KR100960418B1 - Apparatus and method for receiving signal in a communication system - Google Patents

Abstract

According to the present invention, a first channel matrix is formed among a channel matrix formed between a received signal received from a plurality of receive antennas and a transmit signal transmitted from a plurality of transmit and receive antennas, and a first transmission of the transmit signal using candidate symbols of the transmit signal. Calculate a detection error offset for each symbol of the signal, store the detection error offset for each symbol of the first transmitted signal and candidate symbols of the first transmitted signal, and store each symbol of the first transmitted signal The log likelihood ratio (LLR) of the first transmission signal is calculated using the detection error offset for the first transmission signal and the candidate symbols of the first transmission signal, and the above-described procedures are repeated by the number of transmission signals. The total log likelihood ratio of the transmission signal is calculated.

Description

Apparatus and method for receiving signal in communication system {APPARATUS AND METHOD FOR RECEIVING SIGNAL IN A COMMUNICATION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and more particularly, to an apparatus and method for receiving a signal in a multi-input multi-output (MIMO) type communication system.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16a / d communication system and the IEEE 802.16e communication system support orthogonal frequency division multiplexing (OFDM) to support a broadband transmission network on a physical channel of the WMAN system. Orthogonal Frequency Division Multiplexing (hereinafter referred to as "OFDM") / Orthogonal Frequency Division Multiple Access (OFDMA) is a communication system employing the scheme. The IEEE 802.16a / d communication system currently considers only a single cell structure and a state in which a subscriber station (SS) (hereinafter referred to as SS) is fixed, i.e., does not consider SS mobility at all. System. In contrast, the IEEE 802.16e communication system is a system that considers the mobility of the SS in the IEEE 802.16a communication system, and the SS having the mobility is referred to as a mobile station (MS). do.

In addition, the Institute of Electrical and Electronics Engineers (IEEE) 802.16a / d communication system and the IEEE 802.16e communication system can be applied to the MIMO scheme having a plurality of receive antennas and a plurality of transmit antennas. In the MIMO communication system, what data is transmitted to each of a plurality of transmit antennas is determined by space-time encoding, and each of the receive antennas receives a signal transmitted from each of the transmit antennas and performs space-time decoding. Such space-time encoding is implemented by a space-time transmit diversity scheme for encoding the same data in different formats to transmit the same data through different transmit antennas, or a spatial multiplexing technique for transmitting different data through different transmit antennas.

In general, in a spatial multiplexing technique, a space-time encoded signal is decoded through a joint or separate detection scheme at a receiver. In the joint detection scheme, not only signals transmitted from one transmitting antenna but also signals transmitted from another transmitting antenna should be considered. Due to these characteristics, a minimum mean square error (MMSE) or zero-forcing (ZF) is used as a multiplexing scheme for using a spatial multiplexing MIMO communication system. Multiplexing schemes are known that detect and decode a transmission signal from a received signal on the basis of a " ZF ".

These multiplexing schemes exhibit different data performances depending on the signal-to-noise ratio (SNR) of the received signal. For example, the multiplexing scheme decoded through the signal detection using the MMSE has a lower data reception performance than other multiplexing schemes at high SNR, but can obtain higher data reception performance than other multiplexing schemes at low SNR. However, in general, a communication system has a variable SNR in a time-varying wireless channel environment, and a signal reception scheme using a multiplexing scheme that can adaptively obtain high data reception performance corresponding to the variable SNR is required.

Accordingly, an object of the present invention is to provide an apparatus and method for receiving a signal in a communication system of a multiple input multiple output method.

Another object of the present invention is to provide a receiving apparatus and method for improving decoding performance by minimizing a detection error when decoding a received signal in a multiple input multiple output communication system.

In addition, another object of the present invention is to receive a plurality of transmission signals transmitted through a plurality of transmission antennas in a multi-input multiple output communication system to minimize the detection error of the transmission signals through noise and interference cancellation in the received signal The present invention provides a receiving apparatus and method for improving performance.

According to an aspect of the present invention, there is provided a method of receiving a signal in a multiple input multiple output communication system, comprising: a channel matrix formed between a received signal received from a plurality of receive antennas and a transmitted signal transmitted from a plurality of transmit and receive antennas. Calculating a detection error offset for each symbol of the first transmission signal of the transmission signal using a first channel matrix and candidate symbols of the transmission signal, and detecting each symbol of the first transmission signal; Storing an error offset and candidate symbols of the first transmitted signal, a log of the first transmitted signal using detection error offset for each symbol of the first transmitted signal and candidate symbols of the first transmitted signal Calculating a log likelihood ratio (LLR) and repeating the above-described steps as many times as the number of the transmitted signals; It calculates the total log-likelihood ratio.

An apparatus of the present invention for achieving the above objects, in the signal receiving apparatus in a multiple input multiple output communication system, a channel matrix formed between a received signal received from a plurality of receive antennas and a transmit signal transmitted from a plurality of transmit and receive antennas An operation unit for calculating a detection error offset for each symbol of the first transmission signal of the transmission signal by using a first channel matrix and candidate symbols of the transmission signal, and for each symbol of the first transmission signal A decoder including a log likelihood ratio calculator for calculating a log likelihood ratio (LLR) of the first transmitted signal by using a detection error offset and candidate symbols of the first transmitted signal, wherein the decoder includes: The total log likelihood ratio of the transmission signal is calculated by repeating the number of transmission signals.

The present invention can improve the reception performance of a signal by detecting a transmission signal by minimizing a detection error of the transmission signal in the reception signal through noise and interference cancellation of the reception signal in a multiple input multiple output communication system. In particular, the present invention can improve the reception performance of the signal by minimizing the detection error by removing the noise and interference of the received signal with respect to the candidate symbols of the transmission signal, respectively to detect the symbols of the transmission signal. In addition, the decoder repeatedly removes noise and interference of the received signal for each candidate symbol of the transmission signal to detect the symbols of the transmission signal, respectively, thereby reducing the complexity of the decoder. Increasing complexity can be minimized.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

The present invention relates to a signal receiving apparatus and method in an IEEE 802.16 communication system, which is a communication system, for example, a broadband wireless access (BWA) communication system. Suggest. Here, in the embodiment of the present invention to be described later, orthogonal frequency division multiplexing (OFDM) / orthogonal frequency division multiple access (OFDM) in the IEEE 802.16 communication system for convenience of description. Although a communication system employing an Orthogonal Frequency Division Multiple Access (OFDMA) scheme will be described as an example, the reception apparatus and method proposed by the present invention can be applied to other communication systems.

In addition, the present invention is a base station (BS: Base Station, hereinafter 'BS') that manages a predetermined cell in a multi-input multi-output (MIMO: Multi-Input (MIMO)) type communication system The present invention provides an apparatus and method for receiving a signal between a mobile station (MS: Mobile Station, hereinafter referred to as 'MS') within a predetermined cell and receiving a communication service from the BS. In an embodiment of the present invention, when a transmitter of a BS transmits a plurality of transmission signals through a plurality of transmission antennas through a plurality of transmission antennas in downlink (DL: DownLink, hereinafter referred to as 'DL'), a plurality of receptions are performed. The antennas of the MS receive the signals through the antennas, and the MSs of the MS detect the transmission signals by minimizing the detection error of the transmission signals in the received signal through noise and interference cancellation of the received signal. In addition, when each transmitter of a plurality of MSs transmits a signal through a transmission antenna on a radio channel of the UL in uplink (UL: Uplink, hereinafter referred to as 'UL'), the receiver of the BS receives a plurality of receptions. A signal is received through the antennas, and the receiver of the BS detects the transmission signals by minimizing a detection error of the transmission signals in the received signal through noise and interference cancellation of the reception signal.

At this time, in the MIMO communication system according to an embodiment of the present invention, the receiver of the BS and the MS detects the symbols of the respective transmission signals by removing noise and interference of the received signals for the candidate symbols of the respective transmission signals, respectively. After that, a log likelihood ratio (LLR) of each transmission signal is calculated and decoded. In addition, in the MIMO communication system according to an embodiment of the present invention, the receiver detects the symbols of the transmission signal by removing noise and interference of the reception signal for the candidate symbols of the transmission signal by the number of transmission signals, respectively. Then, the procedure of calculating the LLR is repeatedly performed to calculate the LLR for all transmission signals. Then, the communication system according to an embodiment of the present invention will be described in more detail with reference to FIG. 1.

1 is a view schematically showing the structure of a communication system according to an embodiment of the present invention. Here, FIG. 1 shows that in a communication system, each transmitter of two MSs transmits respective transmission signals through a single transmission antenna to a UL wireless channel, and a receiver of a BS transmits transmission signals transmitted by the transmitters through two reception antennas. It is a figure which shows the case of receiving.

Referring to FIG. 1, the transmitters 100 and 130 of the MSs may include generators 102 and 132 for generating binary data to be transmitted to the receiver 150, and the binary data may be converted into a convolutional turbo code (CTC). FEC encoders 104 and 134 for encoding Forward Error Correction (FEC), hereinafter referred to as 'CTC', and modulators for modulating the FEC coded data. 106 and 135, mappers 108 and 138 for mapping the modulated data to two carriers to be transmitted via two transmit antennas 114 and 144, and pilots to the data mapped to the subcarriers. Inserters (110 and 140) for inserting the data, OFDM modulators (112 and 142) for modulating the pilot-inserted data to be transmitted through the wireless channel in the OFDM scheme, and transmission for transmitting the OFDM modulated signal to the wireless channel. within It includes nadeul (114 144).

The receiver 150 performs OFDM demodulation on two reception antennas 152 and 154 for receiving transmission signals transmitted by the transmitter 100 and OFDM modulated signals received through the reception antennas 152 and 154. Demodulators 156 and 158, separators 160 and 162 separating the pilot from the demodulated data, transmit antennas 114 and 144 of the transmitters 100 and 130 and receive antennas 152 and 154 of the receiver 150. Estimators 164 and 166 for estimating the formed channel, demappers 168 and 170 for demapping data mapped to subcarriers of the estimated channel, and the demapped data, i.e. two receive antennas. A decoder 172 which decodes the received signal received through 152 by collaborative spatial multiplexing (CSM), and the CSM decoded data, that is, the decoder ( Output from 172) Calculates a symbol metric of the decoded signals to decode the CSM decoded data, FEC decoders 178 and 180 to FEC decode the data symbols, and binary the FEC decoded data. Restorers 182 and 184 to restore data.

The decoder 172 removes noise and interference of the received signal received by the receiving antennas 152 and 154 with respect to the candidate symbols of the transmitted signals when the transmitting signals transmitted by the transmitting antennas 114 and 144 are detected. The LLR is calculated and decoded after each symbol is detected, thereby minimizing a detection error of the transmission signals, thereby improving reception performance of the receiver 150. Hereinafter, reference to FIG. 2 will be explained a structure of a decoder for the LLR calculation in the communication system according to the present invention in more detail and the following description that the number of transmitting antenna N _t pieces, the number of receive antennas In the case of N _r , the following description will focus on the case where the decoder calculates the LLR.

2 is a diagram schematically illustrating a decoder structure in a communication system according to an embodiment of the present invention.

Referring to FIG. 2, the decoder includes a specific layer, for example, N _t , among candidate symbols of received signals r received by N _r receive antennas and N _t transmitted signals transmitted by N _t transmit antennas. Candidate symbols S _{m, i of} m th transmission signals, a channel matrix h _m of the m th transmission signals, and a channel formed between N _t transmit antennas and N _r receive antennas A first operation unit 210 which receives a channel matrix H and calculates a detection error offset for each symbol of the m th transmission signal generated by noise and interference of the received signal r, and the first operation unit; Detection error offset for each symbol of the m th transmission signal of the first operation unit 210, candidate symbols S _{m, i} of the m th transmission signal, and an m th transmission signal of the N _t transmission signals. A first low storing symbols of remaining transmission signals except for Book 230, a second operation unit 250 for calculating the detection error offset for each of the symbols of the remaining transmission signals, and the detection of each symbol of the remaining transmission signals calculated by the second operation unit 250 A second storage unit 270 for storing an error offset and extended decoded symbols for candidate symbols of the remaining transmission signals, and respective symbols stored in the first storage unit 230 and the second storage unit 270. The LLR operator 290 calculates an LLR using a detection error offset and candidate symbols for the LLR.

Here, _i in candidate symbols S _{m, i} of the m th transmission signal is 1,... , M _m , and M _m denotes a constellation array for the m th transmission signal. In the channel matrix H, as described with reference to FIG. 1, the estimators 164 and 166 use N _t transmit antennas and N _r receive antennas using a pilot separated by the separators 160 and 162 of the receiver 150. The channel matrix H input to the decoder 172 by estimating the channel formed in the liver may be represented by Equation 1 below. In addition, the channel matrix h _m of the m th transmission signal refers to a channel matrix composed only of components corresponding to the m th transmission signal in the channel matrix H represented by Equation 1 below.

In addition, to the candidate symbol (S _{m, i)} corresponds to the modulation method is a modulator of the modulation method, that is, the transmitter is applied to the N _t of transmit signals are transmitted the N _t transmit antennas is applied to the m-th transmission signal The symbols when the symbols of the m th transmission signal can be located in the constellation diagram. In this case, the modulation scheme applied by the transmitter's modulator is already recognized by the receiver in the initial entry procedure between the BS and the MS. In addition, the transmitter may transmit transmission signals by applying different modulation schemes to respective transmission antennas. That is, the transmitter is a PSK (Phase Shift Key, PSK) series and QAM (QAM: Quadrature Amplitude Modulation, hereinafter called 'QAM') series to the N _t transmission signals For example, one or more modulation methods among QPSK (QPSK: Quadrature Phase Shift Key (QPSK), 16QAM, and 64QAM schemes) may be transmitted to the receiver.

Here, the received signal r may be represented by Equation 2 below, in which s means N _t transmitted signals transmitted by N _t transmit antennas, and the transmit signals s Can be expressed as Equation 3 below.

The first operation unit 210 and the first remover 212 for calculating the noise and interference of the received signal (r) with respect to the candidate symbols (S _{m, i} ) of the m-th transmission signal in the received signal (r); The candidate symbols (S) through zero-forcing (ZF: zero-forcing, hereinafter referred to as 'ZF') or minimum mean square error (MMSE). _{m, i} ) and a first calculator 214 for calculating decoding weights for noise and interference, and a decoding value for noise and interference of the candidate symbols S _{m, i} is determined to determine the candidate symbols S. _{m, i} ) a first generator 216 that calculates decoded symbols for noise and interference, a second canceller 218 that calculates noise and interference errors of the candidate symbols S _{m, i} , and the and a second calculator 220 for calculating a detection error offset of each symbol of the m th transmission signal.

)하여 상기 수신 신호(r)의 잡음 및 간섭(

)을 산출하고, 상기 수신 신호(r)의 잡음 및 간섭(

)을 제1계산기(214), 제2제거기(218) 및 제2연산부(250)로 각각 출력한다. 여기서, 상기 제1제거기(212)가 산출한 상기 수신 신호(r)의 잡음 및 간섭(

)은 상기 수신 신호(r)에서 상기 후보 심벌들(S_m,i)에 대한 잡음 및 간섭이라 할 수 있다.The first canceller 212 receives the received signal r, the candidate symbols S _{m, i} of the m th transmission signal and the channel matrix h _{m of} the m th transmission signal. Remove the candidate symbols S _{m, i} from the channel matrix h _m of

Noise and interference of the received signal r

) And noise and interference (

) Are output to the first calculator 214, the second remover 218, and the second calculator 250, respectively. Here, noise and interference of the received signal r calculated by the first remover 212 (

) May be referred to as noise and interference with respect to the candidate symbols S _{m, i} in the received signal r.

)과 채널 행렬(H)에서 m번째 송신 신호에 해당하는 성분들을 제거한 변환 채널 행렬(

)을 입력받는다. 여기서, 상기 제1계산기(214)는, 전술한 바와 같이 상기 m번째 송신 신호의 채널 행렬(h_m)의 입력시 상기 추정기가 채널 추정하여 입력한 채널 행렬(H)에서 상기 m번째 송신 신호에 해당하는 성분들에 '0'이 입력되어 상기 m번째 송신 신호의 채널 행렬(h_m)이 제거된 변환 채널 행렬(

)을 입력받는다. 그런 다음, 상기 제1계산기(214)는 ZF 또는 MMSE를 통해 상기 변환 채널 행렬(

)을 MMSE 널링(nulling)(

)하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭에 대한 복호 가중치(

)를 상기 제1생성기(216)로 출력한다.The first calculator 214 performs noise and interference of the received signal r.

) And a transform channel matrix (without components corresponding to the m th transmission signal from the channel matrix H)

) Is inputted. Here, the first calculator 214, as described above, when the channel matrix h _m of the mth transmission signal is input, the estimator 214 estimates the channel matrix H from the channel matrix H input by the estimator to the mth transmission signal. A transform channel matrix in which '0' is input to corresponding components and the channel matrix h _m of the m th transmission signal is removed.

) Is inputted. The first calculator 214 then uses the transform channel matrix (ZF or MMSE).

) MMSE nulling (

Decoding weights for noise and interference of the candidate symbols S _{m, i}

) Is output to the first generator 216.

)를 입력받아 상기 후보 심벌들(S_m,i)의 잡음 및 간섭에 대한 복호값을 결정하고, 상기 복호값에 대한 비트들을 생성하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭의 복호 심벌들(

)을 산출한 후, 상기 복호 심벌들(

)을 상기 제2제거기(218)로 출력한다.The first generator 216 is the decoding weight (

) Input receives the noise and interference determine the decoded value for the noise and interference, and the candidate symbols to generate bits for the decrypted value (S _{m, i)} of the candidate symbol (S _{m, i)} Decoding Symbols

After calculating the decoded symbols (

) Is output to the second eliminator 218.

)과 복호 심벌들(

)과 상기 변환 채널 행렬(

)을 입력받는다. 그런 다음, 상기 제2제거기(218)는 상기 수신 신호(r)의 잡음 및 간섭(

)에서 상기 변환 채널 행렬(

)에 의한 복호 심벌들(

)을 제거(

)하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭 오류를 산출하고, 상기 후보 심벌들(S_m,i)의 잡음 및 간섭 오류를 상기 제2계산기(220)로 출력한다.The second canceller 218 may reduce noise and interference of the received signal r.

) And decoding symbols (

) And the transform channel matrix (

) Is inputted. Then, the second canceller 218 may generate noise and interference of the received signal r.

In the transform channel matrix (

Decoding symbols by

)

) To calculate the noise and interference error of the candidate symbol (S _{m, i),} and outputs the noise and interference error of the candidate symbol (S _{m, i)} to the second converter (220).

The second calculator 220, the candidate symbols receives the noise and interference error of (S _{m, i),} the m-th transmit using the noise and interference error of the candidate symbol (S _{m, i)} Each symbol of the m th transmission signal is calculated by calculating a Euclidean distance (ED) between the candidate symbols S _{m, i} of the signal and the symbols of the m th transmission signal. Compute error detection offsets ED ² _i , respectively. Then, the second calculator 220 outputs the detection error offsets ED ² _i of each symbol of the m th transmission signal to the first storage unit 230.

The first storage unit 230 may include bit strings 232 and candidate symbols S _{m and i for} candidate symbols S _{m and i} of the m th transmission signal and symbols of the remaining transmission signals. The offset string 234 for the detection error offsets ED ² _i of the respective symbols of the m th transmission signal corresponding to each bit in the constellation diagram of the " That is, the first storage unit 230 offsets bit strings 232 for candidate symbols of the N _t transmission signals and detection error offsets ED ² _i of respective symbols of the m th transmission signal. Save column 234. In addition, the first storage unit 230 outputs the stored bit strings 232 and the offset string 234 to the LLR calculator 290. In addition, the first storage unit 230 is the m after determining a minimum detection error offset (ED ²⁾ in the detection error offset (ED ² _i) of each symbol of the second transmission signal, the minimum detection error offset (ED ²⁾ Is output to the second operation unit 250. For convenience of explanation, it will be described on the assumption that the detection error offset ED ² _p corresponding to the pth constellation array in the bit strings 232 is the minimum detection error offset ED ² .

Then, the second operation unit 250 performs noise and interference on candidate symbols of the remaining transmission signals through inverse bits of the bit strings 232 corresponding to the minimum detection error offset ED ² . A second generator 252 for generating extended decoded symbols with decoded symbols, a third canceller 254 for calculating noise and interference errors of candidate symbols of the remaining transmitted signals, and respective symbols of the remaining transmitted signals. And a third calculator 254 that calculates a detection error offset.

)를 산출하고, 상기 확장 복호 심벌들(

)을 제2제거기(254)와 제2저장부(270)로 출력한다. 여기서, j는 1, …, k_l이며, 상기 l은 1, …, N_t-1로서 상기 나머지 송신 신호들의 후보 심벌들의 잡음 및 간섭에 대한 복호 심벌들을 의미한다. 즉, 상기 제2생성기(252)는 상기 나머지 송신 신호들의 후보 심벌들의 잡음 및 간섭에 대한 복호값으로 상기 확장 복호값을 결정하여 상기 나머지 송신 신호들 의 후보 심벌들의 잡음 및 간섭에 대한 복호 심벌들인 확장 복호 심벌들(

)을 제2제거기(254)와 제2저장부(270)로 각각 출력한다.The second generator 252 determines an extended decoding value through the inverse bits of the bit strings 232 on the basis of the pth constellation array bits corresponding to the minimum detection error offset ED ² . By generating bits for the decoding value, the extended decoding symbols (

) And the extended decoded symbols (

) Is output to the second remover 254 and the second storage unit 270. Where j is 1,... , k _l , where l is 1,... , N _t -1 means decoded symbols for noise and interference of candidate symbols of the remaining transmission signals. That is, the second generator 252 determines the extended decoding value as a decoded value for noise and interference of candidate symbols of the remaining transmission signals, and decodes symbols for noise and interference of candidate symbols of the remaining transmission signals. Extended decoding symbols

) Are output to the second eliminator 254 and the second storage unit 270, respectively.

)에서 상기 최소 검출 오류 오프셋(ED²)에 해당하는 상기 수신 신호(r)의 잡음 및 간섭(

)과 상기 변환 채널 행렬(

) 및 확장 복호 심벌들(

)을 입력받는다. 그런 다음, 상기 제3제거기(254)는 상기 수신 신호(r)의 잡음 및 간섭(

)에서 상기 변환 채널 행렬(

)에 의한 확장 복호 심벌들(

)을 제거(

)하여 상기 나머지 송신 신호들의 후보 심벌들의 잡음 및 간섭 오류를 산출하고, 상기 잡음 및 간섭 오류를 제3계산기(254)로 출력한다.The third canceller 254 may reduce noise and interference of the received signal r.

Noise and interference of the received signal r corresponding to the minimum detection error offset ED ²

) And the transform channel matrix (

) And extended decoding symbols (

) Is inputted. Then, the third canceller 254 may generate noise and interference of the received signal r.

In the transform channel matrix (

Extended decoding symbols by

)

) Calculates noise and interference errors of candidate symbols of the remaining transmission signals, and outputs the noise and interference errors to the third calculator 254.

The third calculator 254 receives noise and interference errors of candidate symbols of the remaining transmission signals and uses the noise and interference errors of the candidate symbols to determine candidate symbols of the remaining transmission signals and the remaining transmission signals. The EDs between the symbols are respectively calculated to calculate detection error offsets of the respective symbols of the remaining transmission signals. Then, the third calculator outputs detection error offsets of the respective symbols of the remaining transmission signals to the second storage unit 270.

The second storage unit 270 may include bit strings 272 of extended decoded symbols for candidate symbols of the remaining transmission signals and the remaining transmission signals corresponding to each bit in constellations of candidate symbols of the remaining transmission signals. Each of the detection error offset columns 274 of each symbol. In addition, the second storage unit 270 may include bit strings 272 of extended decoded symbols and detection error offset columns 274 of respective symbols of the remaining transmission signals in the candidate symbols of the remaining transmission signals. 290).

The LLR calculator 290 may convert the bit strings 232 and the offset string 234 stored in the first storage 230, and the bit strings 272 and the offset string 274 stored in the second storage 270. LLR is calculated by retrieving the minimum detection error offsets of all the bits from the detection error offsets of each symbol of the mth transmission signal and the detection error offsets of each symbol of the remaining transmission signals. Output As such, the decoder decodes the received signal via the LLR. In this case, the decoder described with reference to FIG. 2 stores the candidate symbols of the remaining transmission signals as well as the candidate symbols of the m-th transmission signal, and the second storage unit 250 and the second storage unit ( 270) may increase the complexity of the decoder. In addition, the decoder calculates detection error offsets of each symbol of the remaining transmission signals by using the minimum detection error offsets of detection error offsets of the respective symbols of the m th transmission signal, thereby detecting error offsets of each symbol of the remaining transmission signals. The accuracy of these signals may be degraded, thereby degrading the decoding performance of the received signal. Next, a structure of a decoder for calculating an LLR in a communication system according to another embodiment of the present invention will be described in more detail with reference to FIG. 3.

3 is a diagram schematically illustrating a decoder structure in a communication system according to another embodiment of the present invention.

3, the decoder has N _r receive antennas to receive a received signal (r) and N _t transmit antennas have a specific layer of the candidate symbols of the N _t transmit signal transmitted, for example, N _t transmit signal Among them, candidate symbols S _{m, i} of the m th transmission signal, a channel matrix h _m of the m th transmission signal, and a channel matrix of a channel formed between N _t transmit antennas and N _r receive antennas ( An operation unit 310 for receiving the H) and calculating a detection error offset for each symbol of the m th transmission signal generated by noise and interference of the received signal r, and the m of the operation unit 310. A storage unit 330 for storing the detection error offset for each symbol of the first transmission signal and candidate symbols S _{m, i} of the m th transmission signal, and the m th transmission stored in the storage unit 330. Detection error offset and phase for each symbol in the signal Using the candidate symbol (S _{m, i)} comprises the LLR calculation unit 350 for calculating the LLR of the m-th transmission signal.

Here, _i in candidate symbols S _{m, i} of the m th transmission signal is 1,... , M _m , and M _m denotes a constellation array for the m th transmission signal. In the channel matrix H, as described with reference to FIG. 1, the estimators 164 and 166 use N _t transmit antennas and N _r receive antennas using a pilot separated by the separators 160 and 162 of the receiver 150. A channel matrix H estimated by estimating a channel formed in the liver and input to the decoder 172. The candidate symbols S _{m and i} denote symbols when the symbols of the m th transmission signal are located in constellations corresponding to the modulation scheme applied by the transmitter's modulator to the m th transmission signal. In this case, the modulation scheme applied by the transmitter's modulator is already recognized by the receiver in the initial entry procedure between the BS and the MS as described above. As described above, the transmitter may transmit transmission signals by applying one or more modulation schemes of PSK series and QAM series for each transmission antenna.

The first operation unit 310 includes a first remover 312 calculating noise and interference of the received signal r with respect to the candidate symbols S _{m and i} of the m th transmission signal, and ZF or MMSE. to determine the decoded value for the noise and interference of the first calculator 314 and, of the candidate symbol (s _{m, i)} for calculating the decoding weight for the noise and interference of the candidate symbol (s _{m, i)} and a generator (316) for calculating the decoded symbols for the noise and interference of the candidate symbol (s _{m, i),} the second canceler (318 for calculating the noise and interference error of the candidate symbol (s _{m, i)} And a second calculator 320 for calculating a detection error offset of each symbol of the m th transmission signal. Here, the received signal r, the transmitted signals s, and the channel matrix H may be expressed as in Equations 1, 2, and 3.

)하여 상기 수신 신호(r)에 포함된 수신 신호(r)의 잡음 및 간섭(

)을 산출하고, 상기 수신 신호(r)의 잡음 및 간섭(

)을 제1계산기(314)와 제2제거기(318)로 출력한다. 여기서, 상기 제1제거기(312)가 산출한 상기 수신 신호(r)의 잡음 및 간섭(

)은 상기 수신 신호(r)에서 상기 후보 심벌들(S_m,i)에 대한 잡음 및 간섭이라 할 수 있다.The first remover 312 receives the received signal r, candidate symbols S _{m, i} of the m th transmission signal and a channel matrix h _{m of} the m th transmission signal. Remove the candidate symbols S _{m, i} from the channel matrix h _m of

Noise and interference of the received signal r included in the received signal r

) And noise and interference (

) Is output to the first calculator 314 and the second remover 318. Here, noise and interference of the received signal r calculated by the first remover 312 (

) May be referred to as noise and interference with respect to the candidate symbols S _{m, i} in the received signal r.

)과 채널 행렬(H)에서 m번째 송신 신호에 해당하는 성분들을 제거한 변환 채널 행렬(

)을 입력받는다. 여기서, 상기 제1계산기(314)는, 전술한 바와 같이 상기 m번째 송신 신호의 채널 행렬(h_m)의 입력시 상기 추정기가 채널 추정하여 입력한 채널 행렬(H)에서 상기 m번째 송신 신호에 해당하는 성분들에 '0'이 입력되어 상기 m번째 송신 신호의 채널 행렬(h_m)이 제거된 변환 채널 행렬(

)을 입력받는다. 그런 다음, 상기 제1계산기(314)는 ZF 또는 MMSE를 통해 상기 변환 채널 행렬(

)을 MMSE 널링(

)하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭에 대한 복호 가중치(

)를 상기 생성기(316)로 출력한다.The first calculator 314 is a noise and interference of the received signal (r)

) And a transform channel matrix (without components corresponding to the m th transmission signal from the channel matrix H)

) Is inputted. Here, the first calculator 314, as described above, when the channel matrix h _m of the mth transmission signal is input, the estimator 314 estimates the channel matrix H from the channel matrix H input by the estimator to the mth transmission signal. A transform channel matrix in which '0' is input to corresponding components and the channel matrix h _m of the m th transmission signal is removed.

) Is inputted. The first calculator 314 then uses the transform channel matrix (ZF or MMSE).

) MMSE nulling (

Decoding weights for noise and interference of the candidate symbols S _{m, i}

) Is output to the generator 316.

)를 입력받아 상기 후보 심벌들(S_m,i)의 잡음 및 간섭에 대한 복호값을 결정하고, 상기 복호값에 대한 비트들을 생성하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭의 복호 심벌들(

)을 산출한 후, 상기 복호 심벌들(

)을 상기 제2제거기(318)로 출력한다.The generator 316 is the decoding weight (

) An input receiving the noise and interference determine the decoded value for the noise and interference, and the candidate symbols to generate bits for the decrypted value (S _{m, i)} of the candidate symbol (S _{m, i)} Decoding Symbols

After calculating the decoded symbols (

) Is output to the second eliminator 318.

)과 복호 심벌들(

)과 상기 변환 채널 행렬(

)을 입력받는다. 그런 다음, 상기 제2제거기(318)는 상기 수신 신호(r)의 잡음 및 간섭(

)에서 상기 변환 채널 행렬(

)에 의한 복호 심벌들(

)을 제거(

)하여 상기 후보 심벌들(S_m,i)의 잡음 및 간섭 오류를 산출하고, 상기 후보 심벌들(S_m,i)의 잡음 및 간섭 오류를 상기 제2계산기(320)로 출력한다.The second canceller 318 may reduce noise and interference of the received signal r.

) And decoding symbols (

) And the transform channel matrix (

) Is inputted. Then, the second canceller 318 may generate noise and interference of the received signal r.

In the transform channel matrix (

Decoding symbols by

)

) To calculate the noise and interference error of the candidate symbol (S _{m, i),} and outputs the noise and interference error of the candidate symbol (S _{m, i)} to the second converter 320.

The second calculator 320, the candidate symbols receives the noise and interference error of (S _{m, i),} the m-th transmit using the noise and interference error of the candidate symbol (S _{m, i)} ED between the candidate symbols S _{m and i} of the signal and the symbols of the m th transmission signal are respectively calculated to calculate a detection error offset ED ² _i of each symbol of the m th transmission signal. Then, the second calculator 320 outputs the detection error offset ED ² _i of each symbol of the m th transmission signal to the storage unit 330.

The storage unit 330 corresponds to each bit in the constellation of the bit string 332 for the candidate symbols S _{m, i} of the m th transmission signal and the candidate symbols S _{m, i} . The detection error offset ED ² _i string 334 of each symbol of the m th transmission signal is stored. In addition, the storage unit 330 may include a bit string 332 of candidate symbols S _{m and i} of the m th transmission signal and a detection error offset ED ² _i string of each symbol of the m th transmission signal. 334 is output to the LLR calculator 350.

The LLR operation unit 350 is a searcher 352 for retrieving minimum detection error offsets for bits of the m th transmission signal from detection error offsets of the symbols of the m th transmission signal, and the m th transmission. The minimum detection error offset determined by the first determiner 354 and the second determiner 356, and the first determiner 353 and the second determiner 356, respectively, to determine the minimum detection error offset for the bits of the signal. Includes a summer 358 that adds up to yield an LLR. That is, the LLR calculator 350 searches and determines the minimum detection error offsets of the bits of the m th transmission signal, respectively, and calculates the LLR by summing the determined minimum detection error offsets.

As described above, the decoder calculates the LLR of the m th transmission signal among the N _t transmission signals, and the m th transmission signal described above with respect to any one of the remaining transmission signals except the m th transmission signal. The procedure of calculating the LLR of is performed again to calculate the LLR of the arbitrary transmission signal. That is, the decoder is then to repeat the procedure for calculating the LLR of the m-th transmission signal above for each of the N _t transmit signal calculates the LLR of the N _t of all transmitted signals, respectively, through the LLR Decode the received signal. Next, an operation of calculating the LLR by the decoder in the communication system according to another embodiment of the present invention will be described in more detail with reference to FIG. 4.

4 is a diagram illustrating an operation process of a decoder calculating an LLR in a communication system according to another embodiment of the present invention.

Referring to FIG. 4, in operation S405, a channel matrix H of a channel formed between N _t transmit antennas and N _r receive antennas and a received signal r received by the N _r receive antennas are received. Check it. Next, in step S410, candidate symbols of a corresponding transmission signal, for example, an mth transmission signal, and a channel matrix of the transmission signal among N _t transmission signals transmitted by the reception signal r and the N _t transmission antennas. And receiving a conversion channel matrix of the corresponding transmission signal and storing candidate symbols of the input transmission signal. The received signal r, the candidate symbols of the corresponding transmission signal, and the channel matrix of the transmission signal are input to a first canceller, and the conversion channel matrix of the transmission signal is input to a first calculator. Candidate symbols of are stored in the storage unit. As described above, the transform channel matrix of the corresponding transmission signal is a channel matrix from which the channel matrix of the corresponding transmission signal is removed by inputting '0' to the components corresponding to the transmission signal in the identified channel matrix H. to be.

Next, in step S415, the first calculator receives the received signal r, candidate symbols of the corresponding transmitted signal, and a channel matrix of the corresponding transmitted signal, and then receives a channel matrix of the corresponding transmitted signal from the received signal r. Noise and interference of the received signal r included in the received signal r are calculated by removing the candidate symbols. As described above, noise and interference of the received signal r may be referred to as noise and interference with respect to candidate symbols of the corresponding transmission signal in the received signal r. In operation S420, the first calculator receives the noise and interference of the received signal r and the transform channel matrix of the corresponding transmitted signal, and decodes the noise and interference of candidate symbols of the corresponding transmitted signal through ZF or MMSE. A weight is calculated and a generator receives the decoding weight to calculate decoded symbols of noise and interference of the candidate symbols.

In operation S425, the second remover removes the decoded symbols of the noise and the interference by the transform channel matrix from the noise and the interference of the received signal r to calculate the noise and the interference error of the candidate symbols. Next, in operation S430, the second calculator calculates an ED between candidate symbols of the corresponding transmission signal and symbols of the corresponding transmission signal using noise and interference errors of the candidate symbols to detect each symbol of the corresponding signal. Error offsets are calculated, and the storage stores detection error offsets of each symbol of the corresponding signal.

In operation S435, the LLR calculator determines minimum detection error offsets of bits of the corresponding transmission signal from detection error offsets of the symbols of the transmission signal stored in the storage unit, and then adds the minimum detection error offsets. LLR of the corresponding transmission signal is calculated.

Next, determine whether the LLR is calculated by N _t of all the transmission signal from the S440 step, and the LLR of the check result in the S440 step the N _t of all the transmission signal is not output the corresponding signal the process proceeds to S410 step The above-described procedure is performed on the remaining transmission signals except for the LLRs of the remaining transmission signals. On the other hand, if the LLRs of all the N _t transmission signals are calculated as a result of the checking in step S440, the LLR calculation operation is completed by calculating the LLRs of all the N _t transmission signals in step S445, and the decoder determines the N _t. The received signal through the LLR of all four transmitted signals.

In addition, the method according to the present invention may be implemented via a computer-readable medium including program instructions for performing operations implemented by various computers in a multiple input multiple output communication system. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical recording media such as CD-ROMs, DVDs, magnetic-optical media such as floppy disks, and ROM, RAM, flash memory, and the like. Hardware devices specifically configured to store and execute the same program instructions are included. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

1 schematically illustrates the structure of a communication system according to an embodiment of the invention.

2 is a diagram schematically illustrating a decoder structure in a communication system according to an embodiment of the present invention.

3 is a diagram schematically illustrating a decoder structure in a communication system according to another embodiment of the present invention.

4 is a diagram illustrating an operation process of a decoder calculating an LLR in a communication system according to another embodiment of the present invention.

Claims (19)

delete A signal receiving apparatus in a multiple input multiple output communication system, Each symbol of the first transmission signal among the transmission signals using a first channel matrix among channel matrices formed between the reception signals received by the reception antennas and the transmission signals transmitted by the transmission / reception antennas and candidate symbols of the transmission signals. A calculation unit for calculating a detection error offset for each field; And A log likelihood ratio calculator configured to calculate a log likelihood ratio (LLR) of the first transmitted signal using the detection error offset for each symbol of the first transmitted signal and the candidate symbols of the first transmitted signal Includes a decoder that includes, The calculation unit, A first canceller for calculating noise and interference of the received signal; A first calculator for calculating decoding weights for noise and interference of the candidate symbols; A generator that calculates decoded symbols of noise and interference for the candidate symbols using the decode weights; A second canceller for calculating noise and interference errors of the candidate symbols; And a second calculator for calculating detection error offsets of each symbol of the first transmitted signal using noise and interference errors of the candidate symbols. The method of claim 2, And a storage unit which stores candidate symbols of the first transmission signal and the detection error offsets. The method of claim 3, wherein the calculation unit, A searcher for retrieving minimum detection error offsets for bits of the first transmission signal from the detection error offsets stored in the storage unit, a determiner for determining the minimum detection error offset, and the minimum detection error offset And a summer for calculating the log likelihood ratio. The method of claim 2, wherein the first eliminator, And removing candidate symbols of the first transmission signal from the first channel matrix to calculate noise and interference with respect to candidate symbols of the first transmission signal. The method of claim 2, And the first calculator calculates the decoding weight using a transform channel matrix from which the first channel matrix consisting of only components corresponding to the first transmission signal is removed from the channel matrix. The method of claim 6, The first calculator calculates the decoding weight by nulling the transform channel matrix through zero-forcing (ZF) or minimum mean square error (MMSE). Signal receiving device. The method of claim 6, And the second remover removes the decoded symbols by the transform channel matrix from noise and interference of the received signal to calculate noise and interference errors of the candidate symbols. The method of claim 2, And the second calculator calculates the detection error offsets by calculating an Euclidean distance between the candidate symbols and the symbols of the first transmission signal. In the signal receiving method of a multiple input multiple output communication system, (a) a first channel matrix among channel matrices formed between a received signal received at a plurality of receive antennas and a transmit signal transmitted at a plurality of transmit and receive antennas, and a first transmit signal among the transmit signals using candidate symbols of the transmit signal; Calculating a detection error offset for each symbol of; (b) storing the detection error offset for each symbol of the first transmitted signal and candidate symbols of the first transmitted signal; (c) calculating a log likelihood ratio (LLR) of the first transmitted signal using the detection error offset for each symbol of the first transmitted signal and the candidate symbols of the first transmitted signal; Including, In step (a), (a-1) calculating noise and interference of the received signal; (a-2) calculating decoding weights for noise and interference of the candidate symbols; (a-3) calculating decoded symbols of noise and interference with respect to the candidate symbols using the decode weights; (a-4) calculating noise and interference errors of the candidate symbols; (a-5) calculating detection error offsets of each symbol of the first transmission signal using noise and interference errors of the candidate symbols. The method of claim 10, In the step (c), after retrieving the minimum detection error offsets for the bits of the first transmission signal from the stored detection error offsets, the minimum detection error offsets are summed and the log likelihood of the first transmission signal. A signal receiving method comprising calculating the ratio. delete The method of claim 10, In the step (a-1), the candidate symbols are removed from the first channel matrix to calculate noise and interference for the candidate symbols. The method of claim 10, In the step (a-2), the decoding weight is calculated using a transform channel matrix obtained by removing the first channel matrix including only components corresponding to the first transmitted signal from the channel matrix. Way. The method of claim 14, In the step (a-2), the transform channel matrix is nulled through zero-forcing (ZF) or minimum mean square error (MMSE) to reduce noise of the candidate symbols and A method for receiving a signal, characterized by calculating a decoding weight for interference. The method of claim 15, In the step (a-3), after the decoding value is determined based on the decoding weight, the decoding symbols are generated by generating bits for the decoding value. The method of claim 14, In the step (a-4), the noise and interference errors of the candidate symbols are calculated by removing the decoded symbols by the transform channel matrix from the noise and interference of the received signal. The method of claim 10, In the step (a-5), the detection error offsets are calculated by calculating an Euclidean distance between the candidate symbols and the symbols of the first transmission signal. 19. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 10, 11 and 13-18.

Images