JP2007300586A - Mimo detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection system in which computational complexity can be remarkably reduced while maintaining bit error rate characteristics nearly equal with maximum likelihood detection in MIMO signal detection. <P>SOLUTION: A metric generating circuit 31 corresponding to a metric generating means generates a metric corresponding to a transmission signal candidate on the basis of a reception signal inputted through terminals 29-1 to 29-4, channel information of a transmission line inputted from a terminal 30, and the transmission signal candidate outputted by a signal candidate generating circuit 44. A minimum metric detector 32 corresponding to a minimum metric detecting means inputs the metric and transmission signal candidate to search for a minimum metric, determines a bit of the transmission signal candidate corresponding to the minimum value and outputs the bit to a terminal 33 as a determination value. The transmission signal candidate generating circuit 44 corresponding to a transmission signal candidate generating means adds generation noise generated by a noise generating circuit 38 to the reception signal, performs linear synthesis using a weight coefficient determined from the channel information by a linear conversion circuit 35, then performs hard decision that is a sort of quantization, and generates the transmission signal candidate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to wireless communication such as a mobile phone system, and more particularly to a MIMO (Multiple Input Multiple Output) system that performs spatial multiplexing transmission using a plurality of transmission / reception antennas.

In wireless communication such as cellular phone systems, MIMO transmission that performs spatial multiplexing transmission using multiple transmitting and receiving antennas is known as a technique for increasing the transmission speed without expanding the frequency band.
Fig. 1 shows the configuration of a transmitter for MIMO transmission with the number of transmitting antennas K (K is an integer of 2 or more). First, the transmission bit sequence is input from the input terminal 1 to the serial / parallel converter 2-1, and is divided into K bit sequences. Each bit sequence is input from a corresponding baseband modulation circuit 3-1 to 3-K through a terminal 7-1, and a complex symbol corresponding to a transmission signal is generated as a modulation signal. Although this complex symbol has two components, an in-phase component and a quadrature component, it is regarded as one signal. The modulation signal that is the output of the baseband modulation circuit 3-1 is input to the modulator 4-1 through the terminals 7-2 and 7-3. The carrier signal output from the oscillator 6 is input from the terminal 7-4, and the modulator 4-1 converts the frequency of the modulated signal into the RF frequency band using this carrier signal, and transmits the corresponding transmitting antenna 5-1 through the terminal 8. Send with. The same operation is performed for other modulated signals.

  The configuration of the modulator 4 in FIG. 1 is shown in FIG. The in-phase component and the quadrature component of the complex symbol, which is a modulation signal, are input from the terminal 7-2 and the terminal 7-3, respectively, and the carrier signal is input from the terminal 7-4. The multiplier 9-1 multiplies the in-phase component of the modulation signal by the carrier signal, and the multiplier 9-2 multiplies the quadrature component of the modulation signal by the carrier signal whose phase that is the output of the phase shifter 10 is rotated by 90 degrees. . These multiplication results are added by the adder 11, amplified by the amplifier 12, and then output from the terminal 8.

  The configuration for MIMO single carrier transmission of the baseband modulation circuit 3 in FIG. 1 is shown in FIG. A bit sequence is input from the terminal 7-1 to the complex symbol generation circuit 13, and a complex symbol is generated according to the bit. The in-phase component and quadrature component of the complex symbol are output from terminals 7-2 and 7-3, respectively.

  Furthermore, FIG. 4 shows the configuration of a baseband modulation circuit 3 for MIMO-OFDM (Orthogonal Frequency Division Multiplexing) transmission. First, a bit sequence is input from the terminal 7-1 to the serial / parallel converter 2-2 and divided into bit sequences of N subcarriers (N is an integer of 2 or more). Each of the N bit sequences is input to a corresponding complex symbol generation circuit 13-1 to 13-N, and a complex symbol is generated. An IFFT (Inverse Fast Fourier Transform) circuit multiplies these complex symbols by a carrier signal corresponding to each subcarrier to generate a multicarrier signal. The guard interval adder 15 generates the OFDM modulation signal by adding the last part of the multicarrier signal as a guard interval to the head, and outputs the in-phase component and the quadrature component to terminals 7-2 and 7-3, respectively. Do it.

  Next, Fig. 5 shows the configuration of a receiver for MIMO single carrier transmission with the number of receiving antennas L (L is an integer of 2 or more). First, the received waves received by the receiving antennas 16-1 to 16-L are frequency-converted to the baseband in the corresponding receiving circuits 20-1 to 20-L, and are output as received signals. The receiving circuit 20-1 includes an amplifier 12, a hybrid 17, multipliers 9-1 and 9-2, a phase shifter 10, low-pass filters 18-1 and 18-2, and an A / D converter 19-1. The amplifier 12 and the hybrid 17 branch after amplifying the received wave, and the phase shifter 10 rotates the phase of the carrier signal output from the oscillator 6 by 90 degrees, thereby multiplying circuits 9-1 and 9-2. Multiplies the amplified received signal by the carrier signal and the carrier signal phase rotated by 90 degrees, and outputs two multiplication results. From these multiplication results, high-frequency components are removed by the low-pass filters 18-1 and 18-2, and then the in-phase component and the quadrature component of the received signal which is the baseband signal are extracted. The A / D converters 19-1 and 19-2 convert the received signal into a digital signal and output it. The signal detector 21 detects a complex symbol which is a transmission signal based on the received signal and an estimated value of an impulse response output from the transmission path estimation circuit 43 as channel information of the transmission path, and outputs a transmission bit sequence determination value. Output to terminal 22. The transmission path estimation circuit 43 estimates the impulse response of the transmission path using a known training signal input from the input terminal 23 and the received signal, and outputs this estimated value.

  Figure 6 shows the configuration of the receiver for MIMO-OFDM transmission. First, the received waves received by the receiving antennas 16-1 to 16-L are frequency-converted to baseband in the corresponding OFDM receiving circuits 26-1 to 26-L, respectively, and then separated into subcarrier components. It is output as a signal. The OFDM receiving circuit 26-1 includes a receiving circuit 20-1, a guard interval removing circuit 24, and an FFT (Fast Fourier Transform) arithmetic circuit 25. The receiving circuit 20-1 uses a carrier signal output from the oscillator 6. Frequency conversion of received wave to baseband. The guard interval removal circuit 24 removes a portion corresponding to the guard interval from the frequency-converted signal, and the FFT operation circuit 25 performs FFT, which is the inverse operation of IFFT, and separates it into each subcarrier component as a received signal. Output. Therefore, in-phase and quadrature components with N subcarriers are generated. Signal detection is performed for each subcarrier, a received signal corresponding to the first subcarrier is input to the signal detector 21-1, and a received signal corresponding to the Nth subcarrier is input to the signal detector 21-N. The signal detectors 21-1 to 21 -N use the received signal and the channel frequency response estimation value output from the DFT (Discrete Fourier Transform) circuit 27 as channel information, detect complex symbols that are transmission signals, and transmit bits The judgment value of the series is output. The parallel / serial conversion circuit 28 performs parallel / serial conversion on the determination value of the transmission bit series output from the signal detectors 21-1 to 21 -N and outputs the result to the output terminal 22. The DFT circuit 27 performs DFT on the estimated value of the impulse response of the transmission line output from the transmission line estimation circuit 43, and outputs the estimated value of the frequency response at each subcarrier frequency.

  Among various detection methods applicable to the signal detector 21 of FIGS. 5 and 6, the optimum method is maximum likelihood detection (see Non-Patent Document 1) that can minimize the bit error rate. Figure 7 shows the configuration of the signal detector 21 based on maximum likelihood detection. First, the received signal from each receiving antenna is input to the metric generation circuit 31 via the terminal. Specifically, the in-phase and quadrature components of the reception signal of the reception antenna 16-1 are received from the terminals 29-1 and 29-2, and the reception signal of the reception antenna 16-L is received from the terminals 29-3 and 29-4. In-phase and quadrature components are input respectively. As channel information of the transmission path, an estimated value of the impulse response of the transmission path is input from the terminal 30 in the case of MIMO single carrier transmission, and an estimated value of the frequency response of the transmission path is input in the case of MIMO-OFDM transmission. The metric generation circuit 31 corresponding to the metric generation means generates a metric corresponding to the transmission signal candidate based on the received signal, the channel information of the transmission path, and the transmission signal candidate output from the signal candidate generation circuit 34. This metric will be explained below using MIMO single carrier transmission as an example, using the following formula. All baseband signals are expressed in a complex representation with the in-phase component as the real part and the quadrature component as the imaginary part.

ｋは整数）送信アンテナと第ｐ受信アンテナ間のインパルス応答をｈ_ｐｋ，第ｋ送信アンテナからの送信信号，即ち複素シンボルをｓ_ｋとすると，ｙ_ｐは

と表すことができる．なお，ｎ_ｐは第ｐ受信アンテナの受信信号に加わる雑音であり，ｐが

数選択性と仮定した．

となる．

トを求め，判定値として端子３３へ出力する．なお，この最小メトリック検出器３２は最

と第ｐ受信アンテナ間の周波数応答の推定値に置き換えればよい．
このように最尤検出は，数式２のメトリックを送信信号候補の数だけ計算しなければならず，複素シンボルの多値数をＭとするとＭ^Ｋ回計算する必要がある．したがって，ＭやＫが大きい値のとき演算量が膨大になってしまうという問題がある．

k is an integer) If the impulse response between the transmitting antenna and the p-th receiving antenna is h _pk , and the transmission signal from the k-th transmitting antenna, that is, the complex symbol is s _k , y _p is

It can be expressed as. Note that n _p is noise added to the received signal of the p-th receiving antenna, and p is

Assumed number selectivity.

It becomes.

Is output to the terminal 33 as a judgment value. The minimum metric detector 32 is the maximum

And the estimated value of the frequency response between the pth receiving antennas.
Thus maximum likelihood detection has to compute a metric of Equation 2 for the number of transmission signal candidates, certain multi-level number of complex symbols is necessary to calculate M ^K times when the M. Therefore, there is a problem that the amount of calculation becomes enormous when M and K are large values.

  As explained above, maximum likelihood detection can minimize the bit error rate, but has the problem that the amount of computation is enormous. As a sub-optimal detection method that can reduce the amount of computation, linear reception is known which performs linear operation on the received signal. The configuration of the signal detector 21 based on MMSE (Minimum Mean Square Error) (see Non-Patent Document 2), which is a type of linear reception, is shown in FIG. First, the received signal from each receiving antenna is input to the linear conversion circuit 35 via a terminal. Specifically, the in-phase and quadrature components of the reception signal of the reception antenna 16-1 are received from the terminals 29-1 and 29-2, and the reception signal of the reception antenna 16-L is received from the terminals 29-3 and 29-4. In-phase and quadrature components are input respectively. As channel information of the transmission path, an estimated value of the impulse response of the transmission path is input from the terminal 30 in the case of MIMO single carrier transmission, and an estimated value of the frequency response of the transmission path is input in the case of MIMO-OFDM transmission. The linear conversion circuit 35 performs linear synthesis, which is a linear operation, on the received signal using a weighting coefficient calculated from the channel information, and generates K synthesized signals. Each of the hard discriminators 36-1 to 36-K performs a hard decision which is a kind of quantization on the synthesized signal, and obtains a complex symbol closest to the synthesized signal. The transmission bit is estimated from the complex symbol and input to the parallel / serial converter 28 as a judgment value. The parallel / serial converter 28 converts the judgment value from parallel to serial and outputs the result to the terminal 33.

を（ｐ，ｋ）成分とするＬ×Ｋ行列とする．合成信号を成分とするＫ次元ベクトルをｘとすると

と表すことができる．ここで，Ｗは重み付け係数を成分とするＫ×Ｌ行列，ＩはＫ×Ｋ単位行列である．ＷはＨから求めることができ，ｘを硬判定したものがｓの推定値となる．
この線形受信は最尤検出に較べ演算量を大幅に削減できるものの，送信信号候補の数を実質１にしていることと等価で，ビット誤り率が著しく劣化するという問題がある．The operation of the linear conversion circuit 35 will be described using mathematical expressions. First, an L-dimensional received signal vector y, a K-dimensional transmitted signal vector s, and an L-dimensional noise vector n are defined as follows.

Is an L × K matrix with (p, k) components. If a K-dimensional vector whose component is a composite signal is x,

It can be expressed as. Here, W is a K × L matrix whose components are weighting coefficients, and I is a K × K unit matrix. W can be obtained from H, and a hard decision of x is an estimate of s.
Although this linear reception can greatly reduce the amount of computation compared to maximum likelihood detection, it is equivalent to making the number of transmission signal candidates substantially 1, and has the problem that the bit error rate significantly deteriorates.

X. Zhu and R.K. D. Murch, “Performance analysis of maximum Likelihood detection in a MIMO antenna system,” IEEE Transactions on Communications, vol. 50, no. 2, pp. 187-191, February 2002. Simon Haykin, Adaptive Filter Theory Third Edition, published by Prentice-Hall, 1996.

  Thus, of the MIMO detection methods, maximum likelihood detection is an optimal detection method and can achieve the minimum bit error rate, but the amount of computation becomes enormous. In order to reduce this amount of computation, quasi-optimal detection methods such as linear reception have been proposed in the past, but there was a problem that the bit error rate deteriorated significantly when the amount of computation was reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a detection method that can significantly reduce the amount of computation while maintaining bit error rate characteristics comparable to that of maximum likelihood detection. .

According to the MIMO detection system of the present invention, the above object is achieved by the means described in the claims. That is, the MIMO detection method of the present invention includes (i) metric generation means for generating a metric corresponding to a transmission signal candidate from the received signal, channel information of the transmission path, and a plurality of transmission signal candidates. A minimum metric detecting means for searching for a value and outputting a bit of a transmission signal candidate corresponding to the minimum value as a determination value; (iii) a plurality of transmission signal candidates by linear operation and quantization based on the reception signal and channel information; Is composed of transmission signal candidate generation means for generating. The difference from the prior art is that multiple transmission signal candidates are obtained by linear operation and quantization, and the metrics are generated.
In addition, the MIMO detection method of the present invention can use a signal obtained by frequency-converting received waves received by a plurality of receiving antennas as a received signal, and use an estimated value of the impulse response of the transmission path as channel information.
Also, the MIMO detection method of the present invention performs frequency conversion on received waves received by a plurality of receiving antennas, and then uses a signal obtained by separating each of the subcarrier components as a received signal, and calculates an estimated value of the frequency response of the transmission path. Can be channel information.
Further, the transmission signal generation means (iii) of the MIMO detection system of the present invention adds the generated noise to the received signal, performs a linear operation using a weighting coefficient obtained from the channel information, and then performs a plurality of transmissions by quantization. Generate signal candidates.
In addition, the (iii) transmission signal generation means of the MIMO detection system of the present invention performs a linear operation using a weighting coefficient obtained from the channel information on the received signal, obtains an initial value, and obtains an initial value, channel information, and reception The update value is further obtained based on the signal, and after adding the update value to the initial value, multiple transmission signal candidates are generated by quantization.

The present invention has the following effects.
According to the MIMO detection system of the first aspect of the present invention, the amount of calculation can be greatly reduced while maintaining the bit error rate performance comparable to that of maximum likelihood detection.
The MIMO detection system according to the second aspect of the present invention can be applied to MIMO single carrier transmission.
The MIMO detection system according to the third aspect of the invention can be applied to MIMO-OFDM transmission.
According to the MIMO detection system of the fourth aspect of the invention, the number of transmission signal candidates can be reduced and the amount of calculation can be reduced.
According to the MIMO detection system of the fifth aspect of the invention, the number of transmission signal candidates can be further reduced and the amount of calculation can be greatly reduced.

The best mode for carrying out the present invention will be described below.
First, FIG. 9 shows the configuration of the signal detector 21 using the MIMO detection system of the first invention (claim 4). The difference from the signal detector 21 based on the conventional maximum likelihood detection shown in FIG. 7 is that the signal candidate generation circuit 34 is replaced with a transmission signal candidate generation circuit 44 corresponding to transmission signal candidate generation means. The transmission signal candidate generation circuit 44 includes adder circuits 37-1 to 37-L, a noise generation circuit 38, a linear conversion circuit 35, quantizers 39-1 to 39-K, and a parallel / serial converter 40. The operation of the transmission signal candidate generation circuit 44 will be described in detail below.

信号を生成する．この合成信号を成分とするＫ次元ベクテルをｘとすると

るＫ×Ｌ行列であり，１回目は生成雑音が加わっていないことと等価なので数式７のＷと等しくなるが，２回目以降は分散ξの生成雑音が新たに加わっているのでＷと異なる．なお，ＭＭＳＥではなくＺＦ（Ｚｅｒｏ Ｆｏｒｃｉｎｇ）による線形合成を行うこともでき

とすることもできる．量子化器３９−１から３９−Ｋはそれぞれ，上記の合成信号に量子化の一種である硬判定を行い，合成信号に最も近い複素シンボルを求め，パラレル・シリアル変換器４０へ入力する．パラレル・シリアル変換器４０はこの複素シンボルをパラレル・シリアル変換し，送信信号候補として出力する．
このように，従来の最尤検出では全ての送信信号候補に対してメトリックを計算する必要があったが，本発明では送信信号候補数をＣに削減でき，演算量を大幅に削減できる．また，従来のＭＭＳＥでは送信信号候補の数を実質１としているのに対し，本発明はＭＭＳＥによる送信信号候補を含むＣ個の送信信号候補に対してメトリックを計算し，最小メトリックに相当する送信信号候補を選択するので，ＭＭＳＥよりもビット誤り率が改善できる．
なお，繰り返し処理を行う場合，受信信号の代わりに，最小メトリックに対応する送信信号候補もしくはそのｘを使うこともでき，さらなるビット誤り率改善が期待できる．Let C be the number of transmission signal candidates (C is an integer of 2 or more). The noise generation circuit 38 artificially generates a complex Gaussian signal C times. The first generation generates L signals whose values are zero, and the second and subsequent times are complex values that are uncorrelated with each other with an average value of zero and a variance ξ. Generate L Gaussians. The adding circuits 37-1 to 37-L add the generated noise generated by the noise generating circuit 38 to the received signal. Specifically, for the in-phase component and the quadrature component of the received signal of the receiving antenna 16-1 input from the terminals 29-1 and 29-2, the in-phase component and the quadrature component of the first generated noise are added, respectively. For the in-phase component and the quadrature component of the received signal of the receiving antenna 16-L input from 29-3 and 29-4, the in-phase component and the quadrature component of the Lth generated noise are added, respectively. Adder circuit 3

Generate a signal. If the K-dimensional vector whose component is this synthesized signal is x,

This is equivalent to the fact that the generated noise is not added at the first time, and is equal to W in Equation 7. However, the second time and later are different from W because the generated noise of variance ξ is newly added. It is also possible to perform linear synthesis using ZF (Zero Forcing) instead of MMSE.

Can also be used. Each of the quantizers 39-1 to 39-K performs a hard decision which is a kind of quantization on the above synthesized signal, obtains a complex symbol closest to the synthesized signal, and inputs it to the parallel-serial converter 40. The parallel / serial converter 40 performs parallel / serial conversion on the complex symbol and outputs it as a transmission signal candidate.
As described above, in the conventional maximum likelihood detection, it is necessary to calculate metrics for all transmission signal candidates. However, in the present invention, the number of transmission signal candidates can be reduced to C, and the amount of calculation can be greatly reduced. Also, in the conventional MMSE, the number of transmission signal candidates is substantially 1, whereas in the present invention, metrics are calculated for C transmission signal candidates including transmission signal candidates by MMSE, and transmission corresponding to the minimum metric is performed. Since the signal candidate is selected, the bit error rate can be improved compared to MMSE.
When iterative processing is performed, a transmission signal candidate corresponding to the minimum metric or its x can be used instead of the received signal, and further improvement of the bit error rate can be expected.

  Next, FIG. 10 shows the configuration of the signal detector 21 using the MIMO detection system of the second invention (Claim 5). The difference from the signal detector 21 based on the conventional maximum likelihood detection shown in FIG. 7 is that the signal candidate generation circuit 34 is replaced with a transmission signal candidate generation circuit 45 corresponding to transmission signal candidate generation means. The transmission signal candidate generation circuit 45 includes a linear conversion circuit 35, quantizers 41-1 to 41-K, an update value calculation circuit 42, adder circuits 37-1 to 37-K, and quantizers 39-1 to 39. The operation of the transmission signal candidate generation circuit 45 will be described in detail below.

  First, the received signal from each receiving antenna is input to the linear conversion circuit 35 via a terminal. Specifically, the in-phase and quadrature components of the reception signal of the reception antenna 16-1 are received from the terminals 29-1 and 29-2, and the reception signal of the reception antenna 16-L is received from the terminals 29-3 and 29-4. In-phase and quadrature components are input respectively. The linear conversion circuit 35 calculates a weighting coefficient from the channel information input from the terminal 30 and performs linear composition, which is a linear operation, on the received signal using the weighting coefficient to generate K composite signals. This synthesized signal corresponds to the initial value x. Each of the quantizers 41-1 to 41-K performs a hard decision which is a kind of quantization on the synthesized signal, obtains a complex symbol closest to the synthesized signal, and inputs the complex symbol to the update value calculation circuit. The update value calculation circuit 42 obtains an update value from the complex symbol whose initial value is hard-decided, the received signal, and the channel information. The adder circuits 37-1 to 37-K add the updated value to the initial value, and the quantizers 39-1 to 39-K make a hard decision as a kind of quantization for the addition result, Find the nearest complex symbol and input it to the parallel-serial converter 40. The parallel / serial converter 40 performs parallel / serial conversion on the complex symbol and outputs it as a transmission signal candidate.

ある．また，Ｐは数式１３で定義するＫ×Ｋ行列である．
μ_ｒはｒ＝０では０とする．即ち，ｒ＝０の送信信号候補はｘを単に硬判定したものとなり，ＭＭＳＥと同じになる．ｒが１以上では

このように，μ_ｒはＫ（Ｍ−１）＋１個値が存在する．送信信号候補は，ｘにｕを加算した後，硬判定したものであるから，μ_ｒの数，即ちＫ（Ｍ−１）＋１個存在する．したがって，従来の最尤検出では全ての送信信号候補に対してメトリックを計算する必要があったが，本発明では送信信号候補数をＫ（Ｍ−１）＋１に削減でき，演算量を大幅に削減できる．また，従来のＭＭＳＥでは送信信号候補の数を実質１としているのに対し，本発明はＭＭＳＥによる送信信号候補を含むＫ（Ｍ−１）＋１個の送信信号候補に対してメトリックを計算し，最小メトリックに相当する送信信号候補を選択するので，ＭＭＳＥよりもビット誤り率が改善できる．

く線形操作を行ってもよい．また，初期値としてｘの代わりにｘの硬判定値を用いることも可能である．さらに，数式１２のｕの代わりに

としてもよい．ただし，ｅは零ベクトルとならない任意のＬ次元ベクトルである．The operation of the update value calculation circuit 42 will be described in detail below using mathematical expressions. First, a complex symbol obtained by hard-decision of the synthesized signal, that is, the output of the quantizers 41-1 to 41-K

is there. P is a K × K matrix defined by Equation 13.
μ _r is set to 0 when r = 0. That is, the transmission signal candidate of r = 0 is a hard decision of x, which is the same as MMSE. When r is 1 or more

Thus, mu _r is K (M-1) +1 or value exists. Transmitted signal candidates, after adding u to x, since it is obtained by hard decision, the number of mu _r, i.e. K (M-1) +1 or present. Therefore, in the conventional maximum likelihood detection, it is necessary to calculate a metric for all transmission signal candidates. However, in the present invention, the number of transmission signal candidates can be reduced to K (M−1) +1, which greatly increases the amount of calculation. Can be reduced. Further, in the conventional MMSE, the number of transmission signal candidates is substantially 1, whereas the present invention calculates a metric for K (M−1) +1 transmission signal candidates including transmission signal candidates by MMSE, Since the transmission signal candidate corresponding to the minimum metric is selected, the bit error rate can be improved compared to MMSE.

It is also possible to perform linear operations. It is also possible to use a hard decision value of x instead of x as an initial value. Furthermore, instead of u in Equation 12

It is good. However, e is an arbitrary L-dimensional vector that is not a zero vector.

  Finally, the present invention is not limited to the best mode for carrying out the invention described above, and various other configurations can be adopted without departing from the gist of the present invention.

It is a block diagram of a conventional MIMO radio transmitter. It is a block block diagram of the modulator of FIG. It is a block block diagram of the baseband modulation circuit of FIG. 1 in MIMO single carrier transmission. It is a block block diagram of the baseband modulation circuit of FIG. 1 in MIMO-OFDM transmission. It is a block diagram of a conventional radio receiver in MIMO single carrier transmission. It is a block diagram of a conventional radio receiver in MIMO-OFDM transmission. It is a block block diagram using the conventional maximum likelihood detection in the signal detector of FIG. 5 and FIG. FIG. 7 is a block diagram of the signal detector shown in FIGS. 5 and 6 using a conventional MMSE. 5 is a block configuration diagram of the first invention in the signal detectors of FIGS. 5 and 6. FIG. 5 is a block diagram of the second invention in the signal detectors of FIGS. 5 and 6. FIG.

Explanation of symbols

1 input terminal, 2 serial / parallel converter, 3 baseband modulation circuit, 4 modulator, 5 transmitting antenna, 6 oscillator, 7 terminal, 8 terminal, 9 multiplier, 10 phase shifter, 11 adder, 12 amplifier, 13 complex symbol generation circuit, 14 IFFT arithmetic circuit, 15 guard interval adder, 16 receiving antenna, 17 hybrid, 18 low-pass filter, 19 A / D converter, 20 receiving circuit, 21 signal detector, 22 output terminals, 23 inputs Terminal, 24 guard interval removal circuit, 25 FFT operation circuit, 26 OFDM reception circuit, 27 DFT circuit, 28 parallel-serial converter, 29 terminal, 30 terminal, 31 metric generation circuit, 32 minimum metric detector, 33 terminal, 34 signal candidate generation Circuit, 35 linear conversion circuit, 36 hard discriminator, 37 addition circuit, 38 noise generation circuit, 39 quantity Encoder, 40 a parallel-serial converter, 42 update value calculation circuit, 43 channel estimator 44 transmits the signal candidate generator circuit, 45 the transmission signal candidate generator circuit

Claims (5)

Metric generation means for generating a metric corresponding to the transmission signal candidate based on the received signal, channel information of the transmission path, and a plurality of transmission signal candidates;
A minimum metric detecting means for searching for a minimum value of the metric and outputting a bit of the transmission signal candidate corresponding to the minimum value as a determination value;
A MIMO detection system comprising: transmission signal candidate generation means for generating a plurality of transmission signal candidates by linear operation and quantization based on the received signal and the channel information.   The received signal of claim 1 is a signal obtained by frequency-converting received waves received by a plurality of receiving antennas, and the channel information of claim 1 is an estimated value of an impulse response of a transmission path. MIMO detection method.   The received signal of claim 1 is a signal obtained by frequency-converting received waves received by a plurality of receiving antennas and then separating the signals into subcarrier components, and the channel information of claim 1 is a frequency of a transmission path. A MIMO detection system characterized by an estimated response value.   The transmission signal generation means according to claim 1 adds the generated noise to the reception signal, performs a linear operation using a weighting coefficient obtained from the channel information, and generates a plurality of transmission signal candidates by quantization. MIMO detection system characterized by   The transmission signal generating means according to claim 1 performs a linear operation using a weighting coefficient obtained from the channel information on the received signal, obtains an initial value, and obtains the initial value, the channel information, and the received signal. A MIMO detection method characterized by further obtaining an update value based on the initial value, adding the update value to the initial value, and then generating a plurality of transmission signal candidates by quantization.

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