Receiver, operation method, signal detection method, and computer-readable recording medium

Abstract

A receiver, an operation method, a signal detection method, and a computer-readable recording medium are provided. The receiver includes a demodulator configured to calculate, for each physical channel, the Euclidean distance of one or more of the received symbols relative to all candidate vectors included in an initial candidate vector set, and output information about the Euclidean distance. A vector set detector may select one of a plurality of candidate vector sets having different sizes based on the information as a subsequent candidate vector set for calculating log likelihood ratios (LLRs) of other symbols in the plurality of symbols or log likelihood ratios relative to a second signal received after the first signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2018-0133840 filed in the Korean Intellectual Property Office on November 2, 2018, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a multiple input multiple output (MIMO) receiver and an operating method thereof, and more particularly, to a MIMO receiver for selecting a candidate vector set and an operating method thereof. Background Art

[0004] Wireless communication networks can provide various types of communication content, such as audio data, video data, packet data, message data, etc. With the recent development of mobile services through wireless communication networks, the amount of data to be processed has steadily increased. Therefore, the demand for modems that support high-speed signal processing has also increased.

[0005] When the modem processes data at high speed, it may perform highly complex signal processing operations, such as wideband signal processing operations, multi-antenna signal processing operations, etc. Therefore, the modem performing high-speed signal processing operations increases power consumption and heat generation, which may thus bring about a risk of failure.

[0006] In a modulation method using phase shift keying (PSK) or quadrature amplitude modulation (QAM), the bit stream is divided into n-bit code segments and symbols are sent, where each symbol represents an n-bit code, where "n" depends on the modulation order (for example, n=2 for quadrature PSK and n=3 for 8PSK). Symbols can be represented as reference coordinates in an in-phase-quadrature (IQ) constellation diagram. During modulation, the phase or amplitude and phase of the signal transmitted during the symbol period can represent the reference coordinates in the IQ space. The received signal can be sampled (its phase or amplitude / phase is measured) once per symbol period to determine the nearest reference coordinate in the IQ space of the modulation system used, thereby determining which symbol was sent. However, due to the influence of noise, the measured IQ coordinate corresponding to the sample may be located between two or more reference coordinates, resulting in uncertainty in demodulation. To this end, a technique for obtaining log likelihood ratios (LLRs), which are often referred to as "soft information", can be used, where LLRs are a measure of sample uncertainty. In order to improve the reliability of error correction, LLRs can be provided to the error correction stage. LLRs can be related to the Euclidean distance between the measured coordinates and the reference coordinates in the IQ space, and the reference coordinates can be represented by "candidate vectors". LLR measurement techniques may be particularly useful in MIMO systems, but may consume a lot of processing resources. Therefore, it is necessary to reduce the complexity of the processing tasks used for LLR measurements. Summary of the invention

[0007] Embodiments of the inventive concept provide a multiple-input multiple-output (MIMO) receiver and an operating method thereof, and more particularly, provide a MIMO receiver and an operating method thereof that selects a candidate vector set based on information obtained from generating a previous log-likelihood ratio (LLR).

[0008] According to one aspect of the inventive concept, a receiver for receiving a first signal including multiple symbols through a multiple-input multiple-output (MIMO) channel is provided, the receiver comprising: a demodulator configured to calculate, for each physical channel, the Euclidean distance of at least one or more of the received symbols relative to all candidate vectors included in a candidate vector set, and output information about the Euclidean distance; and a vector set detector configured to select, based on the information, one of a plurality of candidate vector sets having different sizes as a subsequent candidate vector set for calculating log-likelihood ratios of other symbols in the plurality of symbols or log-likelihood ratios relative to a second signal received after the first signal.

[0009] According to another aspect of the inventive concept, there is provided an operating method performed by a receiver for receiving at least a first transmitted signal and a second transmitted signal through multiple antennas, the operating method comprising: calculating the Euclidean distance of all candidate vectors of the first transmitted signal relative to an initial candidate vector set; selecting a first candidate vector set from multiple candidate vector sets based on information about the Euclidean distance; and generating a log-likelihood ratio of symbols of the second transmitted signal based on the first candidate vector set.

[0010] According to another aspect of the inventive concept, a method for detecting signals in a wireless communication system including a multiple-input multiple-output (MIMO) channel performed by a receiver is provided, the method comprising: calculating information based on one or more of the received transmitted signals and a predetermined candidate vector for each physical channel, and generating a log-likelihood ratio (LLR) about one or more of the received signals based on the information; selecting a first candidate vector set from a plurality of candidate vector sets based on the information for generating the log-likelihood ratio; and generating log-likelihood ratios about the remaining received transmitted signals based on the first candidate vector set.

[0011] In another aspect, a receiver receives a signal modulated based on phase shift keying (PSK) or quadrature amplitude modulation (QAM) and including a plurality of symbols transmitted in a wireless communication system. The receiver includes: a demodulator configured to calculate the Euclidean distance of one or more of the received symbols relative to all candidate vectors included in an initial candidate vector set and output information about the Euclidean distance; and a vector set detector configured to select one of a plurality of candidate vector sets having different sizes as a subsequent candidate vector set for calculating log-likelihood ratios of other symbols in the plurality of symbols based on the information.

[0012] A non-transitory computer-readable recording medium may store instructions that, when executed by at least one processor, implement any one of the above methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the inventive concept will be more clearly understood by reading the following detailed description in conjunction with the accompanying drawings, in which like reference characters may refer to like elements, features or operations, wherein:

[0014] Figure 1 is a block diagram of a communication system according to an exemplary embodiment of the inventive concept.

[0015] Figure 2 is a detailed block diagram of a transmitter according to an exemplary embodiment of the inventive concept.

[0016] Figure 3 A structure of a transmission signal output from a transmitter according to an exemplary embodiment of the inventive concept is shown.

[0017] Figure 4 is a detailed block diagram of a receiver according to an exemplary embodiment of the inventive concept.

[0018] Figure 5 is a diagram illustrating a signal constellation for modulating a transmission signal according to an exemplary embodiment of the inventive concept.

[0019] Figure 6 is a diagram for explaining transmission / reception of a modulation signal according to an exemplary embodiment of the inventive concept.

[0020] Fig. 7A is a flowchart of the operation of a receiver according to an exemplary embodiment of the inventive concept, and Figure 7B is a diagram of a complex plane indicating candidate vectors.

[0021] Fig. 8A and Figure 8B Corresponding examples of candidate vector sets according to exemplary embodiments of the inventive concept are shown.

[0022] Fig.9A and Fig. 9B is a diagram for explaining an operation of selecting a candidate vector set according to an exemplary embodiment of the inventive concept.

[0023] Fig.10 is a diagram for explaining the operation of a receiver according to an exemplary embodiment of the inventive concept.

[0024] Fig.11 is a diagram for explaining the operation of a receiver according to another exemplary embodiment of the inventive concept.

[0025] Fig.12 is a diagram for explaining the operation of a receiver according to another exemplary embodiment of the inventive concept.

[0026] Fig.13 is a detailed block diagram of a receiver according to another exemplary embodiment of the inventive concept.

[0027] Fig.14 is a block diagram of a wireless communication device according to an exemplary embodiment of the inventive concept. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the inventive concept will be explained in detail with reference to the accompanying drawings.

[0029] As used herein, the terms "transmit" and "receive" when used as adjectives refer to "transmission" and "reception", respectively.

[0030] Herein, “Euclidean distance” refers to the Euclidean distance in a constellation space (eg, IQ constellation space).

[0031] Figure 1 is a block diagram of a communication system 10 according to an exemplary embodiment of the inventive concept. The communication system 10 may include a transmitter 100 and a receiver 200 that perform wireless communication through a multiple-input multiple-output (MIMO) channel 300.

[0032] The communication system 10 may be any suitable type of wireless communication system including the MIMO channel 300. Some examples of the communication system 10 include fifth generation wireless (5G) th Generation wireless, 5G) system, long term evolution (LTE) system, Wifi, etc. The communication system 10 may also include wired communication system components (not shown in the figure), such as a storage system, a network system, etc. It should also be noted here that some aspects of the inventive concept can be applied to non-MIMO wireless communication systems that utilize PSK or QAM modulation schemes in a noisy environment (and in these cases, a single input single output (SISO) or other type of radio channel can replace the MIMO channel 300). Some aspects of the inventive concept can also be applied to end-to-end wired links with noisy channels.

[0033] For example, the transmitter 100 may be a base station or may be included in a base station. A base station may be a fixed station that communicates with a terminal and / or another base station, and may send / receive data and / or control information by communicating with the terminal and / or another base station. A base station may also be referred to as a Node B, an evolved-Node B (eNB), a base transceiver system (BTS), an access point (AP), etc.

[0034] For example, the receiver 200 may be a terminal or may be included in a terminal. The terminal may be any of various wireless communication devices capable of communicating with the transmitter 100 to send / receive data and / or control information. For example, the terminal may be referred to as user equipment (UE), mobile station (MS), mobile terminal (MT), user terminal (UT), subscriber station (SS), wireless device, portable device, etc.

[0035] The wireless communication network between the transmitter 100 and the receiver 200 may support communication between multiple users sharing available network resources. For example, information may be exchanged in the wireless communication network based on various methods such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc.

[0036] The transmitter 100 may include a plurality of transmit antennas 102-1 to 102-M (hereinafter, M is a positive integer) and may transmit a plurality of symbols x1 to xM (which may be interchangeably referred to as transmit signals herein) through each of the plurality of transmit antennas 102-1 to 102-M, for example, on the same frequency band. The receiver 200 may include a plurality of receive antennas 202-1 to 202-N (hereinafter, N is a positive integer) and may receive a plurality of symbols y1 to yN through each of the plurality of receive antennas 202-1 to 202-N. The signal received by each receive antenna 202-i (i=any one of 1 to N) may contain signal energy from all transmit antennas 102-1 to 102-M. The receiver 200 may effectively isolate the transmit symbols x1 to xM by utilizing information on channel conditions and in combination with a signal processing algorithm that uses the receive signals on all receive antennas 202-1 to 202-N as inputs. Thus, individual channels within MIMO channel 300 may be isolated, where each channel is associated with one of transmit antennas 102-1 through 102-M. Thus, each channel may be a channel for receiving and demodulating symbols x1 through xM transmitted by a respective one of transmit antennas 102-1 through 102-M.

[0037] For example, when the symbol vector transmitted by the transmitter 100 is represented as x=[x1,…xM] T When , the symbol vector y received by the receiver 200 can be expressed by Equation 1 as follows.

[0038] [Equation 1]

[0039]

[0040] In Equation 1, hi,j may indicate the effective channel gain between the jth (j is 1 to M) transmit antenna (or "layer") and the ith (i = 1 to N) receive antenna, and xj may indicate the transmit symbol from the jth transmit antenna. The transmit symbol xj may be measured as a phase value (such as in a PSK modulation scheme) or an amplitude and phase value (such as in a QAM modulation scheme) representing a coordinate in a signal constellation in IQ space. Aspects related to this will be described below.

[0041] Furthermore, in the above equation 1, ni may indicate additive white Gaussian noise (AWGN) from the i-th receive antenna, and ni may have a value of σ with respect to the receive antennas 202-1 to 202-N. 2The variance of AWGN. AWGN may include interference signals. For example, the noise of the receiving antennas in the communication system 10 may be taken into account together with the influence of the interference signals. In this case, the variance of AWGN with respect to each of the receiving antennas 202-1 to 202-N may vary and be spatially correlated. In the following, it is assumed that the variance of AWGN is the same and the AWGN of each receiving antenna is spatially uncorrelated. In this case, AWGN may be the same as the noise to which the whitening filter is applied.

[0042] The receiver 200 may include a MIMO demodulator 250 and a vector set detector 260. For each channel, the MIMO demodulator 250 may calculate the Euclidean distances about one or more of the received symbols and all candidate vectors included in the candidate vector set, and may output information about the Euclidean distances. According to an exemplary embodiment, the MIMO demodulator 250 may calculate the Euclidean distances about the received symbols and the candidate vectors included in the superset of candidate vectors, and may output information about the Euclidean distances. For example, the superset of candidate vectors may be the union of the candidate vector sets.

[0043] In addition, MIMO demodulator 250 may generate a log likelihood ratio (LLR) based on the calculated Euclidean distance. For example, the LLR may be used as a basis for soft output bit probability estimation.

[0044] The vector set detector 260 may select a candidate vector set for generating LLR from a plurality of predetermined candidate vector sets. According to an exemplary embodiment, the vector set detector 260 may select one of the plurality of candidate vector sets based on information about the Euclidean distance output from the MIMO demodulator 250.

[0045] For example, the vector set detector 260 may determine whether each of the candidate vector sets includes a candidate vector having "+1" and "-1" as bits of information included in a transmission symbol corresponding to a reception symbol and having a minimum Euclidean distance. When each of the candidate vector sets includes the candidate vector, the vector set detector 260 may count the number of candidate vectors included in each of the candidate vector sets. The vector set detector 260 may select a candidate vector set by comparing the count value with a predetermined critical value.

[0046] According to an exemplary embodiment, the vector set detector 260 may select a candidate vector set with the smallest size from a candidate vector set having a count value equal to or greater than a predetermined critical value. For example, the vector set detector 260 may compare a predetermined critical value having a fixed value with the count value. As another example, the vector set detector 260 may compare a predetermined critical value having a dynamically changeable value with the count value. For example, the predetermined critical value may change dynamically based on a channel parameter.

[0047] According to an exemplary embodiment, for each physical channel, the MIMO demodulator 250 may generate LLRs about symbols included in the received signal based on the candidate vector set selected by the vector set detector 260. In other words, the MIMO demodulator 250 may send information about the Euclidean distance obtained based on the initial candidate vectors to the vector set detector 260, the vector set detector 260 may select a candidate vector set based on this information, and the MIMO demodulator 250 may generate LLRs about the remaining symbols based on the selected candidate vector set.

[0048] For example, the MIMO demodulator 250 may perform an operation of generating information about the Euclidean distance for each physical channel once, and may fix the candidate vector set selected by the vector set detector 260 based on this operation for calculating the LLR corresponding to the remaining symbols. As another example, the MIMO demodulator 250 may perform an operation of generating information about the Euclidean distance based on a certain cycle for each physical channel, and the vector set detector 260 may select a candidate vector set based on this information generated according to the cycle. In other words, the MIMO demodulator 250 may calculate the LLR about the symbol based on the candidate vector set selected differently according to the certain cycle.

[0049] Therefore, the receiver 200 according to the inventive concept can select an optimal candidate vector set based on the channel condition and can generate LLR based on the optimal candidate vector set. Therefore, power consumption of generating LLR can be minimized and LLR can be generated with a high modulation order with lower complexity.

[0050] Figure 2 is a detailed block diagram of the transmitter 100 according to an exemplary embodiment. For example, Figure 2 Can be Figure 1 A block diagram of components included in transmitter 100 is shown.

[0051] Reference Figure 2The transmitter 100 may include a serial to parallel (S / P) converter 110, a plurality of cyclic redundancy check (CRC) units 120_1 to 120_M, a plurality of forward error correction (FEC) encoders 130_1 to 130_M, a plurality of rate matching units 140_1 to 140_M, a plurality of modulators 150_1 to 150_M, a plurality of layer mapping units 160_1 to 160_M, a precoding unit 170, a plurality of inverse fast Fourier transform (IFFT) units 180_1 to 180_M, and a plurality of antennas 102-1 to 102-M.

[0052] First, an information bit stream BS to be transmitted may be input into the S / P converter 110. The S / P converter 110 may convert the input information bit stream BS into a parallel form to generate a plurality of information bit streams, and may output each of the plurality of information bit streams to the CRC units 120_1 to 120_M. For example, the S / P converter 110 may convert the information bit stream BS into a codeword (or a transport block) as an input unit of channel decoding, convert into a parallel form, and output the converted information bit stream BS.

[0053] The CRC units 120_1 to 120_M may perform a CRC check operation on the bit streams converted into parallel form and may output a signal on which the CRC check operation is performed to each of the FEC encoders 130_1 to 130_M. For example, the CRC units 120_1 to 120_M may perform a CRC check operation to detect errors occurring during transmission.

[0054] The FEC encoders 130_1 to 130_M may apply FEC, which is an error correction symbol for correcting errors occurring due to noise, to the signals received from the CRC units 120_1 to 120_M. For example, in a wireless communication system, at least one of a convolution code, a turbo code, a low-density parity-check code (LDPC) code, and a polar code may be used as FEC. For example, in the case of LTE communication, a convolution code may be used for a control channel, and a turbo code may be used for a traffic channel. In addition, in the case of 5G communication, a polar code may be used for a control channel, and an LDPC code may be used for a traffic channel.

[0055] The rate matching units 140_1 to 140_M may perform a rate matching operation on the signals output from the FEC encoders 130_1 to 130_M based on a predetermined rate matching method, and may output the signals on which the rate matching operation is performed to the modulators 150_1 to 150_M. Based on the rate matching operation, the rate matching units 140_1 to 140_M may match the encoded bit with the number of modulation symbols allocated to each user.

[0056] The modulators 150_1 to 150_M may perform a modulation operation on the signal on which the rate matching operation is performed based on a predetermined modulation method, and may output the signal on which the modulation operation is performed to the layer mapping units 160_1 to 160_M. For example, the modulators 150_1 to 150_M may map the signal on which the rate matching operation is performed using a signal constellation. The layer mapping units 160_1 to 160_M may distribute the modulated signals to correspond to the number of input layers of the precoding unit 170.

[0057] The precoding unit 170 may perform a precoding operation on the signals output from the layer mapping units 160_1 to 160_M based on a predetermined precoding method, and may output the signals on which the precoding operation is performed to the IFFT units 180_1 to 180_M. For example, the precoding method may be determined based on feedback information received by the transmitter 100. The IFFT units 180_1 to 180_M may convert the transmission signal of each transmission antenna in the frequency domain output from the precoding unit 170 into the time domain through IFFT, and may transmit the converted transmission signals s1 to sM to the antennas 102_1 to 102_M.

[0058] Figure 3 1 shows an exemplary structure of a transmission signal output from the transmitter 100 according to an exemplary embodiment of the inventive concept. Figure 3 As shown in , the first transmit signal s1 may include information structured as a plurality of fields x1_1 to x1_4, each of which may contain one or more symbols. In addition, the Mth transmit signal sM may include a plurality of fields xM_2 to xM_4, each of which may have one or more symbols. For example, the first transmit signal s1 and the Mth transmit signal sM may be transmitted from antennas 102_1 and 102_m, respectively, using the same frequency and may have the same timing.

[0059] As an example, the first symbol x1_1 may be a symbol for informing the receiver 200 about a transmission method. For example, the first symbol x1_1 may include information related to an error correction method, such as an error correction method for transmitting data symbols, a coding rate and a modulation method for transmitting data symbols, etc.

[0060] In an example, the second symbols x1_2 and xM_2 may be symbols for estimating channel fluctuations of transmission signals s1 and sM output from the transmitter 100. In addition, the third symbols x1_3 and xM_3 and the fourth symbols x1_4 and xM_4 may be symbols representing data (eg, user data, traffic).

[0061] Figure 4 is a detailed block diagram of a receiver 200 according to an exemplary embodiment. For example, Figure 4 Can be Figure 1 FIG. 2 is a block diagram of components included in the receiver 200. Figure 4 As shown, the receiver 200 may include multiple antennas 202-1 to 202-N, multiple fast Fourier transform (FFT) units 280_1 to 280_N, an effective channel generator 270, a MIMO demodulator 250, a vector set detector 260, multiple rate dematching units 240_1 to 240_N, multiple FEC decoders 230_1 to 230_N, multiple CRC units 220_1 to 220_N and a parallel to serial (P / S) converter 210.

[0062] First, the signals rs1 to rsN received through the antennas 202-1 to 202-N may be input to the FFT units 280_1 to 280_N, and the FFT units 280_1 to 280_N may perform an FFT operation on the signals rs1 to rsN. That is, the FFT units 280_1 to 280_N may convert the received signal of each antenna having a time domain into a frequency domain through FFT, and may send the converted received signal to the effective channel generation unit 270.

[0063] The effective channel generator 270 may reflect the effect of the precoding method applied by the transmitter 100 on the received signals rs1 to rsN converted into the frequency domain, and may output the signals rs1 to rsN reflecting the effect to the MIMO demodulator 250. For example, in a communication system, two types of reference signals (i.e., a cell-specific reference signal and a UE-specific reference signal) may be used to generate a channel (or estimate a channel). The cell-specific reference signal may be a reference signal used in common by all user equipments, while the UE-specific reference signal may be a reference signal used only for a specific user equipment. According to this embodiment, in order to reflect the effect of the precoding applied by the transmitter 100, the effective channel generator 270 may be included in the receiver 200. In other embodiments, the channel estimation may be performed by an external device, and the information of the estimated channel is provided separately from the external device to the MIMO demodulator 250 (so that the effective channel generator 270 may be omitted from the receiver 200).

[0064] The MIMO demodulator 250 may perform a demodulation operation on the signal output from the effective channel generator 270 based on a demodulation method corresponding to the modulation method used by the transmitter 100. For example, the MIMO demodulator 250 may generate LLRs using the effective channel generated from the effective channel generator 270 and the received signals 202_1 to 202_N. For example, the MIMO demodulator 250 may obtain LLRs using the log-MAP method of the following equation 2.

[0065] [Equation 2]

[0066]

[0067] In equation 2, b m,k May refer to the kth bit (k is a positive integer) of a symbol transmitted from the mth transmit antenna (or mth transmit "layer") (m is a positive integer in the range of 1 to M, inclusive). In addition, Refers to the transmission signal vector set C sent from the transmitter 100 M Medium m,k is the set of transmitted signal vectors of “+1”, and It may refer to the transmission signal vector set C transmitted from the transmitter 100. M Medium m,k is the set of transmitted signal vectors of “-1”. For example, when b m,k When it is "+1", b m,k Can be a bit that is 0, and when b m,k When it is "-1", b m,k Can be a bit that is 1.

[0068] To calculate the LLR with less complexity than Equation 2, the following approximation of Equation 3 may be used to calculate the LLR.

[0069] [Equation 3]

[0070]

[0071] However, based on Equation 3, the Euclidean distances of all transmitted signal vectors are calculated and the shortest value is calculated. Therefore, the implementation complexity may increase as the number of transmit antennas or the modulation order increases. To reduce the computational complexity and processing burden, according to an exemplary embodiment of the inventive concept, the receiver 200 may further include a vector set detector 260, which is configured to search and provide a candidate signal vector set (CSVS) for calculating LLR by the MIMO demodulator 250.

[0072] First, for each valid channel, the MIMO demodulator 250 may calculate the Euclidean distances between one or more received symbols and all candidate vectors included in the initial candidate vector set, and may output information I_ED about the calculated Euclidean distances. For example, for the physical channel corresponding to the first antenna 202-1, the MIMO demodulator 250 may calculate the Euclidean distances between one or more of the symbols included in the received signal rs1 and the predetermined initial candidate vector, and may output information I_ED about the calculated Euclidean distances. The MIMO demodulator 250 may calculate LLRs about one or more symbols based on the calculated Euclidean distances.

[0073] According to an exemplary embodiment, the MIMO demodulator 250 may use a "candidate vector superset" as an initial candidate vector set to calculate the Euclidean distance for the output information I_ED. For example, the receiver 200 may include multiple candidate vector sets for calculating LLRs, and the candidate vector superset may be formed as a union of the candidate vector sets. The candidate vector superset may include all candidate vectors. In other instances, the candidate vector superset omits some candidate vectors.

[0074] Next, the vector set detector 260 receiving the information I_ED from the MIMO demodulator 250 may select a candidate vector set for generating LLR from the plurality of candidate vector sets based on the information I_ED. That is, the vector set detector 260 may select one of the plurality of candidate vector sets based on the Euclidean distance included in the information I_ED.

[0075] According to an exemplary embodiment, the vector set detector 260 may determine whether each candidate vector set includes each bit (eg, b for all m and all k in Equation 2) for each channel (or each "layer").m,k ) The candidate vector with the shortest Euclidean distance at "+1" and "-1". Based on this judgment, for each candidate vector set, the vector set detector 260 can count the number of candidate vectors with the shortest Euclidean distance included in each candidate vector set.

[0076] According to an exemplary embodiment, the vector set detector 260 may compare the count value with a predetermined critical value to select a candidate vector set CSVS for calculating LLR from a plurality of candidate vector sets. For example, the vector set detector 260 may select a candidate vector set CSVS of the smallest size from the candidate vector set having a count value equal to or greater than the predetermined critical value. The vector set detector 260 may provide the selected candidate vector set CSVS to the MIMO demodulator 250. According to an exemplary embodiment, the vector set detector 260 may compare the count value with a predetermined critical value having a fixed value. According to another exemplary embodiment, the vector set detector 260 may compare the count value with a predetermined critical value having a dynamically changeable value. For example, the predetermined critical value may change dynamically based on a channel parameter.

[0077] According to an exemplary embodiment, for each physical channel, the MIMO demodulator 250 may generate LLRs about symbols included in the received signal based on the candidate vector set selected by the vector set detector 260. In other words, for each channel, the MIMO demodulator 250 may send information about the Euclidean distance obtained based on one or more symbols and the initial candidate vector to the vector set detector 260, the vector set detector 260 may select a candidate vector set CSVS based on the information, and the MIMO demodulator 250 may generate LLRs about the remaining symbols based on the candidate vector set CSVS selected by the vector set detector 260.

[0078] According to an exemplary embodiment, the MIMO demodulator 250 may perform an operation of generating information I_ED for each channel once, and may fix the candidate vector set CSVS selected by the vector set detector 260 based on the information I_ED as the candidate vector set CSVS for calculating the LLR corresponding to the remaining symbols. According to another exemplary embodiment, the MIMO demodulator 250 may perform an operation of generating information I_ED based on a certain cycle for each channel, and the vector set detector 260 may select the candidate vector set CSVS based on the information I_ED generated according to the cycle. In other words, the MIMO demodulator 250 may calculate the LLR about the symbol based on the candidate vector set CSVS selected differently according to the cycle.

[0079] Therefore, the receiver 200 according to the inventive concept can select an optimal candidate vector set based on the channel condition and can generate LLR based on the optimal candidate vector set. Therefore, power consumption of generating LLR can be minimized and LLR can be generated with lower complexity at a high modulation order.

[0080] Next, the rate dematching units 240_1 to 240_N may perform a rate dematching operation on the signal output from the MIMO demodulator 250 based on a rate dematching method corresponding to the rate matching method used by the transmitter 100. The FEC decoders 230_1 to 230_N may perform a decoding operation on the signal output from the rate dematching units 240_1 to 240_N based on an FEC decoding method corresponding to the FEC encoding method used by the transmitter 100.

[0081] The CRC units 220_1 to 220_N may perform a CRC check operation on the signals output from the FEC decoders 230_1 to 230_N and may output the CRC-checked signals to the P / S converter 210. The P / S converter 210 may convert the signals output from the CRC units 220_1 to 220_N into a serial form and may output the converted signals.

[0082] Figure 5 is a diagram illustrating a signal constellation for modulating a transmitted signal according to an exemplary embodiment of the inventive concept. For example, Figure 5 A signal constellation based on a quadrature phase shift keying (QPSK) method is shown. Below, for ease of explanation, an example of the inventive concept will be described in detail based on the QPSK method. However, the inventive concept can also be applied to other modulation schemes, such as other PSK modulation orders (nPSK, where n is different from 4); and QAM modulation methods, such as 16QAM, 64QAM, 256QAM and 1024QAM.

[0083] Figure 5 A complex plane having an x-axis as a real axis (I) and a y-axis as an imaginary axis (Q) is shown, wherein signal constellations CS0 to CS3 are indicated in each quadrant defined by the x-axis and the y-axis. For example, each of the symbols x1 to xM transmitted by the transmitter 100 may be mapped to one of the signal constellations CS0 to CS3 in a modulation operation. In the QPSK method, each of the signal constellations CS0 to CS3 may represent information of two bits. For example, the signal constellation CS0 may have information of "00", the signal constellation CS1 may have information of "01", the signal constellation CS2 may have information of "10", and the signal constellation CS3 may have information of "11".

[0084] Figure 6 is a diagram for explaining transmission / reception of a modulated signal according to an exemplary embodiment. Figure 6 As shown in , the first symbol x1 transmitted by the first transmitting antenna 102-1 may be mapped to the signal constellation CS0 during modulation, and the Mth symbol xM transmitted by the Mth antenna 102_M may be mapped to the signal constellation CS1 during modulation. The first symbol x1 and the Mth symbol xM may each be received by the first receiving antenna 202-1.

[0085] The first symbol x1 may be transmitted through the channel 300 formed between the two antennas 102-1 and 202-1, and thus may be multiplied by the effective channel gain h1,1. The first symbol x1 multiplied by the effective channel gain h1,1 may be represented as a first vector v1.

[0086] The Mth symbol xM may be transmitted through a channel formed between the two antennas 102-M and 202-1, and thus may be multiplied by an effective channel gain h1, M. The Mth symbol xM multiplied by the effective channel gain h1, M may be represented as a second vector v2.

[0087] The symbol y1 received by the first antenna 202-1 may be represented as a vector sum of a first symbol x1 multiplied by an effective channel gain h1,1 and an Mth symbol xM multiplied by an effective channel gain h1,M. In other words, the symbol y1 may have a vector value based on the sum of the first vector v1 and the second vector v2. The MIMO demodulator 250 may use all signal energy received by the two receive antennas to utilize a signal processing signal decomposition algorithm to identify samples of the symbol x1 taken during a symbol period (e.g., corresponding to the measured amplitude / phase), and samples of the symbol xM taken during the symbol period. The symbols x1 and xM may be referred to as symbols of individual "channels" (e.g., a first channel and an Mth channel), respectively. Each of these channels may also be referred to herein interchangeably as a "physical channel."

[0088] For example, the receiver 200 may receive symbols of each channel as described above, and in order to demodulate the symbols, a candidate vector on the complex plane may be used. When the QPSK method is used and there are two transmit antennas, a symbol based on one of four signal constellations may be transmitted from each transmit antenna. Therefore, in this case, 16 (ie, 4×4) candidate vectors may be provided.

[0089] Fig. 7A is a flowchart of an operation of the receiver 200 according to an exemplary embodiment of the inventive concept, and Figure 7B The complex plane indicating the candidate vectors is shown. Figure 4 Explanation Fig. 7A and Figure 7B .

[0090] Reference Fig. 7A In operation S10, the receiver 200 may generate LLRs based on one or more symbols and a superset of candidate vectors for each channel. For example, for each channel, the MIMO demodulator 250 may obtain the Euclidean distance between the received symbol and the candidate vector and generate the LLRs based on the Euclidean distance.

[0091] Reference Figure 7B , a plurality of candidate vectors C0 to C15 may be indicated on the complex plane. For example, the MIMO demodulator 250 may estimate the effective channel gain of each channel, and may provide a plurality of candidate vectors obtained for each channel based on the estimated effective channel gain. In other words, the position of each of the candidate vectors C0 to C15 on the complex plane may be different for each channel, and may be determined based on the estimated effective channel gain.

[0092] For example, a symbol received through one channel may be represented as a point RP on a complex plane, and the MIMO demodulator 250 may obtain the Euclidean distance ED between the point RP and each of the candidate vectors C0 to C15. The MIMO demodulator 250 may output an LLR based on the obtained Euclidean distance ED, and may output information I_ED about the Euclidean distance ED to the vector set detector 260.

[0093] According to an exemplary embodiment, the candidate vector superset SP_SET may be the largest set of multiple candidate vector sets provided for calculating LLR. The candidate vector superset SP_SET may be formed as a union of the multiple candidate vector sets provided for calculating LLR. For example, the candidate vector superset SP_SET may be a set including all candidate vectors C0 to C15. As described above, some candidate vectors may be omitted in other embodiments.

[0094] Next, in operation S20, the receiver 200 may calculate whether each candidate vector set includes a candidate vector having the shortest Euclidean distance with respect to each bit of each channel. For example, the vector set detector 260 may determine whether each candidate vector set includes a candidate vector having the shortest Euclidean distance at "+1" and "-1" with respect to each bit of each channel based on the received information I_ED. Operation S20 may be represented by the following equation 4.

[0095] [Equation 4]

[0096]

[0097] In Equation 4, K may be the number of bits used in the signal constellation. Additionally, when the statement (state) is true, the Ind(state) function may be 1, and when the statement is false, the Ind(state) function may be 0. Additionally, argmin indicates that a minimum value is to be obtained.

[0098] Next, in operation S30, the receiver 200 may select a candidate vector set CSVS for calculating LLR based on the result of the counting operation. According to an exemplary embodiment, the vector set detector 260 may compare the count value generated in operation S20 with a predetermined critical value to select a candidate vector set CSVS for calculating LLR from the multiple candidate vector sets. For example, the vector set detector 260 may select a candidate vector set with the smallest size from the candidate vector sets having corresponding count values ​​greater than or equal to the predetermined critical value as the candidate vector set CSVS for calculating LLR. The rule for selecting a candidate vector set according to the above example may be represented by the following equation 5.

[0099] [Equation 5]

[0100]

[0101] In equation 5, Can be expressed in a set In addition, δ can also be a critical value to be compared with the count value.

[0102] Fig. 8A and Figure 8B An example of a candidate vector set according to an exemplary embodiment of the inventive concept is shown.

[0103] Reference Fig. 8A , multiple candidate vector sets CSVS1 to CSVS4 may be indicated on a complex plane indicating multiple candidate vectors C0 to C15. For example, the multiple candidate vector sets CSVS1 to CSVS4 may be conceptually represented as squares on the complex plane. In other embodiments, different shapes may be specified. Figure 8B , the candidate vector sets CSVS1a to CSVS4a can be conceptually represented as a circle.

[0104] For example, the first candidate vector set CSVS1 may include two candidate vectors C9 and C13, and the second candidate vector set CSVS2 may include six candidate vectors C8, C9, C11, C12, C13, and C15. In addition, the third candidate vector set CSVS3 may include twelve candidate vectors C4 to C15, and the fourth candidate vector set CSVS4 may include sixteen candidate vectors C0 to C15. According to the present exemplary embodiment, the fourth candidate vector set CSVS4 may be a candidate vector superset.

[0105] As the size of the candidate vector set increases, the accuracy of obtaining LLRs may increase, but the number of calculations and power consumption may increase for the increased size of the candidate vector set. Alternatively, as the size of the candidate vector set decreases, the number of calculations and power consumption for obtaining LLRs may decrease, but the accuracy of obtaining LLRs may decrease. The receiver 200 according to the inventive concept may select the optimal candidate vector set based on the channel state, and thus may meet the target accuracy of obtaining LLRs while reducing power consumption.

[0106] Fig.9A and Fig. 9B is a diagram for explaining an operation of selecting a candidate vector set according to an exemplary embodiment. In detail, Fig.9A yes Fig. 7A The flowchart of an example of operation S30 is shown and Fig. 9B is a conceptual diagram indicating the operation of selecting a candidate vector set based on a critical value. Figure 4 To explain Fig.9A and Fig. 9B .

[0107] Reference Fig.9A In operation S32, the receiver 200 may select one or more candidate vector sets from the plurality of candidate vector sets based on the count value and a predetermined critical value. Fig. 9B The number of candidate vectors having the shortest Euclidean distance for each bit of each channel included in each of the candidate vector sets CSVS1 to CSVS4 is shown. For example, the number of candidate vectors having the shortest Euclidean distance for each bit of each channel included in the first candidate vector set CSVS1 may be Q, the number of candidate vectors having the shortest Euclidean distance for each bit of each channel included in the second candidate vector set CSVS2 may be R, the number of candidate vectors having the shortest Euclidean distance for each bit of each channel included in the third candidate vector set CSVS3 may be S, and the number of candidate vectors having the shortest Euclidean distance for each bit of each channel included in the fourth candidate vector set CSVS4 may be T (Q, R, S and T are all positive integers (Q <R<S<T))。

[0108] For example, when the critical value THR_J is predetermined to be a value greater than Q and equal to or less than R, the first candidate vector set CSVS1 having a count value less than the critical value THR_J may be excluded from selection. In other words, in operation S32, the second candidate vector set CSVS2 to the fourth candidate vector set CSVS4 may be selected based on the critical value THR_J. According to an exemplary embodiment, the critical value THR_J may be a fixed value, or may be dynamically changed based on a channel parameter, etc.

[0109] Next, in operation S34, the receiver 200 may select the candidate vector set with the smallest size from the selected candidate vector sets as the candidate vector set CSVS for calculating the LLR. Therefore, the second candidate vector set CSVS2 with the smallest size may be selected from the second candidate vector set CSVS2 to the fourth candidate vector set CSVS4 selected in operation S32 as the candidate vector set for calculating the LLR, and the second candidate vector set CSVS2 may be provided to the MIMO demodulator 250.

[0110] Fig.10 is a diagram for explaining the operation of the receiver 200 according to an exemplary embodiment. Figure 4 Explanation Fig.10 .

[0111] Reference Fig.10 , the signal y1 received by the first antenna 202-1 may be structured into a plurality of fields y1_1 to y1_3, each field containing one or more symbols. According to an exemplary embodiment, the MIMO demodulator 250 may output information I_ED about the Euclidean distance to the vector set detector 260 based on a portion p_sl of the first field y1_1 (wherein the portion is at least one symbol), and the vector set detector 260 may select a candidate vector set CSVS based on the information I_ED.

[0112] In detail, in operation S100, the MIMO demodulator 250 may obtain the Euclidean distance between the part p_sl of the first field y1_1 and the candidate vector, and may generate the LLR based on the Euclidean distance. According to an exemplary embodiment, the MIMO demodulator 250 may generate the LLR based on the Euclidean distance between the obtained part p_sl of the first field y1_1 and the candidate vector included in the candidate vector superset. The MIMO demodulator 250 may send information I_ED about the obtained Euclidean distance to the vector set detector 260.

[0113] Next, in operation S110, the vector set detector 260 may select a candidate vector set CSVS based on the information I_ED. Therefore, an optimal candidate vector set for calculating LLRs of the remaining symbols may be selected based on only a portion p_sl of the first field y1_1.

[0114] Next, in operation S120, the MIMO demodulator 250 may perform demodulation on the remaining portion of the first field y1_1 and other fields y1_2 and y1_3 based on the selected candidate vector set CSVS. According to an exemplary embodiment, the MIMO demodulator 250 may fix the candidate vector set selected in operation S110 and may perform sequential demodulation based on the fixed candidate vector set.

[0115] Fig.11 is a diagram for explaining the operation of a receiver according to another exemplary embodiment. Figure 4 Explanation Fig.11 .

[0116] Reference Fig.11 , the signal rs1a received by the first antenna 202-1 may include a plurality of fields y1_1 to y1_3, ..., y1_i, y1_i+1, each of which contains one or more symbols. According to an exemplary embodiment, in operation S200-1, the MIMO demodulator 250 may obtain the Euclidean distance between a portion p_sl1 of the first field y1_1 and the candidate vector, and may generate LLR based on the obtained Euclidean distance. In operation S210-1, the vector set detector 260 may select the candidate vector set CSVS based on the information I_ED obtained in operation S200-1.

[0117] According to an exemplary embodiment, in operation S220-1, the MIMO demodulator 250 may perform demodulation based on the candidate vector set CSVS selected in operation S210-1 during a certain cycle. For example, the first cycle P1 may be predetermined, and the MIMO demodulator 250 may perform demodulation based on the candidate vector set CSVS selected according to the part p_sl1 of the first field y1_1 during the first cycle P1.

[0118] After the first loop P1 is completed, the MIMO demodulator 250 may obtain the Euclidean distance between a portion p_sl2 of the i-th field y1_i and the candidate vector, and generate LLR based on the Euclidean distance obtained in operation S200-2. In operation S210-2, the vector set detector 260 may select a candidate vector set CSVS based on the information I_ED obtained in operation S200-2.

[0119] According to an exemplary embodiment, in operation S220-2, the MIMO demodulator 250 may perform demodulation based on the candidate vector set CSVS selected in operation S210-2 during a certain cycle. For example, the second cycle P2 may be predetermined, and the MIMO demodulator 250 may perform demodulation based on the candidate vector set CSVS selected according to the part p_sl2 of the i-th field y1_i during the second cycle P2. (Note—a portion of the signal rs1a may be referred to herein as a “first signal” received during the first cycle P1, and another portion of the signal rs1a may be referred to herein as a “second signal” received during the second cycle P2.)

[0120] Fig.12 is a diagram for explaining the operation of a receiver according to another exemplary embodiment. Fig.12 of Fig.10The same aspects as those shown will not be described again in detail.

[0121] Reference Fig.12 In operation S300, the MIMO demodulator 250 may obtain the Euclidean distance between the entire first field y1_1 and the candidate vector, and generate the LLR based on the obtained Euclidean distance. According to an exemplary embodiment, the MIMO demodulator 250 may generate the LLR based on the Euclidean distance between the entire first field y1_1 and the candidate vector included in the candidate vector superset. The MIMO demodulator 250 may send information I_ED about the obtained Euclidean distance to the vector set detector 260.

[0122] Next, in operation S310, the vector set detector 260 may select a candidate vector set CSVS based on the information I_ED. Therefore, an optimal candidate vector set for calculating LLRs of the remaining symbols may be selected based on the first field y1_1. Next, in operation S320, the MIMO demodulator 250 may perform demodulation on the other fields y1_2 and y1_3 based on the selected candidate vector set CSVS.

[0123] Refer again Figure 3 , can be applied in a similar way Fig.10 , Fig.11 and Fig.12 The method shown is to calculate Figure 3 The LLRs of the symbols in the signals s1 and sM are shown. Fig.10 , Fig.11 or Fig.12 In any of the above, field y1_1 can be Figure 3 The field x1_1 shown, and the superset of candidate vectors may be used to calculate the LLRs of the symbols in the field x1_1. Then, the set of candidate vectors may be selected based on the information I_ED not only for the symbols in the fields x1_2, x1_3, and x1_4, ... of the signal s1, but also for all the symbols of the signal sM. In other words, the symbols in the fields xM_2, xM_3, ... may not use the super CSVS, but instead may use only the selected CSVS, which may be a CSVS smaller than the super CSVS, and the selection is based on the Euclidean distance measured with respect to the symbols of the field x1_1.

[0124] Fig.13 is a detailed block diagram of a receiver 200a according to another exemplary embodiment. Fig.13 Shown with Figure 4 The same components as those shown will not be described again.

[0125] Reference Fig.13, the receiver 200a may further include a channel parameter collector 290a. The channel parameter collector 290a may receive channel parameter information CPR from the effective channel generator 270a. The channel parameter information CPR may include various parameter-related information about the wireless communication channel. For example, the channel parameter information CPR may include at least one of the frequency / time / space correlation between the transmitter 100 and the receiver 200a, the signal-to-noise ratio (SNR), the signal-to-interference-plus-noise ratio (SINR), the Doppler characteristic (e.g., Doppler spread or Doppler shift), the delay characteristic (e.g., maximum / minimum delay path, delay spread, etc.), the temporal dominant path, the spatial dominant path, and the angular characteristic (e.g., angular spread), etc.

[0126] According to an exemplary embodiment, the channel parameter collector 290a may output the channel parameter information CPR to the vector set detector 260a. The vector set detector 260a may predetermine a critical value based on the channel parameter information CPR and select the candidate vector set CSVS based on the predetermined critical value.

[0127] For example, the vector set detector 260a may determine whether a candidate vector having the shortest Euclidean distance at "+1" and "-1" for each bit with respect to each channel (or each layer) is included in each candidate vector set, and when the candidate vector is included in each candidate vector set, the vector set detector 260a may count the number of candidate vectors included in each candidate vector set. The vector set detector 260a may compare the count value with a critical value predetermined based on the channel parameter information CPR to select the candidate vector set CSVS.

[0128] Fig.14 is a block diagram of a wireless communication device 1000 according to an exemplary embodiment. Fig.14As shown, the wireless communication device 1000 may include an application specific integrated circuit (ASIC) 1010, an application specific instruction set processor (ASIP) 1030, a memory 1050, a main processor 1070, and a main memory 1090. At least two of the application specific integrated circuit 1010, the application specific instruction set processor 1030, and the main processor 1070 may communicate with each other. In addition, at least one of the application specific integrated circuit 1010, the application specific instruction set processor 1030, the memory 1050, the main processor 1070, and the main memory 1090 may be embedded in one chip.

[0129] The special instruction set processor 1030 may be a customized integrated circuit for a specific purpose and may support an instruction set dedicated to a specific application and may execute instructions included in the instruction set. The memory 1050 may communicate with the special instruction set processor 1030 and may store a plurality of instructions executed by the special instruction set processor 1030 in a non-transitory storage medium. For example, the memory 1050 may include certain types of memory accessible by the special instruction set processor 1030, such as random access memory (RAM), read only memory (ROM), tape, disk, optical disk, volatile memory, non-volatile memory, and combinations thereof. However, the memory 1050 is not limited thereto.

[0130] The main processor 1070 may control the wireless communication device 1000 by executing a plurality of instructions. For example, the main processor 1070 may control the ASIC 1010 and the ASIC processor 1030, and may process data received through a MIMO channel or a user input for the wireless communication device 1000. The main memory 1090 may communicate with the main processor 1070, and may store a plurality of instructions executed by the main processor 1070 as a non-transitory storage medium.

[0131] According to the exemplary embodiment, the receiver (eg, Figure 4 The components of the receiver 200) or the method of selecting a candidate vector set may be included in at least one component included in the wireless communication device 1000. For example, Figure 4 At least one of the illustrated MIMO demodulator 250 and the vector set detector 260 may be implemented as a plurality of instructions stored in the memory 1050 .

[0132] While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.

Claims

1. A receiver for receiving a first signal including a plurality of symbols via a multiple-input multiple-output channel, the receiver comprising: a demodulator configured to calculate, for each physical channel, a Euclidean distance of one or more of the plurality of received symbols relative to all candidate vectors included in an initial candidate vector set, and output information about the Euclidean distance; as well as A vector set detector is configured to select one of a plurality of candidate vector sets having different sizes as a subsequent candidate vector set for calculating log-likelihood ratios of other symbols in the plurality of symbols or log-likelihood ratios of at least one symbol of a second signal received after the first signal based on the information.

2. The receiver according to claim 1, wherein the demodulator is specifically configured to calculate the Euclidean distance based on a candidate vector superset, wherein the candidate vector superset is a union of the multiple candidate vector sets, wherein the candidate vector superset is used as the initial candidate vector set.

3. The receiver of claim 1 , wherein the vector set detector is further configured to: Determine whether each of the plurality of candidate vector sets includes a candidate vector having "+1" and "-1" to represent bits of information included in a transmission symbol corresponding to the plurality of received symbols and having the shortest Euclidean distance; Counting the number of candidate vectors included in each of the plurality of candidate vector sets, which have "+1" and "-1" to represent the bit and have the shortest Euclidean distance; and The set of subsequent candidate vectors is selected based on a count value generated according to the counted number of candidate vectors.

4. A receiver according to claim 3, wherein the vector set detector is also configured to compare a predetermined critical value with the count value, and based on the comparison, select a candidate vector set having a corresponding count value equal to or greater than the predetermined critical value from the multiple candidate vector sets as the subsequent candidate vector set.

5. A receiver according to claim 4, wherein the vector set detector is further configured to select a candidate vector set with the smallest size from the multiple candidate vector sets each having the corresponding count value equal to or greater than the predetermined critical value as the subsequent candidate vector set.

6. The receiver according to claim 4, further comprising: a channel parameter collector, configured to collect and output channel parameter information for each physical channel, The vector set detector is further configured to dynamically change the predetermined critical value based on the channel parameter information.

7. A receiver according to claim 1, wherein the demodulator is further configured to generate a log-likelihood ratio for the other symbols included in the received first signal based on the subsequent candidate vector set selected by the vector set detector.

8. The receiver of claim 7, wherein the demodulator is further configured to generate the log-likelihood ratios for the other symbols for each physical channel by calculating the Euclidean distances between the received plurality of symbols and the candidate vectors included in the subsequent set of candidate vectors.

9. An operating method performed by a receiver to receive at least a first transmission signal and a second transmission signal through multiple antennas, the operating method comprising: calculating the Euclidean distance of the first transmitted signal relative to all candidate vectors of an initial candidate vector set; selecting one from a plurality of candidate vector sets having different sizes as a first candidate vector set based on the information about the Euclidean distance; as well as A log-likelihood ratio for symbols of the second transmitted signal is generated based on the first set of candidate vectors.

10. The operating method according to claim 9, wherein generating a log likelihood ratio about the symbol of the second transmitted signal comprises: The Euclidean distance between the symbol of the second transmitted signal and all the candidate vectors included in the first candidate vector set is calculated.

11. The operating method according to claim 9, wherein calculating the Euclidean distance comprises: The Euclidean distance of one or more of the received symbols relative to all candidate vectors of a superset of candidate vectors is calculated, wherein the superset of candidate vectors is a union of a plurality of predetermined candidate vector sets, wherein the superset of candidate vectors is used as the initial set of candidate vectors.

12. The operating method according to claim 9, wherein selecting the first candidate vector set comprises: determining whether each of a plurality of predetermined candidate vector sets includes a candidate vector having "+1" and "-1" as bits of information included in a transmission symbol corresponding to a received symbol included in the first transmission signal and the second transmission signal received and having the shortest Euclidean distance; counting the number of candidate vectors included in each of the plurality of predetermined candidate vector sets, which have "+1" and "-1" as the bits and have the shortest Euclidean distance; and The first set of candidate vectors is selected based on the counted number of the candidate vectors.

13. The operating method according to claim 12, wherein selecting the first set of candidate vectors based on the count number of the candidate vectors comprises: comparing a count value generated based on the count number of the candidate vectors with a predetermined critical value; selecting a candidate vector set from the plurality of predetermined candidate vector sets, the candidate vector sets each having a corresponding count value equal to or greater than the predetermined critical value; as well as One of the selected candidate vector sets is selected as the first candidate vector set.

14. The operating method according to claim 13, wherein selecting one of the selected candidate vector sets as the first candidate vector set comprises: A candidate vector set with the smallest size is selected from the selected candidate vector sets as the first candidate vector set.

15. The operating method according to claim 13, further comprising: Acquire channel parameter information of each of the plurality of antennas through which at least the first transmit signal and the second transmit signal are received; as well as Determining whether to change the predetermined threshold is determined based on the channel parameter information. 16 . The operating method according to claim 15 , wherein the channel parameter information comprises at least one of a signal-to-noise ratio, a Doppler characteristic, and a delay characteristic.

17. A method performed by a receiver for detecting a signal in a wireless communication system including a multiple-input multiple-output channel, the method comprising: calculating information based on one or more of the received transmitted signals and a predetermined candidate vector for each physical channel, and generating a log likelihood ratio for one or more of the received transmitted signals based on the information; selecting one from a plurality of candidate vector sets having different sizes as a first candidate vector set based on the information, wherein a candidate vector superset is a union of the plurality of candidate vector sets, and the candidate vector superset includes the predetermined candidate vector; as well as A log-likelihood ratio is generated for the remaining received transmitted signals based on the first set of candidate vectors.

18. The method of claim 17, wherein generating the log-likelihood ratio for one or more of the received transmit signals comprises: calculating, for each physical channel, a Euclidean distance of one or more of the received transmit signals relative to the predetermined candidate vector, generating the log-likelihood ratio for one or more of the received transmit signals based on the Euclidean distance, The information includes information about the Euclidean distance.

19. The method of claim 17, wherein selecting the first set of candidate vectors comprises: searching for a candidate vector having a shortest Euclidean distance based on the information with respect to each of the candidate vectors having "+1" and "-1" as bits of information included in a transmission symbol corresponding to one or more reception symbols of the received transmission signal; counting the number of candidate vectors having the shortest Euclidean distance included in each of the plurality of candidate vector sets; as well as The first set of candidate vectors is selected based on a count value generated according to the counted number of the candidate vectors.

20. The method of claim 19, wherein selecting the first set of candidate vectors comprises: comparing the count value with a predetermined critical value; as well as The candidate vector sets having corresponding count values ​​less than the predetermined critical value in the plurality of candidate vector sets are excluded from selection of the first candidate vector set.

21. A receiver for receiving a signal modulated based on phase shift keying or quadrature amplitude modulation and comprising a plurality of symbols transmitted in a wireless communication system, the receiver comprising: a demodulator configured to calculate a Euclidean distance of one or more of the received plurality of symbols relative to all candidate vectors included in an initial candidate vector set, and output information about the Euclidean distance; as well as A vector set detector is configured to select one of a plurality of candidate vector sets having different sizes as a subsequent candidate vector set for calculating log-likelihood ratios of other symbols in the plurality of symbols based on the information.

22. A non-transitory computer-readable recording medium storing instructions, the instructions, when executed by at least one processor, implementing a method performed by a receiver for detecting a signal in a wireless communication system including a multiple-input multiple-output channel, the method comprising: calculating information based on one or more of the received transmitted signals and a predetermined candidate vector for each physical channel, and generating a log likelihood ratio for one or more of the received transmitted signals based on the information; selecting one from a plurality of candidate vector sets having different sizes as a first candidate vector set based on the information, wherein a candidate vector superset is a union of the plurality of candidate vector sets, and the candidate vector superset includes the predetermined candidate vector; as well as A log-likelihood ratio is generated for the remaining received transmitted signals based on the first set of candidate vectors.

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