JP4863459B2 - MIMO detection method, receiving apparatus and receiving method - Google Patents
MIMO detection method, receiving apparatus and receiving method Download PDFInfo
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本発明は,携帯電話システム等の無線通信に関するものであり,特に複数の送受信アンテナを用いて空間多重伝送を行うMIMO(Multiple Input Multiple Output)検波方式,受信装置及び受信方法に関するものである. The present invention relates to wireless communication such as a mobile phone system, and more particularly to a MIMO (Multiple Input Multiple Output) detection method , a receiving apparatus, and a receiving method for performing spatial multiplexing transmission using a plurality of transmitting and receiving antennas.
携帯電話システム等の無線通信において,周波数帯域を広げずに伝送速度を高める技術として,複数の送受信アンテナを用いて空間多重伝送を行うMIMO伝送が知られている.
図1に,送信アンテナ数K(Kは2以上の整数)のMIMO伝送用送信機の構成を示す.まず,入力端子1から送信ビット系列がシリアル・パラレル変換器2−1へ入力され,K個のビット系列に分けられる.ビット系列は,各々対応するベースバンド変調回路3−1から3−Kへ端子7−1を通って入力され,送信信号に相当する複素シンボルが変調信号として生成される.この複素シンボルは同相成分と直交成分の2成分を持つが,一つの信号と見なす.ベースバンド変調回路3−1の出力である変調信号は,端子7−2と端子7−3を通り変調器4−1へ入力される.発振器6が出力するキャリア信号が端子7−4から入力し,変調器4−1は,このキャリア信号を用いて変調信号をRF周波数帯へ周波数変換し,端子8を通して対応する送信アンテナ5−1で送信する.他の変調信号についても同様の操作が行われる.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
図1の変調器4の構成を図2に示す.端子7−2と端子7−3からそれぞれ,変調信号である複素シンボルの同相成分と直交成分が入力され,端子7−4からキャリア信号が入力される.乗算器9−1は変調信号の同相成分にキャリア信号を乗算し,乗算器9−2は変調信号の直交成分に,移相器10の出力である位相が90度回転したキャリア信号を乗算する.これらの乗算結果は加算器11で足し合わされ,増幅器12で増幅された後,端子8から出力される. The configuration of the
また,図1のベースバンド変調回路3について,MIMOシングルキャリア伝送用の構成を図3に示す.端子7−1からビット系列が複素シンボル生成回路13に入力され,ビットに応じて複素シンボルが生成される.複素シンボルの同相成分と直交成分がそれぞれ,端子7−2及び7−3から出力される. The configuration for MIMO single carrier transmission of the
さらに,MIMO−OFDM(Orthogonal Frequency Division Multiplexing)伝送用のベースバンド変調回路3の構成を,図4に示す.まず,端子7−1からビット系列がシリアル・パラレル変換器2−2へ入力され,サブキャリア数N(Nは2以上の整数)のビット系列に分けられる.N個のビット系列はそれぞれ,対応する複素シンボル生成回路13−1から13−Nへ入力され,複素シンボルが生成される.IFFT(Inverse Fast Fourier Transform)回路はこれらの複素シンボルに対して,各サブキャリアに応じたキャリア信号を乗算して合成し,マルチキャリア信号を生成する.ガードインターバル付加器15は,このマルチキャリア信号の最後の部分をガードインターバルとして先頭に付加してOFDM変調信号を生成し,その同相成分と直交成分をそれぞれ,端子7−2及び7−3へ出力する. Furthermore, FIG. 4 shows the configuration of a
次に,受信アンテナ数L(Lは2以上の整数)のMIMOシングルキャリア伝送用の受信機の構成を図5に示す.まず,受信アンテナ16−1から16−Lで受信した受信波はそれぞれ,対応する受信回路20−1から20−Lにおいてベースバンドへ周波数変換され,受信信号として出力される.受信回路20−1は,増幅器12,ハイブリッド17,乗算器9−1と9−2,移相器10,低域通過フィルタ18−1と18−2,及びA/D変換器19−1及び19−2から構成され,増幅器12とハイブリッド17は受信波を増幅後分岐し,移相器10は発振器6が出力するキャリア信号の位相を90度回転させ,乗算回路9−1及び9−2は増幅された受信波にキャリア信号とキャリア信号の位相を90度回転したものをそれぞれ乗算して,2つの乗算結果を出力する.これらの乗算結果は低域通過フィルタ18−1及び18−2で高周波成分が除去された後,ベースバンド信号である受信信号の同相成分と直交成分が抽出される.A/D変換器19−1及び19−2は受信信号をディジタル信号に変換して出力する.信号検出器21は,受信信号と,伝送路のチャネル情報として伝送路推定回路43が出力するインパルス応答の推定値を基に,送信信号である複素シンボルを検出し送信ビット系列の判定値を出力端子22へ出力する.伝送路推定回路43は,入力端子23から入力する既知のトレーニング信号と,受信信号を用いて,伝送路のインパルス応答を推定し,この推定値を出力する. 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
また,図6にMIMO−OFDM伝送用受信機の構成を示す.まず,受信アンテナ16−1から16−Lで受信した受信波はそれぞれ,対応するOFDM受信回路26−1から26−Lにおいてベースバンドへ周波数変換された後,各サブキャリア成分に分離され,受信信号として出力される.OFDM受信回路26−1は受信回路20−1,ガードインターバル除去回路24,及びFFT(Fast Fourier Transform)演算回路25から構成され,受信回路20−1は,発振器6が出力するキャリア信号を用いて受信波をベースバンドへ周波数変換する.ガードインターバル除去回路24は,周波数変換された信号からガードインターバルに相当する部分を除去し,FFT演算回路25は,IFFTの逆操作であるFFTを行い,各サブキャリア成分へ分離し,受信信号として出力する.したがって,サブキャリア数N個の同相成分と直交成分が生成される.信号検出はサブキャリア毎に行い,第1サブキャリアに相当する受信信号は信号検出器21−1へ入力され,第Nサブキャリアに相当する受信信号は信号検出器21−Nへ入力される.信号検出器21−1から21−Nは,受信信号と,DFT(Discrete Fourier Transform)回路27が出力するチャネルの周波数応答推定値をチャネル情報として用い,送信信号である複素シンボルを検出し送信ビット系列の判定値を出力する.パラレル・シリアル変換回路28は,信号検出器21−1から21−Nが出力する送信ビット系列の判定値をパラレル・シリアル変換して出力端子22へ出力する.DFT回路27は,伝送路推定回路43が出力する伝送路のインパルス応答の推定値にDFTを行い,各サブキャリア周波数における周波数応答の推定値を出力する. 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
図5及び図6の信号検出器21に適用できる各種検出方式の内,最適方式はビット誤り率を最小にできる最尤検出(非特許文献1参照)である.最尤検出に基づく信号検出器21の構成を図7に示す.まず,各受信アンテナからの受信信号が端子を介してメトリック生成回路31へ入力する.具体的には,端子29−1と29−2からは受信アンテナ16−1の受信信号の同相成分及び直交成分が,端子29−3と29−4からは受信アンテナ16−Lの受信信号の同相成分及び直交成分が,それぞれ入力する.伝送路のチャネル情報として端子30から,MIMOシングルキャリア伝送の場合には伝送路のインパルス応答の推定値が,MIMO−OFDM伝送の場合には伝送路の周波数応答の推定値が入力する.メトリック生成手段に相当するメトリック生成回路31は,受信信号,伝送路のチャネル情報,及び信号候補生成回路34が出力する送信信号候補を基に,送信信号候補に対応するメトリックを生成する.このメトリックについて以下数式を用いて,MIMOシングルキャリア伝送を例に説明する.なお,ベースバンドの信号は全て,同相成分を実部,直交成分を虚部とする複素表示で表すものとする. Among various detection methods applicable to the
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hpk,第k送信アンテナからの送信信号,即ち複素シンボルをskとすると,ypは
と表すことができる.なお,np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MK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
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.
以上説明したように,最尤検出はビット誤り率を最小にできるものの,演算量が膨大になるという問題がある.この演算量を削減できる準最適検波方式として,受信信号に線形操作を行う線形受信が知られている.線形受信の一種であるMMSE(Minimum Mean Square Error)(非特許文献2参照)に基づく信号検出器21の構成を図8に示す.まず,各受信アンテナからの受信信号が端子を介して線形変換回路35へ入力する.具体的には,端子29−1と29−2からは受信アンテナ16−1の受信信号の同相成分及び直交成分が,端子29−3と29−4からは受信アンテナ16−Lの受信信号の同相成分及び直交成分が,それぞれ入力する.伝送路のチャネル情報として端子30から,MIMOシングルキャリア伝送の場合には伝送路のインパルス応答の推定値が,MIMO−OFDM伝送の場合には伝送路の周波数応答の推定値が入力する.線形変換回路35は,チャネル情報から算出する重み付け係数を用いて受信信号に線形操作である線形合成を行い,K個の合成信号を生成する.硬判定器36−1から36−Kはそれぞれ,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る.その複素シンボルから送信ビットを推定し,判定値としてパラレル・シリアル変換器28へ入力する.パラレル・シリアル変換器28は判定値をパラレル・シリアル変換して端子33へ出力する. 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
上記の線形変換回路35の動作について数式を用いて説明する.まず,L次元受信信号ベクトルy,K次元送信信号ベクトルs,L次元雑音ベクトルnを以下のように定義する.
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
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.
このように,MIMO検波方式の内,最尤検出は最適検波方式であり最小ビット誤り率を達成できるが,演算量が膨大になってしまう.この演算量を削減するため,従来から線形受信等の準最適検波方式が提案されているが,演算量を削減するとビット誤り率が大幅に劣化するという問題があった. 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.
本発明は,このような課題に鑑みてなされたものであり,最尤検出と同程度のビット誤り率特性を維持しつつ,演算量を大幅に削減できるMIMO検波方式,受信装置及び受信方法を提供することを目的とする. The present invention has been made in view of such a problem, and provides a MIMO detection method , a receiving apparatus, and a receiving method that can significantly reduce the amount of computation while maintaining a bit error rate characteristic comparable to that of maximum likelihood detection. It is intended to provide.
本発明は,受信信号と,伝送路のチャネル情報と,複数の送信信号候補とを基に,前記送信信号候補に対応するメトリックを生成するメトリック生成手段と,前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出手段と,前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成手段と,を備え,前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とするMIMO検波方式である.
また,前記送信信号候補生成手段は,前記受信信号に対して前記チャネル情報から求める重み付け係数を用いて線形操作を行い,初期値を求める線形変換手段と,前記初期値と前記チャネル情報と前記受信信号とを基に更新値を算出する更新値演算手段と,前記初期値に前記更新値を加算する加算手段と,前記加算結果を量子化により複数の前記送信信号候補を生成する量子化手段と,を備えることを特徴とする.
また,前記送信信号候補生成手段は,前記送信信号候補数の回数だけ複素ガウス変数を生成する雑音生成手段と,前記受信信号に前記複素ガウス変数を加算する加算手段と,前記チャネル情報から求める重み付け係数を用いて前記加算結果に対して線形操作を行う線形変換手段と,前記線形変換手段の出力を量子化により複数の前記送信信号候補を生成する量子化手段と,を備えることを特徴とする.
また,前記送信信号候補生成手段は,複素ガウス変数を生成する雑音生成手段と,前記受信信号に前記複素ガウス変数を加算する加算手段と,前記チャネル情報から求める重み付け係数を用いて前記加算結果に対して線形操作を行う線形変換手段と,前記線形変換手段の出力を量子化により複数の前記送信信号候補を生成する量子化手段と,を備えることを特徴とする.
また,前記受信信号は,複数の受信アンテナで受信した受信波を周波数変換して得られる信号とし,前記チャネル情報は,伝送路のインパルス応答の推定値とすることを特徴とする.
また,前記受信信号は,複数の受信アンテナで受信した受信波を周波数変換した後,各サブキャリア成分に分離して得られる信号とし,前記チャネル情報は,伝送路の周波数応答の推定値とすることを特徴とする.
また,本発明は, MIMO多重信号を受信する受信装置であって,受信信号から伝送路のチャネル情報を算出する伝送路推定手段と,前記受信信号と前記チャネル情報とからビット判定値を求める信号検出手段と,を備え,前記信号検出手段は,前記受信信号と,前記チャネル情報と,複数の送信信号候補とを基に,前記送信信号候補に対応するメトリックを生成するメトリック生成手段と,前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出手段と,前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成手段と,を備え,前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とする受信装置である.
また,前記送信信号候補生成手段は,前記受信信号に対して前記チャネル情報から求める重み付け係数を用いて線形操作を行い,初期値を求める線形変換手段と,前記初期値と前記チャネル情報と前記受信信号とを基に更新値を算出する更新値演算手段と,前記初期値に前記更新値を加算する加算手段と,前記加算結果を量子化により複数の前記送信信号候補を生成する量子化手段と,を備えることを特徴とする.
また,本発明は,MIMO多重信号を受信する受信方法であって,受信信号から伝送路のチャネル情報を算出する伝送路推定過程と,前記受信信号と前記チャネル情報とからビット判定値を求める信号検出過程と,を備え,前記信号検出過程は,前記受信信号と,前記チャネル情報と,複数の送信信号候補とを基に,前記送信信号候補に対応するメトリックを生成するメトリック生成過程と,前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出過程と,前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成過程と,を有し、前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とする受信方法である.
The present invention searches for a minimum value of the metric, 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, Based on the received signal and the channel information, a plurality of transmission signal candidates are generated by linear operation and quantization based on minimum metric detection means for outputting the bit of the transmission signal candidate corresponding to the minimum value as a determination value. Transmission signal candidate generation means , wherein the number of transmission signal candidates is equal to or less than the number of quantizations except for one of the same transmission signal candidates, and the others are excluded. This is a detection method.
The transmission signal candidate generation means performs a linear operation on the reception signal using a weighting coefficient obtained from the channel information, and obtains an initial value, linear conversion means for obtaining an initial value, the initial value, the channel information, and the reception Update value calculating means for calculating an update value based on the signal, addition means for adding the update value to the initial value, and quantization means for generating a plurality of transmission signal candidates by quantizing the addition result; , Is provided.
Further, the transmission signal candidate generation means includes noise generation means for generating a complex Gaussian variable by the number of times of the number of transmission signal candidates, addition means for adding the complex Gaussian variable to the received signal, and weighting obtained from the channel information. A linear conversion unit that performs a linear operation on the addition result using a coefficient; and a quantization unit that generates a plurality of transmission signal candidates by quantizing an output of the linear conversion unit. .
In addition, the transmission signal candidate generating means includes a noise generating means for generating a complex Gaussian variable, an adding means for adding the complex Gaussian variable to the received signal, and a weighting coefficient obtained from the channel information. A linear transformation means for performing a linear operation on the output, and a quantization means for generating a plurality of transmission signal candidates by quantizing the output of the linear transformation means.
The received signal is a signal obtained by frequency-converting received waves received by a plurality of receiving antennas, and the channel information is an estimated value of an impulse response of a transmission path.
The received signal is a signal obtained by frequency-converting a received wave received by a plurality of receiving antennas and then separating it into subcarrier components, and the channel information is an estimated value of the frequency response of the transmission path. It is characterized by this.
The present invention is also a receiving apparatus for receiving a MIMO multiplexed signal, a transmission path estimation means for calculating channel information of a transmission path from the received signal, and a signal for obtaining a bit determination value from the received signal and the channel information. Detecting means, and the signal detecting means generates metric corresponding to the transmission signal candidate based on the received signal, the channel information, and a plurality of transmission signal candidates, and A minimum metric detecting unit that searches for a minimum value of a metric and outputs a bit of the transmission signal candidate corresponding to the minimum value as a determination value, and a plurality of values by linear operation and quantization based on the received signal and the channel information. wherein a transmission signal candidate generating means for generating a transmission signal candidates, comprising a number of said transmitted signal candidates, and leaving one of the same of the transmission signal candidates its Except for this, the receiving apparatus is characterized in that it is less than the number of times of quantization.
The transmission signal candidate generation means performs a linear operation on the reception signal using a weighting coefficient obtained from the channel information, and obtains an initial value, linear conversion means for obtaining an initial value, the initial value, the channel information, and the reception Update value calculating means for calculating an update value based on the signal, addition means for adding the update value to the initial value, and quantization means for generating a plurality of transmission signal candidates by quantizing the addition result; , Is provided.
The present invention is also a receiving method for receiving a MIMO multiplexed signal, a transmission path estimation process for calculating channel information of a transmission path from the received signal, and a signal for obtaining a bit determination value from the received signal and the channel information. A detection process, wherein the signal detection process generates a metric corresponding to the transmission signal candidate based on the received signal, the channel information, and a plurality of transmission signal candidates; A minimum metric detection process for searching for a minimum value of a metric and outputting the bit of the transmission signal candidate corresponding to the minimum value as a determination value, and a plurality of operations by linear operation and quantization based on the received signal and the channel information. wherein a transmission signal candidate generating step of generating a transmission signal candidates, the number of the transmission signal candidates, their leaving one of said same transmission signal candidates A receiving method which is characterized in that less than the number and the quantization excluding non.
本発明は,以下に記載されるような効果を奏する.
(1)最尤検出と同程度のビット誤り率特性を維持しつつ,演算量を大幅に削減できる.
(2)送信信号候補の数をさらに抑え演算量を大幅に削減できる.
(3)送信信号候補の数を抑え演算量を削減できる.
(4)MIMOシングルキャリア伝送に適用できる.
(5)MIMO−OFDM伝送に適用できる.
The present invention has the following effects.
(1) The computational complexity can be greatly reduced while maintaining the bit error rate performance comparable to that of maximum likelihood detection.
(2) The amount of computation can be greatly reduced by further reducing the number of transmission signal candidates.
(3) The amount of computation can be reduced by reducing the number of transmission signal candidates.
(4) Applicable to MIMO single carrier transmission.
(5) Applicable to MIMO-OFDM transmission.
以下,本発明を実施するための最良の形態について説明する.
まず,第1の発明のMIMO検波方式を用いた信号検出器21の構成(請求項4)を図9に示す.図7に示す従来の最尤検出に基づく信号検出器21との違いは,信号候補生成回路34を送信信号候補生成手段に相当する送信信号候補生成回路44に置き換えた点にある.なお,送信信号候補生成回路44は,加算回路37−1から37−L,雑音生成回路38,線形変換回路35,量子化器39−1から39−K,及びパラレル・シリアル変換器40から構成され,以下では送信信号候補生成回路44の動作について詳述する.The best mode for carrying out the present invention will be described below.
First, FIG. 9 shows the configuration of the
送信信号候補数をC(Cは2以上の整数)とする.雑音生成回路38はC回人工的に複素ガウス信号を生成するが,1回目は値が零となる信号をL個生成し,2回目以降は平均値零,分散ξで互いに無相関となる複素ガウスをL個発生させる.加算回路37−1から37−Lは,受信信号に雑音生成回路38が生成する生成雑音を加算する.具体的には,端子29−1と29−2から入力する受信アンテナ16−1の受信信号の同相成分及び直交成分については,それぞれ1番目の生成雑音の同相成分及び直交成分を加算し,端子29−3と29−4から入力する受信アンテナ16−Lの受信信号の同相成分及び直交成分については,それぞれL番目の生成雑音の同相成分及び直交成分を加算する.加算回路3
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
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, after the second time, it is 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-
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.
次に,第2の発明のMIMO検波方式を用いた信号検出器21の構成(請求項5)を図10に示す.図7に示す従来の最尤検出に基づく信号検出器21との違いは,信号候補生成回路34を送信信号候補生成手段に相当する送信信号候補生成回路45に置き換えた点にある.なお,送信信号候補生成回路45は,線形変換回路35,量子化器41−1から41−K,更新値演算回路42,加算回路37−1から37−K,量子化器39−1から39−K,及びパラレル・シリアル変換器40から構成され,以下では送信信号候補生成回路45の動作について詳述する. Next, FIG. 10 shows the configuration of the
まず,各受信アンテナからの受信信号が端子を介して線形変換回路35へ入力する.具体的には,端子29−1と29−2からは受信アンテナ16−1の受信信号の同相成分及び直交成分が,端子29−3と29−4からは受信アンテナ16−Lの受信信号の同相成分及び直交成分が,それぞれ入力する.線形変換回路35は,端子30から入力するチャネル情報から重み付け係数を算出し,この重み付け係数を用いて受信信号に線形操作である線形合成を行い,K個の合成信号を生成する.この合成信号が初期値xに相当する.量子化器41−1から41−Kはそれぞれ,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更新値演算回路42に入力する.更新値演算回路42は,初期値を硬判定した複素シンボル,受信信号,並びにチャネル情報から更新値を求める.加算回路37−1から37−Kは初期値に更新値を加算し,量子化器39−1から39−Kはこの加算結果に対して量子化の一種である硬判定を行い,加算結果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. First, the received signal from each receiving antenna is input to the
上記の更新値演算回路42の動作について以下,数式を用いて詳述する.まず,合成信号を硬判定して得られる複素シンボル,即ち量子化器41−1から41−Kの出力を成分
ある.また,Pは数式13で定義するK×K行列である.
μr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,μr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,μr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
is there. P is a K × K matrix defined by
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
It is good. However, e is an arbitrary L-dimensional vector that is not a zero vector.
最後に,本発明は上述の発明を実施するための最良の形態に限らず本発明の要旨を逸脱することなくその他種々の構成を採り得ることはもちろんである. 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.
1入力端子,2シリアル・パラレル変換器,3ベースバンド変調回路,4変調器,5送信アンテナ,6発振器,7端子,8端子,9乗算器,10移相器,11加算器,12増幅器,13複素シンボル生成回路,14IFFT演算回路,15ガードインターバル付加器,16受信アンテナ,17ハイブリッド,18低域通過フィルタ,19A/D変換器,20受信回路,21信号検出器,22出力端子,23入力端子,24ガードインターバル除去回路,25FFT演算回路,26OFDM受信回路,27DFT回路,28パラレル・シリアル変換器,29端子,30端子,31メトリック生成回路,32最小メトリック検出器,33端子,34信号候補生成回路,35線形変換回路,36硬判定器,37加算回路,38雑音生成回路,39量子化器,40パラレル・シリアル変換器,42更新値演算回路,43伝送路推定回路,44送信信号候補生成回路,45送信信号候補生成回路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
Claims (8)
前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出手段と,
前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成手段と,
を備え,
前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とするMIMO検波方式. 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;
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;
Equipped with a,
The number of the transmission signal candidates is equal to or less than the number of times of quantization except for one of the same transmission signal candidates and the rest of the candidates .
前記受信信号に対して前記チャネル情報から求める重み付け係数を用いて線形操作を行い,初期値を求める線形変換手段と,
前記初期値と前記チャネル情報と前記受信信号とを基に更新値を算出する更新値演算手段と,
前記初期値に前記更新値を加算する加算手段と,
前記加算結果を量子化により複数の前記送信信号候補を生成する量子化手段と,
を備えることを特徴とする請求項1に記載のMIMO検波方式. The transmission signal candidate generation means includes:
Performing linear operation on the received signal using a weighting coefficient obtained from the channel information, and obtaining a linear conversion means for obtaining an initial value;
Update value calculation means for calculating an update value based on the initial value, the channel information, and the received signal;
Adding means for adding the updated value to the initial value;
Quantization means for generating a plurality of transmission signal candidates by quantizing the addition result;
The MIMO detection system according to claim 1, comprising:
前記送信信号候補数の回数だけ複素ガウス変数を生成する雑音生成手段と,
前記受信信号に前記複素ガウス変数を加算する加算手段と,
前記チャネル情報から求める重み付け係数を用いて前記加算結果に対して線形操作を行う線形変換手段と,
前記線形変換手段の出力を量子化により複数の前記送信信号候補を生成する量子化手段と,
を備えることを特徴とする請求項1に記載のMIMO検波方式. The transmission signal candidate generation means includes:
Noise generating means for generating complex Gaussian variables as many times as the number of transmission signal candidates;
Adding means for adding the complex Gaussian variable to the received signal;
Linear conversion means for performing a linear operation on the addition result using a weighting coefficient obtained from the channel information;
Quantization means for generating a plurality of transmission signal candidates by quantizing the output of the linear transformation means;
The MIMO detection system according to claim 1, comprising:
前記チャネル情報は,伝送路のインパルス応答の推定値とすること
を特徴とする請求項1から請求項3のいずれかに記載のMIMO検波方式. The received signal is a signal obtained by frequency-converting received waves received by a plurality of receiving antennas,
4. The MIMO detection system according to claim 1, wherein the channel information is an estimated value of an impulse response of a transmission path.
複数の受信アンテナで受信した受信波を周波数変換した後,各サブキャリア成分に分離して得られる信号とし,
前記チャネル情報は,伝送路の周波数応答の推定値とすること
を特徴とする請求項1から請求項3のいずれかに記載のMIMO検波方式. The received signal is
After frequency conversion of the received waves received by multiple receiving antennas, it is a signal obtained by separating each subcarrier component,
4. The MIMO detection system according to claim 1, wherein the channel information is an estimated value of a frequency response of a transmission path.
受信信号から伝送路のチャネル情報を算出する伝送路推定手段と,
前記受信信号と前記チャネル情報とからビット判定値を求める信号検出手段と,
を備え,
前記信号検出手段は,
前記受信信号と,前記チャネル情報と,複数の送信信号候補とを基に,前記送信信号候補に対応するメトリックを生成するメトリック生成手段と,
前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出手段と,
前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成手段と,
を備え,
前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とする受信装置. A receiving device for receiving a MIMO multiplexed signal,
A channel estimation means for calculating channel information of the channel from the received signal;
Signal detection means for obtaining a bit determination value from the received signal and the channel information;
With
The signal detection means includes
Metric generation means for generating a metric corresponding to the transmission signal candidate based on the received signal, the channel information, 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;
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;
Equipped with a,
The number of the transmission signal candidates is equal to or less than the number of times of quantization when one of the same transmission signal candidates is left and the others are excluded .
前記受信信号に対して前記チャネル情報から求める重み付け係数を用いて線形操作を行い,初期値を求める線形変換手段と,
前記初期値と前記チャネル情報と前記受信信号とを基に更新値を算出する更新値演算手段と,
前記初期値に前記更新値を加算する加算手段と,
前記加算結果を量子化により複数の前記送信信号候補を生成する量子化手段と,
を備えることを特徴とする請求項6に記載の受信装置. The transmission signal candidate generation means includes:
Performing linear operation on the received signal using a weighting coefficient obtained from the channel information, and obtaining a linear conversion means for obtaining an initial value;
Update value calculation means for calculating an update value based on the initial value, the channel information, and the received signal;
Adding means for adding the updated value to the initial value;
Quantization means for generating a plurality of transmission signal candidates by quantizing the addition result;
The receiving apparatus according to claim 6, further comprising:
受信信号から伝送路のチャネル情報を算出する伝送路推定過程と,
前記受信信号と前記チャネル情報とからビット判定値を求める信号検出過程と,
を備え,
前記信号検出過程は,
前記受信信号と,前記チャネル情報と,複数の送信信号候補とを基に,前記送信信号候補に対応するメトリックを生成するメトリック生成過程と,
前記メトリックの最小値を探索し,その最小値に対応する前記送信信号候補のビットを判定値として出力する最小メトリック検出過程と,
前記受信信号と前記チャネル情報を基に,線形操作と量子化により複数の前記送信信号候補を生成する送信信号候補生成過程と,
を有し、
前記送信信号候補の数は、同一の前記送信信号候補のうち一つを残してそれ以外を除くと前記量子化の回数以下であることを特徴とする受信方法. A reception method for receiving a MIMO multiplexed signal,
A channel estimation process for calculating channel information from the received signal,
A signal detection process for obtaining a bit decision value from the received signal and the channel information;
With
The signal detection process includes:
A metric generation step of generating a metric corresponding to the transmission signal candidate based on the received signal, the channel information, and a plurality of transmission signal candidates;
Searching for a minimum value of the metric and detecting a bit of the transmission signal candidate corresponding to the minimum value as a determination value;
A transmission signal candidate generation process for generating a plurality of transmission signal candidates by linear operation and quantization based on the received signal and the channel information;
Have
The number of transmission signal candidates is equal to or less than the number of times of quantization when one of the same transmission signal candidates is left and the others are excluded .
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