JPH08298498A - Multi-carrier transmitter and receiver - Google Patents

Abstract

PURPOSE: To reduce the effect of fading by adding an error correcting code to input information, distributing the information to each channel, and respectively subjecting each information to spread spectrum, different frequency modulation, synthesis and transmission. CONSTITUTION: An 8-bit signal added to 8-bit input serial information from a terminal A1 by an error correction coding circuit 1 is converted into 1-bit for each channel by a serial/parallel conversion circuit 2. Then spread spectrum devices 3-1 to 3-n apply spread spectrum modulation using BPSK to the resulting signal. Then the data are mixed at an oscillating frequency different by a frequency corresponding to a data speed B, for example, and superimposed on a subcarrier by frequency modulators 6-1 to 6-n. The frequency interval of the subcarrier is basically made close up to an interval demodulated where each spectrum is not interfered and allocated to a frequency interval corresponding to the data speed B of each subcarrier. Modulated waves are synthesized by a synthesizer 7 and the result is outputted as a synthesis transmission signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicarrier transmitting apparatus and a receiving apparatus, which are one of the information data transmission systems of radio equipment.

[0002]

2. Description of the Related Art A conventional example of a multi-carrier transmitting apparatus in which a large amount of information is divided into a plurality of channels for transmission, and the receiving side combines them to make them meaningful will be described. Fig. 6 shows the multi-carrier used in the current Japanese digital MCA (multi-channel access) system.
A conventional system will be described by showing a system diagram on the transmitting side of a system called 16QAM. In the figure, A1 is an information input terminal, and 21 is a serial / parallel converter that distributes 16-bit serial data into four 4 bits. 22-1
To 22-4 are modulators for modulating 4-bit information to 16QAM, 23-1 to 23-4 are mixers, 24-1
Numerals 24 to 24-4 are oscillators that oscillate different frequencies for each indexer, 25 is a synthesizer that synthesizes four 16QAM-modulated signals, and A2 is an output terminal.

Next, the operation will be described. Input terminal A
The serial / parallel converter 21 converts the input information of the serial data input to 1 into 16 bits in parallel, and divides each into 4 bits. Each of these 4 bits is subjected to orthogonal code modulation by each of 16QAM modulators 22-1 to 22-4, and the signals subjected to each orthogonal code code modulation are further subjected to respective mixers 23-1 to 23-4 of different frequencies. A carrier for each channel is obtained by a modulated wave for each frequency. The local oscillation signal at that time is generated from the oscillators 24-1 to 24-4. This oscillation frequency is usually the information transmission rate B (b
1/16 interval of (its / sec), that is, B / 16 [H
z] every time. The frequency of from oscillator 22-1 22-4, select the _{f 22-1 = f 22-2 + B /} 16 = f 22-3 + 2B / 16 = f 22-4 + 3B / 16. These four modulated signals are combined by the combiner 25 and output as a transmission signal from the signal output terminal A2.

On the receiving side, the components having substantially the same function as described above are connected in reverse and received. The received signal is
First, the distributor distributes to each channel corresponding to the transmitting side,
These distributed signals are returned to the baseband by the modulators having different frequencies, respectively, 16QAM-modulated, and the original 4 bits are restored in each channel. These four
The bit information is restored by the parallel / serial converter to obtain 16-bit received information. As a second conventional example, Japanese Patent Laid-Open No. 5-268189 discloses a method of effectively using the number of channels or a method of increasing the number of channels as a multiplex communication system, although it is not multi-carrier communication. According to this prior art example, each channel information input to each channel is spread with the same PN code, then frequency-modulated with different frequencies and multiplexed and transmitted. In such multiplexed communication, it is required that each channel is independent of each other, that each of them does not interfere with each other, and that accurate information is independently transmitted.

[0005]

Conventionally, for example, M-1
Since the multi-carrier modulation system based on the 6QAM modulation system is configured as described above, there is a problem that it is weak against interference of each modulated wave or interference waves from others. Figure 7
Indicates the situation during this period and means that the overlapping portions of the waveforms in the figure, that is, the hatched portions are affected. Furthermore, the propagation through the communication path causes fluctuations in the waveform and increases the overlapping portion. In order to avoid this, it is sufficient to take a sufficient interval between the modulated waves or to make each spectrum narrower band by a baseband filter, but this causes a problem that the transmission efficiency deteriorates or the fading characteristics deteriorate. . Further, the conventional example 2 has a problem that transmission with low error is required for each channel.

The present invention has been made to solve the above problems. Even when the frequency difference between carrier waves is set, interference between carrier waves is small and the influence of fading is small. Moreover, it is an object of the present invention to provide a multi-carrier transmission / reception device in which a plurality of channels cooperate to obtain correct information comprehensively even if the reliability of each channel is poor.

[0007]

A multicarrier transmission apparatus according to the present invention requires an error correction coding circuit for adding an error correction code to input information as transmission information, and transmission information with this error correction code. Serial / parallel conversion circuit that distributes the distributed transmission information to each channel, a plurality of spread spectrum circuits that spread the distributed distributed transmission information for each channel, and divided transmission information that is spread spectrum for each channel are different from each other. A plurality of frequency modulation circuits for modulating the frequency and a combiner for combining the frequency-modulated divided transmission information and transmitting the combined transmission information to the other party as one transmission signal are provided.

Alternatively, a synchronization code adding circuit for adding a synchronization code to the input information as transmission information, a serial / parallel conversion circuit for distributing the transmission information with the synchronization code to required channels, and the distributed distribution. A plurality of spread spectrum circuits that spread the transmission information for each channel, a plurality of frequency modulation circuits that modulate each spread spectrum divided transmission information for each channel at different frequencies, and these frequency modulated circuits And a combiner for combining the divided transmission information and transmitting the combined transmission information to the other party as one transmission signal.

Further, in the transmitting apparatus having the basic structure, the spread spectrum circuit uses the same code for each channel.

Furthermore, the serial / parallel conversion circuit for distributing the transmission information is provided with the redundancy so that the same part of the divided transmission information is distributed to a plurality of channels.

Furthermore, the spread spectrum circuit has different spread processing gains for the respective channels.

A multicarrier receiver according to the present invention includes a distributor that distributes a received signal to each channel, and frequency-modulates the distributed distributed received signal at a different frequency for each channel corresponding to the transmitting side. Frequency converters for returning to the baseband, a plurality of spectrum despreading circuits for despreading the distributed reception signals returned to these basebands for each channel to obtain distributed reception information, and the output of each channel. A parallel / serial conversion circuit that converts serial information into one piece of serial received information and an error correction decoding circuit that error-corrects and decodes the serial received information to obtain received information are provided.

Further, a distributor for distributing the received signal to each channel, and a plurality of frequencies for frequency-modulating the distributed distributed received signal corresponding to the transmitting side with a frequency different for each channel and returning to the baseband. A converter, a plurality of spectrum despreading circuits for despreading the distributed reception signals returned to these basebands for each channel to obtain distributed reception information, and converting each channel output into serial information to obtain one A parallel / serial conversion circuit for converting serial reception information into a serial reception information and a synchronization code detection circuit for detecting synchronization code for each channel from the serial reception information to obtain synchronization and receive information are provided.

Furthermore, the spectrum despreading circuit in the receiver having the basic structure uses the same code for each channel.

Furthermore, the same distributed reception information is obtained from a plurality of channels as a parallel / serial conversion circuit output for obtaining one serial reception information from the distributed reception information of each channel output, and redundancy is provided.

Furthermore, the spectrum despreading circuit has different spreading processing gains for each channel.

[0017]

In the multicarrier transmission apparatus according to the present invention, an error correction code is added to input information, distributed to each channel, spectrum-spread, modulated at different frequencies, combined, and combined into one meaningful transmission signal. Sent.

Alternatively, a synchronization code is added to the input information, distributed to each channel, spectrum-spreaded,
The signals are modulated at different frequencies, combined, and transmitted as one meaningful transmission signal.

Further, when the spectrum is spread in each channel, the same code is used to spread in synchronization.

Furthermore, the same information portion is modulated as distributed transmission information on a plurality of channels, and is then combined and transmitted as a transmission signal having redundancy.

Furthermore, when the spectrum is spread in each channel, the distributed transmission information of high importance is spread with a lower spreading gain.

In the multicarrier receiver according to the present invention, the received signal is distributed to each channel, modulated at different frequencies, further spectrum-spread-spread, combined and error-correction decoded to obtain one meaningful received information. obtain.

Alternatively, the received signal is distributed to each channel, modulated at different frequencies, further spectrally despread, combined, and the sync code is detected to obtain one meaningful received information.

Furthermore, when the received signal is spectrally inversely transformed in each channel, it is inversely transformed in synchronization with the same code.

Furthermore, the received signal has redundancy, and the same distributed reception information is obtained in a plurality of channels, and after the serial conversion, 1 is obtained.
It is restored as one meaningful reception information.

Furthermore, when the received signal is spectrally inversely transformed in each channel, it is inversely transformed with a different transformation processing gain. For example, important distributed reception information is transformed with a lower transformation gain.

[0027]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a multicarrier transmission apparatus according to an embodiment of the present invention. In the figure, A1 is an information input terminal, 1 is an error correction coding circuit, 2 is a serial / parallel converter for converting information from serial to parallel, 3-
1 to 3-n are spreaders (mixers), 4-1
Numerals 4-n are PN code generators. Further, 6-1 to 6-n are subcarrier oscillators, 5-1 to 5-n are frequency modulators (mixers), and n is the number of subcarriers (multi-frequency carriers). Reference numeral 7 is a combiner for combining the subcarriers, and A2 is a transmission signal output terminal. FIG. 2 is a block diagram of a corresponding multicarrier receiver. In the figure,
C1 is a receiving input terminal, 10 is a distributor, and 12-1 to 12
2-n is a subcarrier oscillator having a frequency corresponding to the frequency of each channel on the transmission side, 11-1 to 11-n are frequency modulators (mixers), and 13-1 to 13-n are despread PN codes respectively. Despreaders, 14-1 to 14-n are PN code generators corresponding to the transmitting side, 15-1 to 15-
n is the synchronization extraction / following unit. 16-1 to 16
-N is a data determination unit, 17 is a parallel / serial converter, 18 is an error correction decoding circuit that performs error correction of the restored reception information with error correction code to obtain reception information, and C2 is information that outputs reception information. It is an output terminal.

The operation of the transmitting apparatus having the above configuration and the receiving apparatus for receiving it will be described. In this embodiment, the spread spectrum method is the BPSK method, the input information is 8 bits, and the correction bits are 8 bits, that is, 16 bits in total, and the number of subcarriers is 16. The 8-bit input serial information from the A1 end is converted by the serial / parallel conversion circuit 2 into 8 bits added by the error correction coding circuit to 1 bit for each channel. Then, the spread spectrum modulators 3-1 to 3-n perform spread spectrum modulation by BPSK. These 16 systems are modulated with the same PN code and at the same phase timing. Then, for example, they are mixed at oscillation frequencies of different frequencies separated by a frequency corresponding to the data rate B [bits / sec], and are mixed on the subcarriers by the frequency modulators 6-1 to 6-n. The frequency interval of these 16 subcarriers is
Basically, it is possible to approach the intervals at which each spectrum can be demodulated without interference, but here, the intervals are arranged at the frequency BHz corresponding to the data rate B [bits / sec] of each subcarrier. The modulated waves of the respective channels are combined by the combiner 7 and output from the output terminal A2 as one combined transmission signal.

The operation on the receiving side is as follows. That is, in the figure, the 16-channel combined reception signal input from the input terminal C1 is distributed by the distributor 10 to each of the 16 channels. The distributed reception signal distributed to each channel is the frequency of each subcarrier and the frequency converter 1
It is mixed with 1-1 to 11-n and returned to the base band. The signal returned to the baseband is despread by the BPSK spread spectrum demodulation units 13-1 to 13-n corresponding to the transmission side. After that, the data determination units 16-1 to 16-n respectively determine the data, and the parallel / serial converter 17 converts the data from parallel to the original 16
Converted to bit serial data. This is further error-corrected by the error-correction decoding circuit 18, and correct reception information is output from the output terminal C2. Even if the distributed reception information of a certain channel is adversely affected and disappears or changes due to noise in the transmission path, it is restored by the error correction decoding circuit using the multiplexed distributed reception information of other channels and interleaved. And correct reception information is obtained. There is also an effect that the burst error is reduced. In the above embodiment, the 8-bit error correction code is added to the 8-bit information input, but the ratio can be changed by adding the 8-bit error correction code to the 32-bit information input.

FIG. 3 is a diagram for explaining the reduction of the influence of fading according to this embodiment. In the figure, B-1 to B-n are diagrams showing the frequency distribution of the power of the distributed transmission (or reception) information of each channel, which is spectrum-spread and modulated at frequencies different by BHz corresponding to the data transmission rate B. Is. The frequency band does not increase so much even if the number of channels increases. Moreover, the effect of fading is negligible due to spread spectrum, and the modulation after reception is not affected by other channels unless the center frequency changes significantly.

Embodiment 2 FIG. In the first embodiment, the same PN code is used with phase synchronization for each channel (thus, the code generators 4-1 to 4-n and 14-1 to 14-n in FIGS. 1 and 2 are used. May be one), but of course different PN codes may be used. By doing so, the separation between the channels becomes easier. Furthermore, as an example of different spreading codes, the same effect can be obtained even if GOLD codes having good mutual characteristics between the codes are used. In the first embodiment, the spread spectrum is performed by BPSK.
Spread spectrum by K, MSK, etc. may be adopted.

Example 3. FIG. 4 is a configuration diagram of a multi-carrier transmission device which is another embodiment of the present invention. In the figure, reference numeral 8 is a sync code adding circuit. Other serial / parallel converter 2, spectrum spreaders 3-1 to 3-n, PN code generators 4-1 to 4-n, frequency modulators 5-1 to 5-n, subcarrier generator 6-1. 6-n, the synthesizer 7 is the same as that in the first embodiment. FIG. 5 is a block diagram of a corresponding multi-carrier receiving device on the receiving side.
In the figure, 19 is a synchronous code detection circuit. Other distributor 10, frequency modulators 11-1 to 11-n, subcarrier generators 12-1 to 12-n, spectrum despreaders 13-1 to 13-n, PN code generators 14-1 to 14 -N, synchronous extraction / following unit 15-1 to 15-
n, the data decision units 16-1 to 16-n, and the parallel / serial converter 17 are the same as those in the first embodiment.

The operation of the apparatus having the above structure is as follows. Note that 8 subcarriers are prepared for 8 bits of input information. The synchronization bit is inserted in each channel, for example, every 32 bytes of data. In FIG. 4, the sync code adding circuit 8 adds a sync bit for each channel, for example, 2 bits for each 256 bits of information input. On the receiving side, these sync bits are detected and deleted by the sync detection circuit 19, and correct reception information is obtained. By inserting this synchronization bit, the synchronization is surely supplemented, burst errors are reduced, and the accuracy of obtaining correct information is improved. It should be noted that this synchronization bit may be given at different timings for each channel. By doing so, the timing of autocorrelation differs for each channel, and separation between channels becomes easier.

Embodiment 4 FIG. In the above embodiment, the input information is distributed to each channel and sent. In this embodiment, the same information is sent on a plurality of subcarriers. In this way, for example, when the same distribution information is distributed to two channels, the information transmission density is reduced to half, but the function of frequency diversity is obtained, the reliability is improved, and fading is further strengthened. .

Example 5. In the first to fourth embodiments, each subcarrier has the same information rate and the same spread spectrum processing gain, but the information transmission rate is changed for each subcarrier according to the content of information, and the processing gain is also changed. Can be changed to transmit information. It is assumed that the number of channels is 8 and the input information is divided into control data and voice data, only the control data is sent through the first channel, and the voice data is distributed through the other 7 channels. 50 on the first channel
The distribution information of 0 bits / sec and the others of 1000 bits / sec is sent, and the first PN code sequence is 200
0 and 1000 are set for the PN code sequences of other channels. By doing so, the spreading gain is changed and the information transmission density of the first channel is lowered, but the reliability is improved.

[0036]

As described above, according to the present invention, the error correction coding circuit, the serial / parallel conversion circuit, the plurality of spread spectrum circuits, the plurality of frequency modulation circuits having different frequencies, and the combiner are provided. There is an effect that a multi-carrier transmitting apparatus that suppresses spectrum interference between channels and is less affected by fading can be obtained.

Alternatively, since the synchronization code adding circuit, the serial / parallel conversion circuit, the plurality of spread spectrum circuits, the plurality of frequency modulation circuits having different frequencies, and the combiner are provided, spectrum interference between channels is suppressed and fading is suppressed. There is an effect that a multicarrier transmission device with less influence is obtained.

Furthermore, since the same code spread spectrum is used, in addition to the above basic effects, there is an effect that the circuit becomes simple.

Furthermore, since redundancy is provided partially, there is an effect that the reliability of the obtained information is increased in addition to the basic effect.

Furthermore, since the spread processing gain of the spread spectrum is changed according to the importance of the distributed transmission information, there is an effect that the reliability of the information of high importance is increased.

Further, since the distributor, the plurality of frequency modulation circuits having different frequencies, the plurality of spectrum inverse conversion circuits, the parallel / serial conversion circuit and the error correction decoding circuit are provided, there is little spectrum interference between the channels and fading occurs. There is an effect that a multi-carrier receiving apparatus with less influence of is obtained.

Further, since the distributor, the plurality of frequency modulation circuits having different frequencies, the plurality of spectrum inverse conversion circuits, the parallel / serial conversion circuit, and the synchronous code detection circuit are provided, there is little spectrum interference between the channels and fading occurs. There is an effect that a multi-carrier receiving device with less influence is obtained.

Furthermore, since the spread spectrum circuit is despread with the same code, there is an effect that the circuit is simplified in addition to the effect of the basic configuration.

Furthermore, since the redundant configuration is used to obtain the same distributed reception information on a plurality of channels, there is an effect that the reliability of the reception information is increased.

Furthermore, since the spread processing gain of spectrum despreading is changed according to the importance of the distributed reception information, there is an effect that the reliability of the important distributed reception information is increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a multicarrier transmission apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a multicarrier receiver according to a first embodiment of the present invention.

FIG. 3 is a diagram showing frequency components of each channel of the multicarrier transmission apparatus of the first embodiment.

FIG. 4 is a configuration diagram of a multicarrier transmission apparatus according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a multicarrier receiver according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional multicarrier transmission device.

FIG. 7 is a diagram for explaining interference between channels of a conventional multicarrier transmission device.

[Explanation of symbols]

1 error correction coding circuit, 2 serial / parallel conversion, 3-1 and 3-n spread spectrum device, 4-1 and 4-
n, 14-1, 14-n PN code generator, 5-1 and 5
-N, 11-1, 11-n frequency modulator (mixer),
6-1, 6-n, 12-1, 12-n Subcarrier oscillator, 7 Combiner, 8 Sync code addition circuit, 10 Distributor, 13-1, 13-n Despreader, 15-1, 15-
n synchronization extraction / following unit, 16-1, 16-n data determination unit, 17 parallel / serial converter, 18 error correction decoding circuit, 19 synchronization code detection circuit, A1 information input terminal, A2 output terminal, C1 input terminal , C2 information output terminal.

Claims (10)

[Claims] 1. An error correction coding circuit for adding error correction code to input information as transmission information, a serial / parallel conversion circuit for distributing the transmission information with the error correction code to required channels, and the above distribution. A plurality of spread spectrum circuits that spread the distributed transmission information for each channel; a plurality of frequency modulation circuits that modulate the divided transmission information that has been spread spectrum for each channel at different frequencies; A multi-carrier transmitting apparatus including a combiner that combines the divided divided transmission information and transmits the combined divided transmission information as one transmission signal to the other party. 2. A synchronization code addition circuit for adding a synchronization code to input information to make transmission information, a serial / parallel conversion circuit for distributing the transmission information with the synchronization code to required channels, and the distributed distribution. A plurality of spread spectrum circuits for spreading the transmission information for each channel, a plurality of frequency modulation circuits for modulating the divided spread information for each spread spectrum for each channel at different frequencies, and the above frequency modulation A multi-carrier transmission device comprising: a combiner that combines divided transmission information and transmits it as one transmission signal to a destination. 3. The multicarrier transmission apparatus according to claim 1, wherein the spread spectrum circuit uses the same code for each channel. 4. A serial / parallel conversion circuit for distributing transmission information, which is provided with the same portion of the divided transmission information so as to be distributed to a plurality of channels to have redundancy. Item 2. The multicarrier transmission device according to item 2. 5. The spread spectrum circuit has different spread processing gains for each channel.
Alternatively, the multicarrier transmission device according to claim 2. 6. A distributor for distributing a received signal to each channel, and a plurality of frequencies for frequency-modulating the distributed distributed received signal at a frequency different for each channel corresponding to a transmission side and returning to a baseband. A converter, a plurality of spectrum despreading circuits for despreading the distributed reception signal returned to the baseband for each channel to obtain distributed reception information, and converting each channel output into serial information to obtain one A multicarrier receiving apparatus comprising a parallel / serial conversion circuit for converting serial reception information, and an error correction decoding circuit for error-correcting and decoding the serial reception information to obtain reception information. 7. A distributor for distributing a received signal to each channel, and a plurality of frequencies for frequency-modulating the distributed distributed received signal at a frequency different for each channel corresponding to a transmission side and returning to a base band. A converter, a plurality of spectrum despreading circuits for despreading the distributed reception signal returned to the baseband for each channel to obtain distributed reception information, and converting each channel output into serial information to obtain one A multicarrier receiving apparatus comprising: a parallel / serial conversion circuit for converting serial reception information; and a synchronous code detection circuit for detecting synchronization code for each channel from the serial reception information to obtain synchronization and receive information. 8. The multicarrier receiver according to claim 6 or 7, wherein the spectrum despreading circuit uses the same code for each channel. 9. A parallel / serial conversion circuit output for obtaining one serial reception information from distributed reception information of each channel output,
8. The multicarrier receiving apparatus according to claim 6 or 7, wherein the same distributed reception information is obtained from a plurality of channels to provide redundancy. 10. The multicarrier receiving apparatus according to claim 6, wherein the spectrum despreading circuit has different spreading processing gains for the respective channels.