JP2009049884A - Diversity receiving circuit and radio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiving circuit attaining high-speed transmission and high-quality radio transmission in a cooperative transmission environment composed of a plurality of terminals equipped with antennas. <P>SOLUTION: The diversity receiving circuit comprises a signal detecting means for receiving signals with multiplexed data streams and separately detecting the signals of the respective streams; a likelihood extracting means for extracting likelihood information of channels from the data streams; a multiplying means for multiplying each of a plurality of separated data streams by a weighting amount detected by the likelihood extracting means; a switching means for switching output destinations of weighting signals output from the multiplying means, according to the attributes of received signals; a storage means for storing the output signals of the switching means; a cumulative adding means for outputting signals obtained by cumulative addition of output signals different from the attributes of the received signals separately output from the switching means, and signals stored in the storage means; and a signal demodulating means for demodulating the signals output from the cumulative adding means, to obtain output signals. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a demodulation circuit that receives a radio signal in a digital radio communication system, and more particularly, to a diversity reception circuit that enables diversity reception between a plurality of signals and a radio apparatus that includes the diversity reception circuit.

  Conventionally, coordinated transmission in which a plurality of terminals cooperate with each other as a partner for communication is known. FIG. 8 shows an operation of performing cooperative transmission using L-1 relay stations. As shown in FIG. 8, a certain transmitting station transfers data from other stations or performs communication on the reverse path. In some cases, only relaying is performed without transmission from the own station. FIG. 9 shows an example of resource utilization applied when L-1 relay stations perform coordinated transmission. FIG. 9 shows a case where segregation is performed using the applied time and frequency in the NW configuration shown in FIG. Data transmitted from the transmitting station is transmitted to the target terminal via the relay station. The packets once transmitted are sequentially transmitted from the relay station to the target station using time and frequency resources while avoiding collision. In this coordinated transmission, packets are assigned using L transmission intervals, and transmission is performed sequentially. In such coordinated transmission, a communication path can be set flexibly, and conventional coordinated transmission has been studied using a particularly simple terminal using a single antenna.

  On the other hand, there is a diversity technique as a technique for improving the reception characteristics of the demodulator. Diversity reception is a technique for improving radio transmission quality by combining a plurality of signals coming from different stations or by receiving a signal transmitted from one station at a plurality of stations to improve the reception level. It is. FIG. 10 shows a diversity technique applied to cooperative transmission when the terminal uses a single antenna. Further, FIG. 11 shows a configuration of a receiving circuit according to this conventional technique. 10 and 11 show configuration examples in which the relay station applies to one coordinated transmission in the coordinated transmission mode shown in FIG. As shown in FIG. 10, in the prior art, radio signals transmitted from single antenna terminals of each station are sequentially stored in the target station in time, and the maximum ratio combining that is a diversity reception technique is performed on the preceding and succeeding packets. To improve the characteristics (see, for example, Non-Patent Document 1).

Here, the operation of the receiving circuit shown in FIG. 11 will be described. A reception signal S101 received by the antenna is input to the output switching circuit 101. The first received signal S102 is input to the signal storage circuit 102. On the other hand, the next received signal S103 is output from the output switching circuit 101 and input to the maximum ratio combining circuit 103 together with the storage circuit output signal S104 output from the signal storage circuit 102. The maximum ratio combining circuit 103 outputs two signals as a signal S 105 after diversity combining, and this signal S 105 is input to the demodulation circuit 104. The demodulation circuit 104 performs signal demodulation and outputs an output signal S106. As described above, the conventional diversity combining / receiving circuit shown in FIG. 11 performs demodulation by combining signals received from a plurality of transmitting terminals having a single antenna with a maximum ratio.
Fukuyama et al., “Relay method for transmitting soft decision symbols based on error detection code results in cooperative communication”, IEICE Tech. 106, no. 119, RCS 2006-45, p59-64

  By the way, in the current radio system, transmission / reception is performed using a plurality of data streams transmitted from a plurality of antennas in order to improve the transmission rate and the error rate characteristics. Even in coordinated transmission, there are cases where signals are exchanged using a plurality of data streams in order to increase the transmission rate. At this time, since a plurality of data streams are overlapped in space and received at the receiver, the coordinated transmission for exchanging signals of one data stream transmitted from one transmission antenna corresponding to the conventional coordinated transmission However, the conventional diversity combining receiver circuit that performs maximum ratio combining cannot be used for signal demodulation.

  The present invention has been made in view of such circumstances, and a diversity receiving circuit and a wireless communication that enable high-speed transmission and high-quality wireless transmission in a cooperative transmission environment including terminals equipped with a plurality of antennas. An object is to provide an apparatus.

  The present invention includes a signal detection unit that receives a signal in which a data stream is multiplexed and separates and detects a signal of each stream, a likelihood extraction unit that extracts channel likelihood information from the data stream, and a plurality of separated Multiplication means for multiplying each of the data streams by the weighting amount detected by the likelihood extraction means, and switching means for switching the output destination of the weighted signal output from the multiplication means in accordance with the attribute of the received signal And a storage means for storing the output signal of the switching means, an output signal different from the attribute of the reception signal separately output from the switching means, and a signal obtained by performing a cumulative addition operation of the signals stored in the storage means A cumulative addition means for outputting; and a signal demodulation means for demodulating a signal output from the cumulative addition means to obtain an output signal.

  The present invention receives a signal in which a data stream is multiplexed and separates and detects a signal of each stream, and converts symbols detected from each of the plurality of separated data streams into bit information. Conversion means, likelihood extraction means for extracting channel likelihood information from the data stream, and multiplication for multiplying each bit information output from the conversion means by the weighting amount detected by the likelihood extraction means Means, switching means for switching the output destination of the weighted signal output from the multiplication means in accordance with the attribute of the received signal, storage means for storing the output signal of the switching means, and the output separately from the switching means Cumulative addition means for outputting an output signal different from the attribute of the received signal and a signal obtained by performing cumulative addition calculation of the signal stored in the storage means Characterized by comprising a signal demodulating means for obtaining an output signal by demodulating the signal output from the cumulative addition means.

  The present invention is characterized by further comprising soft decision means for making a soft decision on the signal output from the cumulative addition means and outputting the signal to the signal demodulation means.

  The present invention is further characterized by further comprising soft decision means for making a soft decision on the weighting signal output from the multiplication means and outputting it to the switching means.

  The present invention is a wireless device including the above-described diversity receiving circuit.

  By using the diversity receiving circuit according to the present invention, it is possible to obtain an effect that high-speed transmission and high-quality radio transmission can be performed in a cooperative transmission environment including terminals including a plurality of antennas.

  Hereinafter, a diversity receiving circuit and a radio apparatus according to an embodiment of the present invention will be described with reference to the drawings. Unlike a conventional method, a radio apparatus equipped with a diversity receiving circuit according to the present invention realizes high-speed radio line transmission and high-quality radio line even in cooperative transmission composed of terminals having a plurality of antennas. Therefore, it is possible to apply a plurality of data streams and to perform high-quality diversity combining reception. As a cooperative transmission to which the present invention is applicable, the model shown in FIG. 8 is also possible. In the case where the conventional diversity combining receiving circuit has been studied, the case where a transmitting station, a relay station, and a target station are each provided with a single antenna has been studied. The present invention can be applied even when all these terminals are provided with a plurality of antennas and transmit a plurality of data streams, thereby realizing a high transmission rate and high-quality data transmission.

  The diversity receiving circuit according to the present invention first performs signal separation of a plurality of data streams. The determination signal vector obtained by this signal detection is multiplied by a weighting amount that is likelihood information obtained from each data stream. Each data stream is a signal from a different transmission station (relay station) in each transmission section. Since each relay station is arranged at a different position as shown in FIG. 8, there is a high possibility that the independence of the MIMO channel matrix of the radio channel arriving from each transmitting station to the target station will increase. In the present invention, the diversity effect is extracted from the MIMO channel matrix with increased independence.

  As a detection method for extracting the likelihood for deriving the weighting amount, it is conceivable to use information from a channel estimation circuit that estimates a transfer function of a MIMO channel. In addition, when maximum likelihood estimation detection (hereinafter referred to as MLD) is used, a detection method for extracting likelihood from information of MLD calculation itself is also applicable.

  The signal multiplied by the weight obtained from the MIMO channel matrix for each stream is stored and held in the demodulator until the next signal is received. Since the next received signal is transmitted from a different transmitting station and is affected by a different MIMO channel matrix, the same weighting operation is performed on this signal. Then, the weighted diversity combining reflecting the influence of the MIMO channel matrix from each transmitting station is possible by adding the weighted signal stored and the weighted signal received at the present time. This addition result is accumulated, and the addition is repeated until reception by the demodulator is completed, thereby enhancing the diversity effect. The synthesized signal is demodulated to obtain a demodulated signal for each stream.

  Moreover, the following likelihood is applicable to the weighting amount applied to the present invention. When the MLD is used for the weighting amount proportional to the SNR or the signal detection, the difference vector A between the second estimation candidate and the determination signal vector, It is also possible to apply AB, which is the difference between the estimation candidate and the difference vector B of the determination signal vector, to weighting. Furthermore, it is also possible to use the multiplication result of the weighting amounts of the two, weighting can be performed using the above-described route values of the respective weighting amounts, and weighting can be performed using a combination thereof.

  Furthermore, when error correction coding is used for a transmission signal and error correction decoding is used on the demodulation side, a combination with soft decision is also effective. In this case, the determination signal vector detected by the MLD is converted into a bit signal, and the bit conversion signal is weighted. The weighted bit signal is stored for each transmission signal, one signal interval, or each packet. From the next transmission interval, addition synthesis is performed with the bit signal obtained from the transmitted packet signal, and signal demodulation is performed on the added synthesis signal. Of course, it is also possible to perform a soft decision on the synthesized signal.

  The present invention is also applicable to communication for each packet that is generally applied in a wireless LAN or the like. This can be realized by operating the operation of the embodiment described later for each packet. Furthermore, since the bit signal storage circuit corresponds to each packet length, diversity combining can be performed for each packet.

  In addition, in the information accumulation addition circuit shown in the embodiment described later, it is possible to realize diversity combining for packet signals by adding packet signals transmitted in a plurality of L transmission intervals. In addition, the above signal demodulation may be performed by performing error correction decoding by performing soft decision processing. It is also possible to perform the above signal synthesis on the bit signal after the soft decision. Of course, it is also possible to perform a soft decision on the synthesized signal.

  In addition to the above MLD, linear signal detection methods such as a ZF (Zero-forcing) method and an MMSE (Minimum mean square estimation) method can be applied to the signal detection circuit. Also, nonlinear signal detection such as BLAST method can be applied. When applied to MLD, a calculation amount reduction technique for suppressing the calculation amount of maximum likelihood signal detection can be applied. In addition, when MLD is applied to the signal detection circuit, a signal in the case where each terminal has one antenna, that is, each data stream can be demodulated, and is exchanged by cooperative transmission. Diversity combining reception independent of the number is possible.

  In addition, as a form of signal transmission to which the present invention can be applied, as shown in FIG. 1, in a transmission / reception system in which each station is provided with a plurality of antennas, the present invention can also be applied to a case where receiving stations are arranged at a plurality of positions. It is. In this case, it is not necessary to accumulate weighted signals in time, and diversity combining can be realized after the operation of the signal storage circuit of the cooperative transmission circuit is stopped and weighted in each branch. Thus, the present invention can be applied not only to cooperative transmission but also to other forms of transmission / reception methods.

  In the above description, the case where the transmission method of each received signal is a single carrier has been described, but application to the case where OFDM (Orthogonal Frequency Division Multiplexing) is used is also possible. In OFDM, after FFT processing of the receiver, signal processing can be performed for each subcarrier. Therefore, the present invention can be applied to the calculation for each subcarrier.

  Also, with respect to a transmission method in which transmission is performed by adding GI on the transmission side of the single carrier scheme and frequency equalization processing is performed on the reception side, the processing on the reception side is performed after the FFT operation as in OFDM, The present invention can be applied. Alternatively, STBC coding may be applied in combination with the transmission method described above as one coding method instead of the modulation method, but the present invention can be applied.

  When the above soft decision circuit is applied, convolutional coding / Viterbi decoding, turbo coding / decoding, or the like can be considered as the error correction coding / decoding method. Any method using information that can be used is applicable. As the soft decision information, it is possible to apply a soft decision method for determining the likelihood of a bit signal. In addition, a soft decision method for detecting LLR information can be applied to the soft decision circuit.

  In addition, in FIG. 9 shown as an example of cooperative transmission, a technique for avoiding signal collision between time and frequency is shown, but in addition to this, when the same frequency is used, the transmission timing is shifted in time. Various forms with different attributes such as orthogonality, spread code orthogonality, spatial orthogonality, and other transmission code orthogonality such as space-time block coding (STBC) However, all of these can be considered as diversity branches, and the present invention can be applied.

  In addition, taking advantage of the high-speed transmission and high-quality transmission of the present invention, the coordinated transmission using the present invention uses a plurality of routes to the target station to move a shield or a terminal station on a wireless line. Along with this, it is possible to greatly suppress the degree of radio link disconnection and propagation environment degradation. Further, since it is not a one-to-one wireless line, each terminal can be flexibly arranged, and an improvement in the reliability of the wireless network utilizing the high-quality features of the present invention can be expected. In addition, since relaying can be realized at each station that takes advantage of the features of high-speed transmission, it is possible to continue communication at a high reception level, and it is possible to expand the area of high-speed transmission speed. It is done.

<First Embodiment>
Next, the operation of the diversity receiver circuit according to the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a circuit configuration of the first embodiment.

  The received signal S601 is input to the signal detection circuit 601. The signal detection circuit 601 performs signal separation detection from the multiplexed signal to obtain a separated data stream signal S602. On the other hand, the received signal S601 is also input to the likelihood extracting circuit 603, and the likelihood extracting circuit 603 detects likelihood information S604 that reflects the reception quality of the input received signal. The multiplication circuit 604 performs a weighting process using the likelihood information S604 on the data stream signal S602, and reflects the reception state in the received signal.

  The weighting signal S607 is input to the output switching circuit 606. The output switching circuit 606 switches the output destination according to the reception order or the attribute state of the received signal such as the frequency. For example, a signal that is earlier in time is input to the signal storage circuit 607 as an output signal S605 for later synthesis. On the other hand, when the attribute is time, the late-arriving signal is output as the output signal S609. When the attribute is frequency, an operation of switching the output is performed so that diversity combining of a signal arriving at a different frequency from a signal arriving at a certain frequency is possible. Further, the same applies to the case where the attribute is location, and an operation of switching the output is performed so that diversity combining of a signal arriving at a location different from a signal arriving at a location is possible.

  The information addition accumulation circuit 608 performs diversity combining by adding the storage circuit output signal S608 and the output signal S609. This addition result is immediately input to the signal demodulation circuit 609 as an output signal S610 in the case of combining two signals. On the other hand, when a plurality of signals are further combined, the information addition / accumulation circuit 608 performs accumulation / addition processing and inputs the signal to the signal demodulation circuit 609 according to the number of signals to be subjected to diversity combining. Finally, the signal demodulation circuit 609 demodulates the signal to obtain an output signal S611 of each stream. The signal demodulation circuit 609 performs signal demodulation according to the modulation method and encoding on the transmission side. Specifically, a signal determination method, a decoding method such as a Viterbi algorithm, or a demodulation method represented by turbo decoding is applicable.

  In this way, high-speed diversity combining is performed on the received signal attributed to resources such as time and frequency, and received signals transmitted from different positions with respect to signals multiplexed with data streams. Transmission rate and high-quality signal demodulation are possible.

<Second Embodiment>
Next, the operation of the modified example of the circuit configuration shown in FIG. 2 will be described with reference to FIG. FIG. 3 is a block diagram showing a circuit configuration of the second embodiment. The circuit configuration shown in FIG. 3 is different from the circuit configuration shown in FIG. 2 in that a symbol / bit conversion circuit 702 is newly provided between the signal detection circuit 701 and the multiplication circuit 704.

  The received signal S701 is input to the signal detection circuit 701. The signal detection circuit 701 performs signal separation detection from the multiplexed signal to obtain a separated data stream signal S702. The symbol / bit conversion circuit 702 converts the symbol signal of the data stream signal S702 subjected to signal separation into a bit signal. Specifically, a plurality of bit signals S703 are output from one symbol signal. On the other hand, the received signal S701 is also input to the likelihood extracting circuit 703, and the likelihood extracting circuit 703 detects likelihood information S704 reflecting the reception quality of the input received signal. The multiplication circuit 704 performs a weighting process using the likelihood information S704 on the bit signal S703, and reflects the reception state in the received signal.

  The weighting signal S707 is input to the output switching circuit 706, and the output switching circuit 706 switches the output destination according to the receiving order or the attribute state of the received signal such as the frequency. For example, a signal earlier in time is input to the signal storage circuit 707 as an output signal S705 for later synthesis. On the other hand, when the attribute is time, the late-arriving signal is output as the output signal S709. When the attribute is frequency, an operation of switching the output is performed so that diversity combining of a signal arriving at a different frequency from a signal arriving at a certain frequency is possible. Further, the same applies to the case where the attribute is location, and an operation of switching the output is performed so that diversity combining of a signal arriving at a location different from a signal arriving at a location is possible.

  The information addition accumulating circuit 708 performs diversity combining by adding the storage circuit output signal S708 and the output signal S709. This addition result is immediately input to the signal demodulation circuit 709 as an output signal S710 in the case of combining two signals. On the other hand, when a plurality of signals are further combined, the information addition / accumulation circuit 708 performs accumulation / addition processing and inputs the signal to the signal demodulation circuit 709 according to the number of signals to be subjected to diversity combining. Finally, the signal demodulation circuit 709 performs signal demodulation and obtains an output signal S711 for each stream. The signal demodulation circuit 709 performs signal demodulation and decoding according to the modulation method and encoding on the transmission side. Specifically, a signal determination method or a decoding method such as a Viterbi algorithm for a bit signal suitable for convolutional coding can be applied. Alternatively, when turbo encoding is applied on the transmission side, turbo decoding or the like using iterative signal processing is also applicable.

  As described above, even after the signal is detected and converted from the symbol to the bit signal, the bit signal can be weighted by the likelihood, and finer diversity combining can be realized, so that a high transmission rate and a high quality can be realized. Signal demodulation is possible.

<Third Embodiment>
Next, the operation of the modified example of the circuit configuration shown in FIG. 3 will be described with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of the third embodiment. The circuit configuration shown in FIG. 4 is different from the circuit configuration shown in FIG. 3 in that a soft decision circuit 805 is newly provided between the information accumulation and addition circuit 808 and the signal demodulation circuit 809.

  The received signal S801 is input to the signal detection circuit 801. The signal detection circuit 801 performs signal separation detection from the multiplexed signal, and obtains a separated data stream signal S802. The symbol / bit conversion circuit 802 converts the symbol signal of the data stream signal S802 obtained by signal separation into a bit signal. Specifically, a plurality of bit signals S803 are output from one symbol signal. On the other hand, the reception signal S801 is also input to the likelihood extraction circuit 803, and the likelihood extraction circuit 803 detects likelihood information S804 reflecting the reception quality of the input reception signal. The multiplication circuit 804 performs a weighting process using the likelihood information S804 on the bit signal S803, and reflects the reception state in the received signal.

  The weighting signal S807 is input to the output switching circuit 806, and the output switching circuit 806 switches the output destination according to the reception order or the attribute state of the received signal such as the frequency. For example, a signal that is earlier in time is input to the signal storage circuit 807 as an output signal S805 for later synthesis. On the other hand, when the attribute is time, the late-arriving signal is output as the output signal S809. When the attribute is frequency, an operation of switching the output is performed so that diversity combining of a signal arriving at a different frequency from a signal arriving at a certain frequency is possible. Further, the same applies to the case where the attribute is location, and an operation of switching the output is performed so that diversity combining of a signal arriving at a location different from a signal arriving at a location is possible.

  The information addition accumulating circuit 808 performs diversity combining by adding the storage circuit output signal S808 and the output signal S809. This addition result is immediately input to the soft decision circuit 805 as an output signal S810 in the case of combining two signals. On the other hand, when a plurality of signals are further combined, the information addition / accumulation circuit 808 performs accumulation / addition processing, and inputs to the soft decision circuit 805 according to the number of signals to be subjected to diversity combining. The soft decision circuit 805 performs soft decision processing on the input composite bit signal. Finally, the signal demodulation circuit 809 demodulates the signal and obtains an output signal S811 of each stream. The signal demodulation circuit 809 performs signal demodulation and decoding according to the modulation method and encoding on the transmission side. Specifically, a signal determination method or a decoding method such as a Viterbi algorithm for a bit signal suitable for convolutional coding can be applied. Alternatively, when turbo encoding is applied on the transmission side, turbo decoding or the like using iterative signal processing is also applicable. In the configuration shown in FIG. 4, diversity combining is performed on the bit signal before the soft decision. Since diversity combining is performed on bit signals that are continuous values before being quantized, highly accurate diversity combining that is not affected by quantization is possible.

  As described above, when error correction decoding or the like in which soft decision processing is effective is performed, it is possible to appropriately reflect the likelihood information, and further, high-quality signal demodulation is possible.

<Fourth Embodiment>
Next, the operation of the modified example of the circuit configuration shown in FIG. 3 will be described with reference to FIG. FIG. 5 is a block diagram showing a circuit configuration of the fourth embodiment. The circuit configuration shown in FIG. 5 is different from the circuit configuration shown in FIG. 3 in that a soft decision circuit 905 is newly provided between the multiplication circuit 904 and the output switching circuit 906.

  The received signal S901 is input to the signal detection circuit 901. The signal detection circuit 901 performs signal separation detection from the multiplexed signal to obtain a separated data stream signal S902. The symbol / bit conversion circuit 902 converts the symbol signal of the data stream signal S902 subjected to signal separation into a bit signal. Specifically, a plurality of bit signals S903 are output from one symbol signal. On the other hand, the reception signal S901 is also input to the likelihood extraction circuit 903, and the likelihood extraction circuit 903 detects likelihood information S904 that reflects the reception quality of the input reception signal.

  The multiplication circuit 904 performs a weighting process using the likelihood information S904 on the bit signal S903, and reflects the reception state in the received signal. The weighting signal S905 is input to the soft decision circuit 905, and the soft decision circuit 905 performs soft decision processing on each weighted bit signal. The weighted signal S906 subjected to the soft decision processing is input to the output switching circuit 906, and the output switching circuit 906 switches the output destination according to the reception order or the attribute state of the received signal such as the frequency. For example, a signal earlier in time is input to the signal storage circuit 907 as an output signal S907 for later synthesis. On the other hand, when the attribute is time, the late-arriving signal is output as the output signal S909. When the attribute is frequency, an operation of switching the output is performed so that diversity combining of a signal arriving at a different frequency from a signal arriving at a certain frequency is possible. Further, the same applies to the case where the attribute is location, and an operation of switching the output is performed so that diversity combining of a signal arriving at a location different from a signal arriving at a location is possible.

  The information addition accumulating circuit 908 performs diversity combining by adding the storage circuit output signal S908 and the output signal S909. The result of the addition is immediately output as an output signal S910 and input to the signal demodulation circuit 909 when two signals are combined. On the other hand, when a plurality of signals are further combined, the information addition / accumulation circuit 908 performs accumulation / addition processing and inputs the signal to the signal demodulation circuit 909 according to the number of signals to be subjected to diversity combining. The signal demodulation circuit 909 performs signal demodulation and obtains an output signal S911 for each stream. This signal demodulation circuit 909 performs signal demodulation and decoding according to the modulation method and encoding on the transmission side. Specifically, a signal determination method or a decoding method such as a Viterbi algorithm for a bit signal suitable for convolutional coding can be applied. Alternatively, when turbo encoding is applied on the transmission side, turbo decoding or the like using iterative signal processing is also applicable. In the configuration shown in FIG. 5, diversity combining is performed on the combined signal after the soft decision. Accordingly, since the diversity combination of quantized bit information is performed, the amount of calculation and the circuit scale can be reduced.

  As described above, when error correction decoding or the like in which soft decision processing is effective can be performed, it is possible to appropriately reflect likelihood information, and further, since diversity combining is performed after soft decision processing, necessary calculations are performed. Since the number of bits can be reduced, further high-quality signal demodulation can be achieved, and in addition to this, the calculation amount and the circuit scale can be reduced.

Next, a description will be given of the results of the characteristic evaluation using computer simulation for the present invention. FIG. 6 shows the conditions of the computer simulation. The basic parameters of each MIMO-OFDM stream conformed to the IEEE802.11a wireless LAN standard. Evaluation was performed for a case where one relay station had L = 2. For basic study, it is assumed that demodulation at the cooperative base station is ideally performed. In this computer simulation, diversity combining reception was performed at the target station, and MLD was used for signal separation used for the combined packet signal. FIG. 7 shows the PER (Packet error rate) characteristics according to the computer simulation result of the present invention. For comparison, in the one-to-one communication that does not use coordinated transmission, the characteristics when MLD is used for signal separation are also shown. As shown in FIG. 7, the required E _b / N ₀ is improved by about 5.1 dB at PER = 0.01. The sufficiently high transmission rate and high quality effectiveness of the present invention in MIMO-OFDM coordinated transmission using a plurality of data streams transmitted from a plurality of antennas of the present invention can be confirmed.

  As described above, according to the present invention, when performing wireless transmission via a plurality of routes, even when a plurality of data streams are transmitted, the packet can be demodulated, and the conventional problems can be solved. .

It is explanatory drawing which shows the form of signal transmission which can apply this invention. It is a block diagram which shows the circuit structure of 1st Embodiment. It is a block diagram which shows the circuit structure of 2nd Embodiment. It is a block diagram which shows the circuit structure of 3rd Embodiment. It is a block diagram which shows the circuit structure of 4th Embodiment. It is explanatory drawing which shows the conditions of computer simulation. It is a figure which shows a computer simulation result. It is explanatory drawing which shows the operation | movement which performs cooperative transmission using a some relay station. FIG. 9 is an explanatory diagram showing segregation using applied time and frequency in the NW configuration shown in FIG. 8. It is explanatory drawing which shows the diversity technique applied to cooperative transmission in case a terminal uses a single antenna. A configuration of a receiving circuit according to the prior art is shown in FIG. It is a block diagram which shows the structure of the receiving circuit by a prior art.

Explanation of symbols

  601, 701, 801, 901... Signal detection circuit, 702, 802, 902... Symbol / bit conversion circuit, 603, 703, 803, 903... Likelihood extraction circuit, 604, 704, 804904. Multiplier circuit, 805, 905 ... soft decision circuit, 606, 706, 806, 906 ... output switching circuit, 607, 707, 807, 907 ... signal storage circuit, 608, 708, 808, 908 ..Accumulative information addition circuit, 609, 709, 809, 909... Signal demodulation circuit

Claims (5)

Signal detection means for receiving a signal in which a data stream is multiplexed and separating and detecting signals of each stream;
Likelihood extraction means for extracting channel likelihood information from the data stream;
Multiplication means for multiplying each of the plurality of separated data streams by a weighting amount detected by the likelihood extraction means;
Switching means for switching the output destination of the weighted signal output from the multiplication means according to the attribute of the received signal;
Storage means for storing an output signal of the switching means;
Cumulative addition means for outputting an output signal different from the attribute of the received signal separately output from the switching means and a signal obtained by performing cumulative addition calculation of the signal stored in the storage means;
A diversity receiving circuit comprising: a signal demodulating unit that demodulates a signal output from the cumulative adding unit to obtain an output signal. Signal detection means for receiving a signal in which a data stream is multiplexed and separating and detecting signals of each stream;
Conversion means for converting symbols detected from each of the plurality of separated data streams into bit information;
Likelihood extraction means for extracting channel likelihood information from the data stream;
Multiplication means for multiplying each bit information output from the conversion means by the weighting amount detected by the likelihood extraction means;
Switching means for switching the output destination of the weighted signal output from the multiplication means according to the attribute of the received signal;
Storage means for storing an output signal of the switching means;
Cumulative addition means for outputting an output signal different from the attribute of the received signal separately output from the switching means and a signal obtained by performing cumulative addition calculation of the signal stored in the storage means;
A diversity receiving circuit comprising: a signal demodulating unit that demodulates a signal output from the cumulative adding unit to obtain an output signal. 3. The diversity receiving circuit according to claim 2, further comprising soft decision means for making a soft decision on the signal output from the cumulative addition means and outputting the soft decision signal to the signal demodulation means. 3. The diversity receiving circuit according to claim 2, further comprising soft decision means for making a soft decision on the weighted signal output from the multiplication means and outputting it to the switching means.   A radio apparatus comprising the diversity receiving circuit according to claim 1.

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