Multi-user symbol level precoding method based on rate splitting and constructive interference

Abstract

The application discloses a multi-user symbol level precoding method based on rate splitting and constructive interference, comprising: establishing a scenario for a downlink multi-user communication system, which meets typical NOMA deployment characteristics; dividing users into weak users and strong users according to channel gain, splitting the original bit stream of the weak users into public and private parts by using the RSMA mechanism, and taking the original bit stream of the strong users as the private part; constructing a minimum power transmission signal that meets the user correct decision constraint and interference direction control requirement through symbol level precoding design; and demodulating and recovering information from the received signal. The application enables the weak users to divide their original bit stream into public and private parts for transmission, effectively avoiding the dilemma that the weak users need to independently judge all interference in the traditional NOMA. Even if the signals are superimposed, the weak users can enhance the judgment by combining the guidance and regulation of the constructive interference technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a multi-user symbol-level precoding method based on rate splitting and constructive interference. Background Art

[0002] In 5G and future 6G wireless communication systems, non-orthogonal multiple access (NOMA) has been proposed as a cutting-edge multiple access technology to meet the multiple requirements of large connections, high spectrum utilization, and low latency. By multiplexing multiple user signals in the power domain and employing successive interference cancellation (SIC) at the receiver, NOMA systems can simultaneously improve system throughput and user fairness in scenarios with significantly varying channel conditions. However, in traditional NOMA systems, weak users often experience interference from signals from users with stronger channel conditions. This interference is considered a detrimental factor in most designs and is minimized as much as possible, which, to a certain extent, limits the performance of NOMA systems.

[0003] To address these issues, constructive interference (CI) and symbol-level precoding (SLP) technologies have gained increasing attention in recent years. Unlike traditional interference suppression methods, CI transforms a portion of multi-user interference into a usable boosting signal. Specifically, by precisely controlling the amplitude and phase of the interference, it acts in the correct direction within the receiver's symbol decision area, thereby improving reception reliability and reducing transmit power consumption. Using SLP in a downlink multi-user NOMA system can significantly reduce system power consumption and improve weak user reception quality by implementing constructive interference constraints, while ensuring weak user constraints and successful SIC.

[0004] While existing CI and NOMA schemes have made some progress in combating constructive interference, they still face challenges such as lengthy decision chains on the receiving side for strong users and increased misjudgment rates due to interference accumulation. This is especially true in scenarios with three or more users, where traditional step-by-step decision making and serial SIC lead to a sharp increase in implementation complexity. Therefore, finding a way to balance the energy efficiency benefits of constructive interference with the information decoupling advantages of RSMA has become a key research focus. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-user symbol-level precoding method based on rate splitting and constructive interference. It aims to combine the information structure design of RSMA with the symbol-level precoding optimization of constructive interference on the basis of NOMA, effectively solving the problems of traditional SIC links being too long, serious error accumulation, and difficult signal decoupling. It provides a new system architecture and precoding idea for multi-user MISO systems in environments with limited antenna resources, severe interference or uneven user distribution.

[0006] In order to achieve the above-mentioned object, the present invention provides, on one hand, a multi-user symbol-level precoding method based on rate splitting and constructive interference, comprising:

[0007] S1. Establish a scenario for downlink multi-user communication system, which includes N t A base station with a transmitting antenna and K users with a single antenna, and K ≥ N t Typical NOMA deployment characteristics;

[0008] S2. Classify K users into weak users and strong users based on channel gain. Use the RSMA mechanism to split the original bit stream of the weak user into a public part and a private part. The original bit stream of the strong user is kept entirely as the private part.

[0009] The private parts of all users are then mapped into private symbols through PSK modulation, and the public parts of each weak user are combined into a common bit stream. This common bit stream is then jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted.

[0010] S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both user correct decision constraints and interference direction control requirements; including:

[0011] Assume that the transmitted signal of the communication system is the sum of the product of the symbol-level transmit vector corresponding to each symbol and the symbol, define the received signal expression of each user, and determine the equivalent receiving gain based on the channel state information;

[0012] For the public and private symbols of weak users, decision constraints are defined separately, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area.

[0013] For strong users, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design, and to control the interference direction of the remaining interference items, including amplitude control and phase direction control;

[0014] S4. Demodulating the received signal and recovering information, including:

[0015] After receiving the signal, the weak user judges the public symbol and its own private symbol in sequence, and then performs serial interference cancellation operation to finally restore the complete initial information stream;

[0016] After receiving the complex baseband signal, the strong user first determines the main interference source, then makes a judgment on the main interference item, performs symbol-level interference cancellation after the judgment is completed, and finally makes a judgment on the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

[0017] A further preferred technical solution of the present invention is that the scenario of the downlink multi-user communication system established in step S1 is specifically:

[0018] Equipped with N t A base station with 1 transmitting antenna provides non-orthogonal access services to K single-antenna users at the same time, satisfying K ≥ N t The typical NOMA deployment feature is that multiple users compete for scarce spatial resources; the base station needs to send corresponding downlink data symbols to K ≥ 3 users at the same time, which are private symbols for weak users and strong users, and public symbols generated by private users through the rate splitting mechanism. The public symbols contain the shared part of multiple user information.

[0019] As a preference, assume that the number of users is 3, where user 1 and user 2 are weak users and user 3 is a strong user. The original bit streams of user 1, user 2 and user 3 are recorded as 、 、 ;

[0020] The RSMA mechanism is used to structurally split the original bit streams of user 1 and user 2. The original bit stream of user 1 It is divided into two parts, namely the public part With private part , user 2's original bitstream Divided into public areas With private part ,in and Represents the sub-flows that will be used to build a communication system to share common information. and represents the exclusive information received and decoded only by user 1 and user 2. The base station then combines the common parts of user 1 and user 2 to construct a common bit stream:

[0021] ;

[0022] At the same time, user 3 adopts the private information transmission mode, and its original bit stream All as its private part to process;

[0023] Merged public bitstream Perform joint coding and modulation at the physical layer and map them into common symbols , transmitted to all users for unified demodulation and interference decoupling; the private part of user 1, user 2 and user 3 、 and , mapped into private symbols through the PSK modulation process 、 and , used for exclusive information transmission of corresponding users; the symbol set to be transmitted in the communication system consists of public symbols and private symbols of each user, expressed as:

[0024] ;

[0025] Jointly participate in subsequent constructive interference optimization and symbol-level precoding design.

[0026] Preferably, in step S3, assuming that the transmitted signal of the communication is the sum of the product of the symbol-level transmit vector corresponding to each symbol and the symbol, defining the received signal expression of each user, and determining the equivalent receiving gain according to the channel state information, specifically includes:

[0027] Will be equipped with N t The signal transmitted by the base station with the root transmitting antenna at time n is expressed as:

[0028] ;

[0029] in, , , , Private symbols , , , The corresponding symbol-level transmit vector, i.e., the variable to be optimized at the current moment;

[0030] Set user The downlink channel vector is , and its received signal is expressed as:

[0031] ;

[0032] The equivalent receiving gain is defined as:

[0033] , , , ;

[0034] Then the user The equivalent expression of the received signal is:

[0035] .

[0036] Preferably, in step S3, decision constraints are defined for the public symbols and private symbols of the weak user respectively, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area; specifically, the following steps are included:

[0037] User 1 is a weak user, and its received signal is equivalently expressed as:

[0038] ;

[0039] in, It is expressed as the equivalent receiving gain of user 1 itself;

[0040] First, the public symbols of weak users Conduct decision constraint design:

[0041] Define normalized reception: , user 1 makes the judgment When the private signal of user 1 and the signals of users 2 and 3 boost the public symbol To fall within the correct decision area, the constructive interference constraint must be satisfied:

[0042] ;

[0043] in, To determine the half angle of the modulation constellation, represents the safety decision margin; represents the imaginary part of a complex number, represents the real part of a complex number;

[0044] Then for the private symbols of the weak user Conduct decision constraint design:

[0045] In the symbol-level precoding framework, all symbol values ​​are known, and user 1 offsets the influence of the public symbols, obtaining:

[0046] ;

[0047] Constructing private symbols Normalized reception ratio of: , establish the decision area constraint:

[0048] ;

[0049] For the remaining weak users, the precoding constraint construction process is the same as that of user 1.

[0050] Preferably, in step S3, for a strong user, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design, and interference direction control is performed on the remaining interference items, including amplitude control and phase direction control; specifically, the following steps are included:

[0051] User 3 is a strong user, and its received signal is equivalently expressed as:

[0052] ;

[0053] in, It is expressed as the equivalent receiving gain of user 3 itself; and are the interference from user 1 and user 2 respectively, is the common signal of user 1 and user 2;

[0054] Introducing dynamic main interference judgment mechanism, comparing and The size of , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is Considered as the main distractor;

[0055] Assume that user 1's private symbol As the main interference item, a constructive judgment design is performed on the main interference item:

[0056] Construct the normalized receiving gain: , and impose constructive interference decision constraints:

[0057] ;

[0058] Then eliminate the main interference term and construct the target symbol, which is the private symbol of user 3 the judgment constraints;

[0059] After removing the main interference, the residual signal is defined as:

[0060] ;

[0061] The target symbol receiving gain is: , construct the CI constraint of the target symbol:

[0062] ;

[0063] For the remaining interference items, including user 2's private symbols and public symbols Perform interference direction control, including amplitude control and phase direction control.

[0064] As a preference, when controlling the interference direction of the remaining interference items, the amplitude control is:

[0065] , ;

[0066] Where, ;

[0067] Phase direction control is:

[0068] ;

[0069] Where, .

[0070] Preferably, step S3 constructs a minimum power transmission signal that satisfies both the user's correct decision constraint and the interference direction control requirement through symbol-level precoding design. The mathematical model of this optimization problem is expressed as:

[0071] ;

[0072] ;

[0073] ;

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] .

[0079] Preferably, after receiving the signal in step S4, the weak user sequentially determines the public symbol and its own private symbol, and then performs a serial interference cancellation operation to finally restore the complete initial information stream; specifically, the process includes:

[0080] User 1 is a weak user, and its received signal is equivalently expressed as:

[0081] ;

[0082] in, It is expressed as the equivalent receiving gain of user 1 itself;

[0083] Under the support of constructive interference, user 1 directly receives the signal Make a constellation judgment:

[0084] ;

[0085] in, Restored for judgment Signal;

[0086] After obtaining the public symbol decision, user 1 removes its public terms from the received signal and performs serial interference cancellation to obtain a new decision sub-signal:

[0087] ;

[0088] Then user 1 continues to use the new decision sub-signal Determine its private symbols ,Right now:

[0089] ;

[0090] in, Restored for judgment Signal;

[0091] Last user 1 pair of public symbols Demodulate and extract the public bit stream containing its own information through physical layer channel decoding and CRC check , then Demodulate and obtain private bit stream , and restore the two together to the complete initial information flow, expressed as:

[0092] ;

[0093] User 1 completes the judgment and recovery of all his / her information;

[0094] The process of demodulating the received signal and recovering information for the remaining weak users is the same as that of user 1.

[0095] Preferably, after the strong user receives the complex baseband signal in step S4, the main interference source is first determined, and then the main interference term is judged. After the judgment is completed, symbol-level interference cancellation is performed, and finally the target symbol is judged on the interference-optimized signal, and the judgment output is mapped into a private bit stream; specifically:

[0096] User 3 is a strong user, and its received signal is equivalently expressed as:

[0097] ;

[0098] in, It is expressed as the equivalent receiving gain of user 3 itself;

[0099] First determine the main interference source, compare and The size of , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is Considered as the main distractor;

[0100] Assume that user 1's private symbol The main interference item is judged first at the receiving end:

[0101] ;

[0102] After the decision is made, user 3 performs symbol-level interference cancellation, which is expressed as:

[0103] ;

[0104] Then user 3 interferes with the signal after optimization Target symbol decision is performed on:

[0105] ;

[0106] Finally, the judgment is output and directly mapped into a private bit stream , completing the judgment and recovery of all its own information.

[0107] Another aspect of the present invention provides a non-transitory computer-readable storage medium having computer instructions stored thereon, which enable a computer to execute the multi-user symbol-level precoding method based on rate splitting and constructive interference.

[0108] Yet another aspect of the present invention provides an electronic device comprising: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus, and the processor calls logic instructions in the memory to execute the above-mentioned multi-user symbol-level precoding method based on rate splitting and constructive interference.

[0109] On the other hand, the present invention provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer executes the above-mentioned multi-user symbol-level precoding method based on rate splitting and constructive interference.

[0110] Beneficial effects: The multi-user symbol-level precoding method based on rate splitting and constructive interference of the present invention enables weak users to divide their original bit streams into public and private parts for separate transmission, effectively avoiding the dilemma of weak users in traditional NOMA having to independently judge all interferences. Combined with the guidance and control of constructive interference (CI) technology, the judgment of weak users can be enhanced even if their signals are superimposed. In addition, the present invention only needs to judge one main interference symbol and perform one SIC operation, which significantly reduces the complexity of system judgment and reduces the traditional SIC multi-layer error propagation problem, thereby improving system stability and real-time decoding while maintaining high performance. The present invention supports dynamic heterogeneous configuration of users and has higher system flexibility and wide adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Figure 1 A schematic diagram of a scenario of a downlink multi-user communication system in the present invention;

[0112] Figure 2 This is a model diagram of the communication system in Example 1;

[0113] Figure 3 Schematic diagram of the rate splitting multiple access mechanism in Example 1. DETAILED DESCRIPTION

[0114] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments, and they should not be understood as limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be understood that the terms used are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0115] The following combination Figure 1-Figure 3 The present invention describes a multi-user symbol-level precoding method based on rate splitting and constructive interference.

[0116] Embodiment 1: This embodiment provides a multi-user symbol-level precoding method based on rate splitting and constructive interference, including:

[0117] S1. Establish a scenario for downlink multi-user communication system, such as Figure 1 As shown, this scenario includes N t A base station with a transmitting antenna and K users with a single antenna, and K ≥ N t The typical NOMA deployment feature is that multiple users compete for scarce spatial resources.

[0118] In this embodiment, the base station needs to send corresponding downlink data symbols to K=3 users at the same time, namely user 1, user 2 and user 3, forming a Figure 2 The communication system shown.

[0119] Signals for users S2 and S3 are transmitted using Rate Split Multiple Access (RSMA). RSMA is an advanced non-orthogonal multiple access technology that optimizes spectrum utilization and interference management through rate splitting and Successful Interference Cancellation (SIC). RSMA splits user information into a common stream and a dedicated stream, transmits them using super-position coding, and employs SIC decoding at the receiver to reduce interference and improve throughput.

[0120] The three users are divided into weak users and strong users according to the channel gain. The original bit stream of the weak user is split into a public part and a private part. The original bit stream of the strong user is all used as the private part. The private parts of all users are then mapped into private symbols through PSK modulation. The public parts of each weak user are merged into a public bit stream, and the public bit stream is jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted. Specifically:

[0121] The original bit streams of user 1, user 2, and user 3 are recorded as 、 、 Among the three users, user 1 and user 2 are weak users. To achieve multi-user interference decoupling and flexible resource control, the RSMA mechanism is used to perform structured splitting of their original bit streams, such as Figure 3 As shown, the original bit stream of user 1 It is divided into two parts, namely the public part With private part , user 2's original bitstream Divided into public areas With private part ,in and Represents the sub-flows that will be used to build a communication system to share common information. and represents the exclusive information received and decoded only by user 1 and user 2. The base station then combines the common parts of user 1 and user 2 to construct a common bit stream:

[0122] ;

[0123] User 3 is a strong user, so it adopts the private information transmission mode and does not participate in the public information construction process. Its original bit stream All as its private part to process;

[0124] Merged public bitstream Joint coding and modulation are performed at the physical layer and mapped into a common symbol S c , carrying the shared information of multiple weak users in the system, transmitted to all users for unified demodulation and interference decoupling. Private part of user 1, user 2 and user 3 、 and , mapped into private symbols through the PSK modulation process 、 and , used for exclusive information transmission of corresponding users; the symbol set to be transmitted in the communication system consists of public symbols and private symbols of each user, expressed as:

[0125] ;

[0126] Jointly participate in subsequent constructive interference optimization and symbol-level precoding design.

[0127] S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both the user's correct decision constraints and the interference direction control requirements. Specifically, it includes:

[0128] Will be equipped with N t The signal transmitted by the base station with the root transmitting antenna at time n is expressed as:

[0129] ;

[0130] in, , , , Private symbols , , , The corresponding symbol-level transmit vector is the variable to be optimized at the current moment.

[0131] Assume that the downlink channel vector of user 1 is , and its received signal is expressed as:

[0132] ;

[0133] The equivalent receiving gain is defined as:

[0134] , , , ;

[0135] Then the received signal of user 1 is equivalently expressed as:

[0136] .

[0137] Because of the symbol It is a public symbol shared by multiple users. User 1 needs to make a correct judgment on it first. Therefore, the public symbol S of user 1 is first c Conduct decision constraint design:

[0138] Define normalized reception: , in order to ensure that user 1 When the private signal of user 1 and the signals of user 2 and user 3 can boost To fall within the correct decision area, the constructive interference constraint must be satisfied:

[0139] ;

[0140] in, To determine the half angle of the modulation constellation (e.g. QPSK takes ), represents the safety decision margin; represents the imaginary part of a complex number, represents the real part of a complex number;

[0141] Then for the private symbols of the weak user Conduct decision constraint design:

[0142] In the symbol-level precoding framework, all symbol values ​​are known, and user 1 offsets the influence of the public symbols, obtaining:

[0143] ;

[0144] Constructing private symbols Normalized reception ratio of: , establish the decision area constraint:

[0145] ;

[0146] The process of constructing precoding constraints for user 2 is the same as that for user 1.

[0147] User 3 is a strong user, and its received signal is equivalently expressed as:

[0148] ;

[0149] in, It is expressed as the equivalent receiving gain of user 3 itself; and are the interference from user 1 and user 2 respectively, is the common signal for user 1 and user 2.

[0150] In order to reduce the complexity and misjudgment risk brought by multi-stage serial judgment, this embodiment introduces a dynamic main interference judgment mechanism. That is, user 3 compares and The most important interference item is determined by the size of , and only one of them is subjected to constructive decision design, while the other one is soft-processed through interference guidance constraint. , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is considered as the main interference item.

[0151] In this embodiment, the private symbol of user 1 is As the main interference item, a constructive judgment design is performed on the main interference item:

[0152] Construct the normalized receiving gain: , and impose constructive interference decision constraints:

[0153] ;

[0154] Then eliminate the main interference term and construct the target symbol, which is the private symbol of user 3 the judgment constraints;

[0155] After removing the main interference, the residual signal is defined as:

[0156] ;

[0157] The target symbol receiving gain is: , construct the CI constraint of the target symbol:

[0158] ;

[0159] For the remaining interference items, including user 2's private symbols and public symbols Perform interference direction control and guiding constraints to ensure that the interference items will not be seriously offset The constellation decision boundary is set, thereby avoiding the complexity caused by too many decisions and improving the accuracy of the decision at the receiving end.

[0160] Interference direction control for other interference items includes amplitude control and phase direction control.

[0161] In order to avoid excessive interference amplitude, amplitude control is performed, which is expressed as:

[0162] , ;

[0163] Where, ;

[0164] To guide the interference Within the allowable angle range, the phase direction is controlled, which is expressed as:

[0165] ;

[0166] Where, .

[0167] Finally, through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both the user's correct decision constraints and the interference direction control requirements. The mathematical model of this optimization problem is expressed as:

[0168] ;

[0169] ;

[0170] ;

[0171] ;

[0172] ;

[0173] ;

[0174] ;

[0175] .

[0176] S4. Demodulate the received signal and recover the information. Specifically including:

[0177] User 1 is a weak user, and its receiving end needs to judge the two target symbols in sequence according to the serial structure. The first is the public symbol shared by all users. , followed by its own private symbols Since the transmitter has adopted a constructive interference control strategy, the interference symbol and The amplitude and direction of have been pre-adjusted so that it will not cause harmful interference to user 1, but will instead enhance the success rate of target symbol decision in a constructive sense.

[0178] The signal received by user 1 is:

[0179] ;

[0180] With the support of constructive interference, user 1 can directly receive the signal Make a constellation judgment:

[0181] ;

[0182] in, Restored for judgment Signal;

[0183] After obtaining the public symbol decision, user 1 removes its public terms from the received signal and performs serial interference cancellation to obtain a new decision sub-signal:

[0184] ;

[0185] Then user 1 continues to use the new decision sub-signal Determine its private symbols ,Right now:

[0186] ;

[0187] in, Restored for judgment Signal;

[0188] Last user 1 pair of public symbols Demodulate and extract the public bit stream containing its own information through physical layer channel decoding and CRC check , then Demodulate and obtain private bit stream , and restore the two together to the complete initial information flow, expressed as:

[0189] ;

[0190] At this point, user 1 has successfully completed the judgment and recovery of all its own information through the serial demodulation process based on the assistance of constructive interference.

[0191] The decision process of user 2, as well as the process of demodulating the received signal and recovering the information are the same as those of user 1.

[0192] After receiving the complex baseband signal, the strong user first determines the main interference source, then makes a judgment on the main interference item, performs symbol-level interference cancellation after the judgment is completed, and finally makes a judgment on the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

[0193] The complex baseband signal received by user 3 is:

[0194] ;

[0195] First determine the main interference source, compare and The size of , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is Considered as the main distractor;

[0196] In this embodiment, the private symbol of user 1 is The main interference item is judged first at the receiving end:

[0197] ;

[0198] Based on the transmitter has been protected by constructive interference precoding Falling in the correct judgment sector, this item can achieve high-confidence judgment.

[0199] After the decision is made, user 3 performs symbol-level interference cancellation, which is expressed as:

[0200] ;

[0201] Then user 3 interferes with the signal after optimization Target symbol decision is performed on:

[0202] ;

[0203] Finally, the judgment is output and directly mapped into a private bit stream , completing the judgment and recovery of all its own information.

[0204] This embodiment introduces a novel reception mechanism combining partial decision and interference direction control, specifically optimizing the complex decoding paths faced by strong users. For symbols that cannot be fully determined (such as private symbols of other users), SIC is no longer mandatory. Instead, the interference direction and amplitude at the receiver are optimized to stay within the constructive decision region, thereby assisting in the decision of the target symbol. The transmitter solves a joint symbol-level precoding optimization problem to construct a minimum-power transmit signal that simultaneously meets the quality of service for all users, limits interference direction, and maintains a controllable inter-symbol interference structure.

[0205] Embodiment 2: This embodiment provides a non-transitory computer-readable storage medium having computer instructions stored thereon. The computer instructions cause a computer to execute a multi-user symbol-level precoding method based on rate splitting and constructive interference. The method includes the following steps:

[0206] S1. Establish a scenario for downlink multi-user communication system, which includes N t A base station with a transmitting antenna and K users with a single antenna, and K ≥ N t Typical NOMA deployment characteristics;

[0207] S2. Classify K users into weak users and strong users based on channel gain. Use the RSMA mechanism to split the original bit stream of the weak user into a public part and a private part. The original bit stream of the strong user is kept entirely as the private part.

[0208] The private parts of all users are then mapped into private symbols through PSK modulation, and the public parts of each weak user are combined into a common bit stream. This common bit stream is then jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted.

[0209] S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both user correct decision constraints and interference direction control requirements; including:

[0210] Assume that the transmitted signal of the communication system is the sum of the product of the symbol-level transmit vector corresponding to each symbol and the symbol, define the received signal expression of each user, and determine the equivalent receiving gain based on the channel state information;

[0211] For weak users, public and private symbols are defined separately, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area. For strong users, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design. The interference direction of the remaining interference items is controlled, including amplitude control and phase direction control.

[0212] S4. Demodulating the received signal and recovering information, including:

[0213] After receiving the signal, the weak user judges the public symbol and its own private symbol in sequence, and then performs serial interference cancellation operations to finally restore the complete initial information stream; after the strong user receives the complex baseband signal, it first determines the main interference source, then judges the main interference item, and after completing the judgment, performs symbol-level interference cancellation. Finally, it judges the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

[0214] Embodiment 3: This embodiment provides an electronic device, which may include: a processor, a communications interface, a memory, and a communications bus, wherein the processor, the communications interface, and the memory communicate with each other via the communications bus. The processor may invoke logic instructions in the memory to execute a multi-user symbol-level precoding method based on rate splitting and constructive interference, the method comprising the following steps:

[0215] S1. Establish a scenario for downlink multi-user communication system, which includes N tA base station with a transmitting antenna and K users with a single antenna, and K ≥ N t Typical NOMA deployment characteristics;

[0216] S2. Classify K users into weak users and strong users based on channel gain. Use the RSMA mechanism to split the original bit stream of the weak user into a public part and a private part. The original bit stream of the strong user is kept entirely as the private part.

[0217] The private parts of all users are then mapped into private symbols through PSK modulation, and the public parts of each weak user are combined into a common bit stream. This common bit stream is then jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted.

[0218] S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both user correct decision constraints and interference direction control requirements; including:

[0219] Assume that the transmitted signal of the communication system is the sum of the product of the symbol-level transmit vector corresponding to each symbol and the symbol, define the received signal expression of each user, and determine the equivalent receiving gain based on the channel state information;

[0220] For weak users, public and private symbols are defined separately, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area. For strong users, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design. The interference direction of the remaining interference items is controlled, including amplitude control and phase direction control.

[0221] S4. Demodulating the received signal and recovering information, including:

[0222] After receiving the signal, the weak user judges the public symbol and its own private symbol in sequence, and then performs serial interference cancellation operations to finally restore the complete initial information stream; after the strong user receives the complex baseband signal, it first determines the main interference source, then judges the main interference item, and after completing the judgment, performs symbol-level interference cancellation. Finally, it judges the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

[0223] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0224] Embodiment 4: This embodiment provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can perform a multi-user symbol-level precoding method based on rate splitting and constructive interference. The method includes the following steps:

[0225] S1. Establish a scenario for downlink multi-user communication system, which includes N t A base station with a transmitting antenna and K users with a single antenna, and K ≥ N t Typical NOMA deployment characteristics;

[0226] S2. Classify K users into weak users and strong users based on channel gain. Use the RSMA mechanism to split the original bit stream of the weak user into a public part and a private part. The original bit stream of the strong user is kept entirely as the private part.

[0227] The private parts of all users are then mapped into private symbols through PSK modulation, and the public parts of each weak user are combined into a common bit stream. This common bit stream is then jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted.

[0228] S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both user correct decision constraints and interference direction control requirements; including:

[0229] Assume that the transmitted signal of the communication system is the sum of the product of the symbol-level transmit vector corresponding to each symbol and the symbol, define the received signal expression of each user, and determine the equivalent receiving gain based on the channel state information;

[0230] For weak users, public and private symbols are defined separately, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area. For strong users, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design. The interference direction of the remaining interference items is controlled, including amplitude control and phase direction control.

[0231] S4. Demodulating the received signal and recovering information, including:

[0232] After receiving the signal, the weak user judges the public symbol and its own private symbol in sequence, and then performs serial interference cancellation operations to finally restore the complete initial information stream; after the strong user receives the complex baseband signal, it first determines the main interference source, then judges the main interference item, and after completing the judgment, performs symbol-level interference cancellation. Finally, it judges the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

[0233] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0234] Through the description of the above embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0235] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A multi-user symbol-level precoding method based on rate splitting and constructive interference, characterized in that: include: S1. Establish a scenario for downlink multi-user communication system, which includes N t A base station with a transmitting antenna and K users with a single antenna, and K ≥ N t Typical NOMA deployment characteristics; S2. Classify K users into weak users and strong users based on channel gain. Use the RSMA mechanism to split the original bit stream of the weak user into a public part and a private part. The original bit stream of the strong user is kept entirely as the private part. The private parts of all users are then mapped into private symbols through PSK modulation, and the public parts of each weak user are combined into a common bit stream. This common bit stream is then jointly coded and modulated at the physical layer and mapped into public symbols. All private symbols and public symbols are used as the symbol set to be transmitted. Assume that the number of users is 3, where user 1 and user 2 are weak users and user 3 is a strong user. The original bit streams of user 1, user 2 and user 3 are recorded as 、 、 ; The RSMA mechanism is used to structurally split the original bit streams of user 1 and user 2. The original bit stream of user 1 It is divided into two parts, namely the public part With private part , user 2's original bitstream Divided into public areas With private part ,in and Represents the sub-flows that will be used to build a communication system to share common information. and represents the exclusive information received and decoded only by user 1 and user 2. The base station then combines the common parts of user 1 and user 2 to construct a common bit stream: ； At the same time, user 3 adopts the private information transmission mode, and its original bit stream All as its private part to process; Merged public bitstream Perform joint coding and modulation at the physical layer and map them into common symbols , transmitted to all users for unified demodulation and interference decoupling; the private part of user 1, user 2 and user 3 、 and , mapped into private symbols through the PSK modulation process 、 and , used for exclusive information transmission of corresponding users; the symbol set to be transmitted in the communication system consists of public symbols and private symbols of each user, expressed as: ； Jointly participate in subsequent constructive interference optimization and symbol-level precoding design; S3. Through symbol-level precoding design, a minimum power transmission signal is constructed that satisfies both user correct decision constraints and interference direction control requirements; including: Assuming that the transmitted signal of the communication system is the sum of the products of the symbol-level transmit vector corresponding to each symbol and the symbol, the received signal expression of each user is defined, and the equivalent receiving gain is determined based on the channel state information; specifically, the following is included: Will be equipped with N t The signal transmitted by the base station with the root transmitting antenna at time n is expressed as: ； in, , , , Private symbols , , , The corresponding symbol-level transmit vector, i.e., the variable to be optimized at the current moment; Set user The downlink channel vector is , and its received signal is expressed as: ； The equivalent receiving gain is defined as: ， ， ， ； Then the user The equivalent expression of the received signal is: ； For the public and private symbols of weak users, decision constraints are defined separately, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area. For strong users, a dynamic main interference judgment mechanism is used to determine the main interference item and perform constructive judgment design, and to control the interference direction of the remaining interference items, including amplitude control and phase direction control; S4. Demodulating the received signal and recovering information, including: After receiving the signal, the weak user judges the public symbol and its own private symbol in sequence, and then performs serial interference cancellation operation to finally restore the complete initial information stream; After receiving the complex baseband signal, the strong user first determines the main interference source, then makes a judgment on the main interference item, performs symbol-level interference cancellation after the judgment is completed, and finally makes a judgment on the target symbol on the interference-optimized signal, maps the judgment output into a private bit stream, and completes information recovery.

2. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 1, characterized in that: The scenario of the downlink multi-user communication system established in step S1 is specifically: Equipped with N t A base station with 1 transmitting antenna provides non-orthogonal access services to K single-antenna users at the same time, satisfying K ≥ N t The typical NOMA deployment feature is that multiple users compete for scarce spatial resources; the base station needs to send corresponding downlink data symbols to K ≥ 3 users at the same time, which are private symbols for weak users and strong users, and public symbols generated by private users through the rate splitting mechanism. The public symbols contain the shared part of multiple user information.

3. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 1, characterized in that: In step S3, decision constraints are defined for the public and private symbols of the weak user, respectively, and constructive interference constraints are used to ensure that the symbols fall within the correct decision area. Specifically, the following steps are included: User 1 is a weak user, and its received signal is equivalently expressed as: ； in, It is expressed as the equivalent receiving gain of user 1 itself; First, the public symbols of weak users Conduct decision constraint design: Define normalized reception: , user 1 makes the judgment When the private signal of user 1 and the signals of users 2 and 3 boost the public symbol To fall within the correct decision area, the constructive interference constraint must be satisfied: ； in, To determine the half angle of the modulation constellation, represents the safety decision margin; represents the imaginary part of a complex number, represents the real part of a complex number; Then for the private symbols of the weak user Conduct decision constraint design: In the symbol-level precoding framework, all symbol values ​​are known, and user 1 offsets the influence of the public symbols, obtaining: ； Constructing private symbols Normalized reception ratio of: , establish the decision area constraint: ； For the remaining weak users, the precoding constraint construction process is the same as that of user 1.

4. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 3, characterized in that: In step S3, for strong users, the main interference item is determined and a constructive decision design is performed through a dynamic main interference judgment mechanism. The interference direction of the remaining interference items is controlled, including amplitude control and phase direction control. Specifically, the following steps are performed: User 3 is a strong user, and its received signal is equivalently expressed as: ； in, It is expressed as the equivalent receiving gain of user 3 itself; and are the interference from user 1 and user 2 respectively, is the common signal of user 1 and user 2; Introducing dynamic main interference judgment mechanism, comparing and The size of , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is Considered as the main distractor; Assume that user 1's private symbol As the main interference item, a constructive judgment design is performed on the main interference item: Construct the normalized receiving gain: , and impose constructive interference decision constraints: ； Then eliminate the main interference term and construct the target symbol, which is the private symbol of user 3 the judgment constraints; After removing the main interference, the residual signal is defined as: ； The target symbol receiving gain is: , construct the CI constraint of the target symbol: ； For the remaining interference items, including user 2's private symbols and public symbols Perform interference direction control, including amplitude control and phase direction control.

5. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 4, characterized in that: When controlling the interference direction of the remaining interference items, the amplitude control is: ， ； Where, ; Phase direction control is: ； Where, .

6. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 5, characterized in that: In step S3, a minimum power transmission signal that satisfies both the user's correct decision constraint and the interference direction control requirement is constructed through symbol-level precoding design. The mathematical model of the optimization problem is expressed as: ； ； ； ； ； ； ； 。 7. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 1, characterized in that: After receiving the signal in step S4, the weak user sequentially determines the public symbol and its own private symbol, and then performs a serial interference cancellation operation to finally restore the complete initial information stream; specifically, the process includes: User 1 is a weak user, and its received signal is equivalently expressed as: ； in, It is expressed as the equivalent receiving gain of user 1 itself; Under the support of constructive interference, user 1 directly receives the signal Make a constellation judgment: ； in, Restored for judgment Signal; After obtaining the public symbol decision, user 1 removes its public terms from the received signal and performs serial interference cancellation to obtain a new decision sub-signal: ； Then user 1 continues to use the new decision sub-signal Determine its private symbols ,Right now: ； in, Restored for judgment Signal; Finally, user 1 judges the public symbol restored by the receiving end Demodulate and extract the public bit stream containing its own information through physical layer channel decoding and CRC check , then Demodulate and obtain private bit stream , and restore the two together to the complete initial information flow, expressed as: ； User 1 completes the judgment and recovery of all his / her information; The process of demodulating the received signal and recovering information for the remaining weak users is the same as that of user 1.

8. The multi-user symbol-level precoding method based on rate splitting and constructive interference according to claim 1, characterized in that: After the strong user receives the complex baseband signal in step S4, it first determines the main interference source, then makes a judgment on the main interference term, performs symbol-level interference cancellation after the judgment is completed, and finally makes a judgment on the target symbol on the interference-optimized signal, and maps the judgment output into a private bit stream; specifically: User 3 is a strong user, and its received signal is equivalently expressed as: ； in, It is expressed as the equivalent receiving gain of user 3 itself; First determine the main interference source, compare and The size of , then the private symbol of user 1 is considered is the main interference term, otherwise, the private symbol of user 2 is Considered as the main distractor; Assume that user 1's private symbol The main interference item is judged first at the receiving end: ； After the decision is made, user 3 performs symbol-level interference cancellation, which is expressed as: ； Then user 3 interferes with the signal after optimization Target symbol decision is performed on: ； Finally, the judgment is output and directly mapped into a private bit stream , completing the judgment and recovery of all its own information.

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