Satellite communication signal modulation and demodulation method, device and equipment

Abstract

The invention provides a satellite communication signal modulation and demodulation method, device and equipment, power weighting is performed on signals of multiple users through power allocation, and signals of high-power users cover signals of low-power users, so that signal superposition transmission is realized on the same spectrum resource. A user signal is encoded using a nonlinear precoding technique to enhance the robustness of the user signal in a satellite communication link and reduce signal degradation. In the signal demodulation process, an improved iterative detection and elimination technology is adopted, firstly, a user signal with the highest power is demodulated, and an original signal of each user is gradually stripped out; according to the invention, the concurrent processing capability and the communication efficiency of signals can be effectively improved, and the signal error rate caused by multi-user interference is reduced at the same time.

Description

Technical Field

[0001] The present invention mainly relates to the field of satellite communication technology, and in particular to a satellite communication signal modulation and demodulation method, device and equipment. Background Art

[0002] Orthogonal Multiple Access (OMA) technology ensures the orthogonality of signals between users in satellite communication systems, thereby maintaining the stability of communication. However, the fixed allocation of spectrum resources by this technology often results in spectrum resources not being fully utilized in communication environments with dense users. With the continuous growth of global communication demand, this inherent defect of OMA is particularly evident when the user scale expands rapidly, limiting the concurrent capacity and expansion flexibility of the system. In satellite communications, spectrum resources are particularly valuable, and the inadequacy of OMA technology in effectively supporting large-scale user access has become a key factor restricting its application.

[0003] In addition, the insufficient performance of OMA technology in multipath and dynamic environment adaptability is also one of its main disadvantages. Satellite communication signals are often affected by multipath effects during transmission, that is, signals arrive at the receiver at different times through different transmission paths. Due to the lack of effective multipath interference management strategies, OMA often cannot fully utilize the diversity of these signal paths, resulting in unstable communication quality and signal attenuation. In addition, OMA's signal adjustment strategies are usually relatively fixed and lack the ability to respond to rapidly changing conditions in satellite communication environments, atmospheric disturbances and space weather, which limits its effectiveness in application scenarios that require high dynamic responses.

[0004] In terms of cost and energy consumption, OMA technology usually requires higher transmission power and complex receiving equipment to maintain orthogonality and stable signal transmission between users. This not only increases the energy consumption of the system, but also increases the operation and maintenance costs, especially on satellite platforms operating at a distant location, where this cost increase is particularly significant.

[0005] Compared with OMA, Non-Orthogonal Multiple Access (NOMA) technology allows signals to be superimposed in the power domain, enabling access by multiple users within the same spectrum resource, significantly improving spectrum efficiency and concurrent capacity of the system. However, in the complex environment of satellite communications, how to adjust and optimize the implementation strategy of NOMA to cope with high dynamic range signal reception conditions and multipath interference remains a technical challenge.

[0006] Therefore, the current satellite communication system urgently needs a new signal processing technology that can improve spectrum efficiency, reduce costs, and adapt to dynamic communication environments to meet the dual requirements of modern communication systems for high efficiency and high reliability. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a satellite communication signal modulation and demodulation method, device and equipment.

[0008] The technical solution of the present invention is: On the one hand, the present invention provides a satellite communication signal modulation method, comprising: Initialize user data of satellite communication system; Obtaining the priority index or signal reception quality of each user; Determining a power allocation coefficient for a user based on a priority index or a signal reception quality of the user; Perform weighted processing on the corresponding user signals according to the power allocation coefficient of each user; The weighted user signals are superimposed to form a composite signal as the final transmission signal.

[0009] In a preferred embodiment, obtaining the priority index of each user includes:

[0010] in Is a user The priority index, and is the adjustment coefficient, represents the service type index, Is a user The received signal strength indicator.

[0011] In a preferred embodiment, the power allocation coefficient of the user is determined according to the priority index of the user:

[0012] The number of users is N.

[0013] In a preferred embodiment, obtaining the signal reception quality of each user includes: The signal reception strength and background noise level corresponding to the user are obtained, and the signal reception quality of the user is calculated based on the signal reception strength and background noise level corresponding to the user:

[0014] in and The users are signal reception strength and background noise level.

[0015] In a preferred embodiment, the power allocation coefficient of a user is determined based on the signal reception quality of the user:

[0016] The number of users is N.

[0017] In a preferred embodiment, the user signal is a precoded user signal, and the user signal is encoded based on a nonlinear precoding technology to obtain the precoded user signal.

[0018] In a preferred embodiment, precoding the user signal based on a nonlinear precoding technique includes: Calculate the signal-to-noise ratio of each user's signal based on the signal reception strength and background noise of each user; The signal-to-noise ratio of each user signal is used as the power weighting coefficient of each user signal; The power weighting coefficient of the user signal and the signal reception strength of the user are used to construct a nonlinear function. The amplitude, frequency and phase of the user signal are adjusted to obtain an adjusted user signal, where A , B , C These are nonlinear precoding parameters, which are dynamically adjusted according to the user signal characteristics and communication requirements, and are used to control the amplitude, frequency and phase of the signal. ,in Is a user The signal reception strength is Is a user signal-to-noise ratio; Perform nonlinear transformation on the adjusted user signal to obtain the user signal after nonlinear transformation , so far the precoding of user signals is completed, where n The nonlinear precoding parameters are also dynamically adjusted to control the peak and average power ratio of the user signal.

[0019] In another aspect, the present invention provides a satellite communication signal modulation device, comprising: The first module is used to initialize user data of the satellite communication system; The second module is used to obtain the priority index or signal reception quality of each user; The third module is used to determine the power allocation coefficient of the user based on the priority index or signal reception quality of the user; The fourth module is used to perform weighted processing on the corresponding user signal according to the power allocation coefficient of each user; The fifth module is used to superimpose the weighted user signals to form a composite signal as the final transmission signal.

[0020] On the other hand, the present invention provides a satellite communication signal demodulation method, comprising: (1) Acquiring a received signal, wherein the received signal is a composite signal obtained by the satellite communication signal modulation method provided by any of the above embodiments; (2) Sort the user signals in the composite signal from high to low in terms of power, and select the user signal with the highest power as the current demodulated signal; (3) For the currently demodulated signal, a matched filter is applied to optimize the reception quality of the currently demodulated user signal and then demodulates it; (4) After completing the current demodulated user signal, eliminate it from the composite signal to obtain a new composite signal; (5) Calculate the error vector amplitude of the new composite signal and evaluate the error level of the new composite signal. If the error vector amplitude of the new composite signal is greater than the set threshold, optimize the demodulation strategy. The method of optimizing the demodulation strategy includes adjusting the order of the matched filter and its coefficients. Return to step (2) until the demodulation of all user signals is completed.

[0021] On the other hand, there is provided a satellite communication device, comprising: A transmitting end generates a transmitting signal based on the satellite communication signal modulation method provided in any of the above embodiments; The receiving end receives the signal from the transmitting end and demodulates the received signal.

[0022] The present invention performs power weighting on signals of multiple users through power allocation, wherein the signals of high-power users will cover the signals of low-power users, so as to realize signal superposition transmission on the same spectrum resources.

[0023] Furthermore, the present invention utilizes nonlinear precoding technology to encode user signals to enhance the robustness of user signals in satellite communication links and reduce signal degradation.

[0024] Furthermore, in the signal demodulation process, an improved iterative detection and elimination technique is used to first demodulate the user signal with the highest power, and gradually strip out the original signal of each user. Each step of demodulation is accompanied by the calculation and correction of the error rate to ensure that the final recovered signal has high accuracy and reliability. Through this series of specific modulation and demodulation processes, this method can effectively improve the concurrent processing capability and communication efficiency of the signal, while reducing the signal error rate caused by multi-user interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0026] Figure 1 is a flow chart of a satellite communication signal modulation method provided by one embodiment of the present invention; DETAILED DESCRIPTION The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] Reference Figure 1 , an embodiment provides a satellite communication signal modulation method, comprising: Initialize user data of satellite communication system; Obtaining the priority index or signal reception quality of each user; Determining a power allocation coefficient for a user based on a priority index or a signal reception quality of the user; Perform weighted processing on the corresponding user signals according to the power allocation coefficient of each user; The weighted user signals are superimposed to form a composite signal as the final transmission signal.

[0028] In the present invention, power allocation can be used to comprehensively consider user service requirements and channel state information (CSI) for precise adjustment to optimize signal processing and spectrum resource allocation. The above embodiment performs power weighting on multi-user signals through power allocation, wherein the signals of high-power users will cover the signals of low-power users to achieve signal superposition transmission on the same spectrum resource.

[0029] When the system is initialized, it collects the user's service type (voice, video, data transmission, etc.), channel information, and communication demand level. Based on this data, users are classified and given a priority index based on service urgency and signal reception conditions.

[0030] In a preferred embodiment, a method for determining a power allocation coefficient of a user based on a priority index of the user is proposed, comprising: Get the priority index of each user:

[0031] in Is a user The priority index, and is the adjustment coefficient, Represents the service type index (a set indicator used to reflect the priority of different user service types, which is a known quantity). Is a user The received signal strength indicator.

[0032] user Signal reception strength ( ) is the physical signal strength value directly measured, such as the user in the embodiment -65 dBm, which is an absolute physical quantity used to calculate signal quality . The signal reception strength indicator ( ) is an indicator value converted based on the actual signal reception strength and is used in the priority calculation formula In the example, the logarithmic operation is used to compress the value range and make the system calculation more reasonable. Therefore, the signal reception strength is the original measurement value, and the signal reception strength indication is the indicator value actually used by the system.

[0033] According to the user's priority index, the user's power allocation coefficient is determined to ensure that the sum of the power weights of all users is 1:

[0034] The number of users is N.

[0035] According to the calculated power allocation coefficient, the system performs weighted processing on the signal of each user. The signal of a high-priority user is given a higher weight and is linearly superimposed with other user signals at the transmitting end to form the final transmitted signal. These signals are transmitted through the satellite transmission system and processed at the receiving end according to the preset demodulation parameters to recover the respective data from the superimposed signal. This method ensures that on the same spectrum resource, signal transmission can be effectively managed according to the actual needs of users and signal quality, significantly improving the communication efficiency and quality of the system.

[0036] In a preferred embodiment, a method for determining a power allocation coefficient of a user based on the signal reception quality of the user is proposed, comprising: Get the signal reception quality of each user, including: The signal reception strength and background noise level corresponding to the user are obtained, and the signal reception quality of the user is calculated based on the signal reception strength and background noise level corresponding to the user:

[0037] in and The users are signal reception strength and background noise level.

[0038] Based on the signal reception quality of the user, determine the power allocation coefficient of the user:

[0039] The number of users is N.

[0040] In one embodiment, the satellite communication device serves three users, and the signal data of each user includes detailed signal reception strength and background noise level, as follows: User A: Signal reception strength: -65 dBm Background noise level: -95 dBm User B: Signal reception strength: -75 dBm Background noise level: -90 dBm User C: Signal reception strength: -80 dBm Background noise level: -88 dBm The user's signal reception quality (QoR) is calculated for each user based on the ratio of the signal reception strength to the background noise level, using the following formula:

[0041] in and The users are signal reception strength and background noise level. The signal reception quality calculated for each user is as follows:

[0042]

[0043]

[0044] Calculation of power allocation coefficient: The power allocation coefficient is based on the QoR of each user and is adjusted to keep the total power constant. Therefore, the calculated power allocation coefficient is as follows:

[0045]

[0046]

[0047] Using the above power allocation coefficients, the signal of each user is weighted. For example, if the initial signal power is set to 1 unit, the weighted signal is as follows:

[0048]

[0049]

[0050] In this way, each user's signal is allocated the appropriate power according to its reception quality, thereby optimizing the performance of the entire communication system. This approach ensures the optimal operation of the system under different users and different signal conditions.

[0051] In a preferred embodiment, the user signal is a precoded user signal, which is obtained by encoding the user signal based on a nonlinear precoding technique. This technique mainly optimizes the overall transmission performance by adjusting the amplitude and phase response of the signal, especially in a complex superposition environment where high-power users cover low-power user signals.

[0052] In a preferred embodiment, precoding the user signal based on a nonlinear precoding technique includes: Calculate the signal-to-noise ratio of each user's signal based on the signal reception strength and background noise of each user; The signal-to-noise ratio of each user signal is used as the power weighting coefficient of each user signal; The power weighting coefficient of the user signal and the signal reception strength of the user are used to construct a nonlinear function. The amplitude, frequency and phase of the user signal are adjusted to obtain an adjusted user signal, where A , B , C These are nonlinear precoding parameters, which are dynamically adjusted according to the user signal characteristics and communication requirements, and are used to control the amplitude, frequency and phase of the signal. ,in Is a user The signal reception strength is Is a user signal-to-noise ratio; Perform nonlinear transformation on the adjusted user signal to obtain the user signal after nonlinear transformation , so far the precoding of user signals is completed, where n The nonlinear precoding parameters are also dynamically adjusted to control the peak-to-average power ratio (PAPR) of the user signal. The purpose of this step is to reduce the peak power of the superimposed signal while increasing its anti-interference capability. After the transmission signal is sent out, the satellite communication equipment evaluates the effect of precoding through the feedback data (such as bit error rate and signal quality) from the receiving end. Based on this feedback, the nonlinear precoding parameters A, B, C and n are dynamically adjusted to ensure the optimal communication performance under various channel conditions.

[0053] Nonlinear precoding technology can significantly improve the transmission quality and overall efficiency of satellite communication systems in complex signal environments. The application of this technology not only optimizes the transmission characteristics of the signal, but also enhances the system's resistance to interference in a multi-user environment, ensuring high-quality communication services.

[0054] Precoding gain G is an important indicator for evaluating the precoding effect. It is dynamically calculated based on the priority of user signals and channel conditions. Precoding gain G is calculated by the formula SNR Determine, among which It is a coefficient adjusted according to the channel quality, aiming to optimize the performance of the signal under different channel conditions. The precoded user signals are synthesized into a composite signal and subjected to high-order modulation (such as 64QAM). In the high-order modulation process, the nonlinear characteristics of each user signal are used to improve the bit error rate (BER) and signal-to-interference-plus-noise ratio of the modulated signal. .

[0055] In one embodiment, the satellite communication device serves three users, and the signal data of each user includes detailed signal reception strength and background noise level, as follows: User A: Signal reception strength: -65 dBm Background noise level: -95 dBm User B: Signal reception strength: -75 dBm Background noise level: -90 dBm User C: Signal reception strength: -80 dBm Background noise level: -88 dBm The signal-to-noise ratio (SNR) of each signal is calculated based on the received signal strength of each user and the background noise. These SNR values ​​are used to determine the initial power weighting factor for each signal.

[0056] User A:

[0057] User B:

[0058] User C:

[0059] Each user's signal passes through a nonlinear function This helps reduce the peak-to-average power ratio (PAPR) of the signal while preserving the dynamic range of the signal.

[0060] Non-linear precoding: User A:

[0061] User B:

[0062] User C:

[0063] The user signals after nonlinear precoding are superimposed and subjected to high-order modulation (e.g. 64-QAM) in preparation for transmission.

[0064] Amplitude adjustment and phase alignment of superimposed signals:

[0065] After sending the transmit signal, the precoding effect is evaluated at the receiving site by measuring the bit error rate (BER) and signal to interference plus noise ratio (SINR). If the performance does not meet expectations, the nonlinear precoding parameters A, B, C and n as well as the power allocation will be adjusted based on the feedback to further optimize the signal processing.

[0066] In another embodiment, a satellite communication signal modulation device is provided, comprising: The first module is used to initialize user data of the satellite communication system; The second module is used to obtain the priority index or signal reception quality of each user; The third module is used to determine the power allocation coefficient of the user based on the priority index or signal reception quality of the user; The fourth module is used to perform weighted processing on the corresponding user signal according to the power allocation coefficient of each user; The fifth module is used to superimpose the weighted user signals to form a composite signal as the final transmission signal.

[0067] In another embodiment, a satellite communication signal demodulation method is provided. After the previous signal superposition and nonlinear precoding processing, the system uses an improved iterative detection and elimination technology to demodulate the signal. The detailed implementation steps of this technology are as follows, ensuring that the original signal of each user is accurately restored from the composite signal and optimizing the performance of the entire communication system. Specifically, it includes: (1) Acquiring a received signal, wherein the received signal is a composite signal obtained by the satellite communication signal modulation method provided by any of the above embodiments; (2) Sort the user signals in the composite signal from high to low in terms of power, and select the user signal with the highest power as the current demodulated signal; (3) For the currently demodulated signal, a matched filter is applied to optimize the reception quality of the currently demodulated user signal and then demodulates it; (4) After completing the current demodulated user signal, eliminate it from the composite signal to obtain a new composite signal; (5) Calculate the error vector amplitude of the new composite signal and evaluate the error level of the new composite signal. If the error vector amplitude of the new composite signal is greater than the set threshold, optimize the demodulation strategy. The method of optimizing the demodulation strategy includes adjusting the order of the matched filter and its coefficients. Return to step (2) until the demodulation of all user signals is completed.

[0068] Through the improved iterative detection and elimination technology in the present invention, the system can efficiently recover the original signal of each user from the composite signal after nonlinear precoding. This process not only improves the accuracy of signal demodulation, but also optimizes the performance in a highly complex communication environment.

[0069] The successful implementation of the present invention is of great significance for the design and optimization of future complex communication systems, especially in satellite communication systems facing multi-user and dynamic channel conditions. Combining the early nonlinear precoding with the subsequent iterative detection and elimination, the present invention provides strong technical support for efficient and highly reliable communication, ensuring the optimal performance of the communication system under various operating conditions.

[0070] On the other hand, there is provided a satellite communication device, comprising: A transmitting end generates a transmitting signal based on the satellite communication signal modulation method provided in any of the above embodiments; The receiving end receives the signal from the transmitting end and demodulates the received signal. The method for demodulating the received signal can be implemented by the method provided in the above embodiment, which will not be repeated here.

[0071] Compared with the prior art, the present invention can adjust the power allocation strategy in real time, more accurately reflecting the user's urgency and service needs. In addition, the network status is automatically updated through periodic communication tests, including real-time monitoring and analysis of signal attenuation and interference levels. This dynamic network status update mechanism enables the system to flexibly adjust the power allocation strategy according to the current channel conditions, thereby more effectively coping with the rapid changes in channel conditions and improving the stability and reliability of communications.

[0072] Nonlinear precoding technology optimizes transmission performance by adjusting the amplitude and phase response of the signal, especially in complex overlapping environments where high-power users cover low-power user signals. This technology significantly improves the transmission quality of the signal, reduces the peak-to-average power ratio (PAPR), and enhances the system's resistance to interference in multi-user environments. Through precise power adjustment and advanced signal processing technology, the present invention significantly reduces the bit error rate (BER) during communication and improves the signal-to-interference-plus-noise ratio (SINR). These improvements ensure higher quality and more reliable data transmission in complex communication environments.

[0073] It provides significant technical advantages in dynamic power allocation, signal processing efficiency and communication quality improvement, making it of great application value in modern communication systems, especially in satellite communication systems with limited resources and diverse user needs. These technical advantages not only optimize the overall performance of the system, but also lay a solid technical foundation for the design and optimization of future complex communication systems.

[0074] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A satellite communication signal modulation method, characterized in that: include: Initialize user data of satellite communication system; Obtaining the priority index or signal reception quality of each user; Determining a power allocation coefficient for a user based on a priority index or a signal reception quality of the user; Perform weighted processing on the corresponding user signals according to the power allocation coefficient of each user; The weighted user signals are superimposed to form a composite signal as the final transmission signal.

2. The satellite communication signal modulation method according to claim 1, characterized in that: Get the priority index of each user, including: in Is a user The priority index of and is the adjustment coefficient, represents the service type index, Is a user The received signal strength indicator.

3. The satellite communication signal modulation method according to claim 2, characterized in that: According to the user's priority index, the user's power allocation coefficient is determined: The number of users is N.

4. The satellite communication signal modulation method according to claim 1, characterized in that: Get the signal reception quality of each user, including: The signal reception strength and background noise level corresponding to the user are obtained, and the signal reception quality of the user is calculated based on the signal reception strength and background noise level corresponding to the user: in and The users are signal reception strength and background noise level.

5. The satellite communication signal modulation method according to claim 3, characterized in that: Based on the signal reception quality of the user, determine the power allocation coefficient of the user: The number of users is N.

6. The satellite communication signal modulation method according to any one of claims 1 to 5, characterized in that: The user signal is a precoded user signal, and the user signal is encoded based on a nonlinear precoding technology to obtain the precoded user signal.

7. The satellite communication signal modulation method according to claim 6, characterized in that: The user signal is precoded based on the nonlinear precoding technology, including: Calculate the signal-to-noise ratio of each user's signal based on the signal reception strength and background noise of each user; The signal-to-noise ratio of each user signal is used as the power weighting coefficient of each user signal; The power weighting coefficient of the user signal and the signal reception strength of the user are used to construct a nonlinear function. The amplitude, frequency and phase of the user signal are adjusted to obtain an adjusted user signal, where A , B , C These are nonlinear precoding parameters, which are dynamically adjusted according to the user signal characteristics and communication requirements, and are used to control the amplitude, frequency and phase of the signal. ,in Is a user The signal reception strength is Is a user signal-to-noise ratio; Perform nonlinear transformation on the adjusted user signal to obtain the user signal after nonlinear transformation , so far the precoding of user signals is completed, where n The nonlinear precoding parameters are also dynamically adjusted to control the peak and average power ratio of the user signal.

8. A satellite communication signal modulation device, characterized in that: include: A first module is used to initialize user data of the satellite communication system; The second module is used to obtain the priority index or signal reception quality of each user; The third module is used to determine the power allocation coefficient of the user based on the priority index or signal reception quality of the user; The fourth module is used to perform weighted processing on the corresponding user signal according to the power allocation coefficient of each user; The fifth module is used to superimpose the weighted user signals to form a composite signal as the final transmission signal.

9. A satellite communication signal demodulation method, characterized in that: include: (1) obtaining a received signal, wherein the received signal is a composite signal obtained by the satellite communication signal modulation method according to claim 1, 2, 3, 4, 5 or 7; (2) Sort the user signals in the composite signal from high to low in terms of power, and select the user signal with the highest power as the current demodulated signal; (3) For the currently demodulated signal, a matched filter is applied to optimize the reception quality of the currently demodulated user signal and then demodulates it; (4) After completing the current demodulated user signal, eliminate it from the composite signal to obtain a new composite signal; (5) Calculate the error vector amplitude of the new composite signal and evaluate the error level of the new composite signal. If the error vector amplitude of the new composite signal is greater than the set threshold, optimize the demodulation strategy. The method of optimizing the demodulation strategy includes adjusting the order of the matched filter and its coefficients. Return to step (2) until the demodulation of all user signals is completed.

10. Satellite communication equipment, characterized in that include, A transmitting end, generating a transmitting signal based on the satellite communication signal modulation method according to claim 1, 2, 3, 4, 5 or 7; The receiving end receives a signal from the transmitting end and demodulates the received signal. The receiving end demodulates the received signal. The method includes: (1) Acquire a received signal, where the received signal is a composite signal; (2) Sort the user signals in the composite signal from high to low in terms of power, and select the user signal with the highest power as the current demodulated signal; (3) For the currently demodulated signal, a matched filter is applied to optimize the reception quality of the currently demodulated user signal and then demodulates it; (4) After completing the current demodulated user signal, eliminate it from the composite signal to obtain a new composite signal; (5) Calculate the error vector amplitude of the new composite signal and evaluate the error level of the new composite signal. If the error vector amplitude of the new composite signal is greater than the set threshold, optimize the demodulation strategy. The method of optimizing the demodulation strategy includes adjusting the order of the matched filter and its coefficients. Return to step (2) until the demodulation of all user signals is completed.

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