（１）〜５２（Ｎ）には、局部発振器５５から共通の局部発振信号が供給される。
周波数変換器５２（１）〜５２（Ｎ）から出力されるＯＦＤＭ信号は、それぞれ高速フーリエ変換器５３（１）〜５３（Ｎ）に入力され、高速フーリエ変換（ＦＦＴ）処理を施される。高速フーリエ変換器５３（１）〜５３（Ｎ）から出力されるＯＦＤＭシンボルの信号は、それぞれ復調器５４（１）〜５４（Ｎ）に入力されビット列に復調される。
【００９６】
なお、図９に示すＯＦＤＭ信号受信装置５０には干渉キャンセラに相当する要素は含まれていない。このＯＦＤＭ信号伝送システムにおいては、ＯＦＤＭ信号送信装置３０側の前置干渉キャンセラ３２の働きによって干渉がキャンセルされる。ＯＦＤＭ信号受信装置５０に干渉キャンセラを設ける必要がないので、ＯＦＤＭ信号受信装置５０の構成が簡素化され、消費電力も抑制される。
【００９７】
逆行列演算器５７は、高速フーリエ変換器５３（１）〜５３（Ｎ）のそれぞれの出力から受信したパイロット信号を抽出する。そして、サブキャリアの成分毎に、Ｎ個の送信側のアンテナ３７（１）〜３７（Ｎ）とＮ個の受信側のアンテナ５１（１）〜５１（Ｎ）との各々の組み合わせに対応する（Ｎ×Ｎ）個のパイロット信号の受信振幅及び位相を検出する。すなわち、パイロット信号は既知であるので、受信したパイロット信号を既知信号を用いて正規化することにより、送信側のアンテナと受信側のアンテナとの間の伝達関数を表す伝達係数を検出することができる。
【００９８】
また、逆行列演算器５７は検出した伝達係数を成分とし（Ｎ×Ｎ）個の要素で構成される行列Ａ_ｉの逆行列Ａ_ｉ ^−１を演算して求める。
送信機５８は、逆行列演算器５７が求めた逆行列Ａ_ｉ ^−１の情報を、送信アンテナ５９を介してＯＦＤＭ信号送信装置３０に送信する。
なお、この形態ではＯＦＤＭ信号受信装置５０側の逆行列演算器５７が求めた逆行列Ａ_ｉ ^−１の情報をＯＦＤＭ信号送信装置３０に伝達するために送信機５８，送信アンテナ５９，受信アンテナ４０及び受信機４１を格別に備えているが、予め備わっている構成要素で置き換えることもできる。
【００９９】
例えば、送信アンテナ５９の代わりにアンテナ５１を利用したり、受信アンテナ４０の代わりにアンテナ３７を利用することもできる。
次に、ＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０の各部の動作について更に詳細に説明する。
ＯＦＤＭ信号送信装置３０において各パイロット信号発生器３４（１）〜３４（Ｎ）から出力される既知のパイロット信号は、それぞれ多重化回路３３（１）〜３３（Ｎ）で送信信号に多重化され、アンテナ３７（１）〜３７（Ｎ）からそれぞれ送信される。
【０１００】
ここでは、各アンテナ３７（ｊ）からそれぞれ送信されるパイロット信号をＰ_ｊで表す。各パイロット信号Ｐ_ｊは、送信データの信号と同様に多重化回路３３，高速逆フーリエ変換器３５，周波数変換器３６を通るので、送信データと同様にＯＦＤＭ変調される。
また、高速逆フーリエ変換器３５（１）〜３５（Ｎ）にはタイミング信号発生器３８から共通のシンボルタイミングがそれぞれ供給され、周波数変換器３６（１）〜３６（Ｎ）には局部発振器３９から共通の局部発振周波数が供給される。
【０１０１】
このため、アンテナ３７（１）〜３７（Ｎ）からそれぞれ送信される各ＯＦＤＭ信号の各サブキャリアのＯＦＤＭシンボルタイミングは全ての系統について共通になる。また、ＯＦＤＭ信号の搬送波信号はコヒーレントになる。
したがって、ＯＦＤＭ信号受信装置５０においては自動周波数制御やＯＦＤＭシンボルタイミング再生を各ＯＦＤＭ信号毎に個別に行う必要がない。このため、ＯＦＤＭ信号受信装置５０における信号処理量は比較的少ない。
【０１０２】
各アンテナ３７（ｊ）からそれぞれ送信されるパイロット信号をＰ_ｊを含むＯＦＤＭ信号は、ＯＦＤＭ信号受信装置５０内のアンテナ５１（１）〜５１（Ｎ）でそれぞれ受信される。
ここで、送信側のｊ番目のアンテナ３７（ｊ）から送信され、受信側のｋ番目のアンテナ５１（ｋ）で受信される受信パイロット信号をＰ_ｊ，ｋで表し、送信側のアンテナ３７（ｊ）と受信側のアンテナ５１（ｋ）との間の伝達応答をＨ_ｊ，ｋで表すと、次式の関係が成立する。
【数７】

ＯＦＤＭ信号受信装置５０においては、受信パイロット信号をＰ_ｊ，ｋは周波数変換器５２で周波数変換された後、高速フーリエ変換器５３でフーリエ変換される。これによって、受信パイロット信号Ｐ_ｊ，ｋは各サブキャリアの成分毎に分離される。
逆行列演算器５７は、サブキャリアの成分毎に分離された受信パイロット信号Ｐ_ｊ，ｋを高速フーリエ変換器５３の出力から入力し、逆行列を演算する。
【０１０３】
なお、ＯＦＤＭ信号受信装置５０が受信信号の中から受信パイロット信号を抽出するためにはパイロット信号を識別する必要があるが、例えばＯＦＤＭ信号送信装置３０側が送信する信号においてパイロット信号の前にそれを識別するためのプリアンブルを付加しておけば容易に識別できる。
また、例えばＯＦＤＭ信号送信装置３０において、送出する各パイロット信号Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎが時間軸上で重ならないようにタイミングを互いにずらして送信すれば、ＯＦＤＭ信号受信装置５０では各パイロット信号Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎを互いに分離することができる。
【０１０４】
逆行列演算器５７は、送信側のアンテナ３７（１）〜３７（Ｎ）と受信側のアンテナ５１（１）〜５１（Ｎ）との各々の組み合わせに対応する（Ｎ×Ｎ）組のそれぞれについて、入力された受信パイロット信号の受信振幅及び位相（同期検波に用いる基準キャリアの振幅及び位相）をサブキャリア毎に検出する。
したがって、サブキャリアの成分毎に、送信側のアンテナ３７（１）〜３７（Ｎ）と受信側のアンテナ５１（１）〜５１（Ｎ）との各々の組み合わせに対応する（Ｎ×Ｎ）個の要素をもつ伝達係数の行列Ａ_ｉ（添字ｉは各サブキャリアの成分を表す）が得られる。
【０１０５】
さらに、逆行列演算器５７は、サブキャリアの成分毎に伝達係数の行列Ａ_ｉの逆行列Ａ_ｉ ^−１を演算し、この逆行列Ａ_ｉ ^−１の情報を送信機５８に出力する。
ここで、受信パイロット信号Ｐ_ｊ，ｋ，パイロット信号Ｐ_ｊ，及び伝達応答Ｈ_ｊ，ｋのｉ番目のサブキャリアの成分をそれぞれｐ_{ｉ：ｊ，ｋ}，パイロット信号ｐ_ｉ：ｊ，及び伝達応答ｈ_{ｉ：ｊ，ｋ}で表すと、前記第（７）式と同様に次式が成立する。
【数８】

したがって、行列Ａ_ｉの各成分は伝達応答ｈ_{ｉ：ｊ，ｋ}そのものであり、行列Ａ_ｉは次式で表される。
【数９】

逆行列演算器５７の求めた逆行列Ａ_ｉ ^−１の情報は、送信機５８の内部で変調され送信アンテナ５９を介して電波として送信される。この逆行列Ａ_ｉ ^−１の情報は、ＯＦＤＭ信号送信装置３０側の受信アンテナ４０で受信され、受信機４１の内部で復調される。受信機４１の取得した逆行列Ａ_ｉ ^−１の情報が前置干渉キャンセラ３２に入力される。
【０１０６】
前置干渉キャンセラ３２は、逆行列Ａ_ｉ ^−１の情報を用いて、送信するデータ信号（Ｔ_１，Ｔ_２，・・・，Ｔ_Ｎ）に対応するデータ変換器３１（１）〜３１（Ｎ）の出力信号（Ｍ_１，Ｍ_２，・・・，Ｍ_Ｎ）のｉ番目のサブキャリア成分に（ｍ_ｉ１，ｍ_ｉ２，・・・，ｍ_ｉＮ）対して（（ｍ_ｉ１，ｍ_ｉ２，・・・，ｍ_ｉＮ）×Ａ_ｉ ^−１）の演算を全てのサブキャリア成分に対して行う。
【０１０７】
そして、前置干渉キャンセラ３２の演算結果のｊ（ｊ＝１〜Ｎ）番目の各成分が、それぞれｊ番目のアンテナ３７（ｊ）に対応する多重化回路３３（ｊ）に入力される。
各多重化回路３３（１）〜３３（Ｎ）で多重化されたデータ信号は、それぞれ高速逆フーリエ変換器３５（１）〜３５（Ｎ）で逆フーリエ変換され、周波数変換器３６（１）〜３６（Ｎ）で無線周波数の信号に周波数変換され、各アンテナ３７（１）〜３７（Ｎ）からＯＦＤＭ信号受信装置５０に向けて送信される。
【０１０８】
各アンテナ３７（１）〜３７（Ｎ）から送信されるデータ信号のｉ番目のサブキャリア成分（ｔ_ｉ：１，ｔ_ｉ：２，・・・，ｔ_ｉ：Ｎ）は、次式で表される。
【数１０】

送信されたデータ信号は、ＯＦＤＭ信号受信装置５０の各アンテナ５１（１）〜５１（Ｎ）で受信されるが、受信される信号は前記伝達応答ｈ_{ｉ：ｊ，ｋ}の影響を受ける。すなわち、受信されるデータ信号のｉ番目のサブキャリア成分を（ｒ_ｉ：１，ｒ_ｉ：２，・・・，ｒ_ｉ：Ｎ）で表すと次式が成立する。
【数１１】

前記第（１０）式，第（１１）式に基づき次式が得られる。
【数１２】

すなわち、ＯＦＤＭ信号送信装置３０が送信するデータ信号のシンボル（ｍ_ｉ１，ｍ_ｉ２，・・・，ｍ_ｉＮ）をＯＦＤＭ信号受信装置５０は受信信号（ｒ_ｉ：１，ｒ_ｉ：２，・・・，ｒ_ｉ：Ｎ）からそのまま取得することができる。
【０１０９】
また、高速フーリエ変換器５３（１）〜５３（Ｎ）の出力に得られる受信信号、すなわちシンボル（ｍ_ｉ１，ｍ_ｉ２，・・・，ｍ_ｉＮ）を復調器５４（１）〜５４（Ｎ）で復調しビット列に変換することにより、ＯＦＤＭ信号送信装置３０が送信する元のデータ信号（Ｔ_１，Ｔ_２，・・・，Ｔ_Ｎ）が取得できる。
以上のように動作するので、同一伝搬路の同一周波数帯域を用いてＮ個のＯＦＤＭ信号を同時に伝送するにもかかわらず、ＯＦＤＭ信号受信装置５０側に干渉キャンセルのための構成要素を設けることなく、図１に示す実施の形態と同様にそれぞれのデータ信号を分離して受信することができる。
【０１１０】
この形態では、干渉キャンセルのための前置干渉キャンセラ３２をＯＦＤＭ信号送信装置３０側に設けるので、ＯＦＤＭ信号受信装置５０側の信号処理が簡素化される。すなわち、ＯＦＤＭ信号受信装置５０の構成の簡略化や消費電力の軽減が実現するので、例えば移動端末にＯＦＤＭ信号受信装置５０を搭載する場合を想定すると、移動端末の小型化及び経済化が可能になる。
【０１１１】
（第８の実施の形態）
次に、本発明のもう１つの実施の形態について、図１０を参照しながら説明する。この形態は、請求項２２〜請求項２４及び請求項２５に対応する。図１０はこの形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。この形態は、第７の実施の形態の変形例である。図１０において、図９と対応する要素は同一の符号を付けて示してある。
【０１１２】
この形態では、請求項２２の送信アンテナ，ＯＦＤＭ信号送信装置，受信アンテナ，ＯＦＤＭ信号受信装置は、それぞれアンテナ３７，ＯＦＤＭ信号送信装置３０，アンテナ５１，ＯＦＤＭ信号受信装置５０に対応する。
また、請求項２２におけるＯＦＤＭ信号送信装置のパイロット信号発生手段，データ変換手段，情報受信手段，逆行列演算手段，多重化手段，高速逆フーリエ変換手段，シンボルタイミング発生手段，送信用周波数変換手段及び送信用局部発振手段はそれぞれパイロット信号発生器３４，データ変換器３１，受信機４１，逆行列演算器４２，多重化回路３３，高速逆フーリエ変換器３５，タイミング信号発生器３８，周波数変換器３６及び局部発振器３９に対応し、ＯＦＤＭ信号受信装置の受信用周波数変換手段，受信用局部発振手段，高速フーリエ変換手段，復調手段，タイミング信号発生手段及び情報送信手段は、それぞれ周波数変換器５２，局部発振器５５，高速フーリエ変換器５３，復調器５４，タイミング信号発生器５６及び送信機６０に対応する。
【０１１３】
また、請求項２５の情報送信用アンテナ及び情報受信用アンテナは、それぞれ送信アンテナ５９及び受信アンテナ４０に対応する。
図１０に示すＯＦＤＭ信号伝送システムは、図９のシステムと同様にＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０で構成されている。なお、このＯＦＤＭ信号伝送システムを移動体通信などに適用する場合には、ＯＦＤＭ信号送信装置３０を基地局側に搭載し、ＯＦＤＭ信号受信装置５０を利用者側の移動端末に搭載するのが望ましい。
【０１１４】
図１０に示すように、ＯＦＤＭ信号送信装置３０には、データ変換器３１，前置干渉キャンセラ３２，多重化回路３３，パイロット信号発生器３４，高速逆フーリエ変換器３５，周波数変換器３６，アンテナ３７，タイミング信号発生器３８，局部発振器３９，受信アンテナ４０，受信機４１及び逆行列演算器４２が備わっている。
【０１１５】
また、データ変換器３１，多重化回路３３，パイロット信号発生器３４，高速逆フーリエ変換器３５，周波数変換器３６及びアンテナ３７は、それぞれＮ個（複数）が備わっている。
一方、ＯＦＤＭ信号受信装置５０にはアンテナ５１，周波数変換器５２，高速フーリエ変換器５３，復調器５４，局部発振器５５，タイミング信号発生器５６，送信機６０及び送信アンテナ５９が備わっている。
【０１１６】
また、アンテナ５１，周波数変換器５２，高速フーリエ変換器５３及び復調器５４は、それぞれＮ個（複数）が備わっている。
ＯＦＤＭ信号送信装置３０における構成要素数ＮとＯＦＤＭ信号受信装置５０における構成要素数Ｎとは同一である。すなわち、後述する逆行列を求めるためには送信側のアンテナ数Ｎと受信側のアンテナ数Ｎとを同一にする必要がある。
【０１１７】
データ変換器３１（１）〜３１（Ｎ）は、それぞれ入力される送信データＴ_１〜Ｔ_ＮをＯＦＤＭシンボルに変換する。各データ変換器３１は、シリアル信号として入力されるデータ列を各々シンボルに変調するための変調器（例えばＢＰＳＫ，ＱＰＳＫ，ＡＳＫなどの変調器）とシンボルをパラレル信号に変換する直並列変換器とを内蔵している。すなわち、入力された送信データに対応するシンボルがパラレル信号形式でデータ変換器３１から出力される。
【０１１８】
受信機４１は、ＯＦＤＭ信号受信装置５０から送信される受信パイロット信号の情報を受信アンテナ４０を介してＯＦＤＭ信号受信装置５０から受信し、受信した信号を復調する。
逆行列演算器４２は、受信機４１の受信した受信パイロット信号の情報に基づいて、検出された伝達係数を成分とし（Ｎ×Ｎ）個の要素で構成される行列Ａ_ｉの逆行列Ａ_ｉ ^−１を演算して求める。
【０１１９】
前置干渉キャンセラ３２は、逆行列演算器４２が求めた逆行列を用いて干渉キャンセルのための前置処理を行う。具体的には、送信データＴ_１〜Ｔ_Ｎに対してデータ変換器３１（１）〜３１（Ｎ）が出力するＯＦＤＭシンボル（Ｍ_１，Ｍ_２，・・・，Ｍ_Ｎ）の各々のサブキャリア成分（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）の全てについて前記逆行列を乗算する。
【０１２０】
Ｎ個のパイロット信号発生器３４（１）〜３４（Ｎ）は、それぞれ互いに異なる既知のパイロット信号を出力する。
多重化回路３３（１）〜３３（Ｎ）のそれぞれは、前置干渉キャンセラ３２から出力されるＯＦＤＭシンボルと、パイロット信号発生器３４（１）〜３４（Ｎ）から出力されるパイロット信号とを時間軸上で多重化した信号を出力する。
【０１２１】
高速逆フーリエ変換器３５（１）〜３５（Ｎ）のそれぞれは、多重化回路３３（１）〜３３（Ｎ）から出力される信号に対して高速逆フーリエ変換（ＩＦＦＴ）処理を施す。Ｎ個の高速逆フーリエ変換器３５（１）〜３５（Ｎ）には、タイミング信号発生器３８から共通のシンボルタイミング信号が供給される。
【０１２２】
高速逆フーリエ変換器３５（１）〜３５（Ｎ）のそれぞれが出力するＯＦＤＭ信号は、周波数変換器３６（１）〜３６（Ｎ）で無線周波数に周波数変換される。Ｎ個の周波数変換器３６（１）〜３６（Ｎ）には、局部発振器３９から共通の局部発振信号が供給される。
従って、周波数変換器３６（１）〜３６（Ｎ）の出力と接続されたＮ個のアンテナ３７（１）〜３７（Ｎ）からは、同一の無線周波数のＯＦＤＭ信号が電波として同時に送信される。
【０１２３】
アンテナ３７（１）〜３７（Ｎ）から送信されたＮ個のＯＦＤＭ信号は、空間上で加算され、ＯＦＤＭ信号受信装置５０側の互いに異なる位置に配置されたＮ個のアンテナ５１（１）〜５１（Ｎ）でそれぞれ受信される。
アンテナ５１（１）〜５１（Ｎ）で受信されたＯＦＤＭ信号は、それぞれ周波数変換器５２（１）〜５２（Ｎ）を通って信号処理に適した比較的低い周波数のＯＦＤＭ信号に周波数変換される。周波数変換器５２（１）〜５２（Ｎ）には、局部発振器５５から共通の局部発振信号が供給される。
【０１２４】
周波数変換器５２（１）〜５２（Ｎ）から出力されるＯＦＤＭ信号は、それぞれ高速フーリエ変換器５３（１）〜５３（Ｎ）に入力され、高速フーリエ変換（ＦＦＴ）処理を施される。高速フーリエ変換器５３（１）〜５３（Ｎ）から出力されるＯＦＤＭシンボルの信号は、それぞれ復調器５４（１）〜５４（Ｎ）に入力されビット列に復調される。
【０１２５】
図１０のＯＦＤＭ信号伝送システムにおいては、ＯＦＤＭ信号送信装置３０側の前置干渉キャンセラ３２の働きによって干渉がキャンセルされる。ＯＦＤＭ信号受信装置５０に干渉キャンセラを設ける必要がないので、ＯＦＤＭ信号受信装置５０の構成が簡素化され、消費電力も抑制される。
【０１２６】
送信機６０は、高速フーリエ変換器５３（１）〜５３（Ｎ）のそれぞれの出力から受信したパイロット信号を抽出する。そして、サブキャリアの成分毎に、Ｎ個の送信側のアンテナ３７（１）〜３７（Ｎ）とＮ個の受信側のアンテナ５１（１）〜５１（Ｎ）との各々の組み合わせに対応する（Ｎ×Ｎ）個のパイロット信号の受信振幅及び位相を検出する。すなわち、パイロット信号は既知であるので、受信したパイロット信号を既知信号を用いて正規化することにより、送信側のアンテナと受信側のアンテナとの間の伝達関数を表す伝達係数を検出することができる。
【０１２７】
高速フーリエ変換器５３の出力から検出された受信パイロット信号の情報（サブキャリア毎の（Ｎ×Ｎ）の振幅及び位相の情報）は、送信機６０の内部で変調され、送信アンテナ５９を介して電波としてＯＦＤＭ信号送信装置３０に送信される。
なお、この形態ではＯＦＤＭ信号受信装置５０側で検出された受信パイロット信号の情報をＯＦＤＭ信号送信装置３０に伝達するために送信機５８，送信アンテナ５９，受信アンテナ４０及び受信機４１を格別に備えているが、予め備わっている構成要素で置き換えることもできる。
【０１２８】
例えば、送信アンテナ５９の代わりにアンテナ５１を利用したり、受信アンテナ４０の代わりにアンテナ３７を利用することもできる。
この形態では、図９に示される逆行列演算器５７の機能を逆行列演算器４２としてＯＦＤＭ信号送信装置３０側に移した点が図９の構成と大きく異なっている。以下、図１０のＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０の主要部分の動作について更に詳細に説明する。
【０１２９】
図９のＯＦＤＭ信号伝送システムと同様に、図１０のＯＦＤＭ信号送信装置３０は、ＯＦＤＭ変調されたデータ信号及び既知のパイロット信号を各アンテナ３７（１）〜３７（Ｎ）から送信し、ＯＦＤＭ信号受信装置５０はデータ信号及びパイロット信号をＯＦＤＭ信号としてアンテナ５１（１）〜５１（Ｎ）で受信する。
【０１３０】
また、ＯＦＤＭ信号送信装置３０においては、前置干渉キャンセラ３２でデータ信号のＯＦＤＭシンボルの各サブキャリア成分（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）に逆行列Ａ_ｉ ^−１を積算し、各アンテナ３７（１）〜３７（Ｎ）から逆行列Ａ_ｉ ^−１の積算されたデータ信号を送信する。
アンテナ５１（１）〜５１（Ｎ）で受信される信号には、送信側で既に逆行列Ａ_ｉ ^−１が積算されているので、ＯＦＤＭ信号受信装置５０においては、アンテナ５１（１）〜５１（Ｎ）で受信した信号からデータ信号（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）を直接分離して取り出すことができる。
【０１３１】
なお、ＯＦＤＭ信号受信装置５０においては、受信した各々のパイロット信号を互いに分離して取り出す必要があるが、例えばＯＦＤＭ信号送信装置３０側において、各パイロット信号（Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎ）を時間軸上で互いに重ならないようにタイミングをずらして送出することにより、容易に分離できる。
上記のように、図１０のＯＦＤＭ信号伝送システムでは、ＯＦＤＭ信号受信装置５０側からＯＦＤＭ信号送信装置３０に対して受信パイロット信号の情報を伝送し、ＯＦＤＭ信号送信装置３０側では受け取った受信パイロット信号の情報（受信振幅及び位相）に基づいて逆行列を求める点に特徴がある。
【０１３２】
このように、図１０のＯＦＤＭ信号伝送システムでは、逆行列の演算機能及び干渉キャンセルの機能をＯＦＤＭ信号受信装置５０側に搭載する必要がない。したがって、ＯＦＤＭ信号受信装置５０側の信号処理が簡素化される。すなわち、ＯＦＤＭ信号受信装置５０の構成の簡略化や消費電力の軽減が実現するので、例えば移動端末にＯＦＤＭ信号受信装置５０を搭載する場合を想定すると、移動端末の小型化及び経済化が可能になる。
【０１３３】
（第９の実施の形態）
次に、本発明のもう１つの実施の形態について、図１１を参照しながら説明する。この形態は、請求項２６〜請求項２８に対応する。図１１はこの形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。この形態は、第８の実施の形態の変形例である。図１１において、図１０と対応する要素は同一の符号を付けて示してある。
【０１３４】
この形態では、請求項２６の送信アンテナ，ＯＦＤＭ信号送信装置，受信アンテナ，ＯＦＤＭ信号受信装置は、それぞれアンテナ３７，ＯＦＤＭ信号送信装置３０，アンテナ５１，ＯＦＤＭ信号受信装置５０に対応する。
また、請求項２６におけるＯＦＤＭ信号受信装置のパイロット信号発生手段，逆高速フーリエ変換手段，送信用周波数変換手段，受信用周波数変換手段，高速フーリエ変換手段，復調手段，局部発振手段及び送受信切替スイッチ手段は、それぞれパイロット信号発生器８１，高速逆フーリエ変換器８２，周波数変換器８３，５２，高速フーリエ変換器５３，復調器５４，局部発振器５５及び切替スイッチ８６に対応し、ＯＦＤＭ信号送信装置のデータ変換手段，受信用周波数変換手段，高速フーリエ変換手段，タイミング信号発生手段，逆行列演算手段，高速逆フーリエ変換手段，送信用周波数変換手段，局部発振手段及び送受信切替スイッチ手段は、それぞれデータ変換器３１，周波数変換器７１，高速フーリエ変換器７２，タイミング信号発生器７３，逆行列演算器４２，高速逆フーリエ変換器３５，周波数変換器３６及び切替スイッチ７５に対応する。
【０１３５】
図１１に示すＯＦＤＭ信号伝送システムは、図１０のシステムと同様にＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０で構成されている。なお、このＯＦＤＭ信号伝送システムを移動体通信などに適用する場合には、ＯＦＤＭ信号送信装置３０を基地局側に搭載し、ＯＦＤＭ信号受信装置５０を利用者側の移動端末に搭載するのが望ましい。
【０１３６】
また、図１１のＯＦＤＭ信号伝送システムにおいては、ＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０のそれぞれが送信と受信とで同一のアンテナを利用し、送信モードと受信モードとを時分割により切り替えるＴＤＤ（Ｔｉｍｅ Ｄｉｖｉｓｉｏｎ Ｄｕｐｌｅｘ）を前提としたシステムを想定している。さらに、図１１のＯＦＤＭ信号伝送システムでは、パイロット信号を発生する機能がＯＦＤＭ信号受信装置５０側に設けてある。
【０１３７】
図１１に示すように、ＯＦＤＭ信号受信装置５０にはアンテナ５１，周波数変換器５２，高速フーリエ変換器５３，復調器５４，局部発振器５５，タイミング信号発生器５６，パイロット信号発生器８１，高速逆フーリエ変換器８２，周波数変換器８３，シンボルタイミング発生器８４，切替制御部８５及び切替スイッチ８６が備わっている。
【０１３８】
また、アンテナ５１，周波数変換器５２，高速フーリエ変換器５３，復調器５４，パイロット信号発生器８１，高速逆フーリエ変換器８２，周波数変換器８３及び切替スイッチ８６は、それぞれＮ個（複数）が備わっている。
一方、図１１のＯＦＤＭ信号送信装置３０にはデータ変換器３１，前置干渉キャンセラ３２，高速逆フーリエ変換器３５，周波数変換器３６，アンテナ３７，タイミング信号発生器３８，局部発振器３９，周波数変換器７１，高速フーリエ変換器７２，タイミング信号発生器７３，切替制御部７４及び切替スイッチ７５が備わっている。
【０１３９】
また、データ変換器３１，高速逆フーリエ変換器３５，周波数変換器３６，アンテナ３７，周波数変換器７１，高速フーリエ変換器７２及び切替スイッチ７５は、それぞれＮ個（複数）が備わっている。
ＯＦＤＭ信号送信装置３０における構成要素数ＮとＯＦＤＭ信号受信装置５０における構成要素数Ｎとは同一である。すなわち、後述する逆行列を求めるためには送信側のアンテナ数Ｎと受信側のアンテナ数Ｎとを同一にする必要がある。
【０１４０】
ＯＦＤＭ信号受信装置５０における周波数変換器５２，高速フーリエ変換器５３，復調器５４，局部発振器５５及びタイミング信号発生器５６については、図１０の対応する要素と同じ機能を果たすので説明は省略する。
【０１４１】
Ｎ個のパイロット信号発生器８１（１）〜８１（Ｎ）は、それぞれ互いに異なる既知のパイロット信号を出力する。高速逆フーリエ変換器８２（１）〜８２（Ｎ）は、それぞれパイロット信号発生器８１（１）〜８１（Ｎ）から出力されるパイロット信号に対して逆フーリエ変換処理を施す。高速逆フーリエ変換器８２（１）〜８２（Ｎ）には、シンボルタイミング発生器８４から共通のシンボルタイミングの信号が与えられる。
【０１４２】
周波数変換器８３（１）〜８３（Ｎ）は、高速逆フーリエ変換器８２（１）〜８２（Ｎ）からＯＦＤＭ信号として出力されるパイロット信号を無線周波数に周波数変換する。周波数変換器８３（１）〜８３（Ｎ）には、局部発振器５５から共通の局部発振信号が与えられる。
従って、周波数変換器８３（１）〜８３（Ｎ）の出力に現れるＮ系統のパイロット信号は同じ無線周波数になる。周波数変換器８３（１）〜８３（Ｎ）から出力されるＮ系統のパイロット信号は、ＯＦＤＭ信号受信装置５０が送信モードである時に、それぞれ切替スイッチ８６（１）〜８６（Ｎ）を通ってアンテナ５１（１）〜５１（Ｎ）から送信される。
【０１４３】
切替制御部８５は、ＯＦＤＭ信号送信装置３０とＯＦＤＭ信号受信装置５０との間の通信状態を識別し、ＯＦＤＭ信号受信装置５０が送信モードか受信モードかに応じてＮ個の切替スイッチ８６（１）〜８６（Ｎ）の状態を切り替える。
ＯＦＤＭ信号送信装置３０におけるデータ変換器３１，前置干渉キャンセラ３２，高速逆フーリエ変換器３５，周波数変換器３６，タイミング信号発生器３８及び局部発振器３９については、図１０の対応する要素と同じ機能を果たすのでこれらの説明は省略する。
【０１４４】
アンテナ３７（１）〜３７（Ｎ）で受信された信号は、ＯＦＤＭ信号送信装置３０が受信モードの時に、切替スイッチ７５（１）〜７５（Ｎ）を介して周波数変換器７１（１）〜７１（Ｎ）に入力される。
【０１４５】
切替制御部７４は、ＯＦＤＭ信号送信装置３０とＯＦＤＭ信号受信装置５０との間の通信状態を識別し、ＯＦＤＭ信号送信装置３０が送信モードか受信モードかに応じてＮ個の切替スイッチ７５（１）〜７５（Ｎ）の状態を切り替える。
周波数変換器７１（１）〜７１（Ｎ）は、それぞれアンテナ３７（１）〜３７（Ｎ）で受信された信号（パイロット信号）を信号処理に適した比較的低い周波数に周波数変換する。周波数変換器７１（１）〜７１（Ｎ）には、局部発振器３９から共通の局部発振信号が与えられる。
【０１４６】
高速フーリエ変換器７２（１）〜７２（Ｎ）は、周波数変換器７１（１）〜７１（Ｎ）から出力されるＯＦＤＭ信号として受信されたパイロット信号に高速フーリエ変換を施す。したがって、高速フーリエ変換器７２（１）〜７２（Ｎ）の出力には、それぞれアンテナ３７（１）〜３７（Ｎ）で受信されたパイロット信号がサブキャリアの成分毎に分離されて現れる。
【０１４７】
高速フーリエ変換器７２（１）〜７２（Ｎ）には、受信した各パイロット信号を取り出すためにタイミング信号発生器７３から共通のシンボルタイミングの信号が与えられる。
逆行列演算器４２は、高速フーリエ変換器７２（１）〜７２（Ｎ）から出力される信号に基づいて、受信した各パイロット信号の受信振幅及び位相をサブキャリア成分毎に検出し、検出結果に基づいて逆行列を求める。
【０１４８】
次に、図１１のＯＦＤＭ信号送信装置３０及びＯＦＤＭ信号受信装置５０の主要部分の動作について詳細に説明する。
ＯＦＤＭ信号送信装置３０においては、受信したパイロット信号に基づいて逆行列演算器４２が各サブキャリアの伝達係数の行列Ａ_ｉの逆行列Ａ_ｉ ^−１を演算する。そして、前置干渉キャンセラ３２はデータ変換器３１（１）〜３１（Ｎ）から出力されるデータ信号の各サブキャリア成分（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）に対して、逆行列演算器４２から入力される逆行列Ａ_ｉ ^−１を乗算する。
【０１４９】
前置干渉キャンセラ３２から出力される信号は、高速逆フーリエ変換器３５（１）〜３５（Ｎ）で逆フーリエ変換の処理を施され、ＯＦＤＭ信号として出力される。これらのＯＦＤＭ信号は、周波数変換器３６（１）〜３６（Ｎ）で無線周波数に周波数変換され、切替スイッチ７５（１）〜７５（Ｎ）を介してアンテナ３７（１）〜３７（Ｎ）から送信される。
【０１５０】
アンテナ３７（１）〜３７（Ｎ）からそれぞれ送信された信号は、空間上で加算されアンテナ５１（１）〜５１（Ｎ）のそれぞれで受信される。しかし、データ信号（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）は予め前置干渉キャンセラ３２で逆行列Ａ_ｉ ^−１が乗算されてから送信されるので、図９，図１０のシステムの場合と同様に、アンテナ５１（１）〜５１（Ｎ）では、データ信号（ｍ_１，ｍ_２，・・・，ｍ_Ｎ）が分離して受信される。
【０１５１】
したがって、干渉をキャンセルするための機能をＯＦＤＭ信号受信装置５０側に設ける必要はない。すなわち、ＯＦＤＭ信号送信装置３０においてパイロット信号の情報を取得する方法が図１０のシステムと異なっている。
ＯＦＤＭ信号受信装置５０では、送信モードの時に、パイロット信号（Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎ）を各アンテナ５１（１）〜５１（Ｎ）から送信する。これらのパイロット信号（Ｐ_１，Ｐ_２，・・・，Ｐ_Ｎ）は、ＯＦＤＭ信号送信装置３０においてアンテナ３７（１）〜３７（Ｎ）で受信され、ＯＦＤＭ復調され、各サブキャリアの成分に分離されて逆行列演算器４２に入力される。
【０１５２】
逆行列演算器４２は、受信したパイロット信号から、サブキャリアの成分毎に、アンテナ５１（１）〜５１（Ｎ）とアンテナ３７（１）〜３７（Ｎ）との各組み合わせの伝達係数を成分とする行列Ａ_ｉの逆行列Ａ_ｉ ^−１を演算し記憶する。
前置干渉キャンセラ３２は、データ変換器３１（１）〜３１（Ｎ）から出力されるデータ信号に逆行列Ａ_ｉ ^−１を乗算する。その結果が高速逆フーリエ変換器３５（１）〜３５（Ｎ）及び周波数変換器３６（１）〜３６（Ｎ）を介してアンテナ３７（１）〜３７（Ｎ）から送信される。
【０１５３】
ＯＦＤＭ信号受信装置５０では、各アンテナ５１（１）〜５１（Ｎ）において、データ信号にアンテナ３７（１）〜３７（Ｎ）からアンテナ５１（１）〜５１（Ｎ）へ信号を送信した場合の伝達応答行列が付加されて受信されるが、送信と受信とで共通の局部発振器を使用しているので、前記伝達応答行列の伝達係数は前述の行列Ａ_ｉと同一になる。
【０１５４】
したがって、ＯＦＤＭ信号受信装置５０の各アンテナ５１（１）〜５１（Ｎ）では、各データ信号（ｍ_ｉ１，ｍ_ｉ２，・・・，ｍ_ｉＮ）が分離して受信される。このため、高速フーリエ変換器５３（１）〜５３（Ｎ）の出力に現れるデータ信号（Ｍ_ｉ１，Ｍ_ｉ２，・・・，Ｍ_ｉＮ）を復調器５４（１）〜５４（Ｎ）で復調することにより、ＯＦＤＭ信号送信装置３０の送信したデータ信号（Ｔ_１，Ｔ_２，・・・，Ｔ_Ｎ）が得られる。
【０１５５】
この形態では、ＯＦＤＭ信号受信装置５０側にパイロット信号発生器８１を設けているので、ＯＦＤＭ信号送信装置３０側にはパイロット信号の発生機能を設ける必要がなく、ＯＦＤＭ信号送信装置３０には図１０の多重化回路３３を設ける必要がない。また、アンテナ３７（１）〜３７（Ｎ）及びアンテナ５１（１）〜５１（Ｎ）を送信と受信とで共用するので、図１０の受信アンテナ４０及び送信アンテナ５９は不要になる。
【０１５６】
また、図１１のＯＦＤＭ信号伝送システムでは、逆行列の演算機能及び干渉キャンセルの機能をＯＦＤＭ信号受信装置５０側に搭載する必要がない。したがって、ＯＦＤＭ信号受信装置５０側の信号処理が簡素化される。すなわち、ＯＦＤＭ信号受信装置５０の構成の簡略化や消費電力の軽減が実現するので、例えば移動端末にＯＦＤＭ信号受信装置５０を搭載する場合を想定すると、移動端末の小型化及び経済化が可能になる。
【０１５７】
なお、本発明は広帯域移動通信システムのみならず、ポイント・ツー・マルチポイントの固定無線アクセスシステムのようにＯＦＤＭ方式を用いて多数のユーザ無線局を基地局に接続する無線システムに広く適用できる。
【０１５８】
【発明の効果】
本発明によれば、等化器による時間軸での伝達関数の推定ではなく、直接、ＯＦＤＭ信号におけるパイロット信号を用いてキャリア毎の伝達係数（振幅・位相）の測定し、サブキャリア毎にＯＦＤＭ信号間の干渉をキャンセルするための伝達係数を取得するため、容易に、かつ精度の高いチャネル間の干渉キャンセルが可能になると共に、等化器のようなフィードバック制御を行うことなく、フィードフォワード処理ができるため、厳しい周波数選択性フェージング環境下においても安定な動作が期待できる。
【０１５９】
また、請求項７に係る発明によれば、請求項１記載の送受信装置において、サブキャリア方向（周波数軸方向）と送信アンテナ方向（空間方向）の２つの次元に対してインタリーブを行うため、短遅延のフェージングにおいても連続誤りの発生が軽減され、誤り訂正符号化利得の低下を小さくすることができ、高品質化を図ることができる。
【０１６０】
さらに、請求項４，請求項１０及び請求項１６に係る発明によれば、請求項１，請求項７及び請求項１３の送受信装置において、送信アンテナ数を２、受信アンテナ数を２とし、双方に直交偏波（例えば水平偏波と垂直偏波、または右旋偏波と左旋偏波）とすることにより、送受信アンテナの偏波識別度を大きくでき、２つのチャネルの分離度を大きくできることから、高品質化を図ることができる。
【０１６１】
また、請求項１３に係る発明においては、送信情報信号を分配して同じ送信情報信号を２つのＯＦＤＭ変調器に入力する場合と、直並列変換した２つの送信情報信号を入力する場合とで切り替え、切替判定のための閾値に応じてこれらを変更して制御することにより、品質と伝送容量を伝搬環境や受信品質に応じて適応的に制御することが可能になる。
【０１６２】
さらに、請求項１９の発明では、演算量、すなわち回路規模の大きな干渉キャンセラの機能をＯＦＤＭ信号送信装置側に配備できるので、ＯＦＤＭ信号受信装置の回路規模が軽減できる利点があり、本発明を適用することにより、移動端末を小型・経済化が実現する。
また、請求項２２の発明では、干渉キャンセラだけでなく逆行列演算器の機能をもＯＦＤＭ信号送信装置側に配備できるので、ＯＦＤＭ信号受信装置の回路規模を更に軽減できる。
【０１６３】
また、請求項２６の発明では、同一のアンテナを送信と受信とで共用するので、パイロット信号の情報や逆行列の情報を伝送するために特別なアンテナを追加する必要がない。さらに、請求項１９及び請求項２２の発明と同様にＯＦＤＭ信号受信装置の回路規模を更に軽減できる。
【図面の簡単な説明】
【図１】第１の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図２】パイロット信号を含む送信ＯＦＤＭ信号の例を示すタイムチャートである。
【図３】第２の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図４】フェージングの特性例を示すグラフである。
【図５】第３の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図６】第４の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図７】第５の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図８】第６の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図９】第７の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図１０】第８の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図１１】第９の実施の形態のＯＦＤＭ信号伝送システムの構成を示すブロック図である。
【図１２】ＭＩＭＯチャネルにおける従来の送受信装置の構成例を示すブロック図である。
【符号の説明】
１−１〜１−Ｎ ＯＦＤＭ変調器
２ ＯＦＤＭシンボルタイミング制御回路
３−１〜３−Ｎ 周波数変換器
４ 局部発振器
５−１〜５−Ｎ 送信アンテナ
５−１Ａ 垂直偏波の送信アンテナ
５−２Ａ 水平偏波の送信アンテナ
６−１〜６−Ｎ パイロット信号発生手段
７−１〜７−Ｎ 多重化手段
８−１〜８−Ｎ 受信アンテナ
８−１Ａ 垂直偏波の受信アンテナ
８−２Ａ 水平偏波の受信アンテナ
９−１〜９−Ｎ 周波数変換器
１０ 局部発振器
１１−１〜１１−Ｎ 高速フーリエ変換器
１２ ＯＦＤＭシンボルタイミング再生手段
１３ 逆行列演算手段
１４ サブキャリア復調手段
１５−１〜１５−Ｎ 誤り訂正符号器
１６，１６−１〜１６−Ｎ インタリーバ
１７，１７−１〜１７−Ｎ デインタリーバ
１８−１〜１８−Ｎ 誤り訂正復号器
２０ 第１の切替器
２１ 第２の切替器
２２ 通信品質測定手段
３０ ＯＦＤＭ信号送信装置
３１ データ変換器
３２ 前置干渉キャンセラ
３３ 多重化回路
３４ パイロット信号発生器
３５ 高速逆フーリエ変換器
３６ 周波数変換器
３７ アンテナ
３８ タイミング信号発生器
３９ 局部発振器
４０ 受信アンテナ
４１ 受信機
４２ 逆行列演算器
５０ ＯＦＤＭ信号受信装置
５１ アンテナ
５２ 周波数変換器
５３ 高速フーリエ変換器
５４ 復調器
５５ 局部発振器
５６ タイミング信号発生器
５７ 逆行列演算器
５８ 送信機
５９ 送信アンテナ
６０ 送信機
７１ 周波数変換器
７２ 高速フーリエ変換器
７３ タイミング信号発生器
７４ 切替制御部
７５ 切替スイッチ
８１ パイロット信号発生器
８２ 高速逆フーリエ変換器
８３ 周波数変換器
８４ シンボルタイミング発生器
８５ 切替制御部
８６ 切替スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an Orthogonal Frequency Division Multiplexing (OFDM) signal transmission system used in broadband mobile communication and the like. More specifically, in a multipath fading environment, OFDM signal transmission that achieves dramatic frequency utilization efficiency by using multiple transmitting antennas and multiple receiving antennas, and also performs high-quality, large-capacity, high-speed signal transmission. About the system.
[0002]
[Prior art]
For example, in broadband mobile communication, the frequency band that can be used is limited, and in order to support full-fledged multimedia, it is required to achieve high frequency use efficiency equivalent to fixed microwave communication, and it is difficult. There is a need to overcome frequency selective fading and achieve high quality transmission.
[0003]
The following methods have been proposed to realize large capacity and high speed mobile communication using a limited frequency band. That is, a MIMO (Multiple Input Multiple Output) channel is configured using a plurality of transmission antennas and a plurality of reception antennas, and a plurality of channels are transmitted using the same frequency on the transmission side, and an equalizer is configured on the reception side. In addition, each channel is separated by an interference canceller to increase the capacity.
[0004]
In a MIMO Rayleigh fading channel formed when N transmitting antennas are used on the transmitting side and M (M ≧ N) receiving antennas are used on the receiving side, the Shannon capacity limit is given by the following equation.
[Expression 1]

Here, H is an M × N matrix, and its element (i, j) is a transfer function between the i-th transmitting antenna and the j-th receiving antenna. I is an M × N eigenvalue matrix, and ρ is an average SNR. Further, det represents determination, and * represents complex conjugate. When M = N, the lower limit of the capacity is given by the following equation.
[Expression 2]

Where χ² _2kIndicates the effect of k-th order diversity. That is, in the MIMO channel, the capacity is N times that of a single channel. Thus, if interference cancellation can be ideally performed in the MIMO channel, large capacity and high speed transmission can be realized in broadband mobile communication.
An example of the configuration of a conventional transmission / reception apparatus in this MIMO channel is shown in FIG. This is a configuration example of a transmission / reception apparatus that performs space-time equalization using N transmission antennas 110-1 to 110-N and N reception antennas 111-1 to 111-N. Are encoded by encoders 101-1 to 101-N, interleaved by interleavers 102-1 to 102-N, distributed to N modulators 103-1 to 103-N, and then transmitted.
[0005]
On the other hand, N interference cancellers 114-1 to 114-N and N equalizers 115-1 to 115-N are arranged on the receiving side. The reception signal of the reception antenna 111-1 is first equalized by the equalizer 115-1, deinterleaved by the deinterleaver 116-1, and input to the decoder 118-1. The decoder 118-1 performs decoding corresponding to the encoding in the encoder 101-1.
[0006]
The interference component is extracted by taking the difference between the output of the decoder 118-1 and the output of the deinterleaver 116-1. This interference component is input to the interleaver 117-1, and the output is fed back to the equalizer 115-1 as control information. On the other hand, the interference component which is the output of the interleaver 117-1 is subtracted from the output of the equalizer 115-1, and is input again to the deinterleaver 116-1.
[0007]
Through the repetition process here, the reliability of the output of the decoder 118-1 is increased. In the receiving antenna 111-1, all N transmission signals from the transmitting antennas 110-1 to 110-N are combined and received. In interference canceller 114-1, the output of decoder 118-1 is subtracted from the reception signal of reception antenna 111-1 in which all N transmission signals are combined.
[0008]
Thereby, the signal transmitted by the transmission antenna 110-1 is removed from the signal received by the reception antenna 111-1, and (N-1) transmission signals of the transmission antennas 110-2 to 110-N are combined. Signal. This signal is input to the next equalizer 115-2. In the equalizer 115-2, similarly to the processing in the system of the equalizer 115-1, after being equalized by the equalizer 115-2, it is deinterleaved by the deinterleaver 116-2, and the decoder 118- 2 is input.
[0009]
In the decoder 118-2, decoding corresponding to the encoding in the encoder 101-2 is performed. The interference component is extracted by taking the difference between the output of the decoder 118-2 and the output of the deinterleaver 116-2. This interference component is input to the interleaver 117-2, and the output is fed back to the equalizer 115-2 as control information. On the other hand, the interference component which is the output of the interleaver 117-2 is subtracted from the output of the equalizer 115-2, and is input again to the deinterleaver 116-2.
[0010]
Through the repetition processing here, the reliability of the output of the decoder 118-2 is increased. In the interference canceller 114-2, the output of the decoder 118-2 is subtracted from the input from the decoder 118-1. Thereby, the signal transmitted by the transmission antenna 110-2 is further removed, and the (N-1) transmission signals of the transmission antennas 110-3 to 110-N are combined.
[0011]
This signal is input to the next equalizer 115-3. In this manner, the interference canceller 114 sequentially removes the interference signal decoded by the decoder 118, and the output of the interference canceller 114- (N-1) finally becomes the transmission signal of the transmission antenna 110-N, and is equalized. It is equalized by the unit 115-N and decoded by the deinterleaver 116-N and the decoder 118-N. This operation is performed for the receiving antennas 111-2, 111-3,.
[0012]
The decoding result from each of the decoders 118-1 to 118N repeats a series of processes, and the output of the final N decoders is sent to the converter 119 and converted into serial received data. This is equivalent to estimating the transfer function in each path between the transmitting antenna 110-i and the receiving antenna 111-j by an equalizer and performing interference cancellation based on this.
[0013]
Therefore, as an operation of the equalizer, it is necessary to equalize N × N paths and perform (N−1) × N interference cancellation based on the result.
[0014]
[Problems to be solved by the invention]
In the conventional transmission / reception apparatus in the MIMO channel as shown in FIG. 12, N equalizers are required for each reception system corresponding to the reception antenna of the reception apparatus. In addition, when performing broadband transmission in a severe multipath fading environment, frequency selective fading occurs, and it is necessary to identify the frequency characteristics of amplitude and phase generated by fading in a very short time with high accuracy for each system.
[0015]
However, in an actual fading environment, the number and intensity of incoming delayed waves, so-called delay profiles, vary, and it is extremely difficult to realize an equalizer that is effective for all such environments. For this reason, although a transmission / reception apparatus in a MIMO channel may be realized in an environment close to a Gaussian channel such as fixed communication, an extremely large signal processing capability is required in a MIMO channel in which severe multipath fading occurs. It has been difficult to realize a transmission / reception device in a channel.
[0016]
In the conventional MIMO channel transmission / reception device as shown in FIG. 12, interference and interference are obtained by estimating and subtracting the amplitude / phase frequency characteristics distorted by multi-wave fading in the fading propagation path from the output of the decoder 118-1. Will cancel. In this case, each equalizer is required to have high estimation accuracy with respect to frequency characteristics of amplitude and phase. This is because if the equalization accuracy cannot be achieved, the interference canceller cannot sufficiently remove the interference, resulting in residual interference noise.
[0017]
However, since it is difficult to equalize the frequency characteristics of the amplitude and phase with high accuracy in the equalizer, there is a problem that the signal-to-interference noise ratio is likely to deteriorate.
Furthermore, when assuming a system for wireless communication between a fixed base station and a mobile terminal, if a complicated processing function is provided on the mobile terminal side, the hardware scale and power consumption of the mobile terminal increase. This leads to problems in terms of downsizing and cost reduction of the mobile terminal.
[0018]
In view of the above-described circumstances, an object of the present invention is to achieve a stable operation in a severe frequency selective fading environment in an OFDM signal transmission system used for broadband mobile communication or the like, and to improve the quality.
[0019]
[Means for Solving the Problems]
The problems described above are solved by the invention described in the claims.
[0021]
Claim1Is a system comprising a plurality of N transmit antennas and a plurality of N receive antennas, which are connected to each transmit antenna, use the same radio frequency, and operate based on symbol timing And a frequency converter connected to the transmitting antenna for converting the output of the OFDM modulator to a radio frequency using a local oscillation frequency, means for generating a known pilot signal corresponding to each OFDM modulator, and each OFDM modulation At least one OFDM signal transmitting apparatus having means for multiplexing the transmission information signal and the pilot signal, and means for supplying a common OFDM symbol timing to all of the OFDM modulators according to the OFDM signal transmitting apparatus And a station that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal transmission apparatus. Connected to the oscillator and each receiving antenna, using the local oscillation frequency to convert the radio frequency received signal to a frequency suitable for demodulation, and to each OFDM modulator connected to the frequency converter The pilot signal reception amplitude and phase are known for all combinations of the fast Fourier transform and the transmission antenna and the reception antenna that operate based on the timing signal for receiving the pilot signal transmitted by the reception antenna. Each received OFDM signal output from the inverse matrix computing means and the fast Fourier transformer that normalizes the phase and measures the transfer coefficient, calculates and stores the inverse matrix for the matrix related to each subcarrier, and any subcarrier And the inverse matrix, the amplitude of the subcarrier of each transmitted OFDM signal, At least one OFDM signal receiving device having a subcarrier demodulating means for outputting a phase, a local oscillator for supplying a common local oscillation signal to all frequency converters of the OFDM signal receiving device, and the OFDM signal receiving device. It is characterized by comprising a timing signal generating means for receiving a pilot signal transmitted corresponding to each OFDM modulator by a receiving antenna.
[0022]
Claim2Claims1A transmission apparatus used in the described OFDM signal transmission system, which is connected to each transmission antenna, uses the same radio frequency, operates based on symbol timing, and is connected to the transmission antenna. Converter for converting the output of the signal into a radio frequency using a local oscillation frequency, means for generating a known pilot signal corresponding to each OFDM modulator, and a transmission information signal and the pilot connected to each OFDM modulator Means for multiplexing the signal;
[0023]
Claim3Claims1A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix Taking, with a sub-carrier demodulating means for outputting the subcarrier amplitude and phase of each transmission OFDM signal.
[0024]
Claim4Claims1In the described OFDM signal transmission system, two transmission antennas using orthogonal polarizations as transmission antennas and two reception antennas using orthogonal polarizations as reception antennas are used.
Claim5Claims4A transmission apparatus used in the described OFDM signal transmission system, which is connected to each transmission antenna, uses the same radio frequency, operates based on symbol timing, and is connected to the transmission antenna. Converter for converting the output of the signal into a radio frequency using a local oscillation frequency, means for generating a known pilot signal corresponding to each OFDM modulator, and a transmission information signal and the pilot connected to each OFDM modulator Means for multiplexing the signal;
[0025]
Claim6Claims4A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix Taking, with a sub-carrier demodulating means for outputting the subcarrier amplitude and phase of each transmission OFDM signal.
[0026]
Claim7Is a system including a plurality of N transmitting antennas and a plurality of N receiving antennas, which are connected to each transmitting antenna, use the same radio frequency, and operate based on symbol timing. A frequency converter for connecting the output of the OFDM modulator to a radio frequency using a local oscillation frequency, means for generating a known pilot signal corresponding to each OFDM modulator, and each OFDM Means for multiplexing transmission information signal and pilot signal connected to modulator, error correction encoder for performing error correction coding on transmission information, and output of error corrector by combination of OFDM modulator and subcarrier At least one OFDM signal transmission device having an interleaver for performing interleaving, and the OFDM signal transmission device Means for supplying a common OFDM symbol timing to all of the OFDM modulators, a local oscillator for supplying a common local oscillation signal to all of the frequency converters according to the OFDM signal transmitting apparatus, and each receiving antenna. A frequency modulator that converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and a pilot signal that is connected to the frequency converter and transmitted for each OFDM modulator. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on timing signals for reception by the antenna, normalize the reception amplitude and phase of the pilot signal with the known pilot signal amplitude and phase, and transfer coefficients. Inverse matrix operation to measure and calculate and store the inverse matrix for each subcarrier matrix Subcarrier demodulation that takes the product of the inverse matrix of each received OFDM signal that is output from the stage and the fast Fourier transformer and relates to an arbitrary subcarrier, and outputs the amplitude and phase of the subcarrier of each transmitted OFDM signal At least one OFDM signal receiving apparatus having a deinterleaver that receives the demodulated output of the means and the subcarrier demodulating means as input and performing an operation reverse to that of the interleaver, and an error correction decoder that decodes the error correction code, and the OFDM signal receiving apparatus A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the above, and a timing for receiving a pilot signal transmitted by each OFDM modulator according to the OFDM signal receiving apparatus with a receiving antenna It is characterized by comprising signal generating means.
[0027]
Claim8Is a transmitting apparatus used in the OFDM signal transmission system according to claim 8, wherein the transmitting apparatus is connected to each transmitting antenna, uses the same radio frequency, and is connected to an OFDM modulator and a transmitting antenna that operate based on symbol timing. A frequency converter for converting the output of the OFDM modulator to a radio frequency using a local oscillation frequency, a means for generating a known pilot signal corresponding to each OFDM modulator, and a transmission connected to each OFDM modulator Means for multiplexing information signal and pilot signal, error correction encoder for performing error correction coding on transmission information, and interleaver for interleaving output of error corrector by combination of OFDM modulator and subcarrier .
[0028]
Claim9Claims7A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix The subcarrier demodulation means for outputting the amplitude and phase of the subcarrier of each transmission OFDM signal, and the deinterleaver for performing the reverse operation of the interleaver with the demodulation output of the subcarrier demodulation means as input, and the error for decoding the error correction code. It has a correction decoder.
[0029]
Claim 10Claims7In the described OFDM signal transmission system, two transmission antennas using orthogonal polarizations as transmission antennas and two reception antennas using orthogonal polarizations as reception antennas are used.
Claim 11Claim 10A transmission apparatus used in the described OFDM signal transmission system, which is connected to each transmission antenna, uses the same radio frequency, and is connected to an OFDM modulator and a transmission antenna that operate based on symbol timing. A frequency converter for converting the output of the transmitter into a radio frequency using a local oscillation frequency, means for generating a known pilot signal corresponding to each OFDM modulator, a transmission information signal connected to each OFDM modulator, and Means for multiplexing the pilot signal, an error correction encoder that performs error correction coding on transmission information, and an interleaver that interleaves the output of the error corrector by a combination of an OFDM modulator and a subcarrier.
[0030]
Claim 12Claim 10A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix The subcarrier demodulating means for outputting the amplitude and phase of the subcarrier of each transmission OFDM signal, the deinterleaver that performs the reverse operation of the interleaver with the demodulated output of the subcarrier demodulating means as input, and the error correcting code are decoded. It has an error correction decoder.
[0031]
Claim 13 is a system comprising a plurality of N transmitting antennas and a plurality of N receiving antennas, connected to each transmitting antenna, using the same radio frequency, and operating based on symbol timing A frequency converter that is connected to an OFDM modulator and a transmission antenna that converts the output of the OFDM modulator to a radio frequency using a local transmission frequency and a signal obtained by serial-parallel conversion of a transmission information signal or the same transmission information signal A transmission switch, means for generating a known pilot signal corresponding to each OFDM modulator, means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator, and transmission information The error correction encoder that performs error correction coding and the output of the error corrector are interleaved by a combination of an OFDM modulator and a subcarrier. At least one OFDM signal transmission device having an interleaver for performing a signal, means for supplying a common OFDM symbol timing to all OFDM modulators according to the OFDM signal transmission device, and a frequency converter according to the OFDM signal transmission device. A local oscillator that supplies a local oscillation signal common to all, a frequency converter that is connected to each receiving antenna, and that converts a received signal of a radio frequency to a frequency suitable for demodulation using the local oscillation frequency, and the frequency conversion Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Received amplitude and phase of known pilot signal amplitude and phase Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And a de-interleaver that performs the reverse operation of the interleaver with the demodulation output of the sub-carrier demodulation means as an input and outputs the amplitude and phase of the sub-carrier of each transmission OFDM signal An error correction decoder that decodes the error correction code, a means for measuring the reception quality of the output of the subcarrier demodulation means for an arbitrary subcarrier of the transmission OFDM signal, and a signal obtained by serial-parallel conversion of the transmission information signal at the transmission side In this case, the subcarrier demodulation output is output. When the same transmission information signal is transmitted, the subcarrier demodulation output is output. A common local oscillation signal is supplied to at least one OFDM signal receiving device having a switch for adding or outputting a higher reception level of subcarrier demodulated outputs and all of the frequency converters of the OFDM signal receiving device. And a timing signal generating means for receiving a pilot signal transmitted corresponding to each OFDM modulator according to the OFDM signal receiving apparatus by a receiving antenna.
[0032]
Claim 14Claim 13A transmission apparatus used in the described OFDM signal transmission system, which is connected to each transmission antenna, uses the same radio frequency, operates based on symbol timing, and is connected to the transmission antenna. Corresponding to a frequency converter that converts the output of the signal into a radio frequency using a local oscillation frequency, a signal that is obtained by serial-parallel conversion of a transmission information signal, or a switch that switches and transmits the same transmission information signal, and each OFDM modulator Means for generating a known pilot signal, means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator, and an error correction encoder and error corrector for performing error correction coding on the transmission information Is provided with an interleaver that performs interleaving by using a combination of an OFDM modulator and a subcarrier.
[0033]
Claim 15Claim 13A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix The subcarrier demodulating means for outputting the amplitude and phase of the subcarrier of each transmission OFDM signal, the deinterleaver for performing the reverse operation of the interleaver with the demodulated output of the subcarrier demodulating means as input, and the error for decoding the error correcting code. Means for measuring the reception quality of the output of the correction decoder and the subcarrier demodulating means related to an arbitrary subcarrier of the transmission OFDM signal, and subcarrier demodulation output when transmitting a signal obtained by serial-parallel conversion of the transmission information signal on the transmission side When the same transmission information signal is transmitted, a sub-carrier demodulation output is added or a switch for outputting the higher reception level of the sub-carrier demodulation outputs is provided.
[0034]
Claim 16Claim 13In the described OFDM signal transmission system, two transmission antennas using orthogonal polarizations as transmission antennas and two reception antennas using orthogonal polarizations as reception antennas are used.
Claim 17Claim 16A transmission apparatus used in the described OFDM signal transmission system, which is connected to each transmission antenna, uses the same radio frequency, operates based on symbol timing, and is connected to the transmission antenna. Corresponding to a frequency converter that converts the output of the signal into a radio frequency using a local oscillation frequency, a signal that is obtained by serial-parallel conversion of a transmission information signal, or a switch that switches and transmits the same transmission information signal, and each OFDM modulator Means for generating a known pilot signal, means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator, and an error correction encoder and error corrector for performing error correction coding on the transmission information Is provided with an interleaver that performs interleaving by using a combination of an OFDM modulator and a subcarrier.
[0035]
Claim 18Claim 16A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and the frequency converter connected to each receiving antenna Pilot signals for all combinations of transmit and receive antennas and fast Fourier transforms that operate on the basis of timing signals for receiving pilot signals transmitted to the respective OFDM modulators corresponding to each OFDM modulator. Normalization of received signal amplitude and phase with known pilot signal amplitude and phase, measurement of transfer coefficient, calculation and storage of inverse matrix for matrix related to each subcarrier, and output of inverse matrix calculation means and fast Fourier transformer Product of each received OFDM signal related to an arbitrary subcarrier and the inverse matrix The subcarrier demodulating means for outputting the amplitude and phase of the subcarrier of each transmission OFDM signal, the deinterleaver that performs the reverse operation of the interleaver with the demodulated output of the subcarrier demodulating means as input, and the error correcting code are decoded. Means for measuring the reception quality of the output of the error correction decoder and the subcarrier demodulating means related to an arbitrary subcarrier of the transmission OFDM signal, and subcarrier for sending a signal obtained by serial-parallel conversion of the transmission information signal on the transmission side When outputting the demodulated output and transmitting the same transmission information signal, a switch for adding the subcarrier demodulated output or outputting the higher reception level of the subcarrier demodulated outputs is provided.
[0036]
Claim19Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal transmission system for transmitting from a plurality of transmitting antennas, wherein the OFDM signal transmitting apparatus includes pilot signal generating means for generating known N types of pilot signals corresponding to each of the N transmitting antennas, N pieces of data conversion means for converting each of N input transmission data into OFDM symbols, an inverse matrix reception means for receiving information on an inverse matrix transmitted from the OFDM signal receiver, and the data conversion means Multiply each inverse carrier of each OFDM symbol generated by the inverse matrix acquired by the inverse matrix receiving means N interference means for multiplexing N types of pilot signals output from the pilot signal generating means to each of N signals output from the front interference canceling means, N interference signals output from the front interference canceling means, and N N fast inverse Fourier transform means for performing inverse Fourier transform on the signals output from the multiple multiplexing means, and symbol timing generating means for giving a common OFDM symbol timing to all of the N fast inverse Fourier transform means And N transmission frequency converting means for converting the frequency of the signal output from the fast inverse Fourier transform means to a radio frequency, and a transmission signal for supplying a common local oscillation signal to all of the N transmission frequency converting means. And a radio frequency reception signal received by the N reception antennas. N receiving frequency converting means for converting to a frequency suitable for demodulation, a receiving local oscillating means for supplying a common local oscillation signal to all of the N receiving frequency converting means, and the N receiving receiving means N fast Fourier transform units that perform a Fourier transform process on each of N systems of received signals output from the frequency transform unit, and N demodulations that convert the OFDM symbols output from the fast Fourier transform unit into bit strings Means, a timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted from each of the N transmitting antennas from a received signal, and an output of the fast Fourier transform means The amplitude and phase are detected for each subcarrier from the received N pilot signals appearing at, and based on the detected amplitude and phase, the N Inverse matrix computing means for computing an inverse matrix of a matrix composed of transfer coefficients of N × N elements corresponding to each combination of a transmitting antenna and N receiving antennas, and an inverse obtained by the inverse matrix computing means Inverse matrix information transmitting means for transmitting matrix information to the OFDM signal transmitting apparatus is provided.
[0037]
Claim 20Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal transmitting apparatus used in an OFDM signal transmission system for transmitting from a plurality of transmitting antennas, the pilot signal generating means for generating known N types of pilot signals corresponding to each of the N transmitting antennas, and an input N data conversion means for converting each of the N transmission data to be converted into OFDM symbols, an inverse matrix reception means for receiving information on an inverse matrix transmitted from the OFDM signal receiving device, and a data conversion means Multiplication of the inverse matrix acquired by the inverse matrix receiving means is performed for each subcarrier of each generated OFDM symbol. Pre-interference canceling means; N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N systems of signals output from the pre-interference canceling means; N fast inverse Fourier transform means for performing inverse Fourier transform on the signals output from the N multiplexing means, and symbol timing generation for giving a common OFDM symbol timing to all of the N fast inverse Fourier transform means A common local oscillation signal for all of the N transmission frequency converting means for converting the frequency of the signal output from the fast inverse Fourier transform means to a radio frequency, and the N transmitting frequency converting means Transmitting local oscillation means is provided.
[0038]
Claim 21Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal receiving apparatus used in an OFDM signal transmission system for transmitting from a plurality of transmitting antennas, wherein N receiving frequencies for converting radio frequency received signals received by the N receiving antennas into frequencies suitable for demodulation A conversion means, a reception local oscillation means for supplying a common local oscillation signal to all of the N reception frequency conversion means, and an N-system reception signal output from the N reception frequency conversion means. N fast Fourier transform means for performing a Fourier transform process on the signal, and an OFDM symbol output from the fast Fourier transform means for converting to a bit string Demodulating means, timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted from each of the N transmitting antennas from a received signal, and the fast Fourier transform The amplitude and phase are detected for each subcarrier from the received N pilot signals appearing at the output of the means, and each of the N transmitting antennas and the N receiving antennas is detected based on the detected amplitude and phase. Inverse matrix computing means for computing an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to the combination, and information on the inverse matrix obtained by the inverse matrix computing means to the OFDM signal transmitting apparatus Inverse matrix information transmitting means for transmitting the information is provided.
[0039]
Claim 22Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal transmission system for transmitting from a plurality of transmitting antennas, wherein the OFDM signal transmitting apparatus includes pilot signal generating means for generating known N types of pilot signals corresponding to each of the N transmitting antennas, N data conversion means for converting each of N input transmission data into OFDM symbols, information receiving means for receiving reception information of a pilot signal transmitted from the OFDM signal receiving apparatus, and the information receiving means On the basis of the received information of the N pilot signals received by the OFDM signal receiving apparatus. For each subcarrier, and based on the detected amplitude and phase, a matrix composed of transfer coefficients of N × N elements corresponding to each combination of the N transmitting antennas and the N receiving antennas Inverse matrix computing means for computing the inverse matrix of the above, and pre-interference canceling means for multiplying each subcarrier of each OFDM symbol generated by the data converting means by the inverse matrix obtained by the inverse matrix computing means, N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N systems of signals output from the pre-interference canceling means, and the N multiplexing means N fast inverse Fourier transform means for performing inverse Fourier transform on the signal output from the signal, and OFDM symbol timing common to all the N fast inverse Fourier transform means Common to all of the N transmission frequency conversion means, the N timing transmission frequency conversion means for converting the frequency of the signal output from the fast inverse Fourier transform means to a radio frequency, A local oscillation means for transmitting that provides a local oscillation signal, and the OFDM signal receiving apparatus includes N reception signals for converting radio frequency reception signals received by the N reception antennas into frequencies suitable for demodulation. Frequency conversion means, reception local oscillation means for providing a common local oscillation signal to all of the N reception frequency conversion means, and N systems of received signals output from the N reception frequency conversion means N fast Fourier transform means for applying a Fourier transform process to each, and N for converting the OFDM symbol output from the fast Fourier transform means into a bit string Demodulating means, timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted from each of the N transmitting antennas from a received signal, and the fast Fourier transform means And an information transmission means for detecting the amplitude and phase of the received N pilot signals for each subcarrier and transmitting the detected information to the OFDM signal transmission apparatus.
[0040]
Claim 23Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal transmission apparatus for use in an OFDM signal transmission system for transmitting from a plurality of transmission antennas, wherein pilot signal generation means for generating known N types of pilot signals corresponding to each of the N transmission antennas is input N data converting means for converting each of the N transmission data to be converted into OFDM symbols, information receiving means for receiving reception information of a pilot signal transmitted from the OFDM signal receiving apparatus, and reception of the information receiving means Based on the obtained information, the amplitude and phase of N pilot signals received by the OFDM signal receiver A matrix composed of N × N element transfer coefficients corresponding to each combination of the N transmit antennas and the N receive antennas based on the detected amplitude and phase. An inverse matrix computing means for computing an inverse matrix; a pre-interference canceling means for performing multiplication of the inverse matrix obtained by the inverse matrix computing means for each subcarrier of each OFDM symbol generated by the data converting means; N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N systems of signals output from the pre-interference canceling means; and N multiplexing means The N fast inverse Fourier transforming means for performing inverse Fourier transform on the output signal and the OFDM symbol timing common to all the N fast inverse Fourier transforming means. Common symbol timing generation means, N transmission frequency conversion means for converting the frequency of a signal output from the fast inverse Fourier transform means to a radio frequency, and a local portion common to all of the N transmission frequency conversion means Transmitting local oscillation means for providing an oscillation signal is provided.
[0041]
Claim 24Comprises an OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, and the OFDM signal transmitting apparatus transmits OFDM signals of the same radio frequency to the N signals. An OFDM signal receiving apparatus used in an OFDM signal transmission system for transmitting from a plurality of transmitting antennas, wherein N receiving frequencies for converting radio frequency received signals received by the N receiving antennas into frequencies suitable for demodulation A conversion means, a reception local oscillation means for supplying a common local oscillation signal to all of the N reception frequency conversion means, and an N-system reception signal output from the N reception frequency conversion means. N fast Fourier transform means for performing a Fourier transform process on the signal, and an OFDM symbol output from the fast Fourier transform means for converting to a bit string Demodulating means, timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted from each of the N transmitting antennas from a received signal, and the fast Fourier transform And an information transmitting means for detecting the amplitude and phase of the received N pilot signals for each subcarrier from the output of the means and transmitting the detected information to the OFDM signal transmitting apparatus. .
[0042]
Claim 25Claims19Or claims22In the OFDM signal transmission system, the OFDM signal receiving apparatus further includes at least one information transmitting antenna, and the OFDM signal transmitting apparatus further includes at least one information receiving antenna. .
A twenty-seventh aspect includes an OFDM signal transmitting apparatus including a plurality of N first sets of antennas and an OFDM signal receiving apparatus including a plurality of N second sets of antennas, and the OFDM signal transmitting apparatuses are the same An OFDM signal transmission system for transmitting an OFDM signal having a radio frequency from the N first sets of antennas, and the OFDM signal receiving apparatus includes known N types corresponding to each of the first sets of antennas. Pilot signal generating means for generating a pilot signal, N inverse fast Fourier transform means for performing inverse fast Fourier transform on N types of pilot signals output from the pilot signal generating means, and the inverse fast Fourier transform means N transmission frequency converting means for converting a signal output from the radio frequency for transmission, and a radio frequency received by the second set of antennas. N reception frequency conversion means for converting a number of reception signals to a frequency suitable for demodulation, and Fourier transform processing is performed on each of N systems of reception signals output from the N reception frequency conversion means N fast Fourier transform means, N demodulating means for transforming the OFDM symbol output from the fast Fourier transform means into a bit string, the N transmitting frequency converting means and the N receiving frequency converting means Are provided with local oscillation means for giving a signal common to all of the antennas, and transmission / reception change-over switch means for switching between transmission and reception for the N second sets of antennas. N data conversion means for converting each of the transmission data of the system into OFDM symbols, and the first set of antennas transmitted from the OFDM signal receiving apparatus N reception frequency conversion means for converting the received radio frequency pilot signal to a frequency suitable for demodulation, and N fast Fourier transforms for performing Fourier transform on the signal output from the reception frequency conversion means And a timing signal generating means for generating a timing signal necessary for extracting each of the N pilot signals transmitted via the second set of antennas from the received signal output from the fast Fourier transform means And the amplitude and phase of the N pilot signals transmitted from the OFDM signal transmission device are detected for each subcarrier based on the signal extracted from the output of the fast Fourier transform means, and the detected amplitude and phase are detected. N × N element transmission corresponding to each combination of the N first set of antennas and the N second set of antennas. Inverse matrix calculation means for calculating an inverse matrix of a matrix composed of coefficients, and multiplication of the inverse matrix obtained by the inverse matrix calculation means for each subcarrier of each OFDM symbol generated by the data conversion means Pre-interference canceling means, N fast inverse Fourier transform means for performing inverse Fourier transform on the signal output from the pre-interference canceling means, and the frequency of the signal output from the fast inverse Fourier transform means as a radio frequency N transmission frequency conversion means for converting to N, local oscillation means for providing a common local oscillation signal to all of the N transmission frequency conversion means and the N reception frequency conversion means, Transmission / reception changeover switch means for switching between transmission and reception for the first set of antennas is provided.
[0043]
Claim 27Comprises an OFDM signal transmitting apparatus including a plurality of N first sets of antennas and an OFDM signal receiving apparatus including a plurality of N second sets of antennas, and the OFDM signal transmitting apparatuses have the same radio frequency. OFDM signal receiving apparatus for use in an OFDM signal transmission system that transmits a plurality of OFDM signals from the N first sets of antennas, and generates known N types of pilot signals corresponding to each of the first sets of antennas Pilot signal generating means, N inverse fast Fourier transform means for performing inverse fast Fourier transform on N types of pilot signals output from the pilot signal generating means, and signals output from the inverse fast Fourier transform means N transmission frequency conversion means for converting the signal into a radio frequency for transmission, and a radio frequency reception signal received by the second set of antennas. N receiving frequency converting means for converting the signal to a frequency suitable for demodulation, and N high-speeds for performing Fourier transform processing on each of the N received signals output from the N receiving frequency converting means Common to all of the Fourier transforming means, the N demodulating means for converting the OFDM symbol output from the fast Fourier transforming means into a bit string, and the N transmitting frequency converting means and the N receiving frequency converting means And a transmission / reception selector switch for switching between transmission and reception for the N second sets of antennas.
[0044]
Claim 28Comprises an OFDM signal transmitting apparatus including a plurality of N first sets of antennas and an OFDM signal receiving apparatus including a plurality of N second sets of antennas, and the OFDM signal transmitting apparatuses have the same radio frequency. An OFDM signal transmission apparatus for use in an OFDM signal transmission system for transmitting a plurality of OFDM signals from the N first sets of antennas, wherein N pieces of data for converting each of N input transmission data into OFDM symbols Conversion means; N reception frequency conversion means for converting a radio frequency pilot signal transmitted from the OFDM signal receiving apparatus and received by the first set of antennas into a frequency suitable for demodulation; and the reception frequency N fast Fourier transform means for performing Fourier transform on the signal output from the transform means, and the received signal output from the fast Fourier transform means. Timing signal generating means for generating a timing signal necessary for extracting each of the N pilot signals transmitted through the second set of antennas, and a signal extracted from the output of the fast Fourier transform means And detecting the amplitude and phase of the N pilot signals transmitted from the OFDM signal transmitting apparatus for each subcarrier, and based on the detected amplitude and phase, the N first set of antennas and Inverse matrix calculation means for calculating an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to each combination of N second antennas, and each OFDM generated by the data conversion means Pre-interference canceling means for multiplying each subcarrier of the symbol by the inverse matrix obtained by the inverse matrix calculating means, and the output of the pre-interference canceling means N fast inverse Fourier transform means for performing inverse Fourier transform on the signal, N transmission frequency transforming means for transforming the frequency of the signal output from the fast inverse Fourier transform means to a radio frequency, and the N Local oscillation means for supplying a common local oscillation signal to all of the transmission frequency conversion means and the N reception frequency conversion means, and a transmission / reception changeover switch means for switching between transmission and reception for the first set of N antennas And is provided.
[0045]
(Function)
In the present invention, the OFDM system is used to realize a signal transmission system using a MIMO channel without using an equalizer. Then, instead of estimating the transfer function on the time axis by the equalizer, for example, the transfer coefficient (amplitude / phase) for each subcarrier is directly measured using a pilot signal, and interference cancellation between OFDM signals is performed for each subcarrier. Get the transfer coefficient for
[0046]
Therefore, since interference cancellation is performed for each subcarrier, it is possible to easily and accurately perform interference cancellation. Further, according to this system, it is necessary to perform feedback control as in the case of using an equalizer. Therefore, stable operation can be achieved even in a severe frequency selective fading environment.
[0047]
Claim 1In claim 18,It is assumed that the inverse matrix calculation means and the interference cancellation means are arranged on the OFDM signal receiving apparatus side.
[0048]
However, since the inverse matrix calculation means and the interference cancellation means are complicated in processing, the hardware scale of the apparatus increases and the power consumption increases when these functions are provided. Therefore, it is not desirable to mount the inverse matrix calculation means and the interference cancellation means on the mobile terminal.
Claim19-Claim 28In this case, it is assumed that at least one of the inverse matrix calculation means and the interference cancellation means is mounted on the OFDM signal transmission apparatus side. For example, an OFDM signal transmission device may be considered in association with a base station that manages a plurality of mobile terminals, and an OFDM signal reception device may be considered in association with each mobile terminal. Therefore, problems such as downsizing of the mobile terminal and reduction of power consumption can be overcome.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Claim1One embodiment of the invention is shown in FIG. In this embodiment, the OFDM signal transmission system includes N OFDM signal transmission apparatuses each including two or more N transmission antennas and connected to each antenna and using the same radio frequency, and N reception antennas. It is composed of N OFDM signal receivers connected to each antenna and using the same radio frequency.
The received signals are frequency-converted to frequencies suitable for demodulation by the frequency converters 9-1 to 9-N, and Fourier-transformed by the fast Fourier transformers 11-1 to 11-N. Here, the OFDM symbol timing of the OFDM signal to be Fourier-transformed is supplied from the OFDM symbol timing recovery means 9 and is all common.
As a method for realizing the OFDM symbol timing recovery means 9, various methods such as separately transmitting a special preamble for symbol timing recovery to recover the OFDM symbol timing can be used. An example of an OFDM modulated signal transmitted from the transmission antennas 5-1 to 5-N is shown in FIG. In the example of FIG. 2, for simplicity, the pilot signal P₁, P₂, ..., P_NAre transmitted so as not to overlap each other on the time axis.
[0050]
The configuration and operation of the embodiment shown in FIG. 1 will be described in detail. In the present embodiment, N OFDM modulators 1-1 to 1-N are arranged corresponding to N transmission antennas 5-1 to 5-N. The OFDM modulators 1-1 to 1-N perform subcarrier modulation and inverse Fourier transform. A common OFDM symbol timing is supplied from the OFDM symbol timing control circuit 2 to these OFDM modulators 1-1 to 1-N.
[0051]
Transmission information signal T₁~ T_NAre known pilot signals P corresponding to the respective OFDM modulators 1-1 to 1-N.₁, P₂, ..., P_NPilot signal P input from pilot signal generating means 6-1 to 6-N₁~ P_NAnd multiplexed on the time axis by the multiplexing means 7-1 to 7-N. The multiplexed signals are input to the OFDM modulators 1-1 to 1-N, respectively.
[0052]
Pilot signal P_iIs used to measure the transfer coefficient between the transmitting antenna 5-i and the receiving antennas 8-1 to 8-N. These pilot signals and transmission information signals are multiplexed and input to N OFDM modulators 1-1 to 1-N, respectively. Since these OFDM modulators 1-1 to 1-N all need to operate at a common OFDM symbol timing, the OFDM symbol timing common to all of the OFDM modulators 1-1 to 1-N is OFDM symbol timing. Supplied from the control circuit 2.
[0053]
The modulation outputs of the OFDM modulators 1-1 to 1-N are input to N frequency converters 3-1 to 3-N for conversion to radio frequencies. A common local oscillation signal is supplied from the local oscillator 4 to these frequency converters 3-1 to 3 -N. As a result, the phase noise and frequency variation of the OFDM signals transmitted from the transmitting antennas 5-1 to 5-N are all the same.
[0054]
On the other hand, in the OFDM signal receiving apparatus, since a common local oscillation signal is supplied from the local oscillator 10 to the frequency converters 9-1 to 9-N, the phase noise and frequency fluctuation of the received OFDM signal are all the same. become. For this reason, since each transmission OFDM signal has a common frequency fluctuation, it is possible to facilitate interference cancellation and synchronous detection between subcarriers.
[0055]
The OFDM signals frequency-converted by the frequency converters 3-1 to 3 -N are respectively input to the transmission antennas 5-1 to 5 -N and transmitted to the OFDM signal receiving apparatus. In the OFDM signal receiving apparatus, N OFDM signals transmitted from the transmitting antennas 5-1 to 5-N are received by the receiving antennas 8-1 to 8-N as signals obtained by adding them in space, respectively.
[0056]
The received signals are frequency-converted to frequencies suitable for demodulation by the frequency converters 9-1 to 9-N, and Fourier-transformed by the fast Fourier transformers 11-1 to 11-N. Here, the OFDM symbol timing of the OFDM signal to be Fourier-transformed is supplied from the OFDM symbol timing recovery means 9 and is all common.
As a method for realizing the OFDM symbol timing recovery means 9, various methods such as separately transmitting a special preamble for symbol timing recovery to recover the OFDM symbol timing can be used. An example of an OFDM modulated signal transmitted from the transmission antennas 5-1 to 5-N is shown in FIG. In the example of FIG. 2, for simplicity, the pilot signal P₁, P₂, ..., P_NAre transmitted so as not to overlap each other on the time axis.
[0057]
On the other hand, the transmission information signal T₁~ T_NThe OFDM signals modulated in (1) are transmitted superimposed on the time axis. Pilot signal P₁, P₂, ..., P_NIs used to know the transfer function from the transmitting antenna 5-i to the receiving antenna 8-j. Pilot signal P₁~ P_NAs a general rule, if all the amplitudes of the subcarriers are the same, the same processing may be performed for each subcarrier and for each system of the receiving antenna, so that signal processing can be facilitated.
[0058]
When this pilot signal is used, each subcarrier of the OFDM signal is a signal having a constant amplitude and a constant phase within the OFDM symbol. Therefore, the transfer function from the transmitting antenna 5-1 to the receiving antenna 8-i is as follows. Is required.
Pilot signal Pi transmitted from transmitting antenna 5-1 is received by receiving antennas 8-1 to 8-N. The received pilot signals are frequency-converted by frequency converters 9-1 to 9-N, and then sent to N fast Fourier transformers 11-1 to 11-N.
[0059]
In the fast Fourier transformers 11-1 to 11-N, the received pilot signal is separated for each subcarrier. By detecting the amplitude and phase of each received subcarrier signal, the transfer function for each subcarrier can be measured as a complex number.
The transfer function of the subcarrier transmitted from the transmitting antenna 5-i and received by the receiving antenna 8-j is a complex number s._i,_jAs obtained. Here, a complex number s which is a transfer function for each subcarrier._i,_jIs called the transfer coefficient.
[0060]
When the number of subcarriers of the OFDM signal is M, the transfer function from the transmitting antenna 5-i to the receiving antenna 8-j is a complex number s for each subcarrier._i,_jA set of M complex numbers s_i,_jRepresented by This transfer function is obtained by the product (N × N) of the number N of transmitting antennas and the number N of receiving antennas.
That is, a transfer function of a combination of all transmission antennas 5-1 to 5-N and reception antennas 8-1 to 8-N is obtained by (M × N × N) complex numbers.
[0061]
Here, paying attention to one subcarrier, the transmission signals from the transmission antennas 5-1 to 5-N are expressed as (t₁, T₂, ..., t_N), Received signals received by the receiving antennas 8-1 to 8-N (r₁, R₂, ..., r_N).
The transfer coefficient of the i-th subcarrier is determined according to the combination of the transmitting antennas 5-1 to 5-N and the receiving antennas 8-1 to 8-N._iCan be expressed as a determinant of (N × N) elements. This determinant S_iIs given by:
[Equation 3]

Focusing on the i-th subcarrier, the received signal (r) received by the receiving antennas 8-1 to 8-N.₁, R₂, ..., r_N) Is a transmission signal (t) transmitted from the transmission antennas 5-1 to 5-N.₁, T₂, ..., t_N) And determinant S_iIs represented by the following formula.
[Expression 4]

Since the reception antennas 8-1 to 8-N receive the OFDM signals transmitted from the transmission antennas 5-1 to 5-N in a superimposed manner, the received signals (r₁, R₂, ..., r_N) To the original transmission signal (t₁, T₂, ..., t_NNeed to restore). Received signal (r₁, R₂, ..., r_N) To the transmitted signal (t₁, T₂, ..., t_N) For each subcarrier,_iInverse matrix S_i ^-1And the following equation may be calculated for each subcarrier.
[Equation 5]

In the inverse matrix calculation means 13, the reception amplitude and phase of the reception pilot signal are thus obtained for each combination of the N transmission antennas 5-1 to 5-N and the N reception antennas 8-1 to 8-N. (N × N) determinant S that is normalized by the amplitude and phase of a known pilot signal and has a complex number as a transfer coefficient for each i-th subcarrier._iIs obtained by measurement, and its inverse matrix S_i ^-1Is calculated and stored.
[0062]
Inverse matrix S obtained for each i-th subcarrier_i ^-1The subcarrier demodulating means 14 is the i-th subcarrier of each received OFDM signal that is the output of N fast Fourier transformers 11-1 to 11-N (r_i1, R_i2, ..., r_iN) For ((r_i1, R_i2, ..., r_iN) × S_i ^-1). As a result, an amplitude / phase output based on a pilot signal serving as a reference for the amplitude / phase can be obtained. However, this is not a matter of course, and the demodulated output is synchronously detected for each subcarrier.
[0063]
Thus, ((r_i1, R_i2, ..., r_iN) × S_i ^-1) Is the i-th subcarrier of each transmitted OFDM signal (t_i1, T_i2, ..., t_iN) Demodulation output can be obtained. By performing this calculation for all subcarriers, the transmission information signal (t_i1, T_i2, ..., t_iN) Can be demodulated.
Thus, by measuring the amplitude and phase for each subcarrier using the pilot signal, the received signal (r_i1, R_i2, ..., r_iN) To the transmitted signal (t_i1, T_i2, ..., t_iN) To restore the transfer function S_iAnd its inverse matrix S_i ^-1And ((r_i1, R_i2, ..., r_iN) × S_i ^-1) To obtain the transmission signal (t_i1, T_i2, ..., t_iN) And a demodulated output can be obtained.
[0064]
Thus, according to the present invention, the transfer coefficient S for interference cancellation for each subcarrier.ⁱAnd ((r_i1, R_i2, ..., r_iN) × S_i ^-1), The interference between channels is canceled and the transmission signal (t_i1, T_i2, ..., t_iN) Can be restored and demodulated.
Further, as described here, the present invention does not need to perform complicated signal processing in the equalizer, and does not perform feedback control, so-called feedforward control, so even in a severe multipath fading environment, Stable operation can be expected.
[0065]
(Second Embodiment)
Next, the claim1Another embodiment of the present invention will be described with reference to FIG. In order to improve the performance against fading, OFDM is generally used in combination with error correction and interleaving. An embodiment combining error correction and interleaving is shown in FIG.
[0066]
In FIG. 3, the transmission information signal (t_i1, T_i2, ..., t_iNAfter error correction coding is performed in the error correction encoders 15-1 to 15-N, interleaving is performed in the subcarrier direction, that is, in the frequency axis direction, in the interleavers 16-1 to 16-N. This is done to avoid continuous errors for level drops (notches) in the vicinity of a certain frequency and to obtain a high error correction coding gain.
[0067]
On the receiving side, the demodulated output is deinterleaved by deinterleavers 17-1 to 17-N, which is the reverse of the interleaving on the transmitting side, and then decoded by error correction decoders 18-1 to 18-N. Is done.
This embodiment is a modification of the first embodiment, and includes the same components as those of the first embodiment. Since the other constituent elements are the same as those in the first embodiment, description thereof will be omitted.
[0068]
(Third embodiment)
In the configuration of FIG. 3, in the case of fading with a relatively long delay, continuous characteristics do not occur and good characteristics can be obtained. Since it becomes longer, the notch becomes wider, and there is a problem that continuous errors are likely to occur in this portion, and the error correction gain is reduced.
[0069]
Claim7The invention according to will be described with reference to FIG. The present invention is an invention for improving the reduction in error correction gain as described above.
Transmission information signal (t_i1, T_i2, ..., t_iN) In the subcarrier direction (frequency axis direction) and the transmission antenna direction (spatial direction) in the interleaver 16 after error correction coding is performed in the error correction encoders 15-1 to 15-N shown in FIG. Combine and interleave.
[0070]
On the receiving side, the demodulated output is deinterleaved by the deinterleaver 17, which is the reverse of the interleaving on the transmitting side, and then decoded by the error correction decoders 18-1 to 18 -N.
By doing so, since interleaving is performed by combining the antenna direction and the frequency axis direction, an antenna (space) diversity effect can be obtained in addition to the frequency diversity effect. For this reason, even in the case of fading with a short delay, the occurrence of continuous errors is reduced, the reduction in error correction coding gain can be reduced, and high quality can be achieved.
[0071]
The output of one error correction encoder is interleaved by the interleaver 16 in the subcarrier direction and the transmission antenna direction, deinterleaved by the deinterleaver 17 on the receiving side, and decoded by one error correction decoder. The same effect can be obtained when doing so.
(Fourth embodiment)
Next, the claim4And claim 10One embodiment of the present invention will be described with reference to FIG. As shown in FIG. 6, in the present invention, the number of transmitting antennas is 2, and the number of receiving antennas is also 2.
[0072]
On the transmission side, the transmission antenna 5-1A and the transmission antenna 5-2A have different polarizations, for example, vertical polarization and horizontal polarization, and on the reception side, the reception antenna 8-1A and the reception antenna 8- 2A is similarly different polarization, for example, vertical polarization and horizontal polarization, respectively.
Thereby, for example, the path between the transmitting antenna 5-1A and the receiving antenna 8-1A and the path between the transmitting antenna 5-2A and the receiving antenna 8-2A are separated by the polarization discrimination of the transmitting and receiving antennas. be able to. Here, the transfer function S of the i-th subcarrier_iIs given by the following equation as a determinant of (2 × 2) elements.
[Formula 6]

In this determinant, the fact that it can be separated by the polarization discrimination of the transmitting and receiving antennas₁₁, S₂₂The absolute value of is S₁₂, S₂₁It means that it is sufficiently larger than the absolute value of. Therefore, S_iInverse matrix S for_i ^-1Is calculated so that the denominator of the determinant does not become 0 in the inverse matrix operation, so that the OFDM signal R received for each antenna is calculated.₁, R₂I-th subcarrier set (r₁, R₂) For (r₁, R₂) × S_i ^-1The calculation of becomes difficult to diverge.
[0073]
Therefore, the transmission signal (t₁, T₂) On the receiving side can be increased, and stable communication is possible. In addition, when considering deployment by a cellular configuration using this apparatus, interference can be reduced by the degree of polarization discrimination for cells having different polarizations.
Therefore, even if the power is increased twice to increase the transmission capacity, the interference power can be reduced by the degree of polarization discrimination for different polarizations. Therefore, the interference power does not increase for each polarization. For this reason, since the interference power does not increase even in the deployment by the cellular configuration, the area capacity of the system can be approximately doubled according to the present invention compared to the case where the same polarization is used.
[0074]
(Fifth embodiment)
Next claim4And claim 10Another embodiment of the present invention will be described with reference to FIG. As shown in FIG. 7, in the present invention, the number of transmitting antennas is 2, and the number of receiving antennas is also 2.
[0075]
On the transmission side, the transmission antenna 5-1A and the transmission antenna 5-2A have different polarizations, for example, vertical polarization and horizontal polarization, and on the reception side, the reception antenna 8-1A and the reception antenna 8- 2A is similarly different polarization, for example, vertical polarization and horizontal polarization, respectively.
Thereby, for example, the path between the transmission antenna 5-1A and the reception antenna 8-1A and the path between the transmission antenna 5-2A and the reception antenna 8-2A are separated by the polarization discrimination degree of the transmission / reception antenna. be able to.
[0076]
According to the invention, the transmitted signal (t₁, T₂In addition to the frequency diversity effect peculiar to OFDM, in the case of fading with a relatively short delay as in the embodiment of FIG. The correlation coefficient of diversity due to the antenna (space) and polarization can be reduced. Therefore, a large diversity effect can be obtained, the occurrence of continuous errors can be reduced, the reduction in error correction coding gain can be reduced, and high quality can be achieved.
[0077]
(Sixth embodiment)
Next, claim 16An embodiment according to the invention will be described with reference to FIG. In this embodiment, the number of transmitting antennas is two and the number of receiving antennas is two as in the embodiment of FIG. 6, and on the transmitting side, the polarizations of the transmitting antenna 5-1A and the transmitting antenna 5-2A are different from each other. For example, vertical polarization and horizontal polarization are used, and on the reception side, the reception antenna 8-1A and the reception antenna 8-2A are similarly different polarizations, for example, vertical polarization and horizontal polarization, respectively.
[0078]
According to this, since different polarizations are used, the effect of polarization diversity can be expected, and communication quality can be improved. In the present invention, the case where the transmission information signal is distributed and the same transmission information signal is input to the OFDM modulators 1-1 and 1-2, and the transmission information signal T which has been subjected to serial-parallel conversion are used.₁, T₂Is switched between when inputting. Here, when transmitting a transmission information signal subjected to serial / parallel conversion, the information transmission rate is doubled compared to the case of transmitting the same transmission information signal.
[0079]
On the other hand, when the same transmission information signal is transmitted, the receiving side adds the two subcarrier demodulation outputs or outputs the higher reception level of the two subcarrier demodulation outputs, thereby obtaining a diversity effect. It is possible to improve the quality.
In the present invention, the reception quality is measured by the communication quality measuring means 22 for measuring the reception quality, and the first switch 20 can increase the same transmission information signal if the reception quality is lower than the threshold for switching determination. If the transmission information signal T is serial-parallel converted₁, T₂Are sent to OFDM modulators 1-1 and 1-2.
[0080]
On the other hand, on the receiving side, the second switch 21 adds two subcarrier demodulation outputs if the reception quality is low with respect to the threshold for switching determination, or the reception level of the two subcarrier demodulation outputs Output the larger one. If it is higher than the threshold value, the demodulated output is output as it is. The switching control of the first switch 20 and the second switch 21 is performed based on the measurement result of the communication quality measuring means 22.
[0081]
As a result, although the transmission rate is halved, if the same transmission information signal is transmitted by two OFDM modulators, the polarization diversity effect can be obtained, so that high quality can be achieved. On the other hand, when the propagation environment is good, similar to the embodiment of FIG. 6, since OFDM signals with different polarizations can be separated, different transmission information can be transmitted, and twice the transmission capacity is required. Transmission can be performed without increasing the frequency. In this way, the quality and transmission capacity can be adaptively controlled according to the propagation environment and reception quality.
[0082]
In the above embodiment, in the transmission apparatus, the transmission OFDM symbol timing of each OFDM modulator and the local oscillator of the frequency converter are shared, and a pilot is transmitted to estimate the transfer coefficient between the transmission and reception antennas. Further, in the receiving apparatus, the local oscillator of the frequency converter is made common, and the output of the fast Fourier transformer is used for each subcarrier with respect to the N × N combination of the transmitting and receiving antennas using the pilot signal. The transmission coefficient is measured by detecting the reception amplitude and phase of the pilot signal.
[0083]
Based on this, the inverse matrix S for the N × N matrix Si for each subcarrier._i ^-1For each subcarrier with respect to the output of the fast Fourier transform, the received signal (r₁, R₂, ..., r_N) For ((r₁, R₂, ..., r_N) × S_i ^-1) Is the i-th subcarrier of the transmitted OFDM signal (t₁, T₂, ..., t_N) Can be estimated. Therefore, a signal transmission apparatus using a MIMO channel can be realized by the OFDM method without using an equalizer.
[0084]
(Seventh embodiment)
Next, another embodiment of the present invention will be described with reference to FIG. This form is claimed.19-Claim 21And claim 25Corresponding to FIG. 9 is a block diagram showing the configuration of the OFDM signal transmission system in this state.
In this form, the claim 19Transmit antenna, OFDM signal transmitter, receive antenna, OFDM signal receiverIs, Antenna 37, OFDM signal transmitter 30, antenna 51, OFDM signal receiver 5 respectively.To zeroCorrespond.
[0085]
Claims19Pilot signal generating means, data converting means, inverse matrix receiving means, pre-interference canceling means, multiplexing means, fast inverse Fourier transform means, symbol timing generating means, transmission frequency converting means and transmitting local part The oscillation means are a pilot signal generator 34, data converter 31, receiver 41, pre-interference canceller 32, multiplexing circuit 33, fast inverse Fourier transformer 35, timing signal generator 38, frequency converter 36 and local oscillator, respectively. 39, the receiving frequency converting means, the receiving local oscillating means, the fast Fourier transform means, the demodulating means, the timing signal generating means, the inverse matrix calculating means, and the inverse matrix information transmitting means of the OFDM signal receiving device are respectively frequency converters. 52, local oscillator 55, fast Fourier transformer 53, demodulator 54, timing signal Generator 56, corresponding to the inverse matrix calculator 57 and the transmitter 58.
[0086]
Claim 25The information transmitting antenna and the information receiving antenna correspond to the transmitting antenna 59 and the receiving antenna 40, respectively.
The OFDM signal transmission system shown in FIG. 9 includes an OFDM signal transmission device 30 and an OFDM signal reception device 50. When this OFDM signal transmission system is applied to mobile communication or the like, it is desirable that the OFDM signal transmitting device 30 is mounted on the base station side and the OFDM signal receiving device 50 is mounted on the user side mobile terminal. .
[0087]
As shown in FIG. 9, the OFDM signal transmitter 30 includes a data converter 31, a pre-interference canceller 32, a multiplexing circuit 33, a pilot signal generator 34, a fast inverse Fourier transformer 35, a frequency converter 36, an antenna. 37, a timing signal generator 38, a local oscillator 39, a receiving antenna 40 and a receiver 41 are provided.
Each of the data converter 31, the multiplexing circuit 33, the pilot signal generator 34, the fast inverse Fourier transformer 35, the frequency converter 36, and the antenna 37 includes N pieces (plural pieces).
[0088]
On the other hand, the OFDM signal receiver 50 includes an antenna 51, a frequency converter 52, a fast Fourier transformer 53, a demodulator 54, a local oscillator 55, a timing signal generator 56, an inverse matrix calculator 57, a transmitter 58, and a transmission antenna 59. Is equipped.
The antenna 51, the frequency converter 52, the fast Fourier transformer 53, and the demodulator 54 are each provided with N pieces (plural pieces).
[0089]
The number N of components in the OFDM signal transmitting apparatus 30 is the same as the number N of components in the OFDM signal receiving apparatus 50. That is, in order to obtain an inverse matrix, which will be described later, the number of antennas N on the transmission side and the number N of antennas on the reception side need to be the same.
[0090]
The data converters 31 (1) to 31 (N) respectively receive transmission data T₁~ T_NAre converted into OFDM symbols. Each data converter 31 includes a modulator (for example, a modulator such as BPSK, QPSK, and ASK) that modulates a data string input as a serial signal into symbols, and a serial-parallel converter that converts symbols into parallel signals. Built in. That is, the symbol corresponding to the input transmission data is output from the data converter 31 in the parallel signal format.
[0091]
The receiver 41 receives the inverse matrix information transmitted from the OFDM signal receiving device 50 via the reception antenna 40 and acquires the inverse matrix.
The pre-interference canceller 32 performs pre-processing for interference cancellation using the inverse matrix acquired by the receiver 41. Specifically, the transmission data T₁~ T_NOFDM symbols (M) output from the data converters 31 (1) to 31 (N)₁, M₂, ..., M_N) Each subcarrier component (m₁, M₂, ..., m_N) Is multiplied by the inverse matrix.
[0092]
The N pilot signal generators 34 (1) to 34 (N) output different known pilot signals.
Each of the multiplexing circuits 33 (1) to 33 (N) receives the OFDM symbols output from the pre-interference canceller 32 and the pilot signals output from the pilot signal generators 34 (1) to 34 (N). Outputs the multiplexed signal on the time axis.
[0093]
Each of the fast inverse Fourier transformers 35 (1) to 35 (N) performs a fast inverse Fourier transform (IFFT) process on the signals output from the multiplexing circuits 33 (1) to 33 (N). A common symbol timing signal is supplied from the timing signal generator 38 to the N fast inverse Fourier transformers 35 (1) to 35 (N).
The OFDM signals output from the fast inverse Fourier transformers 35 (1) to 35 (N) are frequency-converted to radio frequencies by the frequency converters 36 (1) to 36 (N). A common local oscillation signal is supplied from the local oscillator 39 to the N frequency converters 36 (1) to 36 (N).
[0094]
Therefore, N antennas 37 (1) to 37 (N) connected to the outputs of the frequency converters 36 (1) to 36 (N) simultaneously transmit OFDM signals having the same radio frequency as radio waves. .
N OFDM signals transmitted from the antennas 37 (1) to 37 (N) are added in space, and the N antennas 51 (1) to 51 (1) are arranged at different positions on the OFDM signal receiving device 50 side. 51 (N).
[0095]
The OFDM signals received by the antennas 51 (1) to 51 (N) are frequency-converted to relatively low frequency OFDM signals suitable for signal processing through the frequency converters 52 (1) to 52 (N), respectively. The A common local oscillation signal is supplied from the local oscillator 55 to the frequency converters 52 (1) to 52 (N).
The OFDM signals output from the frequency converters 52 (1) to 52 (N) are input to the fast Fourier transformers 53 (1) to 53 (N), respectively, and subjected to fast Fourier transform (FFT) processing. The OFDM symbol signals output from the fast Fourier transformers 53 (1) to 53 (N) are respectively input to the demodulators 54 (1) to 54 (N) and demodulated into bit strings.
[0096]
Note that the OFDM signal receiving apparatus 50 shown in FIG. 9 does not include an element corresponding to an interference canceller. In this OFDM signal transmission system, interference is canceled by the action of the front interference canceller 32 on the OFDM signal transmission device 30 side. Since it is not necessary to provide an interference canceller in the OFDM signal receiving apparatus 50, the configuration of the OFDM signal receiving apparatus 50 is simplified and power consumption is also suppressed.
[0097]
The inverse matrix calculator 57 extracts the received pilot signal from each output of the fast Fourier transformers 53 (1) to 53 (N). Then, for each subcarrier component, it corresponds to each combination of N transmitting antennas 37 (1) to 37 (N) and N receiving antennas 51 (1) to 51 (N). The reception amplitude and phase of (N × N) pilot signals are detected. That is, since the pilot signal is known, the transfer coefficient representing the transfer function between the transmitting antenna and the receiving antenna can be detected by normalizing the received pilot signal using the known signal. it can.
[0098]
Further, the inverse matrix calculator 57 uses the detected transfer coefficient as a component, and a matrix A composed of (N × N) elements._iInverse matrix A_i ^-1Is calculated.
The transmitter 58 uses the inverse matrix A obtained by the inverse matrix calculator 57._i ^-1Is transmitted to the OFDM signal transmitter 30 via the transmission antenna 59.
In this embodiment, the inverse matrix A obtained by the inverse matrix calculator 57 on the OFDM signal receiving device 50 side is used._i ^-1The transmitter 58, the transmission antenna 59, the reception antenna 40, and the receiver 41 are provided in order to transmit the above information to the OFDM signal transmission apparatus 30, but may be replaced with components provided in advance.
[0099]
For example, the antenna 51 can be used instead of the transmission antenna 59, or the antenna 37 can be used instead of the reception antenna 40.
Next, the operation of each part of the OFDM signal transmitting apparatus 30 and the OFDM signal receiving apparatus 50 will be described in more detail.
The known pilot signals output from the pilot signal generators 34 (1) to 34 (N) in the OFDM signal transmission apparatus 30 are multiplexed with the transmission signals by the multiplexing circuits 33 (1) to 33 (N), respectively. Are transmitted from the antennas 37 (1) to 37 (N), respectively.
[0100]
Here, the pilot signal transmitted from each antenna 37 (j) is denoted by P._jRepresented by Each pilot signal P_jSince it passes through the multiplexing circuit 33, the fast inverse Fourier transformer 35, and the frequency converter 36 in the same manner as the transmission data signal, it is OFDM-modulated in the same manner as the transmission data.
Further, the common symbol timing is supplied from the timing signal generator 38 to the fast inverse Fourier transformers 35 (1) to 35 (N), respectively, and the local oscillator 39 is supplied to the frequency converters 36 (1) to 36 (N). To supply a common local oscillation frequency.
[0101]
For this reason, the OFDM symbol timing of each subcarrier of each OFDM signal transmitted from each of the antennas 37 (1) to 37 (N) is common to all systems. Further, the carrier signal of the OFDM signal becomes coherent.
Therefore, the OFDM signal receiving apparatus 50 does not need to perform automatic frequency control or OFDM symbol timing recovery individually for each OFDM signal. For this reason, the amount of signal processing in the OFDM signal receiving apparatus 50 is relatively small.
[0102]
The pilot signal transmitted from each antenna 37 (j) is P_jAre received by the antennas 51 (1) to 51 (N) in the OFDM signal receiving apparatus 50, respectively.
Here, a received pilot signal transmitted from the jth antenna 37 (j) on the transmitting side and received by the kth antenna 51 (k) on the receiving side is denoted by P_{j, k}The transmission response between the transmitting antenna 37 (j) and the receiving antenna 51 (k) is represented by H_{j, k}Is expressed by the following equation.
[Expression 7]

In the OFDM signal receiving apparatus 50, the received pilot signal is converted to P._{j, k}Is frequency-converted by the frequency converter 52 and then Fourier-transformed by the fast Fourier transformer 53. As a result, the received pilot signal P_{j, k}Are separated for each subcarrier component.
The inverse matrix calculator 57 receives the received pilot signal P separated for each subcarrier component._{j, k}Is input from the output of the fast Fourier transformer 53 and the inverse matrix is calculated.
[0103]
In order for the OFDM signal receiving apparatus 50 to extract the received pilot signal from the received signal, it is necessary to identify the pilot signal. For example, in the signal transmitted by the OFDM signal transmitting apparatus 30 side, the pilot signal is If a preamble for identification is added, it can be easily identified.
Further, for example, in the OFDM signal transmission apparatus 30, each pilot signal P to be transmitted is transmitted.₁, P₂, ..., P_NIf the timing is shifted from each other so that they do not overlap on the time axis, the OFDM signal receiving apparatus 50 transmits each pilot signal P₁, P₂, ..., P_NCan be separated from each other.
[0104]
The inverse matrix calculator 57 includes (N × N) pairs corresponding to combinations of the antennas 37 (1) to 37 (N) on the transmission side and the antennas 51 (1) to 51 (N) on the reception side. , The reception amplitude and phase of the input reception pilot signal (the amplitude and phase of the reference carrier used for synchronous detection) are detected for each subcarrier.
Therefore, for each subcarrier component, (N × N) antennas corresponding to each combination of the transmitting-side antennas 37 (1) to 37 (N) and the receiving-side antennas 51 (1) to 51 (N). A matrix of transfer coefficients with elements_i(Subscript i represents the component of each subcarrier).
[0105]
Further, the inverse matrix calculator 57 generates a transfer coefficient matrix A for each subcarrier component._iInverse matrix A_i ^-1And the inverse matrix A_i ^-1Is output to the transmitter 58.
Here, the received pilot signal P_{j, k}, Pilot signal P_j,And transfer response H_{j, k}Each of the i-th subcarrier components of p_{i: j, k}, Pilot signal p_{i: j,}And transmission response h_{i: j, k}In the same way as the above expression (7), the following expression is established.
[Equation 8]

Therefore, the matrix A_iEach component is a transmission response h_{i: j, k}Itself, matrix A_iIs expressed by the following equation.
[Equation 9]

Inverse matrix A obtained by the inverse matrix calculator 57_i ^-1Is modulated in the transmitter 58 and transmitted as a radio wave via the transmission antenna 59. This inverse matrix A_i ^-1Is received by the receiving antenna 40 on the OFDM signal transmitting apparatus 30 side, and demodulated inside the receiver 41. Inverse matrix A acquired by receiver 41_i ^-1Is input to the front interference canceller 32.
[0106]
The pre-interference canceller 32 has an inverse matrix A_i ^-1Is used to transmit a data signal (T₁, T₂, ..., T_N) Output signals (M) of the data converters 31 (1) to 31 (N) corresponding to₁, M₂, ..., M_N) To the i-th subcarrier component (m_i1, M_i2, ..., m_iN) Vs. ((m_i1, M_i2, ..., m_iN) × A_i ^-1) Is performed on all subcarrier components.
[0107]
Then, each j (j = 1 to N) -th component of the calculation result of the front interference canceller 32 is input to the multiplexing circuit 33 (j) corresponding to the j-th antenna 37 (j).
The data signals multiplexed by the multiplexing circuits 33 (1) to 33 (N) are inverse Fourier transformed by the fast inverse Fourier transformers 35 (1) to 35 (N), respectively, and the frequency converter 36 (1). The frequency is converted into a radio frequency signal at ˜36 (N) and transmitted from each antenna 37 (1) to 37 (N) to the OFDM signal receiving device 50.
[0108]
The i-th subcarrier component (t of the data signal transmitted from each antenna 37 (1) to 37 (N)_{i: 1}, T_{i: 2}, ..., t_{i: N}) Is expressed by the following equation.
[Expression 10]

The transmitted data signal is received by each of the antennas 51 (1) to 51 (N) of the OFDM signal receiving apparatus 50. The received signal is the transmission response h._{i: j, k}Affected by. That is, the i-th subcarrier component of the received data signal is represented by (r_{i: 1}, R_{i: 2}, ..., r_{i: N}), The following equation holds.
## EQU11 ##

The following equations are obtained based on the equations (10) and (11).
[Expression 12]

That is, the symbol (m_i1, M_i2, ..., m_iN) For the received signal (r_{i: 1}, R_{i: 2}, ..., r_{i: N}) As it is.
[0109]
The received signal obtained at the output of the fast Fourier transformers 53 (1) to 53 (N), that is, the symbol (m_i1, M_i2, ..., m_iN) Are demodulated by the demodulator 54 (1) to 54 (N) and converted into a bit string, whereby the original data signal (T₁, T₂, ..., T_N) Can be acquired.
Since it operates as described above, it is possible to transmit the N OFDM signals at the same time using the same frequency band of the same propagation path without providing a component for interference cancellation on the OFDM signal receiving device 50 side. As in the embodiment shown in FIG. 1, the respective data signals can be received separately.
[0110]
In this embodiment, since the pre-interference canceller 32 for interference cancellation is provided on the OFDM signal transmitting device 30 side, signal processing on the OFDM signal receiving device 50 side is simplified. That is, simplification of the configuration of the OFDM signal receiving apparatus 50 and reduction of power consumption are realized, so that, for example, assuming that the OFDM signal receiving apparatus 50 is mounted on a mobile terminal, the mobile terminal can be reduced in size and economy. Become.
[0111]
(Eighth embodiment)
Next, another embodiment of the present invention will be described with reference to FIG. This form isContractClaim 22-Claim 24And claim 25Corresponding to FIG. 10 is a block diagram showing the configuration of the OFDM signal transmission system of this embodiment. This form is a modification of the seventh embodiment. 10, elements corresponding to those in FIG. 9 are denoted by the same reference numerals.
[0112]
In this form, the claims22Transmitting antenna, OFDM signal transmitting device, receiving antenna, OFDM signal receiving deviceIs, Antenna 37, OFDM signal transmitter 30, antenna 51, OFDM signal receiver 5 respectively.To zeroCorrespond.
Claim 22Pilot signal generating means, data converting means, information receiving means, inverse matrix calculating means, multiplexing means, fast inverse Fourier transform means, symbol timing generating means, transmission frequency converting means, and transmitting local oscillating means Are respectively connected to the pilot signal generator 34, the data converter 31, the receiver 41, the inverse matrix calculator 42, the multiplexing circuit 33, the fast inverse Fourier transformer 35, the timing signal generator 38, the frequency converter 36 and the local oscillator 39. Correspondingly, a receiving frequency converting means, a receiving local oscillating means, a fast Fourier transforming means, a demodulating means, a timing signal generating means and an information transmitting means of an OFDM signal receiving device are respectively a frequency converter 52, a local oscillator 55, and a fast Fourier transform. Corresponds to converter 53, demodulator 54, timing signal generator 56 and transmitter 60.
[0113]
Claim 25The information transmitting antenna and the information receiving antenna correspond to the transmitting antenna 59 and the receiving antenna 40, respectively.
The OFDM signal transmission system shown in FIG. 10 includes an OFDM signal transmission device 30 and an OFDM signal reception device 50 as in the system of FIG. When this OFDM signal transmission system is applied to mobile communication or the like, it is desirable that the OFDM signal transmitting device 30 is mounted on the base station side and the OFDM signal receiving device 50 is mounted on the user side mobile terminal. .
[0114]
As shown in FIG. 10, the OFDM signal transmission apparatus 30 includes a data converter 31, a pre-interference canceller 32, a multiplexing circuit 33, a pilot signal generator 34, a fast inverse Fourier transformer 35, a frequency converter 36, an antenna. 37, a timing signal generator 38, a local oscillator 39, a receiving antenna 40, a receiver 41, and an inverse matrix calculator 42 are provided.
[0115]
Each of the data converter 31, the multiplexing circuit 33, the pilot signal generator 34, the fast inverse Fourier transformer 35, the frequency converter 36, and the antenna 37 includes N pieces (plural pieces).
On the other hand, the OFDM signal receiver 50 includes an antenna 51, a frequency converter 52, a fast Fourier transformer 53, a demodulator 54, a local oscillator 55, a timing signal generator 56, a transmitter 60, and a transmission antenna 59.
[0116]
The antenna 51, the frequency converter 52, the fast Fourier transformer 53, and the demodulator 54 are each provided with N pieces (plural pieces).
The number N of components in the OFDM signal transmitting apparatus 30 is the same as the number N of components in the OFDM signal receiving apparatus 50. That is, in order to obtain an inverse matrix, which will be described later, the number of antennas N on the transmission side and the number N of antennas on the reception side need to be the same.
[0117]
The data converters 31 (1) to 31 (N) respectively receive transmission data T₁~ T_NAre converted into OFDM symbols. Each data converter 31 includes a modulator (for example, a modulator such as BPSK, QPSK, and ASK) that modulates a data string input as a serial signal into symbols, and a serial-parallel converter that converts symbols into parallel signals. Built in. That is, the symbol corresponding to the input transmission data is output from the data converter 31 in the parallel signal format.
[0118]
The receiver 41 receives information on the received pilot signal transmitted from the OFDM signal receiving apparatus 50 from the OFDM signal receiving apparatus 50 via the receiving antenna 40, and demodulates the received signal.
The inverse matrix calculator 42 is based on the information of the received pilot signal received by the receiver 41, and the matrix A composed of (N × N) elements with the detected transfer coefficient as a component._iInverse matrix A_i ^-1Is calculated.
[0119]
The pre-interference canceller 32 performs pre-processing for interference cancellation using the inverse matrix obtained by the inverse matrix calculator 42. Specifically, the transmission data T₁~ T_NOFDM symbols (M) output from the data converters 31 (1) to 31 (N)₁, M₂, ..., M_N) Each subcarrier component (m₁, M₂, ..., m_N) Is multiplied by the inverse matrix.
[0120]
The N pilot signal generators 34 (1) to 34 (N) output different known pilot signals.
Each of the multiplexing circuits 33 (1) to 33 (N) receives the OFDM symbols output from the pre-interference canceller 32 and the pilot signals output from the pilot signal generators 34 (1) to 34 (N). Outputs the multiplexed signal on the time axis.
[0121]
Each of the fast inverse Fourier transformers 35 (1) to 35 (N) performs a fast inverse Fourier transform (IFFT) process on the signals output from the multiplexing circuits 33 (1) to 33 (N). A common symbol timing signal is supplied from the timing signal generator 38 to the N fast inverse Fourier transformers 35 (1) to 35 (N).
[0122]
The OFDM signals output from the fast inverse Fourier transformers 35 (1) to 35 (N) are frequency-converted to radio frequencies by the frequency converters 36 (1) to 36 (N). A common local oscillation signal is supplied from the local oscillator 39 to the N frequency converters 36 (1) to 36 (N).
Therefore, N antennas 37 (1) to 37 (N) connected to the outputs of the frequency converters 36 (1) to 36 (N) simultaneously transmit OFDM signals having the same radio frequency as radio waves. .
[0123]
N OFDM signals transmitted from the antennas 37 (1) to 37 (N) are added in space, and the N antennas 51 (1) to 51 (1) are arranged at different positions on the OFDM signal receiving device 50 side. 51 (N).
The OFDM signals received by the antennas 51 (1) to 51 (N) are frequency-converted to relatively low frequency OFDM signals suitable for signal processing through the frequency converters 52 (1) to 52 (N), respectively. The A common local oscillation signal is supplied from the local oscillator 55 to the frequency converters 52 (1) to 52 (N).
[0124]
The OFDM signals output from the frequency converters 52 (1) to 52 (N) are input to the fast Fourier transformers 53 (1) to 53 (N), respectively, and subjected to fast Fourier transform (FFT) processing. The OFDM symbol signals output from the fast Fourier transformers 53 (1) to 53 (N) are respectively input to the demodulators 54 (1) to 54 (N) and demodulated into bit strings.
[0125]
In the OFDM signal transmission system of FIG. 10, the interference is canceled by the action of the front interference canceller 32 on the OFDM signal transmission device 30 side. Since it is not necessary to provide an interference canceller in the OFDM signal receiving apparatus 50, the configuration of the OFDM signal receiving apparatus 50 is simplified and power consumption is also suppressed.
[0126]
The transmitter 60 extracts the received pilot signal from each output of the fast Fourier transformers 53 (1) to 53 (N). Then, for each subcarrier component, it corresponds to each combination of N transmitting antennas 37 (1) to 37 (N) and N receiving antennas 51 (1) to 51 (N). The reception amplitude and phase of (N × N) pilot signals are detected. That is, since the pilot signal is known, the transfer coefficient representing the transfer function between the transmitting antenna and the receiving antenna can be detected by normalizing the received pilot signal using the known signal. it can.
[0127]
The information of the received pilot signal detected from the output of the fast Fourier transformer 53 ((N × N) amplitude and phase information for each subcarrier) is modulated inside the transmitter 60 and transmitted via the transmission antenna 59. It is transmitted to the OFDM signal transmission device 30 as a radio wave.
In this embodiment, a transmitter 58, a transmission antenna 59, a reception antenna 40, and a receiver 41 are provided in order to transmit information on the received pilot signal detected on the OFDM signal reception device 50 side to the OFDM signal transmission device 30. However, it can be replaced by a component provided in advance.
[0128]
For example, the antenna 51 can be used instead of the transmission antenna 59, or the antenna 37 can be used instead of the reception antenna 40.
This embodiment is greatly different from the configuration of FIG. 9 in that the function of the inverse matrix calculator 57 shown in FIG. 9 is moved to the OFDM signal transmission device 30 side as the inverse matrix calculator 42. Hereinafter, operations of main parts of the OFDM signal transmitting apparatus 30 and the OFDM signal receiving apparatus 50 of FIG. 10 will be described in more detail.
[0129]
Similar to the OFDM signal transmission system of FIG. 9, the OFDM signal transmission apparatus 30 of FIG. 10 transmits an OFDM-modulated data signal and a known pilot signal from each of the antennas 37 (1) to 37 (N). The receiving device 50 receives the data signal and the pilot signal as OFDM signals by the antennas 51 (1) to 51 (N).
[0130]
Further, in the OFDM signal transmitting apparatus 30, each subcarrier component (m₁, M₂, ..., m_N) Inverse matrix A_i ^-1And the inverse matrix A from each antenna 37 (1) to 37 (N)_i ^-1Transmit the accumulated data signal.
The signals received by the antennas 51 (1) to 51 (N) are already transmitted to the inverse matrix A on the transmission side._i ^-1Therefore, in the OFDM signal receiver 50, the data signal (m) is obtained from the signals received by the antennas 51 (1) to 51 (N).₁, M₂, ..., m_N) Can be directly separated and removed.
[0131]
In the OFDM signal receiving apparatus 50, it is necessary to separate the received pilot signals from each other. For example, on the OFDM signal transmitting apparatus 30 side, each pilot signal (P₁, P₂, ..., P_N) Are sent out at different timings so that they do not overlap each other on the time axis.
As described above, in the OFDM signal transmission system of FIG. 10, information on the received pilot signal is transmitted from the OFDM signal receiving apparatus 50 side to the OFDM signal transmitting apparatus 30, and the received pilot signal received on the OFDM signal transmitting apparatus 30 side. This is characterized in that an inverse matrix is obtained based on the information (reception amplitude and phase).
[0132]
In this way, in the OFDM signal transmission system of FIG. 10, it is not necessary to mount the inverse matrix calculation function and the interference cancellation function on the OFDM signal receiving apparatus 50 side. Therefore, signal processing on the OFDM signal receiving apparatus 50 side is simplified. That is, simplification of the configuration of the OFDM signal receiving apparatus 50 and reduction of power consumption are realized, so that, for example, assuming that the OFDM signal receiving apparatus 50 is mounted on a mobile terminal, the mobile terminal can be reduced in size and economy. Become.
[0133]
(Ninth embodiment)
Next, another embodiment of the present invention will be described with reference to FIG. This form isContractClaim 26-Claim 28Corresponding to FIG. 11 is a block diagram showing the configuration of this form of OFDM signal transmission system. This form is a modification of the eighth embodiment. 11, elements corresponding to those in FIG. 10 are denoted by the same reference numerals.
[0134]
In this form, the transmitting antenna, OFDM signal transmitting apparatus, receiving antenna, OFDM signal receiving apparatus of claim 26Is, Antenna 37, OFDM signal transmitter 30, antenna 51, OFDM signal receiver 5 respectively.To zeroCorrespond.
Claim 26Pilot signal generating means, inverse fast Fourier transform means, transmission frequency converting means, receiving frequency converting means, fast Fourier transform means, demodulating means, local oscillating means and transmission / reception changeover switch means in the OFDM signal receiving apparatus in FIG. Corresponding to generator 81, fast inverse Fourier transformer 82, frequency converters 83 and 52, fast Fourier transformer 53, demodulator 54, local oscillator 55 and changeover switch 86, data conversion means of OFDM signal transmission apparatus, for reception Frequency conversion means, fast Fourier transform means, timing signal generation means, inverse matrix calculation means, fast inverse Fourier transform means, transmission frequency conversion means, local oscillation means, and transmission / reception changeover switch means data converter 31 and frequency converter, respectively 71, fast Fourier transformer 72, timing signal generator 73, inverse Column calculator 42, an inverse fast Fourier transformer 35, corresponding to the frequency converter 36 and the changeover switch 75.
[0135]
The OFDM signal transmission system shown in FIG. 11 includes an OFDM signal transmission device 30 and an OFDM signal reception device 50 as in the system of FIG. When this OFDM signal transmission system is applied to mobile communication or the like, it is desirable that the OFDM signal transmitting device 30 is mounted on the base station side and the OFDM signal receiving device 50 is mounted on the user side mobile terminal. .
[0136]
In the OFDM signal transmission system of FIG. 11, each of the OFDM signal transmission device 30 and the OFDM signal reception device 50 uses the same antenna for transmission and reception, and switches the transmission mode and the reception mode by time division. A system based on (Time Division Duplex) is assumed. Further, in the OFDM signal transmission system of FIG. 11, a function for generating a pilot signal is provided on the OFDM signal receiving apparatus 50 side.
[0137]
As shown in FIG. 11, the OFDM signal receiver 50 includes an antenna 51, a frequency converter 52, a fast Fourier transformer 53, a demodulator 54, a local oscillator 55, a timing signal generator 56, a pilot signal generator 81, a high-speed inverse circuit. A Fourier transformer 82, a frequency converter 83, a symbol timing generator 84, a change control unit 85, and a changeover switch 86 are provided.
[0138]
In addition, the antenna 51, the frequency converter 52, the fast Fourier transformer 53, the demodulator 54, the pilot signal generator 81, the fast inverse Fourier transformer 82, the frequency converter 83, and the changeover switch 86 are each N (plural). It is equipped.
On the other hand, the OFDM signal transmitter 30 in FIG. 11 includes a data converter 31, a pre-interference canceller 32, a fast inverse Fourier transformer 35, a frequency converter 36, an antenna 37, a timing signal generator 38, a local oscillator 39, a frequency converter. 71, a fast Fourier transformer 72, a timing signal generator 73, a switching control unit 74, and a changeover switch 75.
[0139]
Further, each of the data converter 31, the fast inverse Fourier transformer 35, the frequency converter 36, the antenna 37, the frequency converter 71, the fast Fourier transformer 72, and the changeover switch 75 is provided with N pieces (a plurality).
The number N of components in the OFDM signal transmitting apparatus 30 is the same as the number N of components in the OFDM signal receiving apparatus 50. That is, in order to obtain an inverse matrix, which will be described later, the number of antennas N on the transmission side and the number N of antennas on the reception side need to be the same.
[0140]
The frequency converter 52, fast Fourier transformer 53, demodulator 54, local oscillator 55, and timing signal generator 56 in the OFDM signal receiving apparatus 50 perform the same functions as the corresponding elements in FIG.
[0141]
N pilot signal generators 81 (1) to 81 (N) output different known pilot signals. High-speed inverse Fourier transformers 82 (1) to 82 (N) perform inverse Fourier transform processing on pilot signals output from pilot signal generators 81 (1) to 81 (N), respectively. The fast inverse Fourier transformers 82 (1) to 82 (N) are given a common symbol timing signal from the symbol timing generator 84.
[0142]
The frequency converters 83 (1) to 83 (N) frequency-convert pilot signals output as OFDM signals from the fast inverse Fourier transformers 82 (1) to 82 (N) to radio frequencies. A common local oscillation signal is supplied from the local oscillator 55 to the frequency converters 83 (1) to 83 (N).
Accordingly, the N pilot signals appearing at the outputs of the frequency converters 83 (1) to 83 (N) have the same radio frequency. N-system pilot signals output from the frequency converters 83 (1) to 83 (N) pass through the changeover switches 86 (1) to 86 (N), respectively, when the OFDM signal receiving apparatus 50 is in the transmission mode. Transmitted from the antennas 51 (1) to 51 (N).
[0143]
The switching control unit 85 identifies the communication state between the OFDM signal transmitting device 30 and the OFDM signal receiving device 50, and N switching switches 86 (1) depending on whether the OFDM signal receiving device 50 is in the transmission mode or the reception mode. ) To 86 (N).
The data converter 31, pre-interference canceller 32, fast inverse Fourier transformer 35, frequency converter 36, timing signal generator 38, and local oscillator 39 in the OFDM signal transmission apparatus 30 have the same functions as the corresponding elements in FIG. These explanations are omitted.
[0144]
Signals received by the antennas 37 (1) to 37 (N) are transmitted from the frequency converters 71 (1) to 75 (N) through the changeover switches 75 (1) to 75 (N) when the OFDM signal transmission device 30 is in the reception mode. 71 (N).
[0145]
The switching control unit 74 identifies a communication state between the OFDM signal transmitting apparatus 30 and the OFDM signal receiving apparatus 50, and N switching switches 75 (1) depending on whether the OFDM signal transmitting apparatus 30 is in the transmission mode or the reception mode. ) To 75 (N).
The frequency converters 71 (1) to 71 (N) convert the signals (pilot signals) received by the antennas 37 (1) to 37 (N), respectively, to relatively low frequencies suitable for signal processing. A common local oscillation signal is applied from the local oscillator 39 to the frequency converters 71 (1) to 71 (N).
[0146]
The fast Fourier transformers 72 (1) to 72 (N) perform fast Fourier transform on the pilot signals received as OFDM signals output from the frequency converters 71 (1) to 71 (N). Therefore, the pilot signals received by the antennas 37 (1) to 37 (N) appear in the outputs of the fast Fourier transformers 72 (1) to 72 (N) separately for each subcarrier component.
[0147]
The fast Fourier transformers 72 (1) to 72 (N) are given a common symbol timing signal from the timing signal generator 73 in order to extract each received pilot signal.
The inverse matrix calculator 42 detects the reception amplitude and phase of each received pilot signal for each subcarrier component based on the signals output from the fast Fourier transformers 72 (1) to 72 (N), and the detection result Find the inverse matrix based on.
[0148]
Next, operations of main parts of the OFDM signal transmission device 30 and the OFDM signal reception device 50 in FIG. 11 will be described in detail.
In the OFDM signal transmitting apparatus 30, an inverse matrix calculator 42 performs a matrix A of transmission coefficients of each subcarrier based on the received pilot signal._iInverse matrix A_i ^-1Is calculated. The pre-interference canceller 32 then outputs each subcarrier component (m of the data signal output from the data converters 31 (1) to 31 (N).₁, M₂, ..., m_N) For the inverse matrix A input from the inverse matrix calculator 42._i ^-1Multiply
[0149]
The signal output from the pre-interference canceller 32 is subjected to inverse Fourier transform processing by the fast inverse Fourier transformers 35 (1) to 35 (N), and is output as an OFDM signal. These OFDM signals are frequency-converted to radio frequencies by frequency converters 36 (1) to 36 (N), and antennas 37 (1) to 37 (N) via changeover switches 75 (1) to 75 (N). Sent from
[0150]
Signals transmitted from the antennas 37 (1) to 37 (N) are added in space and received by the antennas 51 (1) to 51 (N), respectively. However, the data signal (m₁, M₂, ..., m_N) Is pre-interference canceller 32 and inverse matrix A_i ^-1Is transmitted after being multiplied, the data signals (m) are transmitted from the antennas 51 (1) to 51 (N) in the same manner as in the systems of FIGS.₁, M₂, ..., m_N) Are received separately.
[0151]
Therefore, it is not necessary to provide a function for canceling interference on the OFDM signal receiving device 50 side. That is, the method of acquiring pilot signal information in the OFDM signal transmitting apparatus 30 is different from the system of FIG.
In the OFDM signal receiving apparatus 50, the pilot signal (P₁, P₂, ..., P_N) Is transmitted from each of the antennas 51 (1) to 51 (N). These pilot signals (P₁, P₂, ..., P_N) Are received by the antennas 37 (1) to 37 (N) in the OFDM signal transmitting apparatus 30, OFDM demodulated, separated into components of each subcarrier, and input to the inverse matrix calculator 42.
[0152]
The inverse matrix calculator 42 generates, from the received pilot signal, the transfer coefficient of each combination of the antennas 51 (1) to 51 (N) and the antennas 37 (1) to 37 (N) for each subcarrier component. Matrix A_iInverse matrix A_i ^-1Is calculated and stored.
The front interference canceller 32 converts the data signal output from the data converters 31 (1) to 31 (N) into an inverse matrix A._i ^-1Multiply The result is transmitted from the antennas 37 (1) to 37 (N) via the fast inverse Fourier transformers 35 (1) to 35 (N) and the frequency converters 36 (1) to 36 (N).
[0153]
In the OFDM signal receiving device 50, in each of the antennas 51 (1) to 51 (N), a signal is transmitted as a data signal from the antennas 37 (1) to 37 (N) to the antennas 51 (1) to 51 (N). However, since a common local oscillator is used for transmission and reception, the transfer coefficient of the transfer response matrix is the matrix A described above._iWill be the same.
[0154]
Therefore, each antenna 51 (1) to 51 (N) of the OFDM signal receiving apparatus 50 receives each data signal (m_i1, M_i2, ..., m_iN) Are received separately. Therefore, the data signal (M) appearing at the outputs of the fast Fourier transformers 53 (1) to 53 (N)_i1, M_i2, ..., M_iN) Is demodulated by the demodulators 54 (1) to 54 (N), so that the data signal (T₁, T₂, ..., T_N) Is obtained.
[0155]
In this embodiment, since the pilot signal generator 81 is provided on the OFDM signal receiving device 50 side, it is not necessary to provide a pilot signal generating function on the OFDM signal transmitting device 30 side. There is no need to provide the multiplexing circuit 33. Further, since the antennas 37 (1) to 37 (N) and the antennas 51 (1) to 51 (N) are shared for transmission and reception, the reception antenna 40 and the transmission antenna 59 of FIG. 10 are not necessary.
[0156]
Further, in the OFDM signal transmission system of FIG. 11, it is not necessary to mount the inverse matrix calculation function and the interference cancellation function on the OFDM signal receiving apparatus 50 side. Therefore, signal processing on the OFDM signal receiving apparatus 50 side is simplified. That is, simplification of the configuration of the OFDM signal receiving apparatus 50 and reduction of power consumption are realized, so that, for example, assuming that the OFDM signal receiving apparatus 50 is mounted on a mobile terminal, the mobile terminal can be reduced in size and economy. Become.
[0157]
The present invention can be widely applied not only to a broadband mobile communication system but also to a wireless system in which a large number of user radio stations are connected to a base station using the OFDM method, such as a point-to-multipoint fixed radio access system.
[0158]
【The invention's effect】
According to the present invention, the transfer coefficient (amplitude / phase) for each carrier is directly measured using the pilot signal in the OFDM signal, not the estimation of the transfer function on the time axis by the equalizer, and the OFDM is determined for each subcarrier. Since the transfer coefficient for canceling interference between signals is acquired, interference cancellation between channels can be easily performed with high accuracy, and feedforward processing can be performed without performing feedback control like an equalizer. Therefore, stable operation can be expected even in a severe frequency selective fading environment.
[0159]
Claims7According to the invention according to claim1In the transmitter / receiver described, since interleaving is performed in two dimensions of the subcarrier direction (frequency axis direction) and the transmission antenna direction (spatial direction), the occurrence of continuous errors is reduced even in short delay fading, and error correction is performed. A reduction in coding gain can be reduced, and high quality can be achieved.
[0160]
And claims4, Claim 10And claim 16According to the invention according to claim1, Claim7And claim 13In this transmitter / receiver, the number of transmitting antennas is 2, the number of receiving antennas is 2, and both are orthogonally polarized (for example, horizontally polarized waves and vertically polarized waves, or right-handed polarized waves and left-handed polarized waves). Since the degree of polarization discrimination can be increased and the degree of separation between the two channels can be increased, higher quality can be achieved.
[0161]
Claim 13In the present invention, the transmission information signal is distributed and switched between the case where the same transmission information signal is input to the two OFDM modulators and the case where the two transmission information signals converted in series-parallel are input, for switching determination. It is possible to adaptively control the quality and transmission capacity according to the propagation environment and the reception quality by changing and controlling these according to the threshold.
[0162]
And claims19In the present invention, since the function of an interference canceller having a large calculation amount, that is, a circuit scale can be provided on the OFDM signal transmitting apparatus side, there is an advantage that the circuit scale of the OFDM signal receiving apparatus can be reduced. Smaller and more economical terminals are realized.
Claim 22In this invention, since the function of not only the interference canceller but also the inverse matrix calculator can be provided on the OFDM signal transmitting apparatus side, the circuit scale of the OFDM signal receiving apparatus can be further reduced.
[0163]
Claim 26In the present invention, since the same antenna is shared for transmission and reception, it is not necessary to add a special antenna for transmitting pilot signal information or inverse matrix information. And claims19And claim 22As with the invention of, the circuit scale of the OFDM signal receiving apparatus can be further reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an OFDM signal transmission system according to a first embodiment.
FIG. 2 is a time chart showing an example of a transmission OFDM signal including a pilot signal.
FIG. 3 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a second embodiment.
FIG. 4 is a graph showing an example of fading characteristics.
FIG. 5 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a third embodiment;
FIG. 6 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a fourth embodiment.
FIG. 7 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a fifth embodiment;
FIG. 8 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a sixth embodiment.
FIG. 9 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a seventh embodiment.
FIG. 10 is a block diagram illustrating a configuration of an OFDM signal transmission system according to an eighth embodiment.
FIG. 11 is a block diagram illustrating a configuration of an OFDM signal transmission system according to a ninth embodiment.
FIG. 12 is a block diagram illustrating a configuration example of a conventional transmission / reception apparatus in a MIMO channel.
[Explanation of symbols]
1-1 to 1-N OFDM modulator
2 OFDM symbol timing control circuit
3-1 to 3-N frequency converter
4 Local oscillator
5-1 to 5-N transmitting antenna
5-1A Transmitter antenna with vertical polarization
5-2A Horizontally polarized transmitting antenna
6-1 to 6-N Pilot signal generating means
7-1 to 7-N Multiplexing means
8-1 to 8-N receiving antenna
8-1A Vertical polarization receiving antenna
8-2A Horizontally polarized wave receiving antenna
9-1 to 9-N Frequency converter
10 Local oscillator
11-1 to 11-N Fast Fourier Transformer
12 OFDM symbol timing recovery means
13 Inverse matrix calculation means
14 Subcarrier demodulation means
15-1 to 15-N error correction encoder
16,16-1 to 16-N interleaver
17, 17-1 to 17-N deinterleaver
18-1 to 18-N error correction decoder
20 First switch
21 Second switch
22 Communication quality measurement means
30 OFDM signal transmitter
31 Data converter
32 Pre-interference canceller
33 Multiplexing circuit
34 Pilot signal generator
35 Fast Inverse Fourier Transformer
36 Frequency converter
37 Antenna
38 Timing signal generator
39 Local oscillator
40 Receive antenna
41 Receiver
42 Inverse matrix calculator
50 OFDM signal receiving apparatus
51 Antenna
52 Frequency converter
53 Fast Fourier Transform
54 Demodulator
55 Local oscillator
56 Timing signal generator
57 Inverse matrix calculator
58 Transmitter
59 Transmitting antenna
60 transmitter
71 Frequency converter
72 Fast Fourier Transform
73 Timing signal generator
74 Switching control unit
75 selector switch
81 Pilot signal generator
82 Fast Inverse Fourier Transformer
83 Frequency converter
84 symbol timing generator
85 Switching control unit
86 selector switch

Claims (28)

A system comprising a plurality of N transmitting antennas and a plurality of N receiving antennas,
Connected to each transmit antenna, the same radio frequency is used, an OFDM modulator operating based on symbol timing, and connected to the transmit antenna, and the output of the OFDM modulator is converted to a radio frequency using a local transmission frequency At least one OFDM signal having a frequency converter and means for generating a known pilot signal corresponding to each OFDM modulator and means for multiplexing the transmission information signal and the pilot signal connected to each OFDM modulator A transmitting device;
Means for supplying a common OFDM symbol timing to all of the OFDM modulators according to the OFDM signal transmitting apparatus;
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal transmission device;
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. And at least one OFDM signal receiving apparatus having a sub-carrier demodulating unit,
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal receiver;
An OFDM signal transmission system comprising timing signal generating means for receiving a pilot signal transmitted corresponding to each OFDM modulator in the OFDM signal receiving apparatus by a receiving antenna. A transmitter used in the OFDM signal transmission system according to claim 1,
Connected to each transmit antenna, uses the same radio frequency, operates based on symbol timing, and connects to the transmit antenna and converts the output of the OFDM modulator to a radio frequency using a local transmission frequency An OFDM signal transmitting apparatus comprising: a frequency converter; means for generating a known pilot signal corresponding to each OFDM modulator; and means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator . A receiver used in the OFDM signal transmission system according to claim 1 ,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. OFDM signal receiving apparatus having a sub-carrier demodulating unit. The OFDM signal transmission system according to claim 1, wherein two transmitting antennas using orthogonal polarizations as transmitting antennas and two receiving antennas using orthogonal polarizations as receiving antennas are used . A transmission device used in the OFDM signal transmission system according to claim 4,
Connected to each transmit antenna, the same radio frequency is used, an OFDM modulator operating based on symbol timing, and connected to the transmit antenna, and the output of the OFDM modulator is converted to a radio frequency using a local transmission frequency An OFDM signal transmitting apparatus comprising: a frequency converter; means for generating a known pilot signal corresponding to each OFDM modulator; and means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator . A receiver used in the OFDM signal transmission system according to claim 4 ,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. OFDM signal receiving apparatus having a sub-carrier demodulating unit. A system comprising a plurality of N transmitting antennas and a plurality of N receiving antennas,
Connected to each transmit antenna, uses the same radio frequency, operates based on symbol timing, and connects to the transmit antenna and converts the output of the OFDM modulator to a radio frequency using a local transmission frequency Frequency converter, means for generating known pilot signal corresponding to each OFDM modulator, means for multiplexing transmission information signal and pilot signal connected to each OFDM modulator, and error for transmission information At least one OFDM signal transmission device having an error correction encoder that performs correction coding and an interleaver that interleaves the output of the error correction device by a combination of an OFDM modulator and a subcarrier;
Means for supplying a common OFDM symbol timing to all of the OFDM modulators according to the OFDM signal transmitting apparatus;
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal transmission device;
Connected to each receiving antenna and using a local oscillation frequency to convert a radio frequency received signal to a frequency suitable for demodulation, and to each OFDM modulator connected to the frequency converter. For all combinations of transmit antennas and receive antennas, and fast Fourier transforms that operate based on timing signals for receiving transmitted pilot signals at the receive antennas, the received signal amplitude and phase of the pilot signals are known. Each of the received OFDM signals that are output from a fast Fourier transformer and an inverse matrix computing means that calculates and stores an inverse matrix for a matrix related to each subcarrier, which is normalized by Product of the inverse matrix and output the amplitude and phase of the subcarrier of each transmitted OFDM signal And at least one OFDM signal receiving apparatus having a deinterleaver and and error correction decoder for decoding the error correction code as input the demodulated output of the subcarrier demodulation means and the sub-carrier demodulating unit performs the operation of the interleaver and opposite,
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal receiver;
An OFDM signal transmission system comprising timing signal generating means for receiving a pilot signal transmitted corresponding to each OFDM modulator in the OFDM signal receiving apparatus by a receiving antenna . A transmitter used in the OFDM signal transmission system according to claim 7,
Is connected to each transmission antenna conversion, the same radio frequency is used, the radio frequency with the station unit transmitting frequency output of the OFDM modulator and connected to the transmitting antenna the OFDM modulator operates based on the symbol timing A frequency converter, a means for generating a known pilot signal corresponding to each OFDM modulator, a means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator, and transmission information OFDM signal transmitting device which have a interleaver performing interleaving the output of the error correction encoder and the error correction apparatus that performs error correction coding by a combination of OFDM modulator subcarrier. A receiver used in the OFDM signal transmission system according to claim 7 ,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. OFDM signal receiving apparatus which have a deinterleaver and error correction decoder for decoding the error correction code as input the demodulated output of the subcarrier demodulation means and the sub-carrier demodulating unit performs the operation of the interleaver and vice versa. 8. The OFDM signal transmission system according to claim 7, wherein two transmission antennas using orthogonal polarizations as transmission antennas and two reception antennas using orthogonal polarizations as reception antennas are used . A transmitter used in the OFDM signal transmission system according to claim 10,
Connected to each transmit antenna, uses the same radio frequency, operates based on symbol timing, and is connected to the transmit antenna and converts the output of the OFDM modulator to a radio frequency using the local transmission frequency A frequency converter, a means for generating a known pilot signal corresponding to each OFDM modulator, a means for multiplexing a transmission information signal and the pilot signal connected to each OFDM modulator, and transmission information An OFDM signal transmission apparatus having an error correction encoder that performs error correction coding and an interleaver that interleaves the output of the error corrector by a combination of an OFDM modulator and a subcarrier . A receiver for use in claim 1 0, wherein the OFDM signal transmission system,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. Deinterleaver and and OFDM signal receiving apparatus having an error correction decoder for decoding the error correction code as input the demodulated output of the subcarrier demodulation means and the sub-carrier demodulating unit performs the operation of the interleaver and vice versa. A system comprising a plurality of N transmitting antennas and a plurality of N receiving antennas ,
Connected to each transmit antenna, the same radio frequency is used, an OFDM modulator operating based on symbol timing, and connected to the transmit antenna, and the output of the OFDM modulator is converted to a radio frequency using a local transmission frequency Frequency converter, switch for serially parallel conversion of transmission information signal or switch for switching and transmitting the same transmission information signal, means for generating known pilot signal corresponding to each OFDM modulator, and each OFDM modulator interleave error correction encoder performs error correction coding to the connected device and send information to multiplex and transmit information signals and said pilot signal and the output of the error correction device by a combination of OFDM modulator and subcarrier to At least one OFDM signal transmission device having an interleaver for performing
Means for supplying a common OFDM symbol timing to all of the OFDM modulators according to the OFDM signal transmitting apparatus;
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal transmission device;
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. A subcarrier demodulator and a deinterleaver that receives the demodulated output of the subcarrier demodulator as an input, performs an inverse operation of the interleaver, an error correction decoder that decodes the error correction code, and a subcarrier demodulation related to an arbitrary subcarrier of the transmitted OFDM signal The means for measuring the reception quality of the output of the means and the subcarrier demodulation output when outputting the signal obtained by serial-parallel conversion of the transmission information signal on the transmission side, and the subcarrier when transmitting the same transmission information signal At least one OFDM signal receiving device having a switch for adding a demodulated output or outputting a higher reception level of subcarrier demodulated outputs;
A local oscillator that supplies a common local oscillation signal to all of the frequency converters according to the OFDM signal receiver;
An OFDM signal transmission system comprising timing signal generating means for receiving a pilot signal transmitted corresponding to each OFDM modulator in the OFDM signal receiving apparatus by a receiving antenna . A transmitter used in the OFDM signal transmission system according to claim 13,
Connected to each transmit antenna, the same radio frequency is used, an OFDM modulator operating based on symbol timing, and connected to the transmit antenna, and the output of the OFDM modulator is converted to a radio frequency using a local transmission frequency Frequency converter, switch for serially parallel conversion of transmission information signal or switch for switching and transmitting the same transmission information signal, means for generating known pilot signal corresponding to each OFDM modulator, and each OFDM modulator Means for multiplexing the transmission information signal and the pilot signal, and an error correction encoder for performing error correction coding on the transmission information, and the output of the error corrector is interleaved by a combination of an OFDM modulator and a subcarrier. OFDM signal transmitting device which have a interleaver performing. A receiver for use in claims 1 to 3, wherein the OFDM signal transmission system,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. Sub carrier according to any subcarrier of the subcarrier demodulation means and de and the error correction code restoring Gosuru error correction decoder and transmitting OFDM signals as input the demodulated output of the subcarrier demodulation means operating the interleaver opposite The means for measuring the reception quality of the output of the demodulating means and the subcarrier demodulated output are output when a signal obtained by serial-parallel conversion of the transmission information signal is transmitted on the transmission side, and the subcarrier demodulation is transmitted when the same transmission information signal is transmitted. An OFDM signal receiving apparatus having a switch for adding a carrier demodulated output or outputting a higher reception level of subcarrier demodulated outputs . 14. The OFDM signal transmission system according to claim 13, wherein two transmitting antennas using orthogonal polarizations as transmitting antennas and two receiving antennas using orthogonal polarizations as receiving antennas are used . A transmitter used in the OFDM signal transmission system according to claim 16,
Connected to each transmit antenna, the same radio frequency is used, an OFDM modulator operating based on symbol timing, and connected to the transmit antenna, and the output of the OFDM modulator is converted to a radio frequency using a local transmission frequency Frequency converter, switch for serially parallel conversion of transmission information signal or switch for switching and transmitting the same transmission information signal, means for generating known pilot signal corresponding to each OFDM modulator, and each OFDM modulator Means for multiplexing the transmission information signal and the pilot signal, and an error correction encoder for performing error correction coding on the transmission information, and the output of the error corrector is interleaved by a combination of an OFDM modulator and a subcarrier. An OFDM signal transmission apparatus having an interleaver to perform . A receiver used in the OFDM signal transmission system according to claim 16 ,
A frequency converter that is connected to each receiving antenna and converts a received signal of a radio frequency to a frequency suitable for demodulation using a local oscillation frequency, and is transmitted corresponding to each OFDM modulator connected to the frequency converter. For all combinations of transmit and receive antennas and fast Fourier transforms that operate based on the timing signal for receiving the received pilot signal at the receive antenna, the received amplitude and phase of the pilot signal are set to the known pilot signal amplitude and phase. Inverse matrix calculation means for normalizing and measuring the transfer coefficient, calculating and storing the inverse matrix for the matrix related to each subcarrier, and each received OFDM signal output from the fast Fourier transform, related to any subcarrier And the inverse matrix, and output the amplitude and phase of the subcarrier of each transmitted OFDM signal. A subcarrier demodulating means, a deinterleaver that performs the reverse operation of the interleaver with the demodulated output of the subcarrier demodulating means as input, an error correction decoder that decodes the error correction code, and a subcarrier related to an arbitrary subcarrier of the transmitted OFDM signal In the case of outputting a subcarrier demodulated output for sending out a signal obtained by serial-parallel conversion of a transmission information signal on the transmission side and a means for measuring the reception quality of the output of the demodulation means, and sending the same transmission information signal An OFDM signal receiving apparatus having a switch for adding subcarrier demodulation outputs or outputting a higher reception level of subcarrier demodulation outputs . An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. An OFDM signal transmission system for transmitting from a transmission antenna ,
In the OFDM signal transmitter,
Pilot signal generating means for generating known N types of pilot signals corresponding to each of the N transmitting antennas;
N data conversion means for converting each of N input transmission data into OFDM symbols;
Inverse matrix receiving means for receiving information on an inverse matrix transmitted from the OFDM signal receiving device;
Pre-interference canceling means for performing multiplication of the inverse matrix acquired by the inverse matrix receiving means for each subcarrier of each OFDM symbol generated by the data conversion means;
N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N systems of signals output from the front interference canceling means;
And N inverse fast Fourier transform means for performing inverse Fourier transform on the signal output from the N multiplexing means,
Symbol timing generating means for providing a common OFDM symbol timing to all of the N fast inverse Fourier transform means;
N transmission frequency conversion means for converting the frequency of the signal output from the fast inverse Fourier transform means into a radio frequency;
Transmitting local oscillating means for providing a common local oscillating signal to all of the N transmitting frequency converting means;
And the OFDM signal receiving device includes:
N reception frequency conversion means for converting radio frequency reception signals received by the N reception antennas into frequencies suitable for demodulation;
Local oscillation means for receiving that provides a common local oscillation signal to all of the N receiving frequency conversion means;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N receiving frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
Timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted via each of the N transmitting antennas from a received signal;
The amplitude and phase are detected for each subcarrier from the received N pilot signals appearing at the output of the fast Fourier transform means, and the N transmission antennas and N receptions are detected based on the detected amplitude and phase. Inverse matrix computing means for computing an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to each combination of antennas;
Inverse matrix information transmitting means for transmitting information on the inverse matrix obtained by the inverse matrix calculating means to the OFDM signal transmitting apparatus;
OFDM signal transmission system characterized in that a. An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. An OFDM signal transmission apparatus used in an OFDM signal transmission system for transmitting from a transmission antenna,
A pilot signal generating means for generating a known N kinds of pilot signals corresponding to the respective front Symbol N transmit antennas,
N data conversion means for converting each of N input transmission data into OFDM symbols;
Inverse matrix receiving means for receiving information on an inverse matrix transmitted from the OFDM signal receiving device;
Pre-interference canceling means for multiplying each subcarrier of each OFDM symbol generated by the data converting means by the inverse matrix obtained by the inverse matrix receiving means;
N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N signals output from the front interference canceling means;
N fast inverse Fourier transform means for performing inverse Fourier transform on the signals output from the N multiplexing means;
Symbol timing generating means for providing a common OFDM symbol timing to all of the N fast inverse Fourier transform means;
N transmission frequency conversion means for converting the frequency of the signal output from the fast inverse Fourier transform means into a radio frequency;
The N OFDM signal transmitting apparatus characterized by setting digit and transmission local oscillator means for providing a common local oscillator signal to all of the transmission frequency converter. An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. An OFDM signal receiving apparatus used in an OFDM signal transmission system that transmits from a transmitting antenna,
N reception frequency converting means for converting radio frequency reception signals received by the N reception antennas into frequencies suitable for demodulation;
Local oscillation means for receiving that provides a common local oscillation signal to all of the N receiving frequency conversion means;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N receiving frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
Timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted via each of the N transmitting antennas from a received signal;
The amplitude and phase are detected for each subcarrier from the received N pilot signals appearing at the output of the fast Fourier transform means, and the N transmission antennas and N receptions are detected based on the detected amplitude and phase. Inverse matrix computing means for computing an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to each combination of antennas;
An OFDM signal receiving apparatus , comprising: inverse matrix information transmitting means for transmitting information on the inverse matrix obtained by the inverse matrix calculating means to the OFDM signal transmitting apparatus. An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. a OFDM signal transmission system for transmitting from the transmitting antenna,
In the OFDM signal transmitter,
A pilot signal generating means for generating a known N kinds of pilot signals corresponding to each of said N transmit antennas,
N data conversion means for converting each of N input transmission data into OFDM symbols;
Information receiving means for receiving reception information of a pilot signal transmitted from the OFDM signal receiving device;
Based on the information received by the information receiving means, the amplitude and phase of N pilot signals received by the OFDM signal receiving apparatus are detected for each subcarrier, and the N pieces of N pilot signals are detected based on the detected amplitude and phase. Inverse matrix computing means for computing an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to each combination of a transmitting antenna and N receiving antennas;
Pre-interference canceling means for performing multiplication of the inverse matrix obtained by the inverse matrix computing means for each subcarrier of each OFDM symbol generated by the data converting means;
N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N systems of signals output from the front interference canceling means;
N fast inverse Fourier transform means for performing inverse Fourier transform on the signals output from the N multiplexing means;
Symbol timing generating means for providing a common OFDM symbol timing to all of the N fast inverse Fourier transform means;
N transmission frequency conversion means for converting the frequency of the signal output from the fast inverse Fourier transform means into a radio frequency;
Transmitting local oscillating means for providing a common local oscillating signal to all of the N transmitting frequency converting means;
And the OFDM signal receiving device includes:
N reception frequency conversion means for converting radio frequency reception signals received by the N reception antennas into frequencies suitable for demodulation;
Local oscillation means for receiving that provides a common local oscillation signal to all of the N receiving frequency conversion means;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N receiving frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
Timing signal generating means for generating a timing signal necessary for extracting N pilot signals transmitted via each of the N transmitting antennas from a received signal;
Information transmitting means for detecting the amplitude and phase of the received N pilot signals for each subcarrier from the output of the fast Fourier transform means and transmitting the detected information to the OFDM signal transmitting apparatus; An OFDM signal transmission system comprising: An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. An OFDM signal transmission apparatus used in an OFDM signal transmission system for transmitting from a transmission antenna,
Pilot signal generating means for generating known N types of pilot signals corresponding to each of the N transmitting antennas;
N data conversion means for converting each of N input transmission data into OFDM symbols;
Information receiving means for receiving reception information of a pilot signal transmitted from the OFDM signal receiving device;
Based on the information received by the information receiving means, the amplitude and phase of N pilot signals received by the OFDM signal receiving apparatus are detected for each subcarrier, and the N pieces of N pilot signals are detected based on the detected amplitude and phase. Inverse matrix computing means for computing an inverse matrix of a matrix composed of N × N element transfer coefficients corresponding to each combination of a transmitting antenna and N receiving antennas;
Pre-interference canceling means for performing multiplication of the inverse matrix obtained by the inverse matrix computing means for each subcarrier of each OFDM symbol generated by the data converting means;
N multiplexing means for multiplexing N types of pilot signals output from the pilot signal generating means on each of N signals output from the front interference canceling means;
N fast inverse Fourier transform means for performing inverse Fourier transform on the signals output from the N multiplexing means;
Symbol timing generating means for providing a common OFDM symbol timing to all of the N fast inverse Fourier transform means;
N transmission frequency conversion means for converting the frequency of the signal output from the fast inverse Fourier transform means into a radio frequency;
OFDM signal transmitting apparatus characterized by comprising a an <br/> transmission local oscillator means for providing a common local oscillator signal to all of said N transmission frequency conversion means. An OFDM signal transmitting apparatus including a plurality of N transmitting antennas and an OFDM signal receiving apparatus including a plurality of N receiving antennas, wherein the OFDM signal transmitting apparatus transmits the N signals of the same radio frequency to the N signals. An OFDM signal receiving apparatus used in an OFDM signal transmission system that transmits from a transmitting antenna,
N reception frequency converting means for converting radio frequency reception signals received by the N reception antennas into frequencies suitable for demodulation;
Local oscillation means for receiving that provides a common local oscillation signal to all of the N receiving frequency conversion means;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N receiving frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
And timing signal generating means for generating a timing signal necessary to extract the N pilot signals transmitted via each of said N transmit antennas from the reception signal,
Information transmitting means for detecting the amplitude and phase of the received N pilot signals for each subcarrier from the output of the fast Fourier transform means and transmitting the detected information to the OFDM signal transmitting apparatus; An OFDM signal receiving apparatus comprising: 23. The OFDM signal transmission system according to claim 19 or claim 22, wherein the OFDM signal receiving apparatus further includes at least one information transmitting antenna, and the OFDM signal transmitting apparatus further includes at least one information receiving antenna. An OFDM signal transmission system provided. An OFDM signal transmitting apparatus including a plurality of N first set antennas; and an OFDM signal receiving apparatus including a plurality of N second set antennas, wherein the OFDM signal transmitting apparatus uses the same radio frequency OFDM. An OFDM signal transmission system for transmitting signals from the N first sets of antennas,
In the OFDM signal receiving apparatus,
Pilot signal generating means for generating known N types of pilot signals corresponding to each of the first set of antennas;
N inverse fast Fourier transform means for performing inverse fast Fourier transform on the N types of pilot signals output by the pilot signal generating means;
N transmission frequency conversion means for converting a signal output from the inverse fast Fourier transform means into a radio frequency for transmission;
N reception frequency conversion means for converting the radio frequency reception signals received by the second set of antennas into frequencies suitable for demodulation;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N receiving frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
Local oscillation means for providing a common signal to all of the N transmission frequency conversion means and the N reception frequency conversion means;
A transmission / reception change-over switch means for switching between transmission and reception for the N second sets of antennas;
And the OFDM signal transmitter includes:
N data conversion means for converting each of N input transmission data into OFDM symbols;
N receiving frequency converting means for converting a radio frequency pilot signal transmitted from the OFDM signal receiving apparatus and received by the first set of antennas into a frequency suitable for demodulation;
N fast Fourier transform means for performing Fourier transform on the signal output from the reception frequency transform means;
Timing signal generating means for generating a timing signal necessary for extracting each of N pilot signals transmitted via the second set of antennas from the received signal output by the fast Fourier transform means;
Based on the signal extracted from the output of the fast Fourier transform means, the amplitude and phase of N pilot signals transmitted from the OFDM signal transmission device are detected for each subcarrier, and based on the detected amplitude and phase. An inverse matrix operation for calculating an inverse matrix of a matrix composed of N × N elements corresponding to the combinations of the N first antennas and the N second antennas. Means,
Pre-interference canceling means for performing multiplication of the inverse matrix obtained by the inverse matrix computing means for each subcarrier of each OFDM symbol generated by the data converting means;
N fast inverse Fourier transform means for performing an inverse Fourier transform on the signal output from the pre-interference canceling means;
And N transmission credit frequency converting means for converting the frequency of the signal output of the inverse fast Fourier transform unit to a radio frequency,
Local oscillation means for providing a common local oscillation signal to all of the N transmission frequency conversion means and the N reception frequency conversion means;
Transmission / reception changeover switch means for switching between transmission and reception with respect to the N first sets of antennas;
OFDM signal transmission system characterized in that a. An OFDM signal transmitting apparatus including a plurality of N first set antennas; and an OFDM signal receiving apparatus including a plurality of N second set antennas, wherein the OFDM signal transmitting apparatus uses the same radio frequency OFDM. An OFDM signal receiving apparatus for use in an OFDM signal transmission system for transmitting signals from the N first set of antennas,
A pilot signal generating means for generating a known N kinds of pilot signals corresponding to the respective front Symbol first set of antennas,
N inverse fast Fourier transform means for performing inverse fast Fourier transform on the N types of pilot signals output by the pilot signal generating means;
N transmission frequency conversion means for converting a signal output from the inverse fast Fourier transform means into a radio frequency for transmission;
N reception frequency converting means for converting radio frequency reception signals received by the second set of antennas into frequencies suitable for demodulation;
N fast Fourier transform means for performing a Fourier transform process on each of the N received signals output from the N reception frequency transform means;
N demodulation means for converting the OFDM symbol output from the fast Fourier transform means into a bit string;
Local oscillation means for providing a common signal to all of the N transmission frequency conversion means and the N reception frequency conversion means;
It said N second pairs of antenna OFDM signal receiving apparatus characterized in that a <br/> transmitting and receiving changeover switch means for switching between transmission and reception for. An OFDM signal transmitting apparatus including a plurality of N first set antennas; and an OFDM signal receiving apparatus including a plurality of N second set antennas, wherein the OFDM signal transmitting apparatus uses the same radio frequency OFDM. An OFDM signal transmission apparatus for use in an OFDM signal transmission system for transmitting a signal from the N first set of antennas,
N data conversion means for converting each of N input transmission data into OFDM symbols;
N receiving frequency converting means for converting a radio frequency pilot signal transmitted from the OFDM signal receiving apparatus and received by the first set of antennas into a frequency suitable for demodulation ;
N fast Fourier transform means for performing Fourier transform on the signal output from the reception frequency transform means ;
Timing signal generating means for generating a timing signal necessary for extracting each of N pilot signals transmitted via the second set of antennas from the received signal output by the fast Fourier transform means;
Based on the signal extracted from the output of the fast Fourier transform means, the amplitude and phase of N pilot signals transmitted from the OFDM signal transmission device are detected for each subcarrier, and based on the detected amplitude and phase. An inverse matrix operation for calculating an inverse matrix of a matrix composed of N × N elements corresponding to the combinations of the N first antennas and the N second antennas. Means,
Pre-interference canceling means for performing multiplication of the inverse matrix obtained by the inverse matrix computing means for each subcarrier of each OFDM symbol generated by the data converting means;
N fast inverse Fourier transform means for performing an inverse Fourier transform on the signal output from the pre-interference canceling means;
And N transmission credit frequency converting means for converting the frequency of the signal output of the inverse fast Fourier transform unit to a radio frequency,
Local oscillation means for providing a common local oscillation signal to all of the N transmission frequency conversion means and the N reception frequency conversion means;
An OFDM signal transmitting apparatus, comprising: a transmission / reception changeover switch unit that switches between transmission and reception for the N first sets of antennas.

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