Broadband high-speed LoS-MIMO communication subcarrier adaptive modulation coding method and system

Abstract

The invention discloses a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation coding method and system, and the method comprises the steps: a receiving end carries out the grading of the subcarriers of an LoS-MIMO channel after channel estimation at a T moment, obtains a subcarrier grading result, determines a coding modulation scheme corresponding to each subcarrier grade, and carries out the coding modulation of each subcarrier grade; the subcarrier grading result is sent to the sending end; at the T + 1 moment, after the sending end receives the subcarrier grading result, the coding modulation scheme corresponding to each subcarrier grade is determined, and step-by-step subcarrier adaptive coding modulation is carried out; and at the T + 1 moment, after the receiving end receives the OFDM symbols sent by the sending end, according to the selected subcarrier levels and the corresponding coding modulation schemes, corresponding demodulation and decoding are carried out, original bit stream information is recovered, returning is carried out at the T moment, the receiving end carries out grading on the LoS-MIMO channel subcarriers after channel estimation, and the subcarrier grading result is obtained, and the steps are continued to be executed. And the reliability and the effective transmission rate of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of millimeter wave communication technology, and in particular to a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method. Background Art

[0002] At present, MIMO spatial division multiplexing technology mainly uses the characteristics of the LoS-MIMO channel matrix in the LoS-MIMO field to derive the layout expression of the optimal antenna array under the LoS-MIMO channel, optimize the antenna array layout, and thus obtain the maximum spatial division multiplexing gain. For example, "A 60GHz LOS MIMO Backhaul Design Combining Spatial Multiplexing and Beamforming for a 100Gbps Throughput" designs a layered MIMO system under the LOS channel, and provides specific antenna gain and directivity through the upper sub-array division scheduling and the lower sub-array arrangement configuration to ensure full utilization of spatial multiplexing gain. However, this method does not consider the subcarrier splitting phenomenon brought by broadband to the near-field communication model, resulting in possible performance loss in the near-field communication scenario. A high-speed millimeter-wave multiplexing method is disclosed in the Chinese patent with application number "202311087475.4". In this method, in view of the limited layout of aerial platform antenna arrays and the polarization interference in traditional MIMO polarization multiplexing, a joint channel model of line-of-sight MIMO spatial multiplexing and polarization multiplexing is established, breaking through the optimization layout of antenna arrays under line-of-sight MIMO channels, eliminating cross-polarization interference of ultra-wideband signals, and performing low-complexity calibration technology for spatial multi-stream multiplexing systems. This method realizes MIMO multiplexing, but does not consider the subcarrier splitting phenomenon in broadband near-field communications, nor does it perform work on adaptive coding and modulation under different channel conditions, which may lead to performance loss in broadband near-field communication scenarios.

[0003] Since the LoS-MIMO channel model is similar to the near-field channel model, in the broadband high-speed LoS-MIMO communication scenario, large-bandwidth and high-speed near-field communication may cause beam tilt or even beam splitting, which greatly affects the transmission rate. In "Near-Field Wideband Channel Estimation for Extremely Large-Scale MIMO", a bilinear model is used to estimate the angle of arrival (AoA) and distance parameters of each near-field path component at all frequencies, and then the entire broadband XL MIMO channel can be restored through a compressed sensing algorithm. This method takes into account the existence of subcarrier splitting, but does not analyze the impact of subcarrier splitting on channel capacity, nor does it perform corresponding adaptive coding and modulation work.

[0004] Adaptive Modulation and Coding (AMC) is a wireless communication technology that dynamically adjusts the modulation and coding methods according to the quality and capacity of the current communication channel to improve the efficiency and reliability of data transmission. In "Adaptive coded modulation based on LDPC codes", the signal-to-noise ratio is used to measure the channel conditions and different BER performance thresholds are set to adaptively select the appropriate coding and modulation scheme based on the current channel environment conditions and the target BER performance. This method makes a trade-off between communication performance and transmission reliability, but does not consider the impact of actual near-field wideband channel feedback on the selection of adaptive coding and modulation schemes, which may result in performance or energy efficiency loss.

[0005] In summary, in the existing solutions, for LoS-MIMO spatial division multiplexing, only the spatial division multiplexing conditions under the maximum channel capacity are considered, but no optimization is made for the subcarrier splitting problem that may exist in the actual broadband high-speed LoS-MIMO communication scenario. In the research on the subcarrier splitting phenomenon, the impact of the subcarrier splitting phenomenon on the channel capacity is not analyzed, and no corresponding adaptive coding and modulation work is performed according to the channel capacity difference. In the broadband high-speed LoS-MIMO communication scenario, the existing technical solution is for the subcarrier splitting phenomenon. This phenomenon will cause differences in the channel capacity of different subcarriers. Some subcarriers with poor channel quality may not be correctly demodulated, affecting the transmission reliability and effective transmission rate of the system. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, an embodiment of the present invention provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method and system.

[0007] The embodiment of the present invention provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method and system.

[0008] In a first aspect, an embodiment of the present invention provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method, comprising:

[0009] At time T, the receiving end classifies the LoS-MIMO line-of-sight multi-antenna channel subcarriers after channel estimation, and after obtaining the subcarrier classification result, determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table, and sends the subcarrier classification result to the transmitting end;

[0010] At time T+1, after receiving the subcarrier classification result, the transmitting end determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table, and performs subcarrier adaptive coding and modulation step by step;

[0011] At time T+1, after receiving the OFDM orthogonal frequency division multiplexing symbols sent by the transmitter, the receiver performs corresponding demodulation and decoding according to the coding and modulation scheme corresponding to each subcarrier level selected to restore the original bit stream information;

[0012] Returning to time T, the receiving end classifies the LoS-MIMO channel subcarriers after channel estimation, and after obtaining the subcarrier classification result, determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table and continues to execute.

[0013] Preferably, at time T, the receiving end classifies the LoS-MIMO channel subcarriers after channel estimation to obtain a subcarrier classification result, including:

[0014] At time T, the receiver performs channel estimation for each subcarrier of the LoS-MIMO channel;

[0015] At time T, the receiving end calculates the channel capacity of each subcarrier and counts the distribution of the channel capacity of all subcarriers;

[0016] At time T, the receiving end classifies the LoS-MIMO channel subcarriers according to the channel capacity distribution result to obtain the subcarrier classification result.

[0017] Preferably, the receiving end performs channel estimation for each subcarrier of the LoS-MIMO channel, including:

[0018] The receiving end uses the ZF zero-forcing channel estimation method to perform channel estimation according to the following formula:

[0019] H=YX-1

[0020] Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

[0021] Preferably, the LoS MIMO channel is modeled using the ray tracing principle, and the channel between the transmitting antenna n and the receiving antenna m of the (m, n)th channel element in H is expressed as:

[0022]

[0023] Wherein, r(m, n) is the distance between the corresponding transmitting and receiving antennas, λ is the wavelength, and j is a complex number.

[0024] Preferably, according to Calculate the channel capacity of each subcarrier, where is the eigenvalue of the matrix Q in the MIMO channel capacity calculation formula, r represents the rank of the channel gain matrix, and the number of transmitting antennas is N t , i represents the singular value number of the channel gain matrix.

[0025] Preferably, the subcarrier hierarchical adaptive coding modulation mapping table includes a mapping relationship between subcarrier levels and modulation and coding schemes, and the modulation and coding schemes include code rates and modulation modes.

[0026] Preferably, after receiving the subcarrier classification result, the transmitting end performs step-by-step subcarrier adaptive coding and modulation according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and determines the coding and modulation scheme corresponding to each subcarrier level, including:

[0027] The transmitter selects the coding and modulation scheme according to the different subcarrier levels, ensuring that the subcarriers with higher channel capacity levels can achieve high-speed transmission while ensuring the accuracy of transmission of subcarriers with lower channel capacity levels;

[0028] The transmitter performs coding modulation and rate matching for subcarrier sets of different levels;

[0029] The transmitter maps the hierarchically modulated data to the subcarriers of the corresponding levels, and then sends them after being mapped to different antennas.

[0030] In a second aspect, an embodiment of the present invention further provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding system, comprising:

[0031] The receiving end is used to classify the LoS-MIMO line-of-sight multi-antenna channel subcarriers after channel estimation at time T, and after obtaining the subcarrier classification result, determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and send the subcarrier classification result to the transmitting end; after receiving the OFDM orthogonal frequency division multiplexing symbols sent by the transmitting end at time T+1, perform corresponding demodulation and decoding according to the coding and modulation scheme corresponding to each selected subcarrier level, and restore the original bit stream information;

[0032] The transmitting end is used to determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier grading result and the preset subcarrier grading adaptive coding and modulation mapping table after receiving the subcarrier grading result at time T+1, and perform step-by-step subcarrier adaptive coding and modulation.

[0033] Preferably, the receiving end is also used to perform channel estimation on each subcarrier of the LoS-MIMO channel at time T; the receiving end calculates the channel capacity of each subcarrier at time T, and counts the distribution of the channel capacity of all subcarriers; at time T, the receiving end classes the LoS-MIMO channel subcarriers according to the channel capacity distribution results to obtain subcarrier classification results.

[0034] Preferably, the receiving end is used to perform channel estimation using the ZF zero-breaking channel estimation method according to the following formula:

[0035] H=YX-1

[0036] Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

[0037] Compared with the traditional LoS-MIMO communication system, the present invention takes into account the subcarrier splitting problem in the broadband high-speed LoS-MIMO communication scenario. According to the subcarrier classification result, combined with the set subcarrier classification adaptive coding and modulation mapping table, adaptive coding modulation and adaptive demodulation decoding and channel information feedback are performed at the transmitting end and the receiving end for subcarrier sets of different levels. Through hierarchical adaptive modulation and coding, the reliability and effective transmission rate of the system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flowchart of a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method provided by an embodiment of the present invention;

[0039] Figure 2 Another flow chart of the broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method provided by an embodiment of the present invention;

[0040] Figure 3 Another flow chart of the broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method provided by an embodiment of the present invention;

[0041] Figure 4 A schematic diagram of the overall structure of the self-feedback adjustment mechanism provided by an embodiment of the present invention;

[0042] Figure 5 A schematic diagram of the feedback and adaptive structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] Example embodiments will be described more fully below with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be understood as limited to the embodiments set forth herein. On the contrary, the purpose of providing these embodiments is to make the present invention thorough and complete and to enable those skilled in the art to fully understand the scope of the present invention.

[0044] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0045] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof is not excluded.

[0047] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with their meaning in the context of the relevant art and the present invention, and will not be understood to have an idealized or overly formal meaning unless explicitly defined as such herein.

[0048] The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method and system provided by the present invention are designed based on the following LoS-MIMO broadband subcarrier splitting phenomenon.

[0049] First, the LoS-MIMO broadband subcarrier splitting phenomenon is explained: Assume that the number of transmitting antennas in a MIMO transmission system is N t The number of receiving antennas is N r In the millimeter wave broadband high-speed transmission scenario, the carrier frequency is W (W is generally 30-100Ghz), the bandwidth is B is 0.1W, and the OFDM transmission system is usually used in the high-speed MIMO transmission scenario. In the MIMO-OFDM transmission system, the number of subcarriers is M, assuming the center frequency is J c , then the frequency of each subcarrier is:

[0050] In the traditional narrowband signal transmission environment, assuming that all subcarrier frequencies f m ≈f c Therefore, there is no need to consider and analyze each subcarrier separately. However, in a broadband transmission environment, f m ≈f cThis is not true. This phenomenon is called broadband subcarrier splitting. In this case, the channel capacity of each subcarrier is different, and each subcarrier needs to be considered separately. If all subcarriers are considered in a unified manner, some subcarriers with poor conditions will not be able to transmit data at a high rate, resulting in reduced transmission reliability.

[0051] In order to enable those skilled in the art to better understand the technical solution, a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method and system provided by the present invention are described in detail below with reference to the accompanying drawings.

[0052] like Figure 1 , 2 As shown, in a first aspect, an embodiment of the present invention provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method, comprising:

[0053] Step S101, at time T, the receiving end classifies the LoS-MIMO channel subcarriers after channel estimation, and after obtaining the subcarrier classification result, determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table;

[0054] Step S102, at time T, the receiving end sends the subcarrier classification result to the transmitting end;

[0055] Step S103, at time T+1, after receiving the subcarrier classification result, the transmitting end determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and performs step-by-step subcarrier adaptive coding and modulation;

[0056] Step S104, at time T+1, after receiving the OFDM orthogonal frequency division multiplexing symbol sent by the transmitting end, the receiving end performs corresponding demodulation and decoding according to the coding and modulation scheme corresponding to each selected subcarrier level to restore the original bit stream information;

[0057] Return to step S101 and continue execution.

[0058] In an embodiment of the present invention, at time T, the receiving end classifies the LoS-MIMO subcarriers to obtain the subcarrier classification result, and determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table; at time T+1, the transmitting end determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result sent by the receiving end, and then carries out adaptive coding and modulation. After receiving the OFDM symbol, the receiving end performs corresponding demodulation and decoding according to the subcarrier classification result and the coding and modulation scheme for different subcarrier levels of the transmitting end to restore the original bit stream information. After that, the receiving end feeds back the subcarrier classification result after the channel estimation result at time T+1 to the transmitting end for the adaptive coding and modulation of the transmitting end at the next moment. After that, the transmitting end adaptive coding and modulation and the receiving end adaptive demodulation and decoding and channel information feedback are repeated to realize an adaptive transmission mode according to different subcarrier channel capacities, thereby ensuring the transmission rate and accuracy.

[0059] Compared with the traditional LoS-MIMO communication system, the present invention takes into account the subcarrier splitting problem in the broadband high-speed LoS-MIMO communication scenario. According to the subcarrier classification result, combined with the set subcarrier classification adaptive coding and modulation mapping table, adaptive coding modulation and adaptive demodulation decoding and channel information feedback are performed at the transmitting end and the receiving end for subcarrier sets of different levels. Through hierarchical adaptive modulation and coding, the reliability and effective transmission rate of the system are improved.

[0060] The present invention mainly involves MIMO space division multiplexing and adaptive modulation and coding technology. MIMO space division multiplexing is a technology that improves the performance of communication systems. This technology can effectively utilize spatial diversity, improve the performance of wireless communication systems, and provide strong support for improving the transmission efficiency, coverage and reliability of communication systems. In practical applications, reasonable configuration of MIMO technical parameters and optimization algorithms can further improve system performance and user experience.

[0061] Preferably, in step S101, at time T, the receiving end classifies the LoS-MIMO channel subcarriers after channel estimation to obtain a subcarrier classification result, including:

[0062] At time T, the receiver performs channel estimation for each subcarrier of the LoS-MIMO channel;

[0063] At time T, the receiving end calculates the channel capacity of each subcarrier and counts the distribution of the channel capacity of all subcarriers;

[0064] At time T, the receiving end classifies the LoS-MIMO channel subcarriers according to the channel capacity distribution result to obtain the subcarrier classification result.

[0065] In the embodiment of the present invention, according to the above-mentioned channel capacity analysis results, it can be known that the channel conditions and channel capacities of each subcarrier are different in the case of subcarrier splitting, so it is necessary to perform channel estimation on each subcarrier separately, and the results after channel estimation are graded according to the different channel capacities under different subcarriers.

[0066] The overall structure diagram of the self-feedback regulation mechanism is shown in the attached figure. Figure 3 As shown, Figure 3 The first layer from top to bottom is the steps performed by the transmitter, and the second and third layers from top to bottom are the steps performed by the receiver. The specific mechanism process is that at time T, the receiver performs channel estimation on the data after FFT deconstruction of OFDM subcarrier mapping. After obtaining the channel estimation results of all subcarriers, the receiver calculates the channel capacity of each subcarrier, and counts the distribution of the channel capacity of all subcarriers, and then classifies the subcarriers according to the channel capacity distribution results. After that, the receiver sends the subcarrier classification results to the transmitter, so that the transmitter selects the modulation and coding scheme corresponding to each subcarrier according to the subcarrier classification results and the subcarrier classification adaptive coding and modulation mapping table, performs step-by-step subcarrier adaptive coding and modulation, and performs hierarchical subcarrier mapping and layer mapping; at the same time, after receiving the OFDM symbol, the receiver performs subcarrier demapping, and selects the modulation and coding scheme corresponding to each subcarrier according to the subcarrier classification results and the pre-stored subcarrier classification adaptive coding and modulation mapping table, and performs subcarrier classification adaptive soft demodulation and decoding after channel equalization.

[0067] The subcarrier hierarchical adaptive coding and modulation mapping table is shown in Table 1. A high code rate and a high-order modulation method are adopted for subcarriers with a high channel capacity level, and a low code rate and a low-order modulation method are adopted for subcarriers with a low channel capacity level, so as to ensure that subcarriers with a high channel capacity level can achieve high-speed transmission while ensuring the accuracy of transmission of subcarriers with a low channel capacity level. For example, the coding and modulation scheme corresponding to subcarrier level A is MCS1.

[0068] Table 1 Subcarrier hierarchical adaptive coding and modulation mapping table

[0069] Subcarrier level Modulation and coding scheme Modulation method Bitrate A MCS1 QPSK 0.1172 B MCS2 QPSK 0.3001 C MCS3 16QAM 0.4238 D MCS4 16QAM 0.6426 E MCS5 64QAM 0.7539 F MCS6 64QAM 0.9258

[0070] Preferably, the receiving end performs channel estimation for each subcarrier of the LoS-MIMO channel, including:

[0071] The receiving end uses the ZF zero-forcing channel estimation method to perform channel estimation according to the following formula:

[0072] H=YX-1

[0073] Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

[0074] Preferably, the LoS-MIMO channel is modeled using the ray tracing principle, and the channel between the transmitting antenna n and the receiving antenna m of the (m, n)th channel element in H is expressed as:

[0075]

[0076] Wherein, r(m, n) is the distance between the corresponding transmitting and receiving antennas, λ is the wavelength, and j is a complex number.

[0077] In a preferred implementation, using the channel capacity calculation formula and matrix method, it can be known that for the LoS-MIMO channel, the maximum channel capacity condition is that the channel matrix column correlation is 0, that is:

[0078]

[0079] From the above formula, we can see that there are many optimal solutions to maximize the channel capacity. However, in practical applications, the constraints of shortest antenna spacing and maximum channel capacity are often considered:

[0080]

[0081] Among them, θ r and θ t is the angle of the transmitting and receiving antennas, cosθ r , cosθ t Project it on the x-axis.

[0082] Preferably, according to Calculate the channel capacity of each subcarrier, where is the eigenvalue of the matrix Q in the MIMO channel capacity calculation formula, r represents the rank of the channel gain matrix, and the number of transmitting antennas is N t , i represents the singular value number of the channel gain matrix.

[0083] It should be noted that the above formula for calculating the channel capacity of each subcarrier is It is derived according to the following process.

[0084] Considering the subcarrier splitting phenomenon, the channel on the qth subcarrier can be expressed as:

[0085]

[0086] Among them, f q is the corresponding subcarrier frequency.

[0087] The MIMO channel capacity calculation formula is:

[0088]

[0089] Where U is N tand N r The smaller number, I U is the unit matrix of U×U, det() is the determinant operation of the matrix, Q q is the channel gain matrix, expressed as:

[0090]

[0091] For the channel matrix H q Doing singular value decomposition gives:

[0092] H q =UDV H

[0093] Where U and V are unitary matrices, and D is a singular value diagonal matrix. Substituting the above decomposition into the previous channel capacity formula yields:

[0094]

[0095] in, is the eigenvalue of matrix Q, that is, the square of the eigenvalue of matrix D, r represents the rank of the channel gain matrix, i represents the matrix Q q The singular value number of , that is, the number of available data streams.

[0096] It should be noted that directly based on It is also possible to calculate the channel capacity of each subcarrier.

[0097] In a preferred embodiment, under the condition of subcarrier splitting, assuming that the channel capacity maximization antenna array is arranged based on the center frequency, it can be seen that for the remaining frequencies, the channel capacity is not the maximum. For a 16×16, 30Ghz carrier frequency, 3G bandwidth LoS-MIMO system, the subcarrier channel capacity under the optimal transmission distance antenna arrangement is as follows: Figure 4 , as shown in 5. Figure 4 Schematic diagram of subcarrier channel capacity percentage under the optimal transmission distance of LoS-MIMO. Figure 5 Schematic diagram of the subcarrier channel capacity percentage under LoS-MIMO non-optimal transmission distance.

[0098] It can be seen that under the optimal transmission distance, the subcarrier channel capacity is approximately symmetrically distributed at both ends of the center frequency and there is a certain capacity loss. Under non-optimal transmission distance, the subcarrier channel capacity changes irregularly and the channel capacity loss of some subcarriers is large. These subcarriers will not be able to maintain the transmission accuracy under high-speed data transmission. Therefore, in response to this phenomenon, an adaptive coding modulation scheme based on subcarrier channel capacity feedback is proposed to achieve high-speed reliable data transmission under subcarrier splitting. Under the optimal transmission distance and non-optimal transmission distance, the channel capacity of different subcarrier channels is different. Therefore, subcarriers can be graded according to channel capacity.

[0099] Preferably, the subcarrier hierarchical adaptive coding modulation mapping table includes a mapping relationship between subcarrier levels and modulation and coding schemes, and the modulation and coding schemes include code rates and modulation modes.

[0100] Preferably, in step S103, after receiving the subcarrier classification result, the transmitting end performs step-by-step subcarrier adaptive coding and modulation according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and determines the coding and modulation scheme corresponding to each subcarrier level, including:

[0101] The transmitter selects the coding and modulation scheme according to the different subcarrier levels, ensuring that the subcarriers with higher channel capacity levels can achieve high-speed transmission while ensuring the accuracy of transmission of subcarriers with lower channel capacity levels;

[0102] The transmitter performs coding modulation and rate matching for subcarrier sets of different levels;

[0103] The transmitter maps the hierarchically modulated data to the subcarriers of the corresponding levels, and then sends them after being mapped to different antennas.

[0104] The present invention aims at the problem of communication performance loss caused by subcarrier splitting in broadband high-speed LoS-MIM0 communication scenarios, and on this basis analyzes the impact of subcarrier splitting on subcarrier channel capacity. Then, the subcarriers are graded using the calculated subcarrier channel capacity distribution, and the modulation and coding scheme corresponding to each subcarrier is selected according to the subcarrier grading result and the subcarrier graded adaptive coding and modulation mapping table, and step-by-step subcarrier adaptive coding and modulation is carried out. After that, adaptive coding modulation at the transmitting end and adaptive demodulation and decoding at the receiving end are performed at each moment, and an adaptive transmission mode according to different subcarrier channel capacities is realized through channel information feedback to ensure transmission rate and reliability.

[0105] The present invention analyzes the channel capacity of the LoS-MIMO transmission system, and analyzes the situation where the channel capacity of each subcarrier is different under the subcarrier splitting problem in the broadband high-speed LoS-MIMO communication scenario. According to the different channel capacities of each subcarrier under subcarrier splitting, the present invention proposes a subcarrier grading method, which can accurately reflect the difference in subcarrier channel capacity and accurately match different modulation and coding methods for different subcarriers. The advantage of the present invention is that it takes into account the subcarrier splitting phenomenon in the broadband high-speed LoS-MIMO communication scenario, and performs adaptive transmission of different subcarrier channel capacity levels by grading the subcarrier channel capacity to ensure the transmission rate and reliability.

[0106] In a second aspect, an embodiment of the present invention further provides a broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding system, comprising:

[0107] The receiving end is used to classify the LoS-MIMO line-of-sight multi-antenna channel subcarriers after channel estimation at time T, and after obtaining the subcarrier classification result, determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and send the subcarrier classification result to the transmitting end; after receiving the OFDM orthogonal frequency division multiplexing symbols sent by the transmitting end at time T+1, perform corresponding demodulation and decoding according to the selected subcarrier levels and the corresponding coding and modulation schemes to restore the original bit stream information;

[0108] The transmitting end is used to determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier grading result and the preset subcarrier grading adaptive coding and modulation mapping table after receiving the subcarrier grading result at time T+1, and perform step-by-step subcarrier adaptive coding and modulation.

[0109] Preferably, the receiving end is also used to perform channel estimation on each subcarrier of the LoS-MIMO channel at time T; the receiving end calculates the channel capacity of each subcarrier at time T, and counts the distribution of the channel capacity of all subcarriers; at time T, the receiving end classes the LoS-MIMO channel subcarriers according to the channel capacity distribution results to obtain subcarrier classification results.

[0110] Preferably, the receiving end is used to perform channel estimation using the ZF zero-breaking channel estimation method according to the following formula:

[0111] H=YX-1

[0112] Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

[0113] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for limiting purposes. In some embodiments, it will be apparent to those skilled in the art that, unless otherwise expressly noted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method, characterized in that: include: At time T, the receiving end classifies the LoS-MIMO line-of-sight multi-antenna channel subcarriers after channel estimation, and after obtaining the subcarrier classification result, determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table, and sends the subcarrier classification result to the transmitting end; At time T+1, after receiving the subcarrier classification result, the transmitting end determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table, and performs subcarrier adaptive coding and modulation step by step; At time T+1, after receiving the OFDM orthogonal frequency division multiplexing symbols sent by the transmitter, the receiver performs corresponding demodulation and decoding according to the coding and modulation scheme corresponding to each subcarrier level selected to restore the original bit stream information; Returning to time T, the receiving end classifies the LoS-MIMO channel subcarriers after channel estimation, and after obtaining the subcarrier classification result, determines the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table and continues to execute.

2. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 1, characterized in that: At time T, the receiver classifies the LoS-MIMO channel subcarriers after channel estimation and obtains the subcarrier classification results, including: At time T, the receiver performs channel estimation for each subcarrier of the LoS-MIMO channel; At time T, the receiving end calculates the channel capacity of each subcarrier and counts the distribution of the channel capacity of all subcarriers; At time T, the receiving end classifies the LoS-MIMO channel subcarriers according to the channel capacity distribution result to obtain the subcarrier classification result.

3. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 2, characterized in that: The receiving end performs channel estimation for each subcarrier of the LoS-MIMO channel, including: The receiving end uses the ZF zero-forcing channel estimation method to perform channel estimation according to the following formula: H=YX -1 Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

4. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 3, characterized in that: The LoS-MIMO channel is modeled using the ray tracing principle. The channel between the transmitting antenna n and the receiving antenna m in the (m, n)th channel element in H is expressed as: Wherein, r(m, n) is the distance between the corresponding transmitting and receiving antennas, λ is the wavelength, and j is a complex number.

5. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 2, characterized in that: according to Calculate the channel capacity of each subcarrier, where is the eigenvalue of the matrix Q in the MIMO channel capacity calculation formula, r represents the rank of the channel gain matrix, and the number of transmitting antennas is N t , i represents the singular value number of the channel gain matrix.

6. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 1, characterized in that: The subcarrier hierarchical adaptive coding modulation mapping table includes a mapping relationship between subcarrier levels and modulation coding schemes, and the modulation coding scheme includes a code rate and a modulation mode.

7. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding method according to claim 1, characterized in that: After receiving the subcarrier classification result, the transmitting end performs step-by-step subcarrier adaptive coding and modulation according to the subcarrier classification result and the preset subcarrier classification adaptive coding and modulation mapping table, and determines the coding and modulation scheme corresponding to each subcarrier level, including: The transmitter selects the coding and modulation scheme according to the different subcarrier levels, ensuring that the subcarriers with higher channel capacity levels can achieve high-speed transmission while ensuring the accuracy of transmission of subcarriers with lower channel capacity levels; The transmitter performs coding modulation and rate matching for subcarrier sets of different levels; The transmitter maps the hierarchically modulated data to the subcarriers of the corresponding levels, and then sends them after being mapped to different antennas.

8. A broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding system, characterized in that: include: The receiving end is used to classify the LoS-MIMO line-of-sight multi-antenna channel subcarriers after channel estimation at time T, and after obtaining the subcarrier classification result, determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier classification result and a preset subcarrier classification adaptive coding and modulation mapping table, and send the subcarrier classification result to the transmitting end; after receiving the OFDM orthogonal frequency division multiplexing symbols sent by the transmitting end at time T+1, perform corresponding demodulation and decoding according to the coding and modulation scheme corresponding to each selected subcarrier level, and restore the original bit stream information; The transmitting end is used to determine the coding and modulation scheme corresponding to each subcarrier level according to the subcarrier grading result and the preset subcarrier grading adaptive coding and modulation mapping table after receiving the subcarrier grading result at time T+1, and perform step-by-step subcarrier adaptive coding and modulation.

9. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding system according to claim 8, characterized in that: The receiving end is also used to perform channel estimation for each subcarrier of the LoS-MIMO channel at time T; the receiving end calculates the channel capacity of each subcarrier at time T and counts the distribution of the channel capacity of all subcarriers; At time T, the receiving end classifies the LoS-MIMO channel subcarriers according to the channel capacity distribution result to obtain the subcarrier classification result.

10. The broadband high-speed LoS-MIMO communication subcarrier adaptive modulation and coding system according to claim 9, characterized in that: The receiving end is used to perform channel estimation using the ZF zero-breaking channel estimation method according to the following formula: H=YX -1 Wherein, X is the pilot symbol inserted on each subcarrier, and Y is the received signal on each subcarrier.

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