Receiving end signal processing method and system of MIMO (Multiple Input Multiple Output) system

Abstract

The invention relates to a receiving end signal processing method and system of an MIMO system, and the method comprises the steps: obtaining a signal which is transmitted by each transmitting antenna and received by each receiving antenna, and the signal transmitted by each transmitting antenna is a signal obtained after constellation modulation, SFBC coding and OFDM modulation are carried out on transmission data; oFDM demodulation is carried out on the signal received by each receiving antenna to obtain demodulated signals of the receiving antenna, and the demodulated signals comprise demodulated signals on different subcarriers; reorganizing the demodulated signals of the receiving antennas into a time-frequency resource matrix; determining a receiving signal matrix according to the time-frequency resource matrix, and determining an estimated value of a transmitting symbol matrix according to the receiving signal matrix and a predetermined decoding matrix; determining an estimated value of each constellation symbol according to the estimated value of the emission symbol matrix; and performing constellation demodulation on the estimated value of each constellation symbol to obtain an estimated value of the transmission data.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and more particularly to a method and system for processing signals at the receiving end of a MIMO system. Background Art

[0002] Base stations and terminals in special industries need to adapt to various working environments such as plains, mountains, and airborne conditions, with communication distances up to 100 kilometers or even farther. The corresponding wireless channels have characteristics such as rich multipath, beyond line of sight, and many obstacles (such as hills and trees). Facing such a harsh communication environment, in order to ensure highly reliable communication, it is necessary to use MIMO (Multiple Input Multiple Output) technology to enhance the reliability and robustness of the communication link.

[0003] The SFBC (Space Frequency Block Code) technology is an anti-interference technology in the TDD-LTE (Time Division Duplexing Long Term Evolution) system. In a MIMO system, it can be combined with OFDM (Orthogonal Frequency Division Multiplexing) to improve the transmission performance and reliability of the system.

[0004] However, the performance of existing MIMO systems applying SFBC is often troubled by noise and interference, resulting in a reduction in communication performance. Summary of the Invention

[0005] The object of the present invention is to provide a method and system for processing signals at the receiving end of a MIMO system to enhance the ability of the MIMO system to adapt to noise and interference, thereby improving communication performance.

[0006] Based on the above object, on the one hand, the present invention provides a method for processing signals at the receiving end of a MIMO system, including: A method for processing signals at the receiving end of a MIMO system, characterized by including:

[0007] Obtain the signals transmitted by each transmitting antenna received by each receiving antenna, where the signal transmitted by each transmitting antenna is a signal after constellation modulation, SFBC encoding, and OFDM modulation of the transmission data;

[0008] Perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of the receiving antenna, including the demodulated signals on different subcarriers;

[0009] Reorganize the demodulated signals of each receiving antenna into a time-frequency resource matrix;

[0010] Determine the received signal matrix according to the time-frequency resource matrix, and determine an estimated value of the transmitted symbol matrix according to the received signal matrix and a pre-determined decoding matrix;

[0011] Determine the estimated value of each constellation symbol according to the estimated value of the transmitted symbol matrix;

[0012] Perform constellation demodulation on the estimated values of the constellation symbols to obtain the estimated value of the transmitted data.

[0013] Furthermore, the MIMO system includes two transmit antennas and M receive antennas, and the received signal matrix satisfies the following relationship:

[0014]

[0015] where r is the received signal matrix, and r 1,f1 represents the demodulated signal of the first receive antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the first receive antenna on the subcarrier with frequency f2, r 2,f1 represents the demodulated signal of the second receive antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the second receive antenna on the subcarrier with frequency f2, r M,f1 is the demodulated signal of the Mth receive antenna on the subcarrier with frequency f1, is the conjugate of the demodulated signal of the Mth receive antenna on the subcarrier with frequency f2.

[0016] Furthermore, the decoding matrix satisfies the following relationship:

[0017]

[0018]

[0019] c = |h 1,1 | 2 + |h 1,2 | 2 + |h 2,1 | 2 + |h 2,2 | 2 + … + |h M,1 | 2 + |h M,2 | 2

[0020] where W is the decoding matrix, H is the channel matrix, H H is the conjugate transpose matrix of H, c is the channel coefficient, σ 2is the noise interference power, h 1,1 is the channel from the first transmitting antenna to the first receiving antenna, h 1,2 is the channel from the second transmitting antenna to the first receiving antenna, h 2,1 is the channel from the first transmitting antenna to the second receiving antenna, h 2,2 is the channel from the second transmitting antenna to the second receiving antenna, is h 1,2 the conjugate of, is h 1,1 the conjugate of, is h 2,2 the conjugate of, h M,1 is the channel from the first transmitting antenna to the Mth receiving antenna, h M,2 is the channel from the second transmitting antenna to the Mth receiving antenna, is h M,1 the conjugate of, is h M,2 the conjugate of.

[0021] Furthermore, the estimated value of the transmitted symbol matrix satisfies the following relation:

[0022]

[0023] where, is the estimated value of the transmitted symbol matrix, is the estimated value of the constellation symbol s1, is the estimated value of the conjugate of the constellation symbol s2.

[0024] Furthermore, the method for determining the decoding matrix is:

[0025]

[0026] where, represents the value of W when E|s - Wr| 2 reaches the minimum, E|s - Wr| 2 represents the expectation of |s - Wr| 2 s is the transmitted symbol matrix,

[0027] The transmitted symbol matrix satisfies the following relation:

[0028] r = Hs + η

[0029]

[0030] where, η is the noise matrix, η 1,f1 is the noise and interference on the sub - carrier with frequency f1 at the first receiving antenna, is the conjugate of the noise and interference of the first receiving antenna on the subcarrier with frequency f2, η 2,f1 is the noise and interference of the second receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the second receiving antenna on the subcarrier with frequency f2, η M,f1 is the noise and interference of the Mth receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the Mth receiving antenna on the subcarrier with frequency f2.

[0031] On the other hand, the present invention provides a receiving - end signal processing system for a MIMO system, which includes:

[0032] An acquisition module, configured to acquire the signals transmitted by each transmitting antenna received by each receiving antenna, wherein the signal transmitted by each transmitting antenna is a signal after constellation modulation, SFBC coding, and OFDM modulation of the transmission data;

[0033] A first demodulation module, configured to perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of the receiving antenna, including the demodulated signals on different subcarriers;

[0034] An organization module, configured to reorganize the demodulated signals of each receiving antenna into a time - frequency resource matrix;

[0035] A first determination module, configured to determine a received signal matrix according to the time - frequency resource matrix, and determine an estimated value of the transmitted symbol matrix according to the received signal matrix and a pre - determined decoding matrix;

[0036] A second determination module, configured to determine an estimated value of each constellation symbol according to the estimated value of the transmitted symbol matrix;

[0037] A second demodulation module, configured to perform constellation demodulation on the estimated values of each constellation symbol to obtain an estimated value of the transmission data.

[0038] Further, the MIMO system includes two transmitting antennas and M receiving antennas, and the received signal matrix satisfies the following relational expression:

[0039]

[0040] where r is the received signal matrix, r 1,f1 represents the demodulated signal of the first receiving antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the first receiving antenna on the subcarrier with frequency f2, r 2,f1 represents the demodulated signal of the second receiving antenna on the subcarrier with frequency f1, Denote the conjugate of the demodulated signal of the second receiving antenna on the subcarrier with frequency f2, r M,f1 is the demodulated signal of the M-th receiving antenna on the subcarrier with frequency f1, is the conjugate of the demodulated signal of the M-th receiving antenna on the subcarrier with frequency f2.

[0041] Furthermore, the decoding matrix satisfies the following relational expression:

[0042]

[0043]

[0044] c = |h 1,1 | 2 + |h 1,2 | 2 + |h 2,1 | 2 + |h 2,2 | 2 + … + |h M,1 | 2 + |h M,2 | 2

[0045] where W is the decoding matrix, H is the channel matrix, H H is the conjugate transpose matrix of H, c is the channel coefficient, σ 2 is the noise interference power, h 1,1 is the channel from the first transmitting antenna to the first receiving antenna, h 1,2 is the channel from the second transmitting antenna to the first receiving antenna, h 2,1 is the channel from the first transmitting antenna to the second receiving antenna, h 2,2 is the channel from the second transmitting antenna to the second receiving antenna, is the conjugate of h 1,2 , is the conjugate of h 1,1 , is the conjugate of h 2,2 , h M,1 is the channel from the first transmitting antenna to the M-th receiving antenna, h M,2 is the channel from the second transmitting antenna to the M-th receiving antenna, is the conjugate of h M,1 , is the conjugate of h M,2 .

[0046] Furthermore, the estimated value of the transmitted symbol matrix satisfies the following relational expression:

[0047]

[0048] Among them, is the estimated value of the transmitted symbol matrix, is the estimated value of the constellation symbol s1, is the estimated value of the conjugate of the constellation symbol s2.

[0049] Furthermore, the method for determining the decoding matrix is as follows:

[0050]

[0051] Among them, represents the value of W when E|s - Wr| 2 reaches the minimum, and E|s - Wr| 2 represents the expectation of |s - Wr| 2 where s is the transmitted symbol matrix,

[0052] The transmitted symbol matrix satisfies the following relationship:

[0053] r = Hs + η

[0054]

[0055] Among them, η is the noise matrix, and η 1,f1 is the noise and interference on the sub - carrier with frequency f1 of the first receiving antenna, is the conjugate of the noise and interference on the sub - carrier with frequency f2 of the first receiving antenna, and η 2,f1 is the noise and interference on the sub - carrier with frequency f1 of the second receiving antenna, is the conjugate of the noise and interference on the sub - carrier with frequency f2 of the second receiving antenna, and η M,f1 is the noise and interference on the sub - carrier with frequency f1 of the M - th receiving antenna, is the conjugate of the noise and interference on the sub - carrier with frequency f2 of the M - th receiving antenna. Description of the Drawings

[0056] Figure 1 is the flowchart of the receiving - end signal processing method of the MIMO system according to the embodiment of the present invention;

[0057] Figure 2 is the BLER simulation result of receiving - end signal processing using the prior art and the method of the present invention under the 3GPP EPA channel;

[0058] Figure 3 is the BLER simulation result of receiving - end signal processing using the prior art and the method of the present invention under the 3GPP EVA channel;

[0059] Figure 4BLER simulation results of signal processing at the receiving end using the existing technology and the method of the present invention under the 3GPP ETU channel;

[0060] Figure 5 The structural block diagram of the signal processing system at the receiving end of the MIMO system according to another embodiment of the present invention. Detailed implementation manners

[0061] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0062] The signal transmission method of the existing MIMO system applying SFBC is as follows:

[0063] Transmitting end:

[0064] S1: Constellation modulation

[0065] According to the preset modulation method, the transmission data is modulated into P constellation symbols, where P is the number of receiving antennas of the MIMO system. Assuming the size of the transmission data is P*b bits, then the number of bits carried by each constellation symbol is b.

[0066] S2: SFBC coding

[0067] The P constellation symbols are subjected to SFBC coding to obtain an SFBC codeword matrix with a dimension of N×P.

[0068] S3: Resource mapping

[0069] Each column in the SFBC codeword matrix is respectively mapped to N consecutive subcarriers of each receiving antenna of the MIMO system. For example, the first column is mapped to the first receiving antenna, the second column is mapped to the second receiving antenna, and so on.

[0070] S4: OFDM modulation

[0071] Inverse fast Fourier transform and addition of cyclic prefix are performed on the SFBC codewords on each receiving antenna to generate OFDM baseband signals; each transmitting antenna transmits its own OFDM baseband signal, which is received by each receiving antenna.

[0072] Receiving end:

[0073] S5: OFDM demodulation

[0074] Each receiving antenna receives the OFDM baseband signals transmitted by each transmitting antenna, and performs OFDM demodulation (i.e., removing the cyclic prefix and fast Fourier transform) on the OFDM baseband signal received by each receiving antenna to obtain the demodulated signal of that receiving antenna.

[0075] S6: Resource demapping

[0076] Reorganize the demodulated signals of each receiving antenna into a time-frequency resource matrix, where the time-frequency resource matrix includes multiple time-frequency signals.

[0077] S7: SFBC decoding

[0078] Combine the N time-frequency signals belonging to the same SFBC block on the same receiving antenna, perform SFBC decoding, and combine the decoding results of the M receiving antennas to obtain the estimated values of each constellation symbol.

[0079] S8: Constellation demodulation

[0080] Demodulate the estimated values of each constellation symbol according to the constellation diagram to obtain the estimated values of the transmitted data.

[0081] The essence of SFBC decoding in existing MIMO systems is maximum ratio combining (MRC), that is, the signal components on each receiving antenna are weighted and coherently combined, and the noise components are randomly combined. This method can maximize the signal power, but it cannot suppress noise and interference, and the communication performance is limited by noise and interference. The following takes a two-transmitter and one-receiver system as an example for illustration.

[0082] Assume that the transmitting end uses two-antenna SFBC coding in the 3GPP protocol, and the received signals on adjacent subcarriers f1 and f2 can be expressed as follows:

[0083]

[0084] where r f1 and r f2 are the time-frequency signals on subcarriers f1 and f2 respectively; h1 and h2 are the channels from the first transmitting antenna and the second transmitting antenna to the receiving antenna; η f1 and η f2 are the noise and interference on subcarriers f1 and f2 respectively; s0 and s1 are constellation symbols; x * denotes the conjugate of variable x.

[0085] Perform maximum ratio combining on r f1 and r f2 using h1 and h2, and we can get:

[0086]

[0087] where, (|h1| 2 +|h2| 2 ) indicates that the signal components on the two transmitting antennas are coherently combined, and indicate that the noise components are randomly combined.

[0088] This indicates that the maximum ratio combining of SFBC indeed cannot suppress noise and interference, which will lead to a decline in communication performance in low signal-to-noise ratio scenarios (such as users at the cell edge), and even communication interruption.

[0089] To solve the above problems, an embodiment of the present invention provides a method for processing received signals at the receiving end of a MIMO system to enhance its ability to adapt to noise and interference scenarios, improve its communication performance in low signal-to-noise ratio scenarios, and ensure uninterrupted communication.

[0090] As Figure 1 shown, an embodiment of the present invention provides a method for processing received signals at the receiving end of a MIMO system, which includes the following steps S100 - S600:

[0091] S100: Obtain the signals transmitted by each transmitting antenna received by each receiving antenna, where the signal transmitted by each transmitting antenna is a signal after constellation modulation, SFBC coding, and OFDM modulation of the transmission data.

[0092] The methods for constellation modulation, SFBC coding, and OFDM modulation of the transmission data are the same as those in the prior art and will not be elaborated here.

[0093] S200: Perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of this receiving antenna, which include the demodulated signals on different subcarriers.

[0094] S300: Reorganize the demodulated signals of each receiving antenna into a time-frequency resource matrix.

[0095] The time-frequency resource matrix is an N×M-dimensional matrix, where each row represents the demodulated signal of a certain receiving antenna on different subcarriers, and each column represents the demodulated signals of each receiving antenna on a certain subcarrier. Taking a two-transmit and two-receive MIMO system as an example, its time-frequency resource matrix can be expressed as:

[0096]

[0097] where, r 1,f1 represents the demodulated signal of the first receiving antenna on the subcarrier with frequency f1, r 1,f2 represents the demodulated signal of the first receiving antenna on the subcarrier with frequency f2, r 2,f1 represents the demodulated signal of the second receiving antenna on the subcarrier with frequency f1, r 2,f2 represents the demodulated signal of the second receiving antenna on the subcarrier with frequency f2.

[0098] S400: Determine the received signal matrix according to the time-frequency resource matrix, and determine the estimated value of the transmitted symbol matrix according to the received signal matrix and the pre-determined decoding matrix.

[0099] The received signal matrix r is as follows:

[0100]

[0101] where, is the conjugate of r 1,f2 .

[0102] The expression of the decoding matrix W is as follows:

[0103]

[0104] where, H is the channel matrix, H H represents the conjugate transpose matrix of the channel matrix, c is the channel coefficient, and σ 2 is the noise interference power, which can be calculated according to the demodulation reference signal.

[0105] The expression of the channel matrix is as follows:

[0106]

[0107] where, h 1,1 is the channel from the first transmitting antenna to the first receiving antenna, h 1,2 is the channel from the second transmitting antenna to the first receiving antenna, h 2,1 is the channel from the first transmitting antenna to the second receiving antenna, h 2,2 is the channel from the second transmitting antenna to the second receiving antenna, is the conjugate of h 1,2 , is the conjugate of h 1,1 , is the conjugate of h 2,2 .

[0108] The expression of the channel coefficient is as follows:

[0109] c = |h 1,1 | 2 + |h 1,2 | 2 + |h 2,1 | 2 + |h 2,2 | 2

[0110] The calculation method of the estimated value of the transmitted symbol matrix is as follows:

[0111]

[0112]

[0113] where, is the estimated value of the constellation symbol s1, is the estimated value of the conjugate of the constellation symbol s2.

[0114] The calculation method of the pre-determined decoding matrix W is as follows:

[0115]

[0116] The above formula indicates that W is the value of W when E|s - Wr| 2 reaches the minimum, and E|s - Wr| 2 represents the expectation of |s - Wr| 2 where s is the transmitted symbol matrix,

[0117] The transmitted symbol matrix s and the received signal matrix r satisfy the following relationship:

[0118] r = Hs + η

[0119]

[0120] where η is the noise matrix, and η 1,f1 is the noise and interference on the sub-carrier with frequency f1 of the first receiving antenna, and η 1,f2 is the noise and interference on the sub-carrier with frequency f2 of the first receiving antenna, and η 2,f1 is the noise and interference on the sub-carrier with frequency f1 of the second receiving antenna, and η 2,f2 is the noise and interference on the sub-carrier with frequency f2 of the second receiving antenna, is the conjugate of η 1,f2 and is the conjugate of η 2,f2 .

[0121] S500: Determine the estimated value of each constellation symbol according to the estimated value of the transmitted symbol matrix.

[0122] After the estimated value of the transmitted symbol matrix is determined, the estimated value of the constellation symbol s1 can be determined and the estimated value of the conjugate of the constellation symbol s2 Take the conjugate of to obtain the estimated value of the constellation symbol s2

[0123] S600: Perform constellation demodulation on the estimated values of each constellation symbol to obtain the estimated value of the transmitted data.

[0124] After obtaining the estimated values of each constellation symbol, constellation demodulation can be performed on them according to the constellation diagram, thereby obtaining the estimated value of the transmitted data.

[0125] It can be understood that although the above method is described by taking a two - transmit and two - receive MIMO system as an example, it can also be extended to a two - transmit and multi - receive MIMO system. Assuming that the MIMO system includes two transmit antennas and M receive antennas, the expressions for the received signal matrix r, the channel matrix H, the channel coefficient c, and the noise matrix η are as follows:

[0126]

[0127]

[0128] c = |h 1,1 | 2 +|h 1,2 | 2 +|h 2,1 | 2 +|h 2,2 | 2 +…+|h M,1 | 2 +|h M,2 | 2

[0129]

[0130] where M is the number of receive antennas, r M,f1 is the demodulated signal of the M - th receive antenna on the sub - carrier with frequency f1, r M,f2 is the demodulated signal of the M - th receive antenna on the sub - carrier with frequency f2, is the conjugate of r M,f2 ; h M,1 is the channel from the first transmit antenna to the M - th receive antenna, h M,2 is the channel from the second transmit antenna to the M - th receive antenna, is the conjugate of h M,1 ; is the conjugate of h M,2 ; η M,f1 is the noise and interference of the M - th receive antenna on the sub - carrier with frequency f2, η M,f2 is the noise and interference of the M - th receive antenna on the sub - carrier with frequency f2, is the conjugate of η M,f2 ; is the conjugate of η M,f2 ;

[0131] Figure 2 、 Figure 3 and Figure 4The BLER (Block Error Rate) simulation results obtained by performing receiver signal processing using the prior art and the method of the present invention are respectively shown under EPA (Extended Pedestrian Channel Model), EVA (Extended Vehicular Channel Model), and ETU (Extended Typical Urban Channel Model). From Figure 2 , Figure 3 and Figure 4 , it can be seen that in the low SNR (Signal-to-Noise Ratio) scenario, the method of the present invention has a gain of about 1 dB compared to the prior art, that is, the method of the present invention improves the communication reliability.

[0132] In addition, by starting the AMC (Adaptive Modulation and Coding) simulation, the throughputs of the prior art and the method of the present invention under the three channels of EPA, EVA, and ETU can be obtained, and the results are shown in Table 1, Table 2, and Table 3 respectively.

[0133] Table 1 Throughput Gain of the Prior Art and the Method of the Present Invention under the EPA Channel

[0134] Table 2 Throughput Gain of the Prior Art and the Method of the Present Invention under the EVA Channel

[0135] Table 3 Throughput Gain of the Prior Art and the Method of the Present Invention under the ETU Channel

[0136] After removing the maximum and minimum throughput gain values in the table and then calculating the arithmetic mean, the average throughput gain of the method of the present invention compared to the prior art is 14.26% - 18.24%, that is, the present invention indeed improves the communication throughput.

[0137] The receiver signal processing method of the MIMO system according to the embodiment of the present invention can improve the ability of the MIMO system to adapt to noise and interference, thereby improving the communication performance.

[0138] Such as Figure 5As shown in the figure, another embodiment of the present invention provides a receiving - end signal processing system for a MIMO system, which includes an acquisition module 710, a first demodulation module 720, an organization module 730, a first determination module 740, a second determination module 750, and a second demodulation module 760. The acquisition module 710 is used to acquire the signals transmitted by each transmitting antenna received by each receiving antenna, where the signal transmitted by each transmitting antenna is a signal obtained by performing constellation modulation, SFBC coding, and OFDM modulation on the transmission data. The first demodulation module 720 is used to perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of the receiving antenna, including the demodulated signals on different sub - carriers. The organization module 730 is used to reorganize the demodulated signals of each receiving antenna into a time - frequency resource matrix. The first determination module 740 is used to determine the received signal matrix according to the time - frequency resource matrix, and determine the estimated value of the transmitted symbol matrix according to the received signal matrix and the pre - determined decoding matrix. The second determination module 750 is used to determine the estimated value of each constellation symbol according to the estimated value of the transmitted symbol matrix. The second demodulation module 760 is used to perform constellation demodulation on the estimated values of each constellation symbol to obtain the estimated value of the transmission data.

[0139] The calculation methods of the received signal matrix, the decoding matrix, the estimated value of the transmitted symbol matrix, etc. can refer to the method embodiments and will not be elaborated here.

[0140] The receiving - end signal processing system of the MIMO system in the embodiment of the present invention can improve the ability of the MIMO system to adapt to noise and interference, thereby improving communication performance.

[0141] The above - mentioned are only the preferred embodiments of the present invention and are not used to limit the scope of the present invention. Various changes can be made to the above - mentioned embodiments of the present invention. That is, all simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. The content not described in detail in the present invention is all conventional technical content.

Claims

1. A method for processing received signals at the receiving end of a MIMO system, characterized in that, Including: Obtain the signals transmitted by each transmitting antenna received by each receiving antenna, where the signal transmitted by each transmitting antenna is a signal obtained by performing constellation modulation, SFBC coding, and OFDM modulation on the transmission data; Perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of this receiving antenna, including the demodulated signals on different subcarriers; Re-organize the demodulated signals of each receiving antenna into a time-frequency resource matrix; Determine a received signal matrix according to the time-frequency resource matrix, and determine an estimated value of a transmitted symbol matrix according to the received signal matrix and a pre-determined decoding matrix; Determine the estimated values of each constellation symbol according to the estimated value of the transmitted symbol matrix; Perform constellation demodulation on the estimated values of each constellation symbol to obtain the estimated value of the transmission data.

2. The signal processing method at the receiving end of the MIMO system according to claim 1, characterized in that, The MIMO system includes two transmitting antennas and M receiving antennas, and the received signal matrix satisfies the following relational expression: where r is the received signal matrix, r 1,f1 represents the demodulated signal of the first receiving antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the first receiving antenna on the subcarrier with frequency f2, r 2,f1 represents the demodulated signal of the second receiving antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the second receiving antenna on the subcarrier with frequency f2, r M,f1 is the demodulated signal of the Mth receiving antenna on the subcarrier with frequency f1, is the conjugate of the demodulated signal of the Mth receiving antenna on the subcarrier with frequency f2.

3. The method for processing the received signal at the receiving end of the MIMO system according to claim 2, characterized in that, The decoding matrix satisfies the following relational expression: c = |h 1,1 | 2 + |h 1,2 | 2 + |h 2,1 | 2 + |h 2,2 | 2 + … + |h M,1 | 2 + |h M,2 | 2 where W is the decoding matrix, H is the channel matrix, H H is the conjugate transpose matrix of H, c is the channel coefficient, σ 2 is the noise interference power, h 1,1 is the channel from the first transmitting antenna to the first receiving antenna, h 1,2 is the channel from the second transmitting antenna to the first receiving antenna, h 2,1 is the channel from the first transmitting antenna to the second receiving antenna, h 2,2 is the channel from the second transmitting antenna to the second receiving antenna, is the conjugate of h 1,2 , is the conjugate of h 1,1 , is the conjugate of h 2,2 , h M,1 is the channel from the first transmitting antenna to the M-th receiving antenna, h M,2 is the channel from the second transmitting antenna to the M-th receiving antenna, is the conjugate of h M,1 , is the conjugate of h M,2 .

4. The method for processing the received signal at the receiving end of the MIMO system according to claim 3, characterized in that, The estimated value of the transmitted symbol matrix satisfies the following relational expression: Among them, is the estimated value of the transmitted symbol matrix, is the estimated value of the constellation symbol s1, is the estimated value of the conjugate of the constellation symbol s2.

5. The method for processing a received signal at a receiving end of an MIMO system according to claim 3, wherein The method for determining the decoding matrix is: Among them, represents the value of W when E|s - Wr| 2 reaches the minimum, and E|s - Wr| 2 represents the expectation of |s - Wr| 2 , where s is the transmit symbol matrix, The transmitted symbol matrix satisfies the following relational expression: r = Hs + η where η is the noise matrix, and η 1,f1 is the noise and interference of the first receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the first receiving antenna on the subcarrier with frequency f2, and η 2,f1 is the noise and interference of the second receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the second receiving antenna on the subcarrier with frequency f2, and η M,f1 is the noise and interference of the Mth receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the Mth receiving antenna on the subcarrier with frequency f2.

6. A receiving - end signal processing system for a MIMO system, characterized in that, Including: An obtaining module, configured to obtain the signals transmitted by each transmitting antenna received by each receiving antenna, where the signal transmitted by each transmitting antenna is a signal obtained by performing constellation modulation, SFBC coding, and OFDM modulation on the transmission data; A first demodulation module, configured to perform OFDM demodulation on the signals received by each receiving antenna to obtain the demodulated signals of this receiving antenna, including the demodulated signals on different subcarriers; An organizing module, configured to re-organize the demodulated signals of each receiving antenna into a time-frequency resource matrix; A first determining module, configured to determine a received signal matrix according to the time-frequency resource matrix, and determine an estimated value of a transmitted symbol matrix according to the received signal matrix and a pre-determined decoding matrix; A second determining module, configured to determine the estimated values of each constellation symbol according to the estimated value of the transmitted symbol matrix; A second demodulation module, configured to perform constellation demodulation on the estimated values of each constellation symbol to obtain the estimated value of the transmission data.

7. The receiving end signal processing system of the MIMO system according to claim 6, characterized in that, The MIMO system includes two transmitting antennas and M receiving antennas, and the received signal matrix satisfies the following relational expression: where r is the received signal matrix, r 1,f1 represents the demodulated signal of the first receiving antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the first receiving antenna on the subcarrier with frequency f2, r 2,f1 represents the demodulated signal of the second receiving antenna on the subcarrier with frequency f1, represents the conjugate of the demodulated signal of the second receiving antenna on the subcarrier with frequency f2, r M,f1 is the demodulated signal of the Mth receiving antenna on the subcarrier with frequency f1, is the conjugate of the demodulated signal of the Mth receiving antenna on the subcarrier with frequency f2.

8. The receiving end signal processing system of the MIMO system according to claim 7, characterized in that, The decoding matrix satisfies the following relational expression: c = |h 1,1 | 2 + |h 1,2 | 2 + |h 2,1 | 2 + |h 2,2 | 2 + … + |h M,1 | 2 + |h M,2 | 2 where W is the decoding matrix, H is the channel matrix, H H is the conjugate transpose matrix of H, c is the channel coefficient, σ 2 is the noise interference power, h 1,1 is the channel from the first transmit antenna to the first receive antenna, h 1,2 is the channel from the second transmit antenna to the first receive antenna, h 2,1 is the channel from the first transmit antenna to the second receive antenna, h 2,2 is the channel from the second transmit antenna to the second receive antenna, is the conjugate of h 1,2 , is the conjugate of h 1,1 , is the conjugate of h 2,2 , h M,1 is the channel from the first transmit antenna to the Mth receive antenna, h M,2 is the channel from the second transmit antenna to the Mth receive antenna, is the conjugate of h M,1 , is the conjugate of h M,2 .

9. The receiving end signal processing system of the MIMO system according to claim 8, characterized in that, The estimated value of the transmitted symbol matrix satisfies the following relational expression: Among them, is the estimated value of the transmitted symbol matrix, is the estimated value of the constellation symbol s1, is the estimated value of the conjugate of the constellation symbol s2.

10. The receiving end signal processing system of the MIMO system according to claim 8, characterized in that, The method for determining the decoding matrix is: Among them, represents the value of W when E|s - Wr| 2 reaches the minimum, and E|s - Wr| 2 represents the expectation of |s - Wr| 2 , where s is the transmit symbol matrix, The transmitted symbol matrix satisfies the following relational expression: r = Hs + η where η is the noise matrix, and η 1,f1 is the noise and interference of the first receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the first receiving antenna on the subcarrier with frequency f2, and η 2,f1 is the noise and interference of the second receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the second receiving antenna on the subcarrier with frequency f2, and η M,f1 is the noise and interference of the Mth receiving antenna on the subcarrier with frequency f1, is the conjugate of the noise and interference of the Mth receiving antenna on the subcarrier with frequency f2.

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