Rate division multiple access method based on orthogonal resources

Abstract

The invention discloses a rate division multiple access method based on orthogonal resources, and belongs to the technical field of wireless communication. In order to solve the problem of mutual interference of private information of users in the existing rate division multiple access, the private information of different users is distributed to mutually orthogonal time slots for transmission, so that the interference among the private information is eliminated; and meanwhile, superposing the public information and the private information in each time slot in a power domain, and continuously sending the public information and the private information in all the time slots. According to the method, a joint optimization problem with system and rate maximization as a target is also constructed, iterative optimization is carried out on power, common rate proportion and time distribution, and the system capacity and transmission reliability are remarkably improved on the premise that the user service quality requirement is met.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology, specifically relating to a rate division multiple access method based on orthogonal resources. Background Technology

[0002] In wireless communication networks, multiple access technology is crucial for enabling multiple users to share a communication medium. As the number of users grows, the system needs to ensure quality of service and increase capacity within limited spectrum resources. Early orthogonal multiple access schemes, such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Orthogonal Frequency Division Multiple Access (OFDMA), provided interference-free communication for users through orthogonal resource allocation; however, their spectral efficiency was limited, and system capacity could not meet the ever-increasing demand.

[0003] To improve spectrum efficiency, non-orthogonal multiple access (NOA) technology has been extensively studied. NOA allows users to transmit on the same time-frequency resources through power domain superposition, while the receiver uses serial interference cancellation technology to distinguish user signals, thereby increasing system capacity. Building on this, rate-division multiple access (RDMA) further decomposes user information into public and private parts: public information is shared by all users, while private information is specific to certain users. Theoretically, this structure can improve spectrum efficiency while ensuring user fairness.

[0004] However, in existing rate-division multiple access (RDMA) schemes, all users' private information is typically transmitted on the same time-frequency resources, distinguished only by power differences. Under actual channel conditions and power allocation constraints, significant interference still exists between private information. This interference makes it difficult for the receiver to correctly decode the private information of all users, especially when user channel differences are large or power allocation is limited, thus restricting system capacity. Therefore, how to effectively eliminate interference between private information while maintaining the advantages of the RDMA structure has become a key issue in improving the capacity of wireless communication systems. Summary of the Invention

[0005] To overcome the shortcomings of existing rate division multiple access (RDBMI) technologies, such as mutual interference of private information, this application provides a RDBMI scheme based on orthogonal resource allocation. This scheme completely eliminates interference between private information by allocating the private information of different users to orthogonal time slots for transmission. Simultaneously, public information and each user's private information are superimposed in the power domain and transmitted across all time slots to achieve time resource reuse. Therefore, while ensuring reliable decoding of user private information, the overall system capacity is effectively improved.

[0006] To achieve the above technical objectives, this application specifically adopts the following technical solution: In one aspect of this application, a rate-division multiple access method based on orthogonal resources is provided, applicable to systems including base stations andK A communication system for individual users includes the following steps: S1, the first User information Divided into public areas and private parts The common parts for all users Commonly encoded as public information ; S2, transfer the public information Encoded as a common bitstream , will the Private part of each user Encoded as a private bitstream ; S3, for each private bitstream Allocate orthogonal transmission time slots This makes it possible for any different user and The corresponding time slot and satisfy ; for the public bitstream Allocate transmission time slots And satisfy ; S4, is the common bit stream Allocate transmission power For each private bitstream Allocate transmission power The signal sent by the base station for: ; S5, User Received signal Represented as: ,in, Indicates base station and user Channel gain between Gaussian white noise; user First decode the common bit stream Then, serial interference cancellation technology is used to remove the decoded public information, and finally, its own private bitstream is decoded. .

[0007] In one implementation, the user Decoding the common bitstream Signal-to-interference-to-noise ratio for:

[0008] in, Gaussian white noise The variance; user Decoding its own private bitstream Signal-to-interference-to-noise ratio for: .

[0009] In one implementation, the channel gain for each user is set to satisfy... Then the common bitstream achievable rate for:

[0010] in, .

[0011] In one implementation, the user Total rate of acquisition for:

[0012] in, For users The allocated proportion of the common rate satisfies ,as well as .

[0013] In one implementation, the following optimization steps are also included: to maximize the sum and rate of the system. With the objective of [implementing a system for allocating power], under constraints of power, common rate allocation, time, quality of service, and successful serial interference cancellation, [the system aims to optimize power allocation]. Public rate allocation and time allocation Joint optimization was carried out.

[0014] In one implementation, the optimization step includes: The joint optimization problem is decomposed into two subproblems: subproblems The optimization problem for time allocation t and common rate allocation a given power allocation p; subproblems The optimization problem of power allocation p given time allocation t and common rate allocation a; The subproblems are solved alternately using an iterative algorithm. The problem of succubi This continues until the overall system rate converges, thus obtaining a suboptimal solution to the original joint optimization problem.

[0015] In one implementation, the iterative algorithm includes: Initial power allocation Public rate allocation Time allocation Set convergence threshold Number of iterations ; Power allocation based on the (n-1)th iteration Solve the subproblems The time allocation for the nth iteration is obtained. With common rate allocation ; Time allocation based on the nth iteration With common rate allocation Solve the subproblems The power allocation for the nth iteration is obtained. ; Calculate the sum rate of the system in the nth iteration. ; like If the condition is met, stop the iteration and output the result; otherwise, let... Continue iterating.

[0016] In one implementation, the subproblem is solved using a continuous convex approximation method. .

[0017] The beneficial effects of this application are as follows: The rate division multiple access (RDBMA) method based on orthogonal resources proposed in this application fundamentally eliminates mutual interference between private information by allocating the private information of different users to orthogonal time slots for transmission, ensuring reliable decoding of each user's private information. Simultaneously, by multiplexing public information across all time slots and superimposing it with the private information of each time slot in the power domain, the utilization efficiency of time resources is effectively improved. Compared to traditional orthogonal and non-orthogonal multiple access schemes, this application significantly improves the sum rate and overall capacity of the system. Furthermore, the method in this application does not require complex user grouping algorithms, and each user only needs to perform a serial interference cancellation operation once at the receiving end, reducing implementation complexity and the probability of signal processing errors, thus enhancing the practicality and reliability of the system. Attached Figure Description

[0018] Figure 1 This is the user of Embodiment 3 of this application ( K =3) Schematic diagram of power and time resource allocation of the system; Figure 2 This is a comparison of the sum and rate of different multiple access schemes in the embodiments of this application. Detailed Implementation

[0019] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this application, not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] This application addresses the problem of mutual interference between private information in existing rate-segmented multiple access (RSMA) systems by proposing an architecture that integrates orthogonal resource allocation and power domain superposition. This method retains the original design of splitting user information into public and private parts, but allocates the private information of different users to mutually orthogonal time slots for transmission, thereby eliminating interference between private information at the physical level. Simultaneously, public information is still superimposed with the private information in each time slot in the power domain and continuously transmitted throughout all time slots. This allows private information to achieve interference-free decoding using orthogonal time slots, while public information maintains resource utilization efficiency through full-time-slot power multiplexing, eliminating key interferences while also improving system capacity.

[0021] This application presents a rate-division multiple access method based on orthogonal resources, which is implemented through the following steps: S1, the first User information Divided into public areas and private parts The common parts for all users Commonly encoded as public information .

[0022] The system is defined to include K There are users, and the user set is represented as . For the set of... users ( The information to be sent is represented as follows: .

[0023] To achieve Rate Division Multiple Access (RDMA), information for each user is... The sending end is divided into two parts: a common part. and a private part Among them, the private part It contains specific information that is only relevant to that user; public section It contains information that can be received and decoded by all or some users in the system.

[0024] All in the system K Public parts of individual users Joint coding is performed to form unified public information. .

[0025] S2, transfer the public information Encoded as a common bitstream , will the Private part of each user Encoded as a private bitstream .

[0026] The generated unified public information Channel coding and modulation mapping are performed to generate a physical layer transmit symbol sequence carrying this common information, which is defined as a common bit stream. The process is designed to provide Add appropriate error control redundancy and modulate it onto the selected constellation diagram to form a baseband symbol that can be directly transmitted.

[0027] At the same time, for the first A user, who has a portion of it Independent channel coding and modulation mapping are performed to generate a physical layer transmission symbol sequence that carries only the user's private information, defined as a private bit stream. Understandably, each user has their own private bitstream. The generation processes of each are independent of each other.

[0028] S3, for each private bitstream Allocate orthogonal transmission time slots , so that for any have ; for the public bitstream Allocate transmission time slots And satisfy .

[0029] Allocate a dedicated transmission time slot for each user's private bitstream. The allocated private bitstream... time slot Time slot They satisfy an orthogonal relation, meaning that for any two different users... and ( ), and its corresponding time slot and They do not overlap in time, satisfying the requirement. This avoids interference between private bitstreams in the time domain.

[0030] For the common bit stream Allocate transmission time slots The public bitstream transmission slot With all private bitstreams transmission slot Satisfying the coverage relationship, that is . Represents a common bitstream The transmission continues throughout the transmission time slot of each private bitstream. That is, in any time slot allocated to a specific user (e.g., user...) k ) used to send its private bit stream time slot Inside, the base station is also transmitting a public bit stream. This time-slot allocation method allows public information to be transmitted across all time resources, while private information is transmitted in orthogonal time slots, thus achieving the reuse of time resources.

[0031] S4, is the common bit stream Allocate transmission power For each private bitstream Allocate transmission power The signal sent by the base station for: .

[0032] For the public bit stream Allocate transmission power, denoted as At the same time, for the first Private bitstream for each user Allocate transmission power, denoted as .in, With each ( All are non-negative real numbers, representing the power resources occupied during the transmission of the corresponding bit stream.

[0033] Based on the allocated time slots and power, the base station superimposes the common bit stream and each private bit stream in the power domain to form the final transmitted signal.

[0034] Specifically, in the transmission time slot Signals transmitted by internal base stations From public bitstream With all private bitstreams The result is formed by multiplying each power distribution factor by the square root of its respective power distribution factor and then summing them up, as follows: .

[0035] S5, User Received signal Represented as: ;in, Indicates base station and user The channel gain between them reflects the impact of the wireless channel on the signal amplitude; The signal transmitted by the base station within the corresponding time slot; The Gaussian white noise at the user receiver is typically modeled as having zero mean and variance. Complex Gaussian random variable; user First decode the common bit stream Then, serial interference cancellation technology is used to remove the decoded public information, and finally, its own private bitstream is decoded. .

[0036] In some embodiments, the user The decoder performs the following operations sequentially to recover its information: First, decode the co-bit stream. Due to the received signal The signal contains both common and private signal components; in this case, the private signal components are considered interference. The decoder is based on the received signal. Estimating the common bit stream .

[0037] Next, serial interference cancellation is performed. This is done after successfully decoding the common bit stream. Then, the decoder allocates power based on the known common bitstream symbols. and estimated channel gain From the received signal The common signal component is reconstructed and subtracted from the original received signal.

[0038] Finally, decode the private bitstream. After eliminating common signal components, the remaining signal mainly contains target private signal components and noise. The decoder decodes the user's signal based on the remaining signal. Its own private bitstream .

[0039] In some embodiments, the decoding performance of the user equipment during the decoding process described in step S5 can be measured by the signal-to-interference-plus-noise ratio (SINR).

[0040] user Decoding the common bitstream At that time, the power of the common signal component in the received signal is At this point, private signal components from other users are considered interference. Since different users' private information is allocated for transmission in orthogonal time slots, within any given time slot, only one user's private signal is superimposed on the public signal. However, when decoding the public information, the public information needs to be decoded across all its transmission time slots (i.e.,...). The common information is fully decoded within a given timeframe. To ensure successful decoding even under worst-case channel conditions, the rate design for the common information must consider the effective interference faced by all users. Therefore, the signal-to-interference-plus-noise ratio (SIR) used to determine the achievable rate of the common information is calculated. At that time, the sum of the private signal power of all users is conservatively considered as potential interference, and the value of this interference power after passing through the channel is... In addition, receiver noise power ,user Signal-to-interference-plus-noise ratio when decoding common bitstreams Represented as: .

[0041] When users After successful decoding and removal of common signal components using serial interference cancellation technology, the received signal contains only its own private signal components and noise. At this point, the power of the private signal component is... The noise power is Therefore, users Decoding its own private bitstream Signal-to-interference-to-noise ratio Represented as: .

[0042] In some embodiments, for ease of analysis and description, users are sorted according to their channel conditions. It is assumed that the channel gain between each user and the base station satisfies the following relationship. It is understandable that this assumption is only used to clearly illustrate the principle of the solution, and does not constitute a limitation on actual application scenarios, nor does it introduce any performance loss.

[0043] Based on the user defined in step S5 Signal-to-interference-plus-noise ratio when decoding public information ,because and Positive correlation, therefore .

[0044] Due to the public bit stream The public information needs to be successfully decoded by all users in the system. Therefore, the overall system's supported public information transmission rate depends on the lowest signal-to-interference-plus-noise ratio (SIR) among all users decoding the public information. The minimum SIR for all users' public information is defined as... .

[0045] According to Shannon's theorem, in an additive white Gaussian noise channel, the upper limit of the reliable communication rate is determined by the signal-to-noise ratio. Therefore, the common bit stream... In the time slot achievable transmission rate The minimum signal-to-interference-plus-noise ratio The decision, expressed as: .

[0046] In some embodiments, the final information transmission rate obtained by each user is determined.

[0047] user Total rate obtained It consists of two parts: one part is the rate allocated from public information, and the other part is the rate obtained by transmitting private information through its exclusive orthogonal time slots. The specific expression is as follows:

[0048] in, The representative will represent the total rate of public information. Assigned to user The proportion of the part that meets the requirements ,as well as Assigned to user The actual rate of public information is .

[0049] In another specific implementation, the rate division multiple access method based on orthogonal resources also includes a step of optimizing system resources. The aim is to improve the overall transmission performance of the system by jointly adjusting power, time, and common rate allocation.

[0050] The optimization steps aim to maximize the sum and rate of the system. The objective is to optimize the process while satisfying several practical constraints, including but not limited to: the maximum transmit power of the base station. The sum of the public rate allocated to each user does not exceed 1; the total time slot length occupied by the transmission of all users' private information T Each user Total rate of acquisition Not lower than the minimum rate specified in its service quality requirements Ensure that each user can successfully perform serial interference cancellation to decode common information. Optimization variables include: power allocation. Public rate allocation and time allocation .

[0051] To effectively solve the joint optimization problem, it is decomposed into two subproblems that are solved alternately: subproblems The optimization problem for time allocation t and common rate allocation a given power allocation p; subproblems The optimization problem of power allocation p given time allocation t and common rate allocation a.

[0052] An iterative algorithm is used to solve the problem, approximating the optimal solution by alternately solving two subproblems. The specific steps of the iterative algorithm are as follows: 1) Initialization: Set power allocation Public rate allocation Time allocation The initial value. Set a positive convergence threshold. And initialize the iteration count n to 1.

[0053] 2) Update time and common rate allocation: Power allocation based on the previous iteration (n-1th iteration). Solve the subproblems Obtain the time allocation for this iteration (the nth iteration). With common rate allocation .

[0054] 3) Update power allocation: Based on the time allocation obtained in step 2) iteration With common rate allocation Solve the subproblems To obtain the power allocation for this iteration .

[0055] 4) Computational performance metrics: based on the results obtained in this iteration. , , Calculate the total speed that the current system can achieve, denoted as . .

[0056] 5) Convergence determination: Calculate the absolute value of the difference between the sum rate of the current iteration and the sum rate of the previous iteration. If the difference is less than or equal to the set convergence threshold... If the algorithm has converged, it stops iterating and outputs the current value. , , As an optimization result. Otherwise, let the iteration count... Return to step 2) and continue to the next iteration.

[0057] In some embodiments, for sub-problems Because the objective function and some constraints of a problem may be non-convex, directly solving for the global optimum is difficult. Therefore, a continuous convex approximation method can be used. Through a series of iterative steps, in each iteration, the original non-convex problem is approximated as a convex optimization problem near the current solution. The solution is then updated by solving this convex problem, thus gradually approximating a suboptimal solution to the original problem.

[0058] Example Step 1: Represent the user set as , will the The information of each user is represented as follows: Then Divided into two parts: common area and private parts All user information is jointly encoded and combined into public information. Using public bitstreams Indicates public information Private bitstream Indicates private part .

[0059] Step 2: Transfer the user Private bitstream The transmission time slot is represented as Then it needs to satisfy This means that different users' private information is sent in different time slots. The public bitstream of all users is then... The transmission time slot is represented as Then it needs to satisfy This means that each transmission slot contains private information and some public information, and different slots will send private information from different users.

[0060] Step 3: Assign the private bitstream The power is expressed as , will be allocated to public bitstream The power is expressed as The signal sent by the base station for .

[0061] Step 4: User The received signal at that location can be represented as ,in, Indicates base station and user Channel gain between It follows the variance of Gaussian white noise. In the RSMA scheme, the user needs to decode the public information first, and then decode their own private information. Therefore, in the user At this location, the signal-to-interference-to-noise ratio of public information is [value missing]. ,Right now Without loss of generality, we assume ,Right now .user After decoding the public information, serial interference cancellation (SIC) is used to remove it, resulting in a signal-to-interference-plus-noise ratio (SNR) for the private information. .

[0062] because According to Shannon's theorem, in order for all users to be able to successfully decode the public information, the rate of the public information should not exceed [a certain value]. .

[0063] Step 5: After obtaining and After that, you can write the user's... Total rate , ,in To be assigned to users The public information rate ratio must meet the following requirements. ,as well as .

[0064] Based on the above steps, this embodiment proposes an optimization problem for an RSMA scheme based on orthogonal resources, aiming to maximize the system and rate under power and quality of service constraints. Optimization Problem for:

[0065] in, , , , It is the maximum transmission power of the base station. User Minimum rate requirement, It is the minimum difference between the decoded signal power and the interference plus noise power, with the aim of ensuring that the common message is successfully decoded. Therefore, the first four constraints are the maximum power constraint, the common information rate allocation constraint, the maximum time constraint, and the quality of service constraint, respectively. SIC constraints were successfully implemented. It is a non-negativity constraint on the variable.

[0066] Step 6: Decompose the optimization problem in Step 5 into two sub-problems and optimize them separately. The first sub-optimization problem... The time allocation and common rate allocation problem for a given power condition can be expressed as:

[0067] The second subproblem This is a power allocation problem given time allocation and common rate allocation, which can be written as:

[0068] Step 7: First, the subproblems can be obtained by considering the conditions that the optimal solution must satisfy. The closed-form solution is obtained, and then the subproblems are solved using the Continuous Convex Approximation (SCA) method. Finally, the original problem is obtained through a joint iterative algorithm. The suboptimal solution. The specific steps of the joint iterative algorithm are as follows: (1) Input and initialize the optimization variables. , , Convergence parameters Set the number of iterations (2) According to Solve subproblems This yields the optimal common rate allocation variable at this point. and time allocation variables (3) According to and Solve subproblems To obtain power allocation variables (4) According to , and Computational problems The objective function value is denoted as . (5) (6) Repeat steps (1)-(5), when When the time comes, stop the algorithm and output the problem. The objective function value and the corresponding variable values.

[0069] Figure 1 This demonstrates a three-user application of the proposed solution in this embodiment. K =3) Schematic diagram of power and time resource allocation of the system.

[0070] like Figure 1 As shown, the horizontal axis represents time resources, and the vertical axis represents power resources. (User allocation) The power and time of private information are respectively , The power and time allocated to public information are respectively , Obviously Private information from different users is transmitted in different time slots, avoiding interference between private information from different users in the traditional RSMA scheme. At the same time, public information and private information are superimposed in the power domain and transmitted in each time slot to reuse time resources and increase system capacity. Compared with the traditional OMA and NOMA schemes, this effectively improves the system's sum rate.

[0071] Figure 2 It was shown in a 4-user ( K =4) In the system, when using the traditional orthogonal multiple access (OMA) scheme, the traditional non-orthogonal multiple access (NOMA) scheme, and the scheme proposed in this application (O-RSMA), respectively, the overall sum rate of the system varies with the maximum transmit power of the base station. P The changing simulation curve.

[0072] from Figure 2The curves in the figures show that, under the same base station, the maximum transmit power... P Under these conditions, the overall system harmony rate achieved by the O-RSMA scheme proposed in this application is consistently higher than that of the traditional NOMA and OMA schemes. With the maximum transmit power... P With the increase in capacity, the system capacity of all three schemes showed an upward trend, but the O-RSMA scheme showed a more significant performance improvement and maintained its performance advantage.

[0073] This performance gain verifies the effectiveness of the technical solution presented in this application. The fundamental reason is that the O-RSMA scheme eliminates inter-user interference through orthogonal transmission of private information, and extracts additional multiplexing gain through full-time-slot power domain multiplexing of public information. Thus, while ensuring the quality of service for users, it makes more efficient use of limited power and time resources, thereby optimizing the overall spectral efficiency of the system.

[0074] Although the embodiments of this application have been described above in conjunction with the accompanying drawings, this application is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of this application, and these are all within the scope of protection of this application.

Claims

1. A rate-division multiple access method based on orthogonal resources, characterized in that, Applications include base stations and K A communication system for individual users includes the following steps: S1, the first User information Divided into public areas and private parts The common parts for all users Commonly encoded as public information ; S2, transfer the public information Encoded as a common bitstream , will the Private part of each user Encoded as a private bitstream ; S3, for each private bitstream Allocate orthogonal transmission time slots This makes it possible for any different user and The corresponding time slot and satisfy ; for the public bitstream Allocate transmission time slots And satisfy ; S4, is the common bit stream Allocate transmission power For each private bitstream Allocate transmission power The signal sent by the base station for: ; S5, User Received signal Represented as: ,in, Indicates base station and user Channel gain between Gaussian white noise; user First decode the common bit stream Then, serial interference cancellation technology is used to remove the decoded public information, and finally, its own private bitstream is decoded. .

2. The rate-division multiple access method based on orthogonal resources according to claim 1, characterized in that, user Decoding the common bitstream Signal-to-interference-to-noise ratio for: in, Gaussian white noise The variance; user Decoding its own private bitstream Signal-to-interference-to-noise ratio for: 。 3. The rate-division multiple access method based on orthogonal resources according to claim 2, characterized in that, Set the channel gain of each user to meet the following conditions: Then the common bitstream achievable rate for: in, .

4. The rate-division multiple access method based on orthogonal resources according to claim 3, characterized in that, user Total rate of acquisition for: in, For users The allocated proportion of the common rate satisfies ,as well as .

5. The rate-division multiple access method based on orthogonal resources according to claim 1, characterized in that, It also includes optimization steps to maximize the system's sum and rate. With the objective of [implementing a system for allocating power], under constraints of power, common rate allocation, time, quality of service, and successful serial interference cancellation, [the system aims to optimize power allocation]. Public rate allocation and time allocation Joint optimization was carried out.

6. The rate-division multiple access method based on orthogonal resources according to claim 5, characterized in that, The optimization steps include: The joint optimization problem is decomposed into two subproblems: subproblems The optimization problem for time allocation t and common rate allocation a given power allocation p; subproblems The optimization problem of power allocation p given time allocation t and common rate allocation a; The subproblems are solved alternately using an iterative algorithm. The problem of succubi This continues until the overall system rate converges, thus obtaining a suboptimal solution to the original joint optimization problem.

7. The rate-division multiple access method based on orthogonal resources according to claim 6, characterized in that, The iterative algorithm includes: Initial power allocation Public rate allocation Time allocation Set convergence threshold Number of iterations ; Power allocation based on the (n-1)th iteration Solve the subproblems The time allocation for the nth iteration is obtained. With common rate allocation ; Time allocation based on the nth iteration With common rate allocation Solve the subproblems The power allocation for the nth iteration is obtained. ; Calculate the sum rate of the system in the nth iteration. ; like If the condition is met, stop the iteration and output the result; otherwise, let... Continue iterating.

8. A rate-division multiple access method based on orthogonal resources according to claim 6 or 7, characterized in that, The subproblem is solved using a continuous convex approximation method. .

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