KR20060033140A - Method for the intelligent receiving and transmitting in the 2.3 ghz wibro and method thereof - Google Patents

Abstract

The present invention discloses an adaptive multiplexing method and apparatus therefor in a next generation portable Internet.

According to the present invention, a predetermined signal is received through an antenna array, which is a plurality of antenna stages composed of a plurality of antennas, and a channel is calculated by calculating a minimum power or a minimum value of a signal-to-noise ratio of a signal received through a multi-path of the plurality of antennas. It estimates the transmission method according to the calculated minimum power or the area of the minimum value of the signal-to-noise ratio, transmits the signal according to the determined transmission method, and measures the signal-to-noise ratio based on the received signal, thereby making it suitable for the channel environment. By selecting the transmission method, the signal transmission rate and quality improvement can be effectively increased, and the performance of the next-generation portable Internet can be greatly improved.

Description

Adaptive multi-transmission and transmission method and device therefor in next-generation mobile Internet {Method for the intelligent receiving and transmitting in the 2.3 GHz Wibro and method}

1 illustrates a flow of an adaptive multiplexing and transmitting method in a next generation portable Internet according to the present invention.

2 is a block diagram illustrating a configuration of an adaptive multiplexing and transmitting device in a next generation portable Internet according to the present invention.

3 illustrates the basic structure of a conventional space-time diversity technique.

4 illustrates the basic structure of a conventional VBLAST technique.

5 shows the basic structure of a conventional hybrid transmission technique.

6 is a graph showing a simulation result of the conventional multiplex transmission method.

7 is a graph showing an average throughput of a conventional multiplex transmission technique.

8 is a graph showing a simulation result of the multiplex transmission method according to the present invention.

9 is a graph showing the average throughput of the multiplexing technique according to the present invention.

The present invention relates to an adaptive multiplexing device and method for improving data rate and quality in a 2.3GHZ portable Internet using an Orthogonal Frequency Division Multiplexing Access (OFDMA) scheme. The receiving end relates to an apparatus and method for measuring the power (or signal-to-noise ratio) of a received signal and transmitting information to the transmitting end using a feedback channel to change the transmission scheme according to the channel environment.

The next generation wireless system transmission technology is currently receiving the most attention is the multiple input / output method that can increase the transmission speed, capacity, and performance without increasing the bandwidth by using multiple antennas installed in the transmitter and receiver.

Conventional multiple transceivers employ space-time diversity, spatial division multiplexing technology, VBLAST, or hybrid transmission techniques to increase transmission speed and capacity, increase coverage (or improve performance), and the like.

In the space-time diversity scheme, two output channel symbol signals are transmitted simultaneously by using a space-time code having two or four transmit antennas and having a delay of one symbol interval from each other. The space-time diversity technique can obtain the transmission diversity effect by a simple operation, which can increase the stability due to performance improvement, but does not increase the transmission rate.

Meanwhile, the VBLAST technique, a space-time multiplexing transmission technique proposed by Bell Labs, consists of a structure using multiple antennas for a transmitter and a receiver, respectively, and data bits are equally allocated to M transmit antennas, and modulation and encoding at each transmit antenna are performed. Is processed independently of other transmit antennas. VBLAST can increase the data rate by simultaneously transmitting data using multiple antennas, but has a disadvantage in that it does not benefit from space-time diversity in terms of bit error rate (BER) performance.

The hybrid transmission scheme that applies the space-time diversity scheme to each transmission data of the VBLAST scheme has been proposed as the most efficient transmission scheme in terms of performance and implementation complexity. However, this technique also has a weak point in BER performance than the space-time diversity technique.

That is, about three types of transmission technologies of the next generation wireless system are conventionally used, but each transmission scheme has a problem in terms of BER or transmission performance.

The technical problem to be solved by the present invention is to adapt the transmission technique according to the channel environment in order to solve the above problems, the adaptive multiplexing in the next-generation portable Internet that can increase the transmission capacity while increasing the BER performance as a result The present invention provides a method and apparatus for transmitting and receiving.

According to the present invention for solving the above technical problem, the adaptive multiplex transmission and reception method in the next-generation portable Internet, (a) receiving a predetermined signal through an antenna array which is a plurality of antenna terminals consisting of a plurality of antennas; (b) channel estimation by calculating a minimum power or a minimum value of a signal-to-noise ratio of a signal received through the multipaths of the plurality of antennas; (c) determining a transmission scheme according to a region to which the calculated minimum power or signal to noise ratio belongs; And (d) transmitting a signal according to the determined transmission scheme.

At this time, the predetermined signal received in the step (a) is a signal of the form converted to inverse high-speed pre, the minimum power of the received signal based on the symbol signal received by the respective antenna in the step (b) or It is desirable to perform channel estimation by calculating the signal-to-noise ratio.

The transmission method determined in step (c) is any one of space-time diversity, VBLAST, or hybrid transmission method, and the area to which the minimum value of the signal-to-noise ratio of step (c) belongs is 0 dB to 10 dB. 10 dB to 20 dB and 20 dB to 30 dB, and the SNR is 0 dB to 10 dB. The transmission method is space-time diversity, and the SNR is 10 dB to 20 dB. It is preferable to determine the hybrid method and the VBLAST method when the SNR is in the range of 20 dB to 30 dB.

In accordance with another aspect of the present invention, an adaptive multiplexing and transmitting device according to the present invention includes a plurality of antenna stages configured by a plurality of antennas, and receives a signal of a predetermined format converted into an inverse fast free. An antenna array; A channel estimator estimating a channel by calculating a minimum power of a signal received in a multipath through the antenna array or a minimum value of a signal-to-noise ratio; And a transmission technique setting unit for determining a proper transmission scheme according to a region to which the minimum power or the signal-to-noise ratio calculated by the channel estimator belongs and transmitting the signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates a flow of an adaptive multiplexing and transmitting method in a next generation portable Internet according to the present invention.

The method receives a predetermined signal through an antenna array, which is a plurality of antenna stages composed of a plurality of antennas (step 100), and calculates a minimum value of a minimum power or signal-to-noise ratio of a signal received through the multipath of the plurality of antennas. The channel is estimated (step 110), the transmission method is determined according to the area to which the calculated minimum power or signal-to-noise ratio belongs (step 120), and the signal is transmitted according to the determined transmission method (step 130).

FIG. 2 is a block diagram showing the configuration of an adaptive multiplexing and transmitting device in a next generation portable Internet according to the present invention. The method of FIG.

The apparatus includes a plurality of antenna stages composed of a plurality of antennas, the antenna array 200 for receiving a signal of a predetermined type converted in the reverse high-speed free, the minimum power of the signal received in a multipath through the antenna array 200 Alternatively, the channel estimator 210 estimates a channel by calculating a minimum value of the signal-to-noise ratio, and the transmission technique setting unit 220 determines a proper transmission method according to a region to which the calculation result belongs and transmits a signal according to the determined transmission method. It includes.

The transmission technique setting unit 220 is a first transmission unit 230 for transmitting a signal of a predetermined format converted to the inverse fast free by the space-time diversity method, the second transmission unit 240 for transmitting in the space-time hybrid method and VBLAST method And a third transmitter 250 for transmitting.

In FIG. 2, the transmission technique setting unit 220 is illustrated separately from the first to third transmission units 250, but this is only for understanding and convenience.

Hereinafter, an example of implementing the method of FIG. 1 through the configuration of FIG. 2 will be described.

The antenna array 200 is composed of a plurality of antenna stages composed of a plurality of antennas. The transmitters 230 to 250 transmit data signals of a predetermined format converted in reverse high speed free through the antenna array 200.

When receiving a signal, a data signal is received through each antenna provided in the antenna array 200 (step 100).

The channel estimator 210 estimates a channel by calculating a minimum power or a signal-to-noise ratio of a signal received through multiple paths of each receiving antenna (step 110).

The transmission technique setting unit 220 compares the result calculated by the channel estimator 210 with a predetermined threshold value and determines a transmission method based on this (step 120), and according to the determined optimal transmission technique, the first transmission unit The signal is transmitted through any one of the third to third transmitting units 230 to 250 (step 130). The threshold will be described in detail below.

Determining the transmission method again based on the information obtained from the signal received through the antenna array 200 may be regarded as receiving the information as a kind of feedback.

The multiplexing and receiving apparatus having the above-described configuration may independently configure each of the transmitting end and the receiving end. In this case, the transmitting end includes an antenna array 200, a transmission technique setting unit 220, and the first to third transmitting units 230 to 250, and the receiving end includes an antenna array 200 and a channel estimating 210. do. Through this, it is possible to apply an adaptive multi-transceiver and a method capable of increasing capacity by changing the transmission scheme according to the channel environment in the next-generation portable Internet.

On the other hand, in a multi-transmission channel environment in which the multi-transmission and reception apparatus according to the present invention is operated, information on the channel environment is required for effective transmission method setting.

Transmission schemes using multiple antennas select one of the following three schemes.

First, the transmission pattern of the space-time diversity scheme can be expressed by the following equation.

Here, the row represents spatial diversity in which time diversity is opened, and the transmission rate is one.

The second transmission pattern has a data rate of 4 using the VBLAST technique and is represented by the following equation.

Thirdly, the hybrid transmission scheme combining transmission diversity and spatial multiplexing has a data rate of 2 and is represented by the following equation.

If an OFDMA symbol transmitted to an antenna is expressed as a function of time, it is expressed as the following equation.

로 OFDMA 심볼 시작점 이후 경과한 시간을 나타내며,

는 OFDMA 심볼 중 주파수 오프셋 인덱스가 k인 부반송파에 전송되는 데이터를 나타내며,

는 보호구간을,

는 부반송파의 주파수 간격을 나타낸다.Where t is

Denotes the time elapsed since the start of the OFDMA symbol,

Denotes data transmitted on a subcarrier having a frequency offset index k of OFDMA symbols,

The guard interval,

Denotes the frequency interval of the subcarrier.

Description of the various transmission techniques described above is defined in the standard of the next-generation portable Internet, and those skilled in the art can easily understand the necessary contents. For example, a book containing transmission techniques is Introduction to Space-Time Wireless Communications, Cambridge, 2003. (authors Arogyaswami Paulraj, Rohit Nabar and Dhananjay Gore). For more information about space-time diversity techniques, see Starting on page 120 of the book, the BLAST or VBLAST technique starts on page 123 and the hybrid technique starts on page 228.

Therefore, in the following description, each transmission scheme will not be described separately.

In general, in a multiple transmit / receive antenna system, a frequency fading channel is assumed in a wireless environment. Therefore, using a fixed transmission technique in a rapidly changing channel environment may limit the data rate and performance.

In the situation where the channel environment changes as described above, in the case of the adaptive transmission method according to the present invention, the channel information and signal power or signal-to-noise ratio of all paths are measured at each receiving end, compared with a threshold value, and the channel information is compared to the feedback channel. By transmitting the information to the transmitter through the channel, the transmission method is appropriately selected according to the channel environment. Therefore, the high data rate and the performance improvement can be obtained by using the adaptive multiplexing technique.

Conventionally, three transmission schemes are used for antenna encoding.

3 shows the basic structure of a conventional space-time diversity technique. In the space-time diversity scheme, two output channel symbols simultaneously transmit information passing through a modulator with a symbol interval delay using a space-time code having four transmit antennas. The space-time diversity technique can obtain the transmission diversity effect by a simple operation, which can increase the stability due to performance improvement, but has a disadvantage of increasing the transmission rate.

4 shows the basic structure of a conventional VBLAST technique. The VBLAST structure, which is a space-time multiplexing transmission technique proposed by Bell Labs, consists of a structure using multiple antennas for a transmitter and a receiver, and has recently been proposed as a very efficient means for wireless communication in many multipath environments. Typical values of this structure channel capacity are very high compared to the values of existing structures. In the VBLAST transmitting end, data bits are equally allocated to M transmit antennas, and modulation and encoding at each transmit antenna are processed independently of other transmit antennas.

However, the VBLAST technique increases the data rate in proportion to the number of antennas, but has a disadvantage in that the overall performance is degraded when the channel environment is very bad.

In order to secure this, the hybrid transmission scheme is applied to detect the signal by adopting the advantages of the space-time diversity technique and the VBLAST technique in the next-generation portable Internet.

5 shows the basic structure of a circuit implementing the hybrid transmission technique. As shown in FIG. 5, the hybrid transmission scheme performs space-time block encoding on two transmission antennas and transmits different data vectors to each transmission antenna group. The hybrid transmission technique using the space-time diversity technique for each transmission data of the VBLAST scheme is an effective transmission technique in terms of performance and implementation complexity.

In order to apply the adaptive multiplexing technique according to the present invention, a channel environment is estimated from a signal received through an antenna.

The channel estimator 210 calculates the minimum power or signal-to-noise ratio of the received signal to obtain information about the channel environment. The receiving end compares this minimum power or signal-to-noise ratio with a threshold and transmits information on the transmission technique setting to the transmitting end via a feedback channel. The equation for calculating the signal-to-noise ratio is as follows.

Here, R is a coefficient of the frequency axis of the signal received through each path to the j-th antenna, S is a transmission signal vector on the frequency axis, and H is a multipath channel. The minimum value of the signal-to-noise ratio of the signal received at the j-th antenna through each path is selected and compared with the signal-to-noise ratio of the other receiving antennas to obtain the minimum value.

Where j and k represent a receive antenna and a multipath, respectively.

The measured signal-to-noise ratio minimum value is compared with a threshold value, the corresponding value is stored, and the information is transmitted to the transmitting end through a feedback channel, and the transmitting technique setting unit 220 of the transmitting end selects a suitable transmission method based on the channel condition. Will be set.

In fact, to find the threshold, we can estimate the signal-to-noise ratio several times and average it. Based on this, the adaptive transmission method according to the present invention is used.

At this time, the embodiment of the present invention uses a method of setting a threshold value according to the BER performance of each transmission scheme.

In general, since the space-time diversity technique shows good performance even at a low signal-to-noise ratio, it is preferable that the signal-to-noise ratio SNR be adopted in the range of 0 dB to 10 dB.

Hybrid transmission technique is a combination of space-time diversity technique and VBLAST technique, which has lower performance than space-time diversity technique but increases transmission rate, so SNR is applied in the range of 10 dB to 20 dB, and VBLAST technique is applied at high signal-to-noise ratio. Therefore, it is preferable to apply the SNR at 20 dB to 30 dB.

That is, the transmission method setting unit 220 determines the transmission method according to the criteria (step 120). That is, the thresholds are set so that the transmission schemes can achieve the maximum performance according to the channel state.

According to the above criterion, the transmitter punishment setting unit 220 determines the transmission method as the space-time diversity method when the SNR is in the range of 0 dB to 10 dB, and transmits a signal through the first transmitter 230, and the SNR. In the case of the 10 dB to 20 dB region, the transmission method is determined as a space-time hybrid method to transmit a signal through the second transmitter 240, and when the SNR is an area of 20 dB to 30 dB, the transmission scheme is VBLAST. In this manner, the signal is transmitted through the third transmitter 250.

The following is an experiment for verifying the effect of the present invention.

For this experiment, the following parameters defined in the mobile Internet standard were considered. (1) FFT size: 1024, (2) effective symbol time: 102.4us, (3) CP time: 12.8us, (4) OFDMA symbol time: 115.2us, (5) modulation method: QPSK, (6) transmission per second Number of bits: 17Mbit [(1 / 115.2us) * 1024 * 2]. The threshold was set by dividing the signal-to-noise ratio from 0 dB to 30 dB into three sections of 10 dB.

6 is a graph showing the BER performance of the conventional multiple transceiver, Figure 7 is a graph showing the throughput of the conventional multiple transceiver.

The BER performance of the VBLAST technique is significantly reduced, but the throughput is about 4 times that of the space-time diversity technique (STBC) and twice that of the hybrid transmission technique (STBC / BLAST) at high signal-to-noise ratio. At low signal-to-noise ratios, however, the effect of very low BER performance does not lead to a significant increase in throughput. For that reason, an adaptive transmission scheme is required to select an appropriate transmission scheme according to the signal-to-noise ratio and channel conditions.

8 is a graph showing the BER performance of the adaptive multiplexing and transmitting apparatus according to the present invention, and FIG. 9 is a graph showing the throughput of the adaptive multiplexing and transmitting apparatus according to the present invention.

The BER performance can be clearly seen when compared to the case of using the space-time multiplexing technique in FIG. 6, and the throughput at the high signal-to-noise ratio shows that the performance is almost similar to that of the space-time multiplexing technique. Can be.

As a result, the performance of the next generation portable Internet can be improved by providing the performance improvement according to the increase in the number of antennas, and the data transmission rate of the next generation portable Internet can be increased by effectively increasing the signal transmission rate and the quality improvement.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the present invention, a predetermined signal is received through an antenna array, which is a plurality of antenna stages composed of a plurality of antennas, and a channel is calculated by calculating a minimum power or a minimum value of a signal-to-noise ratio of a signal received through a multi-path of the plurality of antennas. It estimates the transmission method according to the calculated minimum power or the area of the minimum value of the signal-to-noise ratio, transmits the signal according to the determined transmission method, and measures the signal-to-noise ratio based on the received signal, thereby making it suitable for the channel environment. By selecting the transmission method, the signal transmission rate and quality improvement can be effectively increased, and the performance of the next-generation portable Internet can be greatly improved.

Claims (9)

(a) receiving a predetermined signal through an antenna array which is a plurality of antenna stages composed of a plurality of antennas; (b) estimating a channel by calculating a minimum power or a minimum value of a signal-to-noise ratio of a signal received through the multipaths of the plurality of antennas; (c) determining a transmission scheme according to a region to which the calculated minimum power or signal to noise ratio belongs; And and (d) transmitting a signal according to the determined transmission scheme. The method of claim 1, The predetermined signal to be transmitted in the step (d) is adaptive multiplex transmission and reception method in the next generation portable Internet, characterized in that the signal of the form converted to inverse high-speed free. The method according to claim 1 or 2, Adaptive multi-transmitting and receiving method in the next generation portable Internet, characterized in that in step (b) to estimate the channel by calculating the minimum power or signal-to-noise ratio of the received signal based on the symbol signal received by each antenna . The method of claim 1, Adaptive transmission and reception method in the next generation portable Internet, characterized in that the transmission method determined in step (c) is any one of space-time diversity, VBLAST or hybrid transmission. The method according to claim 1 or 4, The region to which the minimum value of the signal-to-noise ratio of step (c) belongs includes regions where the signal-to-noise ratio SNR is 0 dB to 10 dB, 10 dB to 20 dB, and 20 dB to 30 dB, When the SNR is in the range of 0 dB to 10 dB, the transmission scheme is space-time diversity, when the SNR is in the range of 10 dB to 20 dB, in the space-time hybrid scheme, and when the SNR is in the range of 20 dB to 30 dB, the VBLAST scheme. Adaptive multiplex transmission and reception method in the next generation portable Internet, characterized in that determined by. An antenna array including a plurality of antenna stages comprising a plurality of antennas, the antenna array receiving a signal of a predetermined type; A channel estimator estimating a channel by calculating a minimum power of a signal received in a multipath through the antenna array or a minimum value of a signal-to-noise ratio; And Adaptive transmission and reception in the next-generation portable Internet, characterized in that it comprises a; transmission technique setting unit for determining the appropriate transmission method according to the region of the minimum power or signal-to-noise ratio calculated by the channel estimator; Device. The method of claim 6, And the channel estimator calculates a minimum power or a signal-to-noise ratio of the received signal based on the received symbol signal. The method of claim 6, The transmission technique setting unit, A first transmitter for transmitting a signal of a predetermined format converted into an inverse high speed pre-space-time diversity scheme; A second transmitter for transmitting the signal in a space-time hybrid manner; And And a third transmitter for transmitting the signal in a VBLAST scheme. The method of claim 8, The area to which the minimum value of the signal-to-noise ratio calculated by the channel estimator belongs includes areas in which the signal-to-noise ratio SNR is 0 dB to 10 dB, 10 dB to 20 dB, and 20 dB to 30 dB, The transmission technique setting unit determines the transmission method as the space-time diversity method when the SNR is in the range of 0 dB to 10 dB, and transmits the signal through the first transmitter, and when the SNR is in the range of 10 dB to 20 dB. The signal is determined by a space-time hybrid method to transmit a signal through the second transmitter. When the SNR is in the range of 20 dB to 30 dB, the transmission method is determined by the VBLAST method to transmit a signal through the third transmitter. Adaptive multiplexing and transmission device in the next generation portable Internet, characterized in that.

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