Parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding

Abstract

The present invention discloses a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding, which relates to the field of communication technology, including a signal transmission platform, wherein the signal transmission platform is communicatively connected with a signal source module, an LDPC coding module, a parallel processing module, a diversity antenna module, a channel estimation and equalization module, a demodulation and decoding module, a signal processing module and a performance monitoring module, wherein the modules are connected with electrical signals; the signal source module is used to generate a high-speed data stream for transmission; the LDPC coding module is used to perform LDPC coding processing on the original data signal generated by the signal source module. The present invention improves the reliability of data transmission by introducing LDPC coding, so that a low bit error rate can be maintained under poor channel conditions or interference, and the application of parallel processing technology enables multiple sub-streams to be processed and transmitted independently, thereby reducing the impact of single path fading on the overall transmission quality.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding. Background Art

[0002] With the rapid development of information technology, especially its wide application in big data, cloud computing, the Internet of Things and other fields, higher requirements are placed on the data transmission rate of communication systems. Microwave transmission systems, as a high-speed, high-bandwidth communication method, can meet these requirements. LDPC code is a linear block code based on graph theory with a very sparse parity check matrix. Under the iterative decoding conditions based on the BF algorithm, its performance can approach the Shannon limit, that is, it reaches the theoretical optimal transmission efficiency. Parallel processing technology can process multiple data streams simultaneously, thereby significantly improving the rate and efficiency of data transmission. In microwave transmission systems, the use of parallel high-speed modulation and demodulation technology can further improve the transmission performance of the system.

[0003] For example, a microwave transmission system, method and storage medium with Chinese patent publication number: CN117896224A belongs to the field of communication technology. The system includes: a main antenna for transmitting a first uplink signal and receiving a main downlink signal; a diversity antenna for transmitting a second uplink signal and receiving a diversity downlink signal; a main RF unit group connected to a modem unit group and a main antenna, for transmitting a first uplink signal obtained from the modem unit group to the main antenna, and transmitting a main downlink signal obtained from the main antenna to the modem unit group.

[0004] In the prior art, the microwave transmission system uses a diversity antenna to cooperate with the main antenna for signal transmission, so as to solve the problem that in the traditional microwave transmission system, all multi-transmit and multi-receive frequency points are concentrated under the same antenna for splitting and combining and carrier aggregation, resulting in large gain loss. Although the diversity reception technology can improve the reliability of the signal, it also increases the complexity of the system and needs to process the signal data of multiple signal paths. At the same time, in the microwave transmission system, the diversity antenna requires accurate channel estimation to optimize the signal processing, but the channel conditions are susceptible to various factors such as weather, terrain and distance, resulting in unstable system performance, which in turn affects the decoding performance of the microwave transmission system. For this reason, a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding is proposed. Summary of the invention

[0005] The present invention aims to provide a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding includes a signal transmission platform, wherein the signal transmission platform is communicatively connected with a signal source module, an LDPC coding module, a parallel processing module, a diversity antenna module, a channel estimation and equalization module, a demodulation and decoding module, a signal processing module, and a performance monitoring module, wherein the modules are electrically connected with each other;

[0008] The signal source module is used to generate a high-speed data stream for transmission and form an original data signal. The original data signal comes from various data sources, such as sensors, computers, communication networks, etc., to provide original data and ensure that the data enters the transmission process at an appropriate rate and format;

[0009] The LDPC encoding module is used to perform LDPC encoding processing on the original data signal generated by the signal source module, and improve the anti-interference ability and transmission reliability of the signal by introducing redundant information. The encoded signal has stronger robustness and can maintain a low bit error rate under poor channel conditions;

[0010] The parallel processing module is used to perform parallel modulation processing on the LDPC-coded signal, convert the coded digital signal into an analog signal for microwave transmission, improve the data processing speed, and use the parallel computing capability to speed up the encoding and modulation speed of the data to meet the high-speed transmission requirements so as to be suitable for transmission in the microwave channel;

[0011] The diversity antenna module, as multiple paths for signal transmission and reception, is composed of multiple antennas, and works in conjunction with the main antenna to receive and transmit signals from different directions. Through diversity technology, the influence of multipath fading and interference is reduced, the signal stability and reception success rate are improved, the signal processing process is optimized, and the gain loss is reduced;

[0012] The channel estimation and equalization module is used to monitor and evaluate the channel conditions, obtain the characteristic parameters of the channel, and perform equalization processing on the received signal according to the channel estimation result, compensate for the influence of the channel on the signal, improve the transmission quality of the signal, help optimize the signal processing, and improve the performance of the system under changing channel conditions;

[0013] The demodulation and decoding module is used to perform LDPC decoding on the equalized signal to restore the original data signal, remove errors that may occur during the transmission process, correctly restore the transmitted digital signal, and use the error correction capability of the LDPC code to restore the original data to the maximum extent;

[0014] The signal processing module is used to further process the results of LDPC decoding output, make final data decisions, and ensure that the output data is accurate and meets data quality requirements;

[0015] The performance monitoring module is used to monitor the working status and performance indicators of each module, and to make adjustments and optimizations, so as to respond to system changes in a timely manner and optimize system configuration.

[0016] A further improvement of the technical solution of the present invention is that: in the signal source module, the process of forming the original data signal is:

[0017] Collect raw data from various data sources, and encode, package and time-synchronize the collected data, where the data sources include but are not limited to sensors, computers and communication networks;

[0018] Use buffers to temporarily store raw data collected from different data sources, smooth out rate fluctuations of data sources, reduce the impact of rate fluctuations on subsequent processing, and ensure the continuity and stability of data transmission;

[0019] Perform pre-processing operations on data, including denoising, filtering, and compression, to improve data quality, reduce the complexity of subsequent processing, and improve the overall efficiency of the system. According to the requirements of the transmission system, adjust the data transmission rate to match the data flow with the processing capacity of the transmission system to avoid data loss or congestion;

[0020] The signal source module outputs the processed original data signal to the LDPC encoding module through the interface to ensure the correct transmission of data.

[0021] A further improvement of the technical solution of the present invention is that: in the LDPC encoding module, the process of performing LDPC encoding processing on the original data signal is:

[0022] Receive the original data signal from the signal source module, divide the data stream into multiple data blocks according to a fixed length, and construct an LDPC check matrix according to the parameters of the LDPC code;

[0023] The data block is encoded using the LDPC check matrix, and redundant information is introduced through matrix multiplication to generate LDPC codewords;

[0024] Generate corresponding redundant bits according to the rows of the LDPC check matrix, and append the generated redundant bits to the end of the original data bits to form a complete LDPC codeword, and obtain a complete coded data stream, so that each data block is converted into a longer codeword containing the original information and redundant information;

[0025] The encoded LDPC codeword is output to the parallel processing module for signal modulation and transmission.

[0026] A further improvement of the technical solution of the present invention is that: in the parallel processing module, the process of parallel modulation processing is:

[0027] Receive the encoded data stream containing redundant information from the LDPC encoding module, divide the encoded data stream into multiple sub-streams, and distribute them to multiple parallel processing units. Each sub-stream can be independently processed to achieve parallel processing;

[0028] Using parallel processing technology, QPSK modulation method is used to modulate each sub-stream, generating I (in-phase) and Q (quadrature-phase) component signals, and superimposing the I and Q components to form a complete QPSK signal. The I component corresponds to the "0" and "1" of the binary data, and the Q component corresponds to the "0" and "1" received subsequently.

[0029] Amplify the superimposed signal to meet the transmission power requirement, and filter to limit the signal bandwidth to reduce out-of-band interference;

[0030] The digital QPSK signal is converted into an analog signal for transmission through a microwave channel, and the analog signal is transmitted to the diversity antenna module.

[0031] A further improvement of the technical solution of the present invention is that the calculation formula of the QPSK modulation is:

[0032]

[0033] Among them, s(t) is the modulated signal at time t, E b is the energy per bit, equal to the signal power multiplied by the duration of the bit, f c is the frequency of the carrier, I(t) is the modulation signal of the in-phase component, Q(t) is the modulation signal of the quadrature-phase component, cos(2πf c t) and sin(2πf c t) are the cosine and sine waves of the carrier respectively.

[0034] A further improvement of the technical solution of the present invention is that in the diversity antenna module, the process of receiving and transmitting signals is:

[0035] Multiple antennas in the diversity antenna module are distributed in different physical locations, transmitting the same information signal simultaneously or alternately from different directions. Through diversity transmission, the signal can reach the receiving end through multiple paths, thereby reducing the signal loss caused by single path fading;

[0036] The diversity antenna at the receiving end receives signals from multiple paths and combines the received multiple signal paths at the receiving end to combine the signals so that the multiple signal paths are combined into a single signal, maximizing signal strength and reducing interference;

[0037] The combined signal is demodulated to restore the original digital data, and the combined signal is sent to the channel estimation and equalization module for equalization. The expression of the combined signal is:

[0038]

[0039] Among them, y is the combined signal, h i is the channel response of the ith path, x i is the signal received by the ith path, N is the total number of paths in the channel response, and P noise，i is the noise power of the ith path.

[0040] A further improvement of the technical solution of the present invention is that: in the channel estimation and equalization module, the process of equalizing the received signal is:

[0041] The channel estimation module first receives the signal from the receiving antenna, extracts the known reference pilot signal from the received signal, and estimates the impulse response of the channel. The expression of the estimated channel impulse response is:

[0042]

[0043] in, is the estimated channel impulse response, r(t) is the received reference pilot signal, τ i is the delay of the ith channel, g(t) is the impulse response of the matched filter, and I is the number of multipath components;

[0044] The characteristic parameters of the channel, including path loss, delay, and Doppler shift, are obtained from the channel estimation, the estimated path loss, estimated delay, and estimated Doppler shift are calculated, and a channel model is established according to the characteristic parameters of the channel. The expression of the estimated path loss is:

[0045]

[0046] where PL is the estimated path loss and |r(t)| 2 is the received signal power, N0 is the noise power spectral density;

[0047] The expression of the estimated delay is:

[0048]

[0049] in, is the estimated average multipath delay, τ i is the delay of the ith channel, I is the number of multipath components;

[0050] The expression for estimating Doppler shift is:

[0051]

[0052] in, is the estimated Doppler shift, ∠r(t) is the phase of the received signal, and f c is the carrier frequency, I is the number of multipath components;

[0053] Using the channel estimation results, the equalizer coefficients of the channel response are calculated, and the received signal is equalized to eliminate interference caused by multipath effects, perform signal adjustments, and optimize system performance;

[0054] The results of channel estimation and equalization processing are fed back to the demodulation and decoding module for decoding processing.

[0055] A further improvement of the technical solution of the present invention is that: the expression for performing equalization processing on the received signal is:

[0056]

[0057]

[0058] Among them, y(t) is the equalized signal, w i is the equalizer coefficient, which represents the equalizer coefficient of the ith channel response, x(t) is the signal received at time t, τ i is the delay of the ith channel, which represents the delay relative to the first arriving channel, is the conjugate of the ith channel response, |h j | 2 is the square of the modulus of the jth channel response, representing the signal power, N is the total number of channel response paths, and h i is the channel response of the ith path.

[0059] A further improvement of the technical solution of the present invention is that: in the demodulation and decoding module, the process of performing LDPC decoding processing on the equalized signal is:

[0060] The demodulation and decoding module receives the equalized signal and demodulates the equalized analog signal back to a digital signal, ensuring that the demodulation process is synchronized with the clock of the original signal to correctly identify the bit boundary;

[0061] Perform soft or hard decision on the demodulated signal. Soft decision retains the amplitude and phase information of the signal, while hard decision only retains the binary decision of the bit.

[0062] The demodulated signal is input into the LDPC decoder, and errors are gradually eliminated through multiple rounds of iterative processing of the belief propagation algorithm. In each round of iteration, the messages of the bit nodes and check nodes are updated and transmitted to the adjacent nodes.

[0063] Use the check matrix of the LDPC code to identify the error bits, and use the redundant information in the check matrix to correct the errors and update the decoding results;

[0064] After LDPC decoding and error correction, the original data signal is output. The expression of the belief propagation algorithm is:

[0065] L(v→c)=Π u∈N(v)\c L(u→v);

[0066]

[0067]

[0068] Where L(v→c) is the message from bit node v to check node c, N(v) is the set of check nodes adjacent to bit node v, L(u→v) is the message from check node u to bit node v, L(c→v) is the message from check node c to bit node v, d v is the hard decision result of bit node v, and L(v) is the accumulated message of bit node v.

[0069] A further improvement of the technical solution of the present invention is that: in the signal processing module, the process of further processing the result of LDPC decoding output is:

[0070] The signal processing module receives the decoded raw data from the LDPC decoding module and performs a data synchronization check to confirm that the data stream is consistent with the expected synchronization mode and ensure the data timing is correct;

[0071] Use CRC checksum to repeatedly check the received data and identify errors that are not corrected by LDPC decoding;

[0072] If an error is detected, locate the location where the error occurred, mark the erroneous data, and request retransmission;

[0073] Clean the data, remove useless or redundant information in the data, retain key information, convert the decoded data into the final application format, and provide the processed data output to the user.

[0074] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0075] 1. The present invention provides a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding. The introduction of LDPC coding improves the reliability of data transmission, so that a low bit error rate can be maintained under poor channel conditions or interference. The application of parallel processing technology enables multiple sub-streams to be processed and transmitted independently, thereby reducing the impact of single path fading on the overall transmission quality. In addition, the use of diversity antennas further enhances the reception quality of signals. By receiving signals through multiple paths, the impact of multipath fading and interference is reduced, ensuring that the system can operate stably under various environmental conditions, thereby improving the reliability and stability of data transmission.

[0076] 2. The present invention provides a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding. By dividing the encoded data stream into multiple sub-streams and distributing them to multiple parallel processing units, each sub-stream can be modulated and processed independently, thereby significantly improving the data processing speed. Parallel processing not only speeds up the encoding and modulation speed of the data, but also enables the system to meet the needs of high-speed transmission. At the signal receiving end, parallel processing technology is also used to quickly demodulate and decode the received signal, further improving the overall throughput of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0078] Figure 1 It is a module diagram of the present invention;

[0079] Figure 2 It is a parallel modulation process flow chart of the present invention;

[0080] Figure 3 The present invention is a flow chart of performing equalization processing on a received signal. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] Embodiment 1, as Figure 1 , Figure 2As shown, the present invention provides a parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding, including a signal transmission platform, the signal transmission platform is communicatively connected with a signal source module, an LDPC coding module, a parallel processing module, a diversity antenna module, a channel estimation and equalization module, a demodulation and decoding module, a signal processing module and a performance monitoring module, wherein the modules are connected by electrical signals;

[0083] The signal source module is used to generate a high-speed data stream for transmission and form an original data signal. The original data signal comes from various data sources, such as sensors, computers, communication networks, etc. It provides original data to ensure that the data enters the transmission process at an appropriate rate and format. It collects original data from various data sources and encodes, packages and synchronizes the collected data. Among them, data sources include but are not limited to sensors, computers and communication networks. Data encoding selects an appropriate data encoding method based on the transmission protocol and the processing capability of the receiving end. Data packaging is used to divide the continuous data stream into fixed-size data packets or frames. Each data packet contains a data portion and possible control information. Time synchronization is used It is used to add timestamps or perform time synchronization processing for data packets to ensure the timing of data. The buffer is used to temporarily store the original data collected from different data sources, smooth the rate fluctuations of the data source, reduce the impact of rate fluctuations on subsequent processing, and ensure the continuity and stability of data transmission. The data is pre-processed, including denoising, filtering, and compression, to improve data quality, reduce the complexity of subsequent processing, and improve the overall efficiency of the system. According to the requirements of the transmission system, the data transmission rate is adjusted to match the data stream with the processing capacity of the transmission system to avoid data loss or congestion. The signal source module outputs the processed original data signal to the LDPC encoding module through the interface to ensure the correct transmission of data;

[0084] The LDPC coding module is used to perform LDPC coding on the original data signal generated by the signal source module, improve the anti-interference ability and transmission reliability of the signal by introducing redundant information, and the coded signal has stronger robustness and can maintain a low bit error rate under poor channel conditions. The original data signal from the signal source module is received, the data stream is divided into multiple data blocks according to a fixed length, and an LDPC check matrix is ​​constructed according to the parameters of the LDPC code. The data block is encoded by using the LDPC check matrix, and redundant information is introduced by matrix multiplication to generate LDPC code words. According to the rows of the LDPC check matrix, corresponding redundant bits are generated, and the generated redundant bits are appended to the end of the original data bits to form a complete LDPC code word, and a complete coded data stream is obtained, so that each data block is converted into a longer code word containing original information and redundant information, and the coded LDPC code word is output to the parallel processing module for signal modulation and transmission;

[0085] A parallel processing module is used to perform parallel modulation processing on the LDPC encoded signal, convert the encoded digital signal into an analog signal for microwave transmission, improve the data processing speed, use parallel computing capabilities to speed up the encoding and modulation speed of data, meet the high-speed transmission requirements, and be suitable for transmission in a microwave channel. The coded data stream containing redundant information is received from the LDPC encoding module, and the coded data stream is divided into multiple sub-streams, which are distributed to multiple parallel processing units. Each sub-stream can be independently processed in the subsequent processing to achieve parallel processing. The parallel processing technology is used to modulate each sub-stream using the QPSK modulation method to generate I (in-phase) and Q (quadrature phase) component signals. The I and Q components are superimposed to form a complete QPSK signal. The I component corresponds to "0" and "1" of the binary data, and the Q component corresponds to the subsequently received "0" and "1". The superimposed signal is amplified to meet the transmission power requirements, and filtering is performed to limit the bandwidth of the signal to reduce out-of-band interference. The digital QPSK signal is converted into an analog signal for transmission through the microwave channel, and the analog signal is transmitted to the diversity antenna module;

[0086] Furthermore, the calculation formula for QPSK modulation is:

[0087]

[0088] Among them, s(t) is the modulated signal at time t, E b is the energy per bit, equal to the signal power multiplied by the duration of the bit, f c is the frequency of the carrier, I(t) is the modulation signal of the in-phase component, Q(t) is the modulation signal of the quadrature-phase component, cos(2πf c t) and sin(2πf c t) are the cosine and sine waves of the carrier respectively. It should be noted that cos(2πf c t) and sin(2πf c t) is a periodic function with a value range of -1 to +1, indicating the phase change of the carrier signal. s(t) is the weighted sum of these two components, so its value range is also between -1 and +1. The specific value depends on the current state of I(t) and Q(t). As time t changes, s(t) will switch between four possible phase states according to the values ​​of I(t) and Q(t), forming a periodic change trend of the QPSK signal.

[0089] The diversity antenna module, as multiple paths for signal transmission and reception, is composed of multiple antennas, and works in conjunction with the main antenna to receive and transmit signals from different directions. Through diversity technology, the impact of multipath fading and interference is reduced, the stability and reception success rate of the signal are improved, the signal processing process is optimized and the gain loss is reduced. The multiple antennas in the diversity antenna module are distributed in different physical locations, and the same information signal is transmitted simultaneously or alternately from different directions. Through diversity transmission, the signal can reach the receiving end through multiple paths, thereby reducing the signal loss caused by the fading of a single path. The diversity antenna at the receiving end receives signals from multiple paths, and merges the received multiple signal paths at the receiving end to merge the signals so that the multiple signal paths are merged into a single signal, maximizing the signal strength and reducing interference. The merged signal is demodulated to restore the original digital data, and the merged signal is sent to the channel estimation and equalization module for equalization processing;

[0090] Furthermore, the expression of the combined signal is:

[0091]

[0092] Among them, y is the combined signal, h i is the channel response of the ith path, x i is the signal received by the ith path, N is the total number of paths in the channel response, and P noise，i is the noise power of the ith path;

[0093] The channel estimation and equalization module is used to monitor and evaluate the channel conditions, obtain the characteristic parameters of the channel, and perform equalization processing on the received signal based on the results of the channel estimation, so as to compensate for the influence of the channel on the signal, improve the transmission quality of the signal, help optimize the signal processing, and improve the performance of the system under changing channel conditions;

[0094] The demodulation and decoding module is used to perform LDPC decoding on the equalized signal, restore the original data signal, remove errors that may occur during the transmission process, correctly restore the transmitted digital signal, and use the error correction capability of the LDPC code to restore the original data to the maximum extent;

[0095] The signal processing module is used to further process the results of LDPC decoding output and make final data decisions to ensure that the output data is accurate and meets data quality requirements;

[0096] The performance monitoring module is used to monitor the working status and performance indicators of each module, and make adjustments and optimizations to respond to system changes in a timely manner and optimize system configuration.

[0097] Embodiment 2, as Figure 3As shown, based on Example 1, the present invention provides a technical solution: Preferably, in the channel estimation and equalization module, the process of performing equalization processing on the received signal is:

[0098] The channel estimation module first receives the signal from the receiving antenna, extracts the known reference pilot signal from the received signal, and estimates the impulse response of the channel. The expression for estimating the impulse response of the channel is:

[0099]

[0100] in, is the estimated channel impulse response, r(t) is the received reference pilot signal, τ i is the delay of the ith channel, g(t) is the impulse response of the matched filter, and I is the number of multipath components;

[0101] The characteristic parameters of the channel, including path loss, delay, and Doppler shift, are obtained from the channel estimation. The estimated path loss, estimated delay, and estimated Doppler shift are calculated, and a channel model is established based on the characteristic parameters of the channel. The expression for the estimated path loss is:

[0102]

[0103] where PL is the estimated path loss and |r(t)| 2 is the received signal power, N0 is the noise power spectral density. It should be noted that PL is a negative number, indicating that the received signal is lower than the noise level;

[0104] The expression for estimating the delay is:

[0105]

[0106] in, is the estimated average multipath delay, τ i is the delay of the ith channel, I is the number of multipath components;

[0107] The expression for estimating Doppler shift is:

[0108]

[0109] in, is the estimated Doppler shift, ∠r(t) is the phase of the received signal, and f c is the carrier frequency, I is the number of multipath components;

[0110] Using the channel estimation results, the equalizer coefficients of the channel response are calculated, and the received signal is equalized to eliminate the interference caused by the multipath effect, perform signal adjustment, optimize system performance, and feed the results of the channel estimation and equalization processing back to the demodulation and decoding module for decoding processing;

[0111] Furthermore, the expression for equalizing the received signal is:

[0112]

[0113]

[0114] Among them, y(t) is the equalized signal, w i is the equalizer coefficient, which represents the equalizer coefficient of the ith channel response, x(t) is the signal received at time t, τ i is the delay of the ith channel, which represents the delay relative to the first arriving channel, is the conjugate of the ith channel response, |h j | 2 is the square of the modulus of the jth channel response, representing the signal power, N is the total number of channel response paths, and h i is the channel response of the ith path;

[0115] In the demodulation and decoding module, the process of performing LDPC decoding on the equalized signal is as follows:

[0116] The demodulation and decoding module receives the equalized signal and demodulates the equalized analog signal back to a digital signal, ensuring that the demodulation process is synchronized with the clock of the original signal to correctly identify the bit boundary, and performs soft or hard decision on the demodulated signal. The soft decision retains the amplitude and phase information of the signal, and the hard decision only retains the binary decision of the bit. The demodulated signal is input into the LDPC decoder, and errors are gradually eliminated through multiple rounds of iterative processing of the belief propagation algorithm. In each round of iteration, the messages of the bit nodes and the check nodes are updated and transmitted to the adjacent nodes. The error bits are identified using the check matrix of the LDPC code, and the errors are corrected using the redundant information in the check matrix. The decoding result is updated, and the original data signal is output after LDPC decoding and error correction.

[0117] Furthermore, the expression of the belief propagation algorithm is:

[0118] L(v→c)=Π u∈N(v)\c L(u→v);

[0119]

[0120]

[0121] Where L(v→c) is the message from bit node v to check node c, N(v) is the set of check nodes adjacent to bit node v, L(u→v) is the message from check node u to bit node v, L(c→v) is the message from check node c to bit node v, and d v is the hard decision result of bit node v, L(v) is the accumulated message of bit node v;

[0122] In the signal processing module, the process of further processing the LDPC decoding output result is as follows:

[0123] The signal processing module receives the decoded raw data from the LDPC decoding module and performs a data synchronization check to confirm that the data stream is consistent with the expected synchronization mode, ensure the correct timing of the data, use the CRC check code to repeat the received data, identify errors that have not been corrected by LDPC decoding, and if an error is detected, locate the location of the error, mark the erroneous data, request retransmission, clean the data, remove useless information or redundant parts in the data, retain key information, convert the decoded data into the final application format, and output the processed data to the user.

[0124] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding, including a signal transmission platform, characterized in that: The signal transmission platform is communicatively connected with a signal source module, an LDPC encoding module, a parallel processing module, a diversity antenna module, a channel estimation and equalization module, a demodulation and decoding module, a signal processing module and a performance monitoring module, wherein the modules are electrically connected with each other; The signal source module is used to generate a high-speed data stream for transmission to form an original data signal; The LDPC encoding module is used to perform LDPC encoding processing on the original data signal generated by the signal source module; The parallel processing module is used to perform parallel modulation processing on the LDPC-coded signal and convert the coded digital signal into an analog signal for microwave transmission; The diversity antenna module, as multiple paths for signal transmission and reception, is composed of multiple antennas and works in conjunction with the main antenna to receive and transmit signals from different directions; The channel estimation and equalization module is used to monitor and evaluate the channel conditions, obtain the characteristic parameters of the channel, and perform equalization processing on the received signal according to the result of the channel estimation to compensate for the influence of the channel on the signal. In the channel estimation and equalization module, the process of performing equalization processing on the received signal is as follows: The channel estimation module first receives the signal from the receiving antenna, extracts the known reference pilot signal from the received signal, and estimates the impulse response of the channel. The expression of the estimated channel impulse response is: in, is the estimated channel impulse response, r(t) is the received reference pilot signal, τ i is the delay of the ith channel, g(t) is the impulse response of the matched filter, and I is the number of multipath components; The characteristic parameters of the channel, including path loss, delay, and Doppler shift, are obtained from the channel estimation, the estimated path loss, estimated delay, and estimated Doppler shift are calculated, and a channel model is established according to the characteristic parameters of the channel. The expression of the estimated path loss is: where PL is the estimated path loss and |r(t)| 2 is the received signal power, N0 is the noise power spectral density; The expression of the estimated delay is: in, is the estimated average multipath delay, τ i is the delay of the ith channel, I is the number of multipath components; The expression for estimating Doppler shift is: in, is the estimated Doppler shift, ∠r(t) is the phase of the received signal, and f c is the carrier frequency, I is the number of multipath components; Using the channel estimation results, the equalizer coefficients of the channel response are calculated, and the received signal is equalized to eliminate interference caused by multipath effects, perform signal adjustments, and optimize system performance; Feedback the results of channel estimation and equalization processing to the demodulation and decoding module for decoding processing; The expression for performing equalization processing on the received signal is: Among them, y(t) is the equalized signal, w i is the equalizer coefficient, which represents the equalizer coefficient of the ith channel response, x(t) is the signal received at time t, τ i is the delay of the ith channel, is the conjugate of the ith channel response, |h j | 2 is the square of the modulus of the jth channel response, representing the signal power, N is the total number of channel response paths, and h i is the channel response of the ith path; The demodulation and decoding module is used to perform LDPC decoding on the equalized signal to restore the original data signal. In the demodulation and decoding module, the process of performing LDPC decoding on the equalized signal is as follows: The demodulation and decoding module receives the equalized signal and demodulates the equalized analog signal back to a digital signal, ensuring that the demodulation process is synchronized with the clock of the original signal to correctly identify the bit boundary; Perform soft or hard decision on the demodulated signal. Soft decision retains the amplitude and phase information of the signal, while hard decision only retains the binary decision of the bit. The demodulated signal is input into the LDPC decoder, and errors are eliminated through multiple rounds of iterative processing of the belief propagation algorithm. In each round of iteration, the messages of the bit nodes and check nodes are updated and transmitted to the adjacent nodes. Use the check matrix of the LDPC code to identify the error bits, and use the redundant information in the check matrix to correct the errors and update the decoding results; After LDPC decoding and error correction, the original data signal is output; The signal processing module is used to further process the result output by LDPC decoding and make a final data decision; The performance monitoring module is used to monitor the working status and performance indicators of each module, and to make adjustments and optimizations, so as to respond to system changes in a timely manner and optimize system configuration.

2. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 1, characterized in that: In the signal source module, the process of forming the original data signal is as follows: Collect raw data from various data sources, and encode, package and time-synchronize the collected data; Use buffers to temporarily store raw data collected from different data sources to smooth out rate fluctuations of data sources; Pre-process the data and adjust the data transmission rate according to the requirements of the transmission system so that the data flow matches the processing capacity of the transmission system; The signal source module outputs the processed original data signal to the LDPC encoding module through an interface.

3. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 2 is characterized in that: In the LDPC encoding module, the process of performing LDPC encoding processing on the original data signal is as follows: Receive the original data signal from the signal source module, divide the data stream into multiple data blocks according to a fixed length, and construct an LDPC check matrix according to the parameters of the LDPC code; The data block is encoded using the LDPC check matrix, and redundant information is introduced through matrix multiplication to generate LDPC codewords; Generate corresponding redundant bits according to the rows of the LDPC check matrix, and append the generated redundant bits to the end of the original data bits to form a complete LDPC codeword, thereby obtaining a complete coded data stream; The encoded LDPC codeword is output to the parallel processing module for signal modulation and transmission.

4. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 3 is characterized in that: In the parallel processing module, the process of parallel modulation processing is: Receive a data stream that has been encoded and contains redundant information from an LDPC encoding module, divide the encoded data stream into multiple sub-streams, and distribute them to multiple parallel processing units to achieve parallel processing; Using parallel processing technology, QPSK modulation method is used to modulate each sub-stream, generate I and Q component signals, and superimpose the I and Q components to form a complete QPSK signal; Amplify the superimposed signal to meet the transmission power requirement, and filter to limit the signal bandwidth to reduce out-of-band interference; The digital QPSK signal is converted into an analog signal and the analog signal is transmitted to the diversity antenna module.

5. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 4 is characterized in that: The calculation formula of the QPSK modulation is: Among them, s(t) is the modulated signal at time t, E b is the energy per bit, equal to the signal power multiplied by the duration of the bit, f c is the frequency of the carrier, I(t) is the modulation signal of the in-phase component, Q(t) is the modulation signal of the quadrature-phase component, cos(2πf c t) and sin(2πf c t) are the cosine and sine waves of the carrier respectively.

6. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 5, characterized in that: In the diversity antenna module, the process of receiving and transmitting signals is as follows: Multiple antennas in the diversity antenna module are distributed at different physical locations and transmit the same information signal simultaneously or alternately from different directions; The diversity antenna at the receiving end receives signals from multiple paths and combines the received multiple signal paths at the receiving end to combine the signals so that the multiple signal paths are combined into a single signal, maximizing signal strength and reducing interference; The combined signal is demodulated to restore the original digital data, and the combined signal is sent to the channel estimation and equalization module for equalization processing.

7. The parallel high-speed modulation and demodulation microwave transmission system based on LDPC coding according to claim 6, characterized in that: In the signal processing module, the process of further processing the result of LDPC decoding output is as follows: The signal processing module receives the decoded raw data from the LDPC decoding module and performs a data synchronization check; Use CRC checksum to repeatedly check the received data and identify errors that are not corrected by LDPC decoding; If an error is detected, locate the location where the error occurred, mark the erroneous data, and request retransmission; Clean the data, remove useless or redundant information in the data, retain key information, convert the decoded data into the final application format, and provide the processed data output to the user.

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