A high energy-efficient transmission method based on non-orthogonal multiple access in industrial Internet environment

Abstract

The present invention proposes a high-energy-efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment. In the proposed communication system, the terminals are first divided into strong terminals and weak terminals according to the distance relationship between the terminals and the access points; then, under the condition of initial equal power allocation, the transmit beam matrix of each terminal is designed respectively; then, based on the obtained results, the optimal power allocation factor is designed and substituted into the previous optimization steps for iterative optimization; finally, when the total energy efficiency of the system converges, the global optimal solution of the terminal transmit beam matrix and the power allocation factor is obtained. The present invention utilizes the advantages of NOMA, and on the premise of ensuring the fairness of terminal communication, it not only improves the spectrum efficiency of the system, but also maximizes the energy efficiency of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial Internet, and specifically relates to a high-energy-efficiency transmission method based on non-orthogonal multiple access (Multiple Input Multiple Output-Non-Orthogonal Multiple Access, MIMO-NOMA) in an industrial Internet environment. Background Art

[0002] In the past few years, the Industrial Internet has been widely used in smart cities, smart homes, smart hospitals, self-driving cars and other fields. However, due to size and cost constraints, energy issues are a key challenge in Industrial Internet applications, especially for systems where replacing batteries for sensor devices is very expensive. Therefore, energy efficiency is a key indicator of the Industrial Internet. As an emerging technology, NOMA can serve multiple terminals simultaneously in the same resource block. By sending superposition coded signals at the transmitting end and demodulating them through continuous interference cancellation technology at the receiving end, it can achieve large-scale connections while ensuring communication fairness between terminals and significantly improving energy efficiency by multiplexing resources. Summary of the invention

[0003] The purpose of the present invention is to provide a high-energy-efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment, which utilizes the advantages of NOMA transmission to effectively improve the energy efficiency of the system while ensuring the fairness of terminal communication.

[0004] A high energy-efficient transmission method based on non-orthogonal multiple access in an industrial Internet environment comprises the following steps:

[0005] S1. Construct a multi-antenna wireless communication system based on non-orthogonal multiple access, wherein the multi-antenna wireless communication system includes an access point equipped with N antennas and two multi-antenna terminals; the two multi-antenna terminals are divided into a strong terminal and a weak terminal, wherein the strong terminal is equipped with n antennas and the weak terminal is equipped with m antennas;

[0006] S2. Design the optimal weak terminal transmit beam matrix according to the strong terminal transmit beam matrix;

[0007] S3, designing the optimal strong terminal transmit beam matrix Q2 according to the weak terminal transmit beam matrix optimized in S2;

[0008] S4, designing an optimal power allocation scheme according to the strong and weak terminal transmission beam matrices obtained in S2 and S3;

[0009] S5. Determine whether the energy efficiency of the multi-antenna wireless communication system converges under the current power allocation scheme. If so, output the current optimal strong and weak terminal transmit beam matrices and power allocation schemes. Otherwise, set Q2=P2Q2, Q1=(P-P2)Q1, and return to S2; where P2 is the optimal transmit power of the weak terminal, and P is the total transmit power of the access point.

[0010] Furthermore, in step S1, the channels between the access point and the strong and weak terminals are as follows:

[0011]

[0012] Where G1 represents the channel between the access point and the strong terminal, G2 represents the channel between the access point and the weak terminal; R i and T i denote the receiving antenna correlation matrix and the transmitting antenna correlation matrix in channel i respectively; X i and represent the random component and line-of-sight component of channel i respectively.

[0013] Furthermore, the initial transmission power allocation scheme for the strong and weak terminals in the multi-antenna wireless communication system is equal power allocation.

[0014] Furthermore, in step S2, the optimal weak terminal transmit beam matrix Q2 is:

[0015]

[0016] Where Λ2 is the diagonal matrix representing power allocation, is the matrix F2=(I N +K 21 Q1) -1 K 21 Perform singular value decomposition to obtain the eigenvector matrix and eigenvalue matrix; I N is the N×N identity matrix, μ2 is the parameter that makes Q2 satisfy the access point transmit power limit, (·) H represents the conjugate transpose of a matrix, (·) + It means taking the maximum value of the elements of the matrix in brackets compared with 0 and generating a new matrix, (·) -1 Indicates the inversion of the matrix; K 21 is the first auxiliary variable, σ 2 is the noise term, I m is the m×m identity matrix; is the equivalent channel parameter of the weak terminal, , T2 is the transmit antenna correlation matrix in the channel between the access point and the weak terminal, R2 is the receive antenna correlation matrix in the channel between the access point and the weak terminal, is the line-of-sight component of the channel between the access point and the weak terminal, tr{·} represents the trace of the matrix, and Q1 is the transmit beam matrix of the strong terminal.

[0017] Furthermore, in step S3, the optimal strong terminal transmit beam matrix is:

[0018]

[0019] Among them, Λ GSVD is a diagonal matrix representing the optimal power allocation. Performing generalized singular value decomposition, we get: and V GSVD is the eigenvector matrix obtained by generalized singular value decomposition, and is the eigenvalue matrix obtained by generalized singular value decomposition; matrices A, K1 and F1 are all channel approximate correlation matrices, F1=(I N +K 21 Q2) -1 K 21 , μ1 is the parameter that makes Q1 meet the access point transmission power limit, σ 2 is the noise term, I n is the n×n identity matrix, is Q1 before iterative optimization; K 22 is the second auxiliary variable, is the equivalent channel parameter of the strong terminal, Diagonal matrix Λ GSVD The kth diagonal element of

[0020]

[0021] Among them, λ K1,k , F1,k are the diagonal matrices Λ K1 ,Λ F1 The kth diagonal element in k is a matrix The kth diagonal element in .

[0022] Furthermore, in step S4, the design method of the power allocation scheme is as follows:

[0023] S401, let the initial value of the optimal transmission power P2 of the weak terminal be Lower bound of transmission power Upper bound of transmission power Update P using the golden section method L and P R : P L = P L + 0.382P R P R = P L + 0.618P R ; where is the transmission power of the weak terminal when the minimum traversal transmission rate is satisfied;

[0024] S402. Calculate the traversal transmission rates r1 and r2 of the strong and weak terminals. If r2 < r1, update P2 to P2 = P L , otherwise update P2 to P2 = P R . At this time, the optimal transmission power of the strong terminal is P1 = P - P2.

[0025] Furthermore, the calculation formulas for the traversal transmission rates r1 and r2 of the strong and weak terminals are respectively:

[0026]

[0027]

[0028] Furthermore, the convergence condition in step S5 is that the increase in the total energy efficiency of the multi-antenna wireless communication system is less than a set threshold.

[0029] Furthermore, the total energy efficiency η of the multi-antenna wireless communication system sum = η1 + η2, the energy efficiency of the strong terminal the energy efficiency of the weak terminal ξ represents the power amplification efficiency, and P0 represents the power consumed by the base station when sending signals;

[0030] Furthermore, the initial value of the transmission beam matrix of the strong terminal is an N×N identity matrix.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The present invention utilizes the advantages of NOMA transmission and establishes a more practical MIMO-NOMA communication system based on statistical channel state information;

[0033] 2. When designing the transmission beam matrix, the present invention considers the spatial correlation between the transmitting antenna and the receiving antenna, and at the same time designs the power allocation factor, so that the total energy efficiency of the system can be maximally improved. Description of the Drawings

[0034] Figure 1 is a flow chart of the present invention;

[0035] Figure 2 Schematic diagram of the MIMO-NOMA communication system in the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings.

[0037] In one embodiment, Figure 1 As shown, a high energy-efficient transmission method based on non-orthogonal multiple access in an industrial Internet environment is provided, comprising the following steps:

[0038] S1. Construct a multi-antenna wireless communication system based on non-orthogonal multiple access;

[0039] S2. Design the optimal weak terminal transmit beam matrix;

[0040] S3, design the optimal strong terminal transmit beam matrix;

[0041] S4. Design the optimal power allocation solution;

[0042] S5. Determine whether the energy efficiency of the multi-antenna wireless communication system converges under the current power allocation scheme. If so, output the current optimal strong and weak terminal transmit beam matrices and power allocation schemes. Otherwise, return to S2.

[0043] In one embodiment, Figure 2 As shown, the system in step S1 includes an access point equipped with N antennas and two multi-antenna terminals. According to the distance relationship between the access point and the terminal, the terminal is divided into a strong terminal and a weak terminal, wherein the strong terminal is equipped with n antennas and the weak terminal is equipped with m antennas. The channels between the access point and the strong and weak terminals are as follows:

[0044]

[0045] Where G1 represents the channel between the access point and the strong terminal, G2 represents the channel between the access point and the weak terminal; R i and T i denote the receiving antenna correlation matrix and the transmitting antenna correlation matrix in channel i respectively; X i and represent the random component and line-of-sight component of channel i respectively.

[0046] In one embodiment, in step S2, the design method of the optimal weak terminal transmit beam matrix is ​​as follows:

[0047] Assume that Q1 and Q2 are both N×N matrices, representing the transmit beam matrices of strong and weak terminals respectively, and the initial transmit power allocation scheme of the two terminals is equal power allocation. Given Q1 (the initial value is the unit matrix), design the optimal weak terminal transmit beam matrix Q2:

[0048]

[0049] Among them, Λ2 is a diagonal matrix representing power allocation, which is expressed as follows:

[0050]

[0051] in, is the matrix F2=(I N +K 21 Q1) -1 K 21 The eigenvector matrix and eigenvalue matrix obtained by singular value decomposition, I N is the N×N identity matrix, μ2 is the parameter that makes Q2 satisfy the access point transmission power limit, (·) H represents the conjugate transpose of a matrix; (·) + It means taking the maximum value of the elements of the matrix in brackets compared with 0 and generating a new matrix; (·) -1 Indicates the inversion of the matrix, K 21 is an auxiliary variable, and the expression is:

[0052]

[0053] Among them, σ 2 is the noise term, I m is the m×m identity matrix; are the equivalent channel parameters of the weak terminal, and their expressions are as follows:

[0054]

[0055]

[0056] Among them, tr means to find the trace of the matrix.

[0057] In one embodiment, in step S3, the design method of the optimal strong terminal transmit beam matrix is ​​as follows:

[0058] According to Q2 obtained in step 2, design the optimal strong terminal transmit beam matrix Q1:

[0059]

[0060] Among them, Λ GSVD is a diagonal matrix representing the optimal power allocation, which can be obtained by The generalized singular value decomposition is obtained. The specific generalized singular value decomposition form is:

[0061]

[0062]

[0063] in, and V GSVD is the eigenvector matrix obtained from the generalized singular values, and is the eigenvalue matrix obtained by generalized singular values. Matrices A, K1 and F1 are all channel approximate correlation matrices, and their expressions are as follows:

[0064]

[0065]

[0066] F1=(I N +K 21 Q2) -1 K 21 ,

[0067] Among them, I n is the n×n identity matrix, is Q1 before iterative optimization, K 22 To calculate the relevant auxiliary variables, as follows:

[0068]

[0069] in, are equivalent channel parameters, and their specific expressions are:

[0070]

[0071]

[0072]

[0073]

[0074] Diagonal matrix Λ GSVD The expression of the kth diagonal element of is:

[0075]

[0076] in, They are diagonal matrices The diagonal elements in μ1 are the parameters that make Q1 satisfy the access point transmit power limit, and ν k is a matrix The diagonal elements in

[0077] In one embodiment, in step S4, the power allocation scheme design method is as follows:

[0078] S401. Assume that the total transmission power of the access point is P, and the optimal transmission power P2 allocated to the weak terminal, then the optimal transmission power allocated to the strong terminal is P - P2;

[0079] S402. Let the initial value of the optimal transmission power P2 of the weak terminal be The transmission power of the weak terminal when meeting the minimum traversal transmission rate, that is When it satisfies:

[0080]

[0081] where r0 is the minimum transmission rate set for the normal communication of the terminal.

[0082] Let the power lower bound Power upper bound Use the golden section method to update P L and P R :

[0083] P L = P L + 0.382P R ,

[0084] P R = P L + 0.618P R ,

[0085] Calculate the traversal transmission rates r1 and r2 of the strong and weak terminals. If r2 < r1, then update P2 to P2 = P L , otherwise update P2 to P2 = P R . The traversal transmission rate r1 of the strong terminal is as follows:

[0086]

[0087] In one embodiment, step S5 is specifically: determine whether the energy efficiency of the multi - antenna wireless communication system converges under the current power allocation scheme. If so, output the current optimal transmission beam matrices and power allocation schemes of the strong and weak terminals. Otherwise, let Q2 = P2Q2, Q1 = (P - P2)Q1, and return to S2; where P2 is the optimal transmission power of the weak terminal and P is the total transmission power of the access point. The convergence condition is that the increase in the total energy efficiency of the multi - antenna wireless communication system is less than the set threshold. The total energy efficiency η of the system sum = η1 + η2, the energy efficiency of the strong terminal Energy efficiency of weak terminals ξ represents the power amplification efficiency, and P0 represents the power consumed when the base station sends a signal. In this embodiment, ξ=0.33.

[0088] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technology can understand and think of any changes or substitutions within the technical scope disclosed by the present invention, which should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment, characterized in that: The following steps are involved: S1. Construct a multi-antenna wireless communication system based on non-orthogonal multiple access, wherein the multi-antenna wireless communication system includes an access point equipped with N antennas and two multi-antenna terminals; the two multi-antenna terminals are divided into a strong terminal and a weak terminal, wherein the strong terminal is equipped with n antennas and the weak terminal is equipped with m antennas; S2. Design the optimal weak terminal transmit beam matrix according to the strong terminal transmit beam matrix; S3. Designing an optimal strong terminal transmit beam matrix according to the weak terminal transmit beam matrix optimized in S2; S4, designing an optimal power allocation scheme according to the strong and weak terminal transmit beam matrices Q1 and Q2 obtained in S2 and S3; S5. Determine whether the energy efficiency of the multi-antenna wireless communication system converges under the current power allocation scheme. If so, output the current optimal strong and weak terminal transmit beam matrices and power allocation schemes. Otherwise, set Q2 = P2Q2, Q1 = (P-P2)Q1, and return to S2. Among them, P2 is the optimal transmit power of the weak terminal, and P is the total transmit power of the access point; In step S2, the optimal weak terminal transmit beam matrix Q2 is: Where Λ2 is the diagonal matrix representing power allocation, is the matrix F2=(I N +K 21 Q1) -1 K 21 Perform singular value decomposition to obtain the eigenvector matrix and eigenvalue matrix; I N is the N×N identity matrix, μ2 is the parameter that makes Q2 satisfy the access point transmit power limit, (·) H represents the conjugate transpose of a matrix, (·) + It means taking the maximum value of the elements of the matrix in brackets compared with 0 and generating a new matrix, (·) -1 Indicates the inversion of the matrix; K 21 is the first auxiliary variable, σ 2 is the noise term, I m is the m×m identity matrix; is the equivalent channel parameter of the weak terminal, T2 is the transmit antenna correlation matrix in the channel between the access point and the weak terminal, R2 is the receive antenna correlation matrix in the channel between the access point and the weak terminal, G2 represents the channel between the access point and the weak terminal, is the line-of-sight component of the channel between the access point and the weak terminal, tr{·} represents the trace of the matrix, and Q1 is the transmit beam matrix of the strong terminal.

2. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 1 is characterized in that: In step S1, the channels between the access point and the strong and weak terminals are as follows: Where G1 represents the channel between the access point and the strong terminal, G2 represents the channel between the access point and the weak terminal; R i and T i denote the receiving antenna correlation matrix and the transmitting antenna correlation matrix in channel i respectively; X i and represent the random component and line-of-sight component of channel i respectively.

3. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 1 is characterized in that: The initial transmission power allocation scheme for strong and weak terminals in the multi-antenna wireless communication system is equal power allocation.

4. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 2 is characterized in that: In step S3, the optimal strong terminal transmit beam matrix is: Among them, Λ GSVD is a diagonal matrix representing the optimal power allocation. Performing generalized singular value decomposition, we get: and V GSVD is the eigenvector matrix obtained by generalized singular value decomposition, and is the eigenvalue matrix obtained by generalized singular value decomposition; matrices A, K1 and F1 are all channel approximate correlation matrices, F1=(I N +K 21 Q2) -1 K 21 , μ1 is the parameter that makes Q1 meet the access point transmission power limit, σ 2 is the noise term, I n is the n×n identity matrix, is Q1 before iterative optimization; K 22 is the second auxiliary variable, is the equivalent channel parameter of the strong terminal, G1 represents the channel between the access point and the strong terminal, G2 represents the channel between the access point and the weak terminal; R i and T i denote the receiving antenna correlation matrix and the transmitting antenna correlation matrix in channel i respectively; X i and Represent the random component and line-of-sight component of channel i, i = 1, 2, I m is the m×m identity matrix; the diagonal matrix Λ GSVD The kth diagonal element of in, They are diagonal matrices The kth diagonal element in k is a matrix The kth diagonal element in .

5. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 4 is characterized in that: In step S4, the design method of the power allocation scheme is as follows: S401, set the initial value of the optimal transmission power P2 of the weak terminal to P2 * , then the lower bound of the transmission power is Transmit power upper bound Update P using the golden section method L and P R :P L =P L +∑0.382P R , P R =P L +0.618P R ;in The transmit power of weak terminals when the minimum ergodic transmission rate is met; S402. Calculate the traversal transmission rates r1 and r2 of the strong and weak terminals. If r2 < r1, update P2 to P2 = P L , otherwise update P2 to P2 = P R . At this time, the optimal transmission power of the strong terminal is P1 = P - P2.

6. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 5, characterized in that: The calculation formulas for the ergodic transmission rates r1 and r2 of strong and weak terminals are: in is the equivalent channel parameter of the strong terminal, I m is the m×m identity matrix, I n is the n×n identity matrix, 7. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 1, characterized in that: The convergence condition in step S5 is that the increase in the total energy efficiency of the multi-antenna wireless communication system is less than a set threshold.

8. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 5, characterized in that: The total energy efficiency η of a multi-antenna wireless communication system sum =η1+η2, energy efficiency of strong terminal Energy efficiency of weak terminals ξ represents the power amplification efficiency, and P0 represents the power consumed when the base station sends a signal.

9. The high energy efficiency transmission method based on non-orthogonal multiple access in an industrial Internet environment according to claim 1, characterized in that: The initial value of the strong terminal transmission beam matrix is ​​an N×N identity matrix.

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