Joint user power allocation design method and system under coexistence of cellular and d2d

Abstract

The application provides a kind of joint user power distribution design method and system under the coexistence system of cellular and D2D, it is related to wireless communication technical field, comprising: step S1: analysis cellular user's data transmission, based on SCMA system using optimal codebook design principle, obtain the total reachable rate of cellular user;Step S2: analysis D2D user's data transmission, obtain the total reachable rate of D2D user;Step S3: according to the total reachable rate of cellular user and D2D user, form specific optimization problem;Step S4: by optimization problem, based on GP and approximate replacement optimization algorithm obtains the power distribution scheme of two kinds of users.The application allocates user sending power by designing suitable optimization algorithm, to realize the improvement of system and rate performance.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically, to a joint user power allocation design method and system for cellular and D2D coexistence systems. Background Technology

[0002] SCMA allocates resource modules in a non-orthogonal manner, thereby achieving overload characteristics for system users. D2D communication has significant advantages in local communication, improving link reliability and spectral efficiency, and increasing system capacity. However, with the increasing demand for larger device connections in B5G and 6G wireless network research, more and more research is focusing on scenarios where SCMA cellular user networks coexist with D2D communication, aiming to further increase the number of user connections the system can support while pursuing higher data rates. In network models where cellular users and D2D users coexist, designing appropriate allocation schemes for various resources has become a key research topic. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a joint user power allocation design method and system for cellular and D2D coexistence systems.

[0004] According to the present invention, a joint user power allocation design method and system for a cellular and D2D coexistence system are provided, the scheme of which is as follows:

[0005] In a first aspect, a joint user power allocation design method is provided for a cellular and D2D coexistence system, the method including: communication between two types of users, cellular users and D2D users;

[0006] In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers, and these OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair selecting a different subcarrier.

[0007] Step S1: Analyze the data transmission of cellular users and obtain the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system.

[0008] Step S2: Analyze the data transmission of D2D users and obtain the total achievable rate of D2D users;

[0009] Step S3: Formulate a specific optimization problem based on the total reachable rate of cellular users and D2D users;

[0010] Step S4: By optimizing the problem, obtain the power allocation scheme for the two types of users based on GP and approximate replacement optimization algorithms.

[0011] Preferably, step S1 includes: analyzing the data transmission of cellular users, assuming the number of cellular users is J and the number of D2D user pairs in the system is J. D The total number of subcarriers occupied by a cellular user is K; the transmitted signal of the j-th cellular user is represented as x. j =(x j1 ,x j2 ,...,x jK ) T The signal y received at the base station will simultaneously contain data transmitted by both cellular users and D2D users, and its expression is:

[0012]

[0013] in, It is the channel vector between the j-th cellular user and the base station. It is the channel state information between the transmitter and the base station of the j-th D2D user pair, while x' j =(x' j1 ,x' j2 ,...,x' jK ) T It is a D2D transmitted codeword vector with non-zero elements in only one row, where n represents an additive white Gaussian noise vector with a mean of 0 and a covariance matrix of N0I, where N0 represents the power spectral density of the noise and I is the identity matrix.

[0014] The expression for the total reachable rate for cellular users is:

[0015]

[0016] For the base station, the received SINR of the j-th cellular user on the k-th subcarrier is expressed as:

[0017]

[0018] Where, ξ k This represents the set of all cellular users occupying the k-th subcarrier, obtained from the factor graph structure of SCMA. P represents the channel state information between the j-th cellular user and the base station on the k-th subcarrier. jk This represents the transmit signal power of the j-th cellular user on the k-th subcarrier. P represents the channel state information between the transmitter and the base station of the D2D user pair on the k-th subcarrier. k ' represents the transmit signal power of the D2D user pair on the k-th subcarrier.

[0019] Preferably, step S2 includes: analyzing the data transmission of D2D users, assuming that the l-th pair of D2D users uses the l-th subcarrier, and the transmission signal of the D2D transmitter is x. l 'Then the expression for the received signal at the corresponding D2D receiver is:'

[0020]

[0021] in, This represents the channel state information between the l-th pair of D2D users. This represents the channel state information between the receivers of the j-th cellular user and the l-th D2D pair, ξ. l Let x represent the set of all cellular users occupying the l-th subcarrier, obtained from the factor graph structure of SCMA. jl This represents the SCMA codeword transmitted by the j-th cellular user on the l-th subcarrier, n l This also represents additive Gaussian white noise;

[0022] The SINR of the receiver for the l-th pair of D2D users during decoding is expressed as:

[0023]

[0024] The expression for the total reachability of D2D users is:

[0025]

[0026] Among them, P l ' represents the transmit signal power of the D2D user pair on the l-th subcarrier, P jl This represents the transmit signal power of the j-th cellular user on the l-th subcarrier.

[0027] Preferably, step S3 includes: the specific optimization problem is formulated as follows:

[0028] P 1:

[0029]

[0030]

[0031]

[0032] C4:0≤P l '≤P0',l=1,...,J D ,

[0033] Among them, constraints C1 and C2 respectively guarantee the QoS requirements of cellular users and D2D users, that is, the corresponding SINR cannot be lower than the corresponding lower limit, while constraints C3 and C4 give the upper limit of the transmission power of the two types of users.

[0034] Preferably, step S4 includes: the objective function of the standard GP problem is a positive term, so the objective function of the original problem needs to be transformed, thus:

[0035]

[0036] The four types of functions are defined as follows:

[0037]

[0038]

[0039]

[0040]

[0041] Problem P1 can be rewritten as:

[0042] P 2:

[0043]

[0044]

[0045]

[0046] C8:P l '(P0)' -1 ≤1,l=1,...,J D ,

[0047] in, This represents the lower limit of SINR for cellular users. This represents the lower bound of SINR for D2D users, d f This represents the total number of subcarriers occupied by each cellular user;

[0048] The constraints of this optimization problem satisfy the standard form of GP. The objective function in problem P2 is the ratio of two positive terms. By simply replacing the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the replacement, the overall problem belongs to the standard GP problem, and a high-quality solution can be obtained using the CVX toolbox.

[0049] Secondly, a joint user power allocation system under a cellular and D2D coexistence system is provided, the system including: communication between two types of users, cellular users and D2D users;

[0050] In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers, and these OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair selecting a different subcarrier.

[0051] Module M1: Analyzes data transmission of cellular users and obtains the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system.

[0052] Module M2: Analyzes data transmission between D2D users and obtains the total achievable rate of D2D users;

[0053] Module M3: Formulates specific optimization problems based on the total reachable rate of cellular users and D2D users;

[0054] Module M4: By solving an optimization problem, it obtains power allocation schemes for two types of users based on GP and approximate replacement optimization algorithms.

[0055] Preferably, module M1 includes: analyzing data transmission of cellular users, assuming the number of cellular users is J and the number of D2D user pairs in the system is J. D The total number of subcarriers occupied by a cellular user is K; the transmitted signal of the j-th cellular user is represented as x. j =(x j1 ,x j2 ,...,x jK ) T The signal y received at the base station will simultaneously contain data transmitted by both cellular users and D2D users, and its expression is:

[0056]

[0057] in, It is the channel vector between the j-th cellular user and the base station. It is the channel state information between the transmitter and the base station of the j-th D2D user pair, while x' j =(x' j1 ,x' j2 ,...,x' jK ) T It is a D2D transmitted codeword vector with non-zero elements in only one row, where n represents an additive white Gaussian noise vector with a mean of 0 and a covariance matrix of N0I, where N0 represents the power spectral density of the noise and I is the identity matrix.

[0058] The expression for the total reachable rate for cellular users is:

[0059]

[0060] For the base station, the received SINR of the j-th cellular user on the k-th subcarrier is expressed as:

[0061]

[0062] Where, ξ k This represents the set of all cellular users occupying the k-th subcarrier, obtained from the factor graph structure of SCMA. P represents the channel state information between the j-th cellular user and the base station on the k-th subcarrier. jk This represents the transmit signal power of the j-th cellular user on the k-th subcarrier. P represents the channel state information between the transmitter and the base station of the D2D user pair on the k-th subcarrier. k ' represents the transmit signal power of the D2D user pair on the k-th subcarrier.

[0063] Preferably, the module M2 includes: analyzing the data transmission of D2D users, assuming that the l-th pair of D2D users uses the l-th subcarrier, and the transmission signal of the D2D transmitter is x. l 'Then the expression for the received signal at the corresponding D2D receiver is:'

[0064]

[0065] in, This represents the channel state information between the l-th pair of D2D users. This represents the channel state information between the receivers of the j-th cellular user and the l-th D2D pair, ξ. l Let x represent the set of all cellular users occupying the l-th subcarrier, obtained from the factor graph structure of SCMA. jl This represents the SCMA codeword transmitted by the j-th cellular user on the l-th subcarrier, n l This also represents additive Gaussian white noise;

[0066] The SINR of the receiver for the l-th pair of D2D users during decoding is expressed as:

[0067]

[0068] The expression for the total reachability of D2D users is:

[0069]

[0070] Among them, Pl ' represents the transmit signal power of the D2D user pair on the l-th subcarrier, P jl This represents the transmit signal power of the j-th cellular user on the l-th subcarrier;

[0071] The module M3 includes: The specific optimization problem is formulated as follows:

[0072] P 1:

[0073]

[0074]

[0075]

[0076] C4:0≤P l '≤P0',l=1,...,J D ,

[0077] Among them, constraints C1 and C2 respectively guarantee the QoS requirements of cellular users and D2D users, that is, the corresponding SINR cannot be lower than the corresponding lower limit, while constraints C3 and C4 give the upper limit of the transmission power of the two types of users.

[0078] The module M4 includes: the objective function of the standard GP problem is a positive term, and the objective function of the original problem needs to be transformed, thus:

[0079]

[0080] The four types of functions are defined as follows:

[0081]

[0082]

[0083]

[0084]

[0085] Problem P1 can be rewritten as:

[0086] P2:

[0087]

[0088]

[0089]

[0090] C8:P l'(P0)' -1 ≤1,l=1,...,J D ,

[0091] in, This represents the lower limit of SINR for cellular users. This represents the lower bound of SINR for D2D users, d f This represents the total number of subcarriers occupied by each cellular user;

[0092] The constraints of this optimization problem satisfy the standard form of GP. The objective function in problem P2 is the ratio of two positive terms. By simply replacing the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the replacement, the overall problem belongs to the standard GP problem, and a high-quality solution can be obtained using the CVX toolbox.

[0093] Thirdly, a computer-readable storage medium storing a computer program is provided, which, when executed by a processor, implements the steps of the joint user power allocation design method under the cellular and D2D coexistence system.

[0094] Fourthly, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the joint user power allocation design method under the cellular and D2D coexistence system.

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] 1. Classic communication systems where cellular users and D2D users coexist do not consider non-orthogonal multiple access technology, while the architecture proposed in this invention adopts SCMA technology for cellular users, which is obviously a solution to improve the system's user carrying capacity.

[0097] 2. When studying the optimization problems of systems and rates, it is difficult to find the global optimum due to the non-convex nature of the problem. However, the iterative algorithm based on generalization proposed in this invention can converge to the global optimum of the original problem, which is obviously a more efficient solution.

[0098] Other beneficial effects of the present invention will be explained in detail through the introduction of specific technical features and technical solutions in specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0099] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0100] Figure 1 A communication system for the coexistence of cellular users and D2D users;

[0101] Figure 2 Simulation results of system and rate performance for several schemes under different SINR constraints for cellular users;

[0102] Figure 3 Simulation results of system and rate performance for several schemes under different D2D user SINR constraints. Detailed Implementation

[0103] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0104] This invention provides a joint user power allocation design method for cellular and D2D coexistence systems, addressing the increased device connectivity demands of B5G and 6G networks. It is a power allocation scheme for two types of users aimed at maximizing system performance and data rate. Uplink cellular users transmit data to the air interface using Sparse Coordinated Multiple Access (SCMA), while D2D users will similarly occupy these subcarriers for communication. Based on theoretical analysis, the problem of maximizing system performance and data rate for power allocation to different users is formally modeled. This invention aims to solve this optimization problem by proposing an iterative algorithm based on geometric programming (GP), which converges to the global optimum of the original problem.

[0105] Because mutual interference exists during communication between the two types of users, the allocation design of relevant resources in the system plays a crucial role in the performance of this hybrid communication system. In this section, the invention designs a power allocation scheme for the two types of users with the goal of maximizing the system's achievable sum of speeds as the performance metric. (Refer to...) Figure 1 As shown, the method specifically includes communication between two types of users: cellular users and D2D users.

[0106] In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers. These OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair using a different subcarrier.

[0107] Step S1: Analyze the data transmission of cellular users and obtain the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system.

[0108] Analyzing data transmission among cellular users, assume the number of cellular users is J, and the number of D2D user pairs in the system is J. D The total number of subcarriers occupied by a cellular user is K; the transmitted signal of the j-th cellular user is represented as x. j =(x j1 ,x j2 ,...,x jK ) T The signal y received at the base station will simultaneously contain data transmitted by both cellular users and D2D users, and its expression is:

[0109]

[0110] in, It is the channel vector between the j-th cellular user and the base station. It is the channel state information between the transmitter and the base station of the j-th D2D user pair, while x' j =(x' j1 ,x' j2 ,...,x' jK ) T It is a D2D transmitted codeword vector where only one row of elements is non-zero. n represents an additive white Gaussian noise vector with a mean of 0 and a covariance matrix of N0I, where N0 represents the power spectral density of the noise and I is the identity matrix.

[0111] Based on the optimal codebook design principle adopted by the SCMA system, the expression for the total achievable rate of cellular users can be derived as follows:

[0112]

[0113] For the base station, the received SINR of the j-th cellular user on the k-th subcarrier is expressed as:

[0114]

[0115] Where, ξ k This represents the set of all cellular users occupying the k-th subcarrier, obtained from the factor graph structure of SCMA. P represents the channel state information between the j-th cellular user and the base station on the k-th subcarrier. jk This represents the transmit signal power of the j-th cellular user on the k-th subcarrier. P represents the channel state information between the transmitter and the base station of the D2D user pair on the k-th subcarrier. k ' represents the transmit signal power of the D2D user pair on the k-th subcarrier.

[0116] Step S2: Analyze the data transmission of D2D users and obtain the total achievable rate of D2D users.

[0117] Analyzing the data transmission of D2D users, assuming the l-th D2D user pair uses the l-th subcarrier, and the transmitted signal at the D2D transmitter is x. l 'Then the expression for the received signal at the corresponding D2D receiver is:'

[0118]

[0119] in, This represents the channel state information between the l-th pair of D2D users. This represents the channel state information between the receivers of the j-th cellular user and the l-th D2D pair, ξ. l Let x represent the set of all cellular users occupying the l-th subcarrier, obtained from the factor graph structure of SCMA. jl This represents the SCMA codeword transmitted by the j-th cellular user on the l-th subcarrier, n l This also represents additive Gaussian white noise.

[0120] The SINR of the receiver for the l-th pair of D2D users during decoding can be expressed as:

[0121]

[0122] The expression for the total reachability of D2D users is:

[0123]

[0124] Among them, P l ' represents the transmit signal power of the D2D user pair on the l-th subcarrier, P jl This represents the transmit signal power of the j-th cellular user on the l-th subcarrier.

[0125] Step S3: Formulate a specific optimization problem based on the total reachability of cellular users and D2D users.

[0126] This invention improves the overall system speed by optimizing the transmission power of two types of users. The specific optimization problem can be formulated as follows:

[0127] P 1:

[0128]

[0129]

[0130]

[0131] C4:0≤P l '≤P0',l=1,...,J D ,

[0132] Among them, constraints C1 and C2 respectively guarantee the QoS requirements of cellular users and D2D users, that is, the corresponding SINR cannot be lower than the corresponding lower limit; constraints C3 and C4 give the upper limit of the transmission power for the two types of users. Since the objective function of this problem is nonlinear and nonconvex, the global optimal solution cannot be directly obtained from the original problem.

[0133] Step S4: By optimizing the problem, obtain the power allocation scheme for the two types of users based on GP and approximate replacement optimization algorithms.

[0134] The objective function of a standard generalization problem is a positive term, so the objective function of the original problem needs to be transformed, hence:

[0135]

[0136] The four types of functions are defined as follows:

[0137]

[0138]

[0139]

[0140]

[0141] Problem P1 can be rewritten as:

[0142] P2:

[0143]

[0144]

[0145]

[0146] C8:P l '(P0)' -1 ≤1,l=1,...,J D ,

[0147] in, This represents the lower limit of SINR for cellular users. This represents the lower bound of SINR for D2D users, d f This represents the total number of subcarriers occupied by each cellular user.

[0148] The constraints of this optimization problem satisfy the standard form of General Purpose (GP). The objective function in problem P2 is the ratio of two positive terms. By approximating the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the substitution, the overall problem remains a standard GP problem, and a high-quality solution can be obtained using the CVX toolbox.

[0149] This invention also provides a joint user power allocation system for a cellular and D2D coexistence system. This joint user power allocation system can be implemented by executing the steps of the joint user power allocation method for a cellular and D2D coexistence system. That is, those skilled in the art can understand the joint user power allocation method for a cellular and D2D coexistence system as a preferred embodiment of the joint user power allocation system. Specifically, this system includes the following: communication between two types of users: cellular users and D2D users.

[0150] In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers. These OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair using a different subcarrier.

[0151] Step S1: Analyze the data transmission of cellular users and obtain the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system.

[0152] Analyzing data transmission among cellular users, assume the number of cellular users is J, and the number of D2D user pairs in the system is J. D The total number of subcarriers occupied by a cellular user is K; the transmitted signal of the j-th cellular user is represented as x. j =(x j1 ,x j2 ,...,x jK ) T The signal y received at the base station will simultaneously contain data transmitted by both cellular users and D2D users, and its expression is:

[0153]

[0154] in, It is the channel vector between the j-th cellular user and the base station. It is the channel state information between the transmitter and the base station of the j-th D2D user pair, while x' j =(x' j1 ,x' j2 ,...,x' jK ) TIt is a D2D transmitted codeword vector where only one row of elements is non-zero. n represents an additive white Gaussian noise vector with a mean of 0 and a covariance matrix of N0I, where N0 represents the power spectral density of the noise and I is the identity matrix.

[0155] Based on the optimal codebook design principle adopted by the SCMA system, the expression for the total achievable rate of cellular users can be derived as follows:

[0156]

[0157] For the base station, the received SINR of the j-th cellular user on the k-th subcarrier is expressed as:

[0158]

[0159] Where, ξ k This represents the set of all cellular users occupying the k-th subcarrier, obtained from the factor graph structure of SCMA. P represents the channel state information between the j-th cellular user and the base station on the k-th subcarrier. jk This represents the transmit signal power of the j-th cellular user on the k-th subcarrier. P represents the channel state information between the transmitter and the base station of the D2D user pair on the k-th subcarrier. k ' represents the transmit signal power of the D2D user pair on the k-th subcarrier.

[0160] Step S2: Analyze the data transmission of D2D users and obtain the total achievable rate of D2D users.

[0161] Analyzing the data transmission of D2D users, assuming the l-th D2D user pair uses the l-th subcarrier, and the transmitted signal at the D2D transmitter is x. l 'Then the expression for the received signal at the corresponding D2D receiver is:'

[0162]

[0163] in, This represents the channel state information between the l-th pair of D2D users. This represents the channel state information between the receivers of the j-th cellular user and the l-th D2D pair, ξ. l Let x represent the set of all cellular users occupying the l-th subcarrier, obtained from the factor graph structure of SCMA. jl This represents the SCMA codeword transmitted by the j-th cellular user on the l-th subcarrier, n l This also represents additive Gaussian white noise.

[0164] The SINR of the receiver for the l-th pair of D2D users during decoding can be expressed as:

[0165]

[0166] The expression for the total reachability of D2D users is:

[0167]

[0168] Among them, P l ' represents the transmit signal power of the D2D user pair on the l-th subcarrier, P jl This represents the transmit signal power of the j-th cellular user on the l-th subcarrier.

[0169] Step S3: Formulate a specific optimization problem based on the total reachability of cellular users and D2D users.

[0170] This invention improves the overall system speed by optimizing the transmission power of two types of users. The specific optimization problem can be formulated as follows:

[0171] P 1:

[0172]

[0173]

[0174]

[0175] C4:0≤P l '≤P0',l=1,...,J D ,

[0176] Among them, constraints C1 and C2 respectively guarantee the QoS requirements of cellular users and D2D users, that is, the corresponding SINR cannot be lower than the corresponding lower limit; constraints C3 and C4 give the upper limit of the transmission power for the two types of users. Since the objective function of this problem is nonlinear and nonconvex, the global optimal solution cannot be directly obtained from the original problem.

[0177] Step S4: By optimizing the problem, obtain the power allocation scheme for the two types of users based on GP and approximate replacement optimization algorithms.

[0178] The objective function of a standard generalization problem is a positive term, so the objective function of the original problem needs to be transformed, hence:

[0179]

[0180] The four types of functions are defined as follows:

[0181]

[0182]

[0183]

[0184]

[0185] Problem P1 can be rewritten as:

[0186] P2:

[0187]

[0188]

[0189]

[0190] C8:P l '(P0)' -1 ≤1,l=1,...,J D ,

[0191] in, This represents the lower limit of SINR for cellular users. This represents the lower bound of SINR for D2D users, d f This represents the total number of subcarriers occupied by each cellular user.

[0192] The constraints of this optimization problem satisfy the standard form of GP. The objective function in problem P2 is the ratio of two positive terms. By simply replacing the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the replacement, the overall problem belongs to the standard GP problem, and a high-quality solution can be obtained using the CVX toolbox.

[0193] The present invention will now be described in more detail.

[0194] This invention provides a joint user power allocation design method for a cellular and D2D coexistence system, such as... Figure 1 As shown. For the communication process of uplink cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers, and these OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair selecting a different subcarrier.

[0195] Regarding data transmission from cellular users, suppose the transmitted signal of the j-th cellular user is represented as x. j =(x j1 ,x j2 ,...,x jK )T The signal y received at the base station will simultaneously contain data transmitted by both cellular users and D2D users, and its expression is:

[0196]

[0197] in, It is the channel vector between the j-th cellular user and the base station. It is the channel state information between the transmitter and the base station of the j-th D2D user pair, while x' j =(x' j1 ,x' j2 ,...,x' jK ) T It is a D2D transmitted codeword vector where only a single row of elements is non-zero. `n` represents an additive white Gaussian noise vector with a mean of 0 and a covariance matrix of N0I, where N0 represents the power spectral density of the noise and I is the identity matrix. Based on the optimal codebook design principle adopted by the SCMA system, two sets ξ can be defined according to the factor graph structure of SCMA. K and ζ J Therefore, for the base station, the received SINR of the j-th cellular user on the k-th subcarrier can be expressed as:

[0198]

[0199] Accordingly, the total reachable rate for cellular users is expressed as:

[0200]

[0201] Where, ξ k This represents the set of all cellular users occupying the k-th subcarrier, obtained from the factor graph structure of SCMA. P represents the channel state information between the j-th cellular user and the base station on the k-th subcarrier. jk This represents the transmit signal power of the j-th cellular user on the k-th subcarrier. P represents the channel state information between the transmitter and the base station of the D2D user pair on the k-th subcarrier. k ' represents the transmit signal power of the D2D user pair on the k-th subcarrier.

[0202] Regarding data transmission between D2D users, assuming the l-th D2D user pair uses the l-th subcarrier, and the transmitted signal from the D2D transmitter is x. l 'Then the expression for the received signal at the corresponding D2D receiver is:'

[0203]

[0204] in, This represents the channel state information between the l-th pair of D2D users. This represents the channel state information between the receivers of the j-th cellular user and the l-th D2D pair, ξ. l Let x represent the set of all cellular users occupying the l-th subcarrier, obtained from the factor graph structure of SCMA. jl This represents the SCMA codeword transmitted by the j-th cellular user on the l-th subcarrier, n l This also represents additive white Gaussian noise. Therefore, the SINR at the receiver of the l-th pair of D2D users during decoding can be expressed as:

[0205]

[0206] Accordingly, the expression for the total reachability rate of D2D users is:

[0207]

[0208] Among them, P l ' represents the transmit signal power of the D2D user pair on the l-th subcarrier, P jl This represents the transmit signal power of the j-th cellular user on the l-th subcarrier.

[0209] This invention designs a transmit power allocation scheme for two types of users, using maximizing the system's achievable sum and rate as the performance metric. The specific optimization problem can be formulated as follows:

[0210] P 1:

[0211]

[0212]

[0213]

[0214] C4:0≤P l '≤P0',l=1,...,J D ,

[0215] Among them, constraints C1 and C2 guarantee the QoS requirements of cellular users and D2D users respectively, that is, the corresponding SINR cannot be lower than the corresponding lower limit; constraints C3 and C4 give the upper limit of the transmission power for the two types of users. Since the objective function of this problem is nonlinear and nonconvex, the global optimal solution cannot be directly obtained from the original problem.

[0216] The power allocation scheme for the two types of users is designed based on GP and approximate replacement optimization algorithms.

[0217] The objective function of a standard generalization problem is a positive term, so we first need to transform the objective function of the original problem. Therefore:

[0218]

[0219] The four types of functions are defined as follows:

[0220]

[0221]

[0222]

[0223]

[0224] The original problem can be rewritten as:

[0225] P2:

[0226]

[0227]

[0228]

[0229] C8:P l '(P0)' -1 ≤1,l=1,...,J D ,

[0230] in, This represents the lower limit of SINR for cellular users. This represents the lower bound of SINR for D2D users, d f This represents the total number of subcarriers occupied by each cellular user.

[0231] It can be seen that the constraints of this optimization problem satisfy the standard form of Generalized ... To uniformly represent the two types of power P and P', the positive terms are expressed as the sum of monomials:

[0232]

[0233] Each monomial Represented as:

[0234]

[0235] Parameter c s >0, while parameters and The power variables of all users are real numbers. This means that after setting the initial values, the corresponding coefficients can be calculated during the i-th iteration:

[0236]

[0237] Therefore, the positive term in the denominator of the objective function in problem P2 can be represented by a monomial. Perform approximate replacement, where The replaced objective function becomes a completely positive term, and the overall problem belongs to the standard general problem (GP), from which a high-quality solution can be obtained using the CVX toolbox. The obtained solution is used as the initial value for the next iteration, thereby improving the accuracy of the next approximate replacement of the objective function. This iterative process can be proven to be completely convergent, and the final solution obtained is the globally optimal solution to problem P2. Therefore, a transmission power allocation scheme for two types of users is obtained.

[0238] Using J=6, K=4, and J D The software platform simulation was conducted for a scheme with a power ≤2. The channel model selected included a path loss model with a normalized Rayleigh fading factor and distance-dependent fading. The power limit for both cellular and D2D users was 30 dBm. The default SINR limit for cellular users was 0 dB, while the default SINR limit for D2D users was 10 dB. The noise power spectral density was -174 dB / Hz. Figure 2 and Figure 3 The performance of the proposed scheme was observed under different SINR constraints for different users. The proposed iterative algorithm was compared with a random allocation scheme for user power, considering scenarios with one pair of D2D users and two pairs of D2D users. As can be seen from the figures, the proposed scheme can perfectly allocate power to both types of users, thereby maximizing the sum-rate performance of the system, and has a significant performance improvement compared with other allocation schemes.

[0239] This invention provides a joint user power allocation design method and system for cellular and D2D coexistence systems. The aim is to improve system and rate performance by designing a suitable optimization algorithm to allocate user transmit power. Compared to traditional power allocation algorithms, it exhibits better performance; therefore, the system model for cellular and D2D user coexistence holds promise for application in next-generation wireless networks.

[0240] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0241] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A joint user power allocation design method in a cellular and D2D coexistence system, characterized in that, include: Communication between two types of users: cellular users and D2D users; In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers, and these OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair selecting a different subcarrier. Step S1: Analyze the data transmission of cellular users and obtain the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system. Step S2: Analyze the data transmission of D2D users and obtain the total achievable rate of D2D users; Step S3: Formulate a specific optimization problem based on the total reachable rate of cellular users and D2D users; Step S4: By optimizing the problem, obtain the power allocation schemes for the two types of users based on GP and approximate replacement optimization algorithms; Step S1 includes: analyzing the data transmission of cellular users, assuming the number of cellular users is... The number of D2D user pairs in the system is The total number of subcarriers occupied by cellular users is ;No. The transmitted signal of a cellular user is represented as The signal received at the base station The expression for transmitting data that includes both cellular and D2D users is: in, It is the first Channel vectors between cellular users and base stations It is the first For D2D users, the channel state information between the transmitter and the base station, and It is a D2D transmit codeword vector where only a single row of elements is non-zero. This represents an additive white Gaussian noise vector with a mean of 1. Its covariance matrix is , The power spectral density represents the noise. It is the identity matrix; The expression for the total reachable rate for cellular users is: For the base station side, the first The number of cellular users in the first The received SINR on each subcarrier is represented as: in, This indicates the occupancy of the factor graph structure obtained from SCMA. The set of all cellular users on each subcarrier. Indicates the first The first cellular user and base station relationship in the [number]th [period] Channel state information on each subcarrier Indicates the first The number of cellular users in the first The transmitted signal power on each subcarrier Indicates the first Channel state information between the transmitter and base station of the D2D user pair on each subcarrier. Indicates the first The transmit signal power of the pair of D2D users on each subcarrier; Step S2 includes: analyzing the data transmission of D2D users, assuming the first... For D2D users, the first The number of subcarriers and the transmitted signal from the D2D transmitter are: Then, the expression for the received signal at the corresponding D2D receiver is: in, It indicates the first Channel state information between D2D users, It indicates the first The cellular user and the Channel state information between the receivers of D2D users, This indicates the occupancy of the factor graph structure obtained from SCMA. The set of all cellular users on each subcarrier. Indicates the first The first subcarrier on the SCMA codewords sent by a cellular user This also represents additive Gaussian white noise; For the The SINR of the receiver at the D2D user during decoding is expressed as: The expression for the total reachability of D2D users is: in, Indicates the first The transmit signal power of the pair of D2D users on each subcarrier Indicates the first The number of cellular users in the first Transmitted signal power on each subcarrier; Step S3 includes: The specific optimization problem can be formulated as follows: in, P j Indicates the first j The transmit signal power of the pair of D2D users on each subcarrier is subject to constraints C1 and C2, which respectively guarantee the QoS requirements of cellular users and D2D users, meaning that the corresponding SINR cannot be lower than the corresponding lower limit; constraints C3 and C4 give the upper limit of the transmit power for the two types of users.

2. The joint user power allocation design method in a cellular and D2D coexistence system according to claim 1, characterized in that, Step S4 includes: the objective function of the standard GP problem is a positive term, so the objective function of the original problem needs to be transformed, thus: The four types of functions are defined as follows: question Rewritten as: in, This represents the lower limit of SINR for cellular users. This represents the lower limit of SINR for D2D users. This represents the total number of subcarriers occupied by each cellular user; The constraints of this optimization problem satisfy the standard form of Generalization. The objective function is the ratio of two positive terms. By simply replacing the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the replacement, the overall problem becomes a standard general problem, and a high-quality solution can be obtained using the CVX toolbox.

3. A joint user power allocation system for cellular and D2D coexistence systems, characterized in that, include: Communication between two types of users: cellular users and D2D users; In the communication process of cellular users, the data transmitted by each cellular user will be extended as SCMA codewords onto OFDM subcarriers, and these OFDM subcarriers will also be used for communication between D2D user pairs, with each D2D user pair selecting a different subcarrier. Module M1: Analyzes data transmission of cellular users and obtains the total achievable rate of cellular users based on the optimal codebook design principle of the SCMA system. Module M2: Analyzes data transmission between D2D users and obtains the total achievable rate of D2D users; Module M3: Formulates a specific optimization problem based on the total reachable rate of cellular users and D2D users; Module M4: Optimizes the power allocation schemes for two types of users using GP and approximate substitution optimization algorithms. The module M1 includes: analyzing data transmission of cellular users, assuming the number of cellular users is... The number of D2D user pairs in the system is The total number of subcarriers occupied by cellular users is ;No. The transmitted signal of a cellular user is represented as The signal received at the base station The expression for transmitting data that includes both cellular and D2D users is: in, It is the first Channel vectors between cellular users and base stations It is the first For D2D users, the channel state information between the transmitter and the base station, and It is a D2D transmit codeword vector where only a certain row of elements is non-zero; This represents an additive white Gaussian noise vector with a mean of 1. Its covariance matrix is , The power spectral density represents the noise. It is the identity matrix; The expression for the total reachable rate for cellular users is: For the base station side, the first The number of cellular users in the first The received SINR on each subcarrier is represented as: in, This indicates the occupancy of the factor graph structure obtained from SCMA. The set of all cellular users on each subcarrier. Indicates the first The first cellular user and base station relationship in the [number]th [period] Channel state information on each subcarrier Indicates the first The number of cellular users in the first The transmitted signal power on each subcarrier Indicates the first Channel state information between the transmitter and base station of the D2D user pair on each subcarrier. Indicates the first The transmit signal power of the pair of D2D users on each subcarrier; The module M2 includes: analyzing the data transmission of D2D users, assuming the first... For D2D users, the first The number of subcarriers and the transmitted signal from the D2D transmitter are: Then, the expression for the received signal at the corresponding D2D receiver is: in, It indicates the first Channel state information between D2D users, It indicates the first The cellular user and the Channel state information between the receivers of D2D users, This indicates the occupancy of the factor graph structure obtained from SCMA. The set of all cellular users on each subcarrier. Indicates the first The first subcarrier SCMA codewords sent by a cellular user This also represents additive Gaussian white noise; For the The SINR of the receiver at the D2D user during decoding is expressed as follows: The expression for the total reachability of D2D users is: in, Indicates the first The transmit signal power of the pair of D2D users on each subcarrier Indicates the first The number of cellular users in the first Transmitted signal power on each subcarrier; The module M3 includes: The specific optimization problem can be formulated as follows: in, P j Indicates the first j The transmit signal power of the pair of D2D users on each subcarrier is subject to constraints C1 and C2, which respectively guarantee the QoS requirements of cellular users and D2D users, meaning that the corresponding SINR cannot be lower than the corresponding lower limit; constraints C3 and C4 give the upper limit of the transmit power for the two types of users.

4. The joint user power allocation system under a cellular and D2D coexistence system according to claim 3, characterized in that, The module M4 includes: the objective function of the standard GP problem is a positive term, and the objective function of the original problem needs to be transformed, thus: The four types of functions are defined as follows: question Rewritten as: in, This represents the lower limit of SINR for cellular users. This represents the lower limit of SINR for D2D users. This represents the total number of subcarriers occupied by each cellular user; The constraints of this optimization problem satisfy the standard form of Generalization. The objective function is the ratio of two positive terms. By simply replacing the positive terms in the denominator with monomials, the objective function can be transformed into a complete positive term. After the replacement, the overall problem becomes a standard general problem, and a high-quality solution can be obtained using the CVX toolbox.

5. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the joint user power allocation design method under the cellular and D2D coexistence system as described in any one of claims 1 to 2.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by the processor, it implements the steps of the joint user power allocation design method under the cellular and D2D coexistence system as described in any one of claims 1 to 2.

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