Rate-adjustable aircraft efficient data transmission method

Abstract

The invention discloses a high-efficiency data transmission method for an aircraft with an adjustable rate, and the method proposes the joint application of a rate splitting multiple access technology and a coherent beam forming technology, and also proposes a joint optimization problem, and the problem achieves the optimization of the rate of the aircraft under the condition that the rate requirement of the aircraft is met. The sum spectrum efficiency of the high-efficiency data transmission system of the aircraft with the adjustable speed is maximized; when an optimization problem is solved, a target problem is divided into three suboptimal problems, the suboptimal problems are solved respectively, then according to the solutions of the suboptimal problems, an iterative algorithm is adopted to approach the optimal solution of an original problem, and high-spectral-efficiency transmission of a multi-aircraft communication system is achieved. And the rate division of the optimal public flow, the optimal power distribution of the public flow and the private flow and the optimal aircraft scheduling scheme are obtained. Compared with the prior art, the method has the advantages that speed-adjustable aircraft data transmission is achieved in a speed splitting mode, application scenes with different transmission requirements can be met, and efficient data transmission between aircrafts is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft wireless communications, and in particular to a rate-adjustable aircraft efficient data transmission method. Background Art

[0002] With the development of wireless communication technology, aircraft application scenarios are becoming more and more extensive, resulting in increasingly tight spectrum resources. As the number of aircraft increases, efficient multi-user multiplexing technology is needed to meet the aircraft's requirements for service quality.

[0003] In order to achieve flexible interference management, a new multi-user multiplexing technology, rate division multiple access technology, is proposed. At present, more and more researches are being conducted on rate division multiple access technology. For example, rate division multiple access technology is applied to downlink multiple-input multiple-output systems to meet the needs of ultra-reliable and low-latency communication (S.Dey, T.Bharti, and R.Budhiraja, "RSMA in massive MIMO systems: analysis and optimization incorrelated Rician-faded channels with phase shifts and aging," IEEE Trans. Commun., vol.72, no.1, pp.239-256, Jan.2024.); a user pairing-based resource allocation algorithm is proposed to obtain the optimal decoding order for the rate division multiple access system with lower complexity (J.Hu, G.Liu, Z.Ma, M.Xiao, and P.Fan, "Low-complexity resource allocation for uplink RSMA in future 6G wireless networks," IEEE Commun.Lett., vol.13, no.2, pp.565-569, Feb.2024.).

[0004] In order to improve the system spectrum efficiency, scholars introduced coherent beamforming technology to eliminate the interference of other independent streams by designing beamforming vectors. The paper (S. Huang, H. Yin, H. Li, and VCM Leung, "Decremental user selection for large-scale multi-user MIMO downlink with zero-forcing beamforming," IEEE Commun. Lett., vol. 1, no. 5, pp. 480-483, Oct. 2012.) For multiple-input multiple-output channels, coherent beamforming is used to assist the decremental user selection strategy to obtain a higher sum rate. In order to improve the performance of wireless relay networks, the paper (H.Gao, T.Lv, S.Zhang, C.Yuen, and S.Yang, “Zero-forcing based MIMO two-way relay with relay antenna selection: transmission scheme anddiversity analysis,” IEEE Trans.Commun., vol.11, no.12, pp.4426-4437, Dec.2012.) proposes the optimization problem of coherent beamforming, while considering the diversity gain introduced by multi-user selection, improving system and spectrum efficiency, and obtaining the user with the largest signal-to-noise ratio from the candidate users for transmission.

[0005] Currently, there is no research on how to simultaneously obtain the advantages of rate division multiple access technology and coherent beamforming technology, so as to improve the spectrum efficiency of the system while flexibly managing interference. Summary of the invention

[0006] The object of the present invention is to provide a method for efficient data transmission of an aircraft with adjustable rate, so as to maximize the efficiency of the system and spectrum of efficient data transmission of an aircraft with adjustable rate while meeting the rate requirements of the aircraft in the air.

[0007] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0008] A method for efficient data transmission of an aircraft with adjustable rate, wherein the aircraft data transmission system targeted by the method includes an information transmitting aircraft and multiple information receiving aircraft; the method includes:

[0009] Step 1: The transmitting aircraft splits the message. Suppose the message to be transmitted by the receiving aircraft k is 1≤k≤K, K represents the total number of receiving aircraft, and the transmitting aircraft will receive the kth receiving aircraft u k Messages to be transmitted The public part messages of K receiving aircraft are then combined into a public message x c , and encode it into a common stream s c ;s c Contains part of the message that needs to be transmitted by each aircraft, and the private part message x k Then they are encoded into K private streams, namely {s1,s2,…,s k ,…,s K}; Public and private streams α It is expressed as:

[0010]

[0011] where α=k,c, represents the expectation, * represents the conjugate; x α Indicates a public message or a private part of a message, w α represents the coherent beamforming vector, (·) T This means to find the transpose:

[0012]

[0013] Where N T Represents the total number of transmitting antennas of the aircraft, n t (1≤n t ≤N T ) represents the ntth transmitting antenna of the aircraft, Represents the nth t coherent beamforming elements on the transmit antennas, Represents 1×N t dimensional complex space; α Designed for:

[0014]

[0015] Where h represents the channel matrix between the transmitting aircraft and the receiving aircraft. and(·) H denote the pseudo-inverse and conjugate transpose of a matrix respectively;

[0016] Step 2: The message transmitting aircraft allocates power to the public flow and the private flow to achieve power reuse. The transmitted signal s after power allocation is expressed as:

[0017]

[0018] Where P c represents the power allocated to the common flow, P k represents the power allocated to the kth private flow, P j represents the power allocated to the jth (j∈K, j≠k) private flow, s j represents the jth (j∈K, j≠k) private flow;

[0019] Step 3, Definition is the information transmitting aircraft and the kth information receiving aircraft u k The channel matrix between them, then the received signal y of the kth receiving information aircraft is k for:

[0020]

[0021] Where z k The variance is σ 2 Additive white Gaussian noise AWGN;

[0022] Step 4: The kth receiving aircraft u k Using serial interference cancellation, the public stream is first decoded and the private stream is treated as noise; the decoded public stream γ c,k The signal-to-noise ratio is:

[0023]

[0024] Where w c represents the coherent beamforming vector of the common stream, w j represents the coherent beamforming vector of the jth (j∈K) private stream;

[0025] Step 5: The kth receiving aircraft u k Successfully decoded public stream s c After that, the decoded common stream is sent from the received signal y k Then, for u k Decode the private stream of u j The private stream of (j∈K,j≠k) is treated as noise; the signal-to-noise ratio of the private stream decoded by the kth receiving aircraft is γ p,k for:

[0026]

[0027] Step 6: The public flow and private flow rates that can be achieved by the kth receiving aircraft are:

[0028] R c,k =log2(1+γ c,k )

[0029] R p,k =log2(1+γ p,k )

[0030] Set the rate of the public flow to:

[0031] R c =min{R c,k}

[0032] The common partial rate μ of the kth aircraft k satisfy:

[0033]

[0034] The spectral efficiency of the kth aircraft is expressed as:

[0035]

[0036] Step 7: Construct the spectrum efficiency model ψ of the aircraft data transmission system sum for:

[0037]

[0038] For the above and spectral efficiency models ψ sum An optimization problem is constructed and solved to obtain the optimal pairing of receiving aircraft, the common part rate of receiving aircraft, the common flow and the power allocation scheme of the optimal pairing of receiving aircraft.

[0039] Furthermore, for the above spectrum efficiency model ψ sum Construct an optimization problem, where the objective function of the optimization problem is expressed as:

[0040]

[0041] in represents the power allocated to the public flow and the private flow of the kth receiving aircraft and the k′th receiving aircraft; (u k ,u k' )(0≤k′≤K, k′≠k) represents the two selected information receiving aircraft that communicate with the information transmitting aircraft.

[0042] Furthermore, the constraints of the objective function include:

[0043] C1:l1=R c -μ k -μ k′ ≥0

[0044] C2:l2=μ k ,μ k′ ≥0

[0045]

[0046] C4:l3=P c ,P k ,P k′ ≥0

[0047]

[0048] C7:l6=P c -P k -P k′ -P Δ ≥0

[0049]

[0050] Where R c =min{R c,k ,R c,k′},μ k , μ k′ denote the common part rate of the kth receiving aircraft and the k′th receiving aircraft respectively. In order to ensure that each aircraft can successfully decode the common stream, the common stream R c The rate is no greater than the common flow rate R that can be achieved by the kth and k′th receiving aircraft. c,k and R c,k′ The minimum value of P Σ is the total transmission power of the transmitting aircraft, P c represents the power allocated to the common flow, P k ,P k′ denote the private flow powers allocated to the kth information receiving aircraft and the k′th information receiving aircraft respectively; represents the spectrum efficiency of the k′th receiving aircraft, and represents the minimum required rate of the kth receiving aircraft and the k′th receiving aircraft; P Δ represents the minimum power difference between the public flow and the private flow; According to the feedback signal-to-noise ratio, a pairing set of aircraft receiving information is obtained from the candidate A pair of receiving aircraft is selected for message transmission.

[0051] Furthermore, the optimization problem is decomposed into three sub-optimization problems for solution, where:

[0052] The first sub-optimization problem is the rate division and power allocation problem of the common flow. This problem aims to maximize the objective function μ k , μ k′ and P cis the target, and the constraints are C1 to C7;

[0053] The second sub-optimization problem is the power allocation problem of private flows. This problem aims to maximize the objective function P k ,P k′ is the target, and the constraints are C1-C7;

[0054] The third sub-optimization problem is the aircraft scheduling problem, which aims to find the pairing of receiving information aircraft (u k ,u k' ) is the target, and the constraints are C5, C6, and C8.

[0055] Furthermore, in the first sub-optimization problem, the KKT condition is introduced to solve the problem, which is expressed as follows:

[0056]

[0057] Auxiliary parameters representing KKT conditions; i and i′ are labels of constraints;

[0058] By solving the above formula, we can get μ k and P c Candidate solution μ k and P c ; According to C1-C7, we get μ k and P c Therefore, compare the values ​​of the objective function Φ1 at the KKT candidate solution and the boundary point, and then select μ k and P c The maximum sum and its corresponding solution are taken as the final solution.

[0059] Furthermore, in the second sub-optimization problem, the KKT condition is introduced to solve the problem, which is expressed as follows:

[0060]

[0061] According to the above formula, P k and P k′ The candidate solution (P k ,P k′ ), P k and P k′ The boundary points of can be obtained by constraints C3-C7, which are respectively represented as the left boundary points and right boundary point Calculate the value and boundary points of the objective function Φ2 under KKT conditions, and then select the point with the largest Φ2 value as the final solution.

[0062] Furthermore, in the third sub-optimization problem, the receiving aircraft with the largest channel gain and the second largest channel gain are selected for transmission. Let these two receiving aircraft be u max ,u max′ ; In order to get u max and u max′ The order of arrangement, assuming:

[0063]

[0064]

[0065] in, and Respectively represent u max and u max′ The channel gain of

[0066] when When max ,u max′ ) is the optimal strategy of the system; when δ<0, choose (u max ,u max′ ) as the pairing method for the final aircraft.

[0067] Furthermore, the three sub-optimization problems are solved by the following joint iterative algorithm:

[0068] Step 1, initialization: set the number of candidate receiving aircraft U, select the receiving aircraft pair (u k ,u k' ), the public part rate μ of the receiving aircraft k and μ k' , the power allocated to the public flow and the kth receiving aircraft, the power allocated to the private flow of the k′th receiving aircraft The power of AWGN noise σ 2 and the corresponding precoding vector w k , w k′ ;

[0069] Step 2, three-layer iteration: In order to obtain the optimal solution to the optimization problem, a three-layer iteration algorithm is used, as shown below:

[0070] (1) Common flow layer: Determine the common sub-part μ k , μ k′ The rate of the public flow P c Power;

[0071] (2) Private flow layer: Allocate power to P k and P k′ two private streams;

[0072] (3) Receive information aircraft pairing layer: select the optimal aircraft pairing strategy for the aircraft efficient data transmission system;

[0073] Computation: Computational and spectral efficiency;

[0074] Step 3, comparison process: compare the sum spectral efficiency with the sum spectral efficiency of the previous iteration;

[0075] Step 4, output: output the maximum and spectrum efficiency, the optimal receiving information aircraft pairing, the common part rate of the receiving information aircraft, the power allocation scheme parameters of the common stream and the optimal receiving information aircraft pairing.

[0076] A terminal device comprises a processor, a memory and a computer program stored in the memory; when the processor executes the computer program, the rate-adjustable aircraft efficient data transmission method is implemented.

[0077] A computer-readable storage medium stores a computer program; when the computer program is executed by a processor, the method for efficient data transmission of an aircraft with adjustable rate is implemented.

[0078] Compared with the prior art, the present invention has the following technical features:

[0079] Compared with traditional aircraft information transmission solutions, the present invention realizes rate-adjustable aircraft data transmission in a rate-splitting manner, can cope with application scenarios with different transmission requirements, and realizes efficient data transmission between aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 The schematic diagram of the efficient data transmission system for aircraft with adjustable rate is shown;

[0081] Figure 2 This is the trend diagram of aircraft spectrum efficiency changing with signal-to-noise ratio;

[0082] Figure 3 The spectrum efficiency of the rate-adjustable aircraft university data transmission scheme and the fixed parameter scheme proposed in the present invention is compared. DETAILED DESCRIPTION

[0083] The rate splitting multiple access technology can dynamically split the aircraft information rate to meet the variable rate data transmission requirements of the aircraft. Therefore, the present invention proposes a rate-adjustable aircraft efficient data transmission method, which jointly applies the rate splitting multiple access technology and the coherent beamforming technology, and proposes a joint optimization problem, which maximizes the sum spectrum efficiency of the rate-adjustable aircraft efficient data transmission system while meeting the rate requirements of the aircraft in the air.

[0084] The present invention proposes a joint optimization problem of maximizing and spectrum efficiency under the premise of meeting the communication rate requirements of different aircraft. The target problem is divided into three suboptimal problems, and the suboptimal problems are solved separately. Then, according to the solutions of the suboptimal problems, an iterative algorithm is used to approximate the optimal solution of the original problem.

[0085] The present invention is applied to multi-aircraft scenarios with limited spectrum resources. The coherent beamforming technology is introduced into the rate division multiple access technology to achieve high spectral efficiency transmission of multi-aircraft communication systems, and obtain the optimal rate division of public flows, the optimal power allocation of public and private flows, and the optimal aircraft scheduling solution.

[0086] Assume that the aircraft data transmission system includes 1 information transmitting aircraft and U information receiving aircraft. The information transmitting aircraft selects K aircraft from the U information receiving aircraft for communication. The information transmitted by the information transmitting aircraft is the information that the selected K aircraft need to transmit. The specific steps are as follows:

[0087] Step 1: The transmitting aircraft splits the message to achieve flexible interference management; suppose the message to be transmitted by the receiving aircraft k (1≤k≤K) is The transmitting aircraft will receive the kth information from the receiving aircraft u k Messages to be transmitted The public part messages of K receiving aircraft are then combined into a public message x c , and encode it into a common stream s c ;s c Contains part of the message that needs to be transmitted by each aircraft, and the private part message x k Then they are encoded into K private streams, namely {s1,s2,…,s k ,…,s K}, where the subscript c represents the parameters of the public flow, and the subscript k represents the parameters of the kth aircraft. Therefore, the public flow and the private flow s α It is expressed as:

[0088]

[0089] where α=k,c, represents the expectation, * represents the conjugate; x α Indicates a public message or a private part of a message, w α represents the coherent beamforming vector, (·) T This means to find the transpose:

[0090]

[0091] Where N TRepresents the total number of transmitting antennas of the aircraft, n t (1≤n t ≤N T ) represents the ntth transmitting antenna of the aircraft, Represents the nth t coherent beamforming elements on the transmit antennas, Represents 1×N t dimensional complex space.

[0092] In order to obtain the interference-free characteristic of coherent beamforming, w α Designed for:

[0093]

[0094] Where h represents the channel matrix between the transmitting aircraft and the receiving aircraft. and(·) H denote the pseudo-inverse and conjugate transpose of a matrix, respectively.

[0095] Step 2: The transmitting aircraft allocates power to the public flow and the private flow to achieve power reuse and improve spectrum efficiency. The transmitted signal s after power allocation can be written as:

[0096]

[0097] Where P c represents the power allocated to the common flow, P k represents the power allocated to the kth private flow, P j represents the power allocated to the jth (j∈K, j≠k) private flow, s j Represents the j-th (j∈K, j≠k) private stream.

[0098] Step 3, Definition is the information transmitting aircraft and the kth information receiving aircraft u k The channel matrix between them, then the received signal y of the kth receiving information aircraft is k for:

[0099]

[0100] Where z k The variance is σ 2 Additive White Gaussian Noise (AWGN).

[0101] Step 4: The kth receiving aircraft u k Using the serial interference cancellation (SIC) method, the public stream is first decoded and the private stream is treated as noise; the decoded public stream γ c,k The signal-to-noise ratio is:

[0102]

[0103] Where w c represents the coherent beamforming vector of the common stream, w j represents the coherent beamforming vector of the jth (j∈K) private stream.

[0104] Step 5: The kth receiving aircraft u k Successfully decoded public stream s c After that, the decoded common stream is sent from the received signal y k Then, for u k Decode the private stream of u j The private stream of (j∈K,j≠k) is treated as noise. The signal-to-noise ratio of the private stream decoded by the kth receiving aircraft is γ p,k for:

[0105]

[0106] Step 6: The public flow and private flow rates that can be achieved by the kth receiving aircraft are:

[0107] R c,k =log2(1+γ c,k )

[0108] R p,k =log2(1+γ p,k )

[0109] To ensure public flow c To be successfully decoded by each receiving aircraft, set the rate of the public stream to:

[0110] R c =min{R c,k}

[0111] Since the common streams transmitted c Contains sub-messages of K aircraft, so the common part rate μ of the kth aircraft k satisfy:

[0112]

[0113] The spectral efficiency of the kth aircraft is expressed as:

[0114]

[0115] Step 7: The spectrum efficiency model of the aircraft data transmission system ψ sum for:

[0116]

[0117] According to the above description, the rate division, power allocation and aircraft scheduling strategy of the common flow affect the overall spectrum efficiency of the system.

[0118] For the above and spectral efficiency models ψ sum An optimization problem is constructed and solved to obtain the optimal information receiving aircraft pairing, the common part rate of the information receiving aircraft, the common flow and the power allocation scheme of the optimal information receiving aircraft pairing.

[0119] In order to retain the generality, the following takes K = 2 as an example; when K ≥ 3, the analysis results are similar. This scheme proposes an optimization problem, and the details of the optimization problem and constraints are as follows:

[0120] A. Objective Function

[0121] Considering the maximization of the system's spectral efficiency, the objective function is expressed as:

[0122]

[0123] in represents the power allocated to the public flow and the private flow of the kth receiving aircraft and the k′th receiving aircraft; (u k ,u k' )(0≤k′≤K,k′≠k) represents the two selected information receiving aircraft that communicate with the information transmitting aircraft; the meaning of the parameters with subscript k′ is the same as the relevant parameters with subscript k, which will not be repeated.

[0124] B. Constraints

[0125] The objective function has several constraints, as follows:

[0126] Common flow rate constraints:

[0127] C1:l1=R c -μ k -μ k′ ≥0

[0128] C2:l2=μ k ,μ k′ ≥0

[0129] Where R c =min{R c,k ,R c,k′},μ k , μ k′ denote the common part rate of the kth receiving aircraft and the k′th receiving aircraft respectively. In order to ensure that each aircraft can successfully decode the common stream, the common stream R cThe rate is no greater than the common flow rate R that can be achieved by the kth and k′th receiving aircraft. c,k and R c,k′ The minimum value of .

[0130] Power allocation constraints:

[0131]

[0132] C4:l3=P c ,P k ,P k′ ≥0

[0133] Where P Σ is the total transmission power of the transmitting aircraft, P c represents the power allocated to the common flow, P k ,P k′ They represent the private flow powers allocated to the kth information receiving aircraft and the k′th information receiving aircraft respectively.

[0134] Aircraft minimum QoS constraints:

[0135]

[0136] in represents the spectrum efficiency of the k′th receiving aircraft, and It represents the minimum required rate of the kth receiving aircraft and the k′th receiving aircraft.

[0137] SIC decoding constraints:

[0138] C7:l6=P c -P k -P k′ -P Δ ≥0

[0139] Where P Δ Indicates the minimum power difference between the public flow and the private flow.

[0140] Select the vehicle pairing constraints to transfer:

[0141]

[0142] in According to the feedback signal-to-noise ratio, a pairing set of aircraft receiving information is obtained from the candidate A pair of receiving aircraft is selected for message transmission.

[0143] Based on the description of the above objective function and constraints, an optimization problem is proposed to maximize the system and spectrum efficiency as follows:

[0144]

[0145] stC1-C8

[0146] Since the proposed optimization problem is non-convex, it is difficult to directly obtain the optimal solution; therefore, consider decomposing the original problem into three sub-optimization problems.

[0147] a. Rate division and power allocation of public flows

[0148] Private Stream P k ,P k′ and receiving information aircraft pair (u k ,u k' ) is fixed, the original optimization problem ψ sum Simplified to a problem of rate division and power allocation considering common flows The details are as follows:

[0149]

[0150] st

[0151] C1:l1=R c -μ k -μ k′ ≥0

[0152] C2:l2=μ k ,μ k′ ≥0

[0153]

[0154] C4:l3=P c ,P k ,P k′ ≥0

[0155]

[0156] C7:l6=P c -P k -P k′ -P Δ ≥0

[0157] To solve this suboptimization problem, the subproblem under the Karush-Kuhn-Tucker (KKT) condition is introduced as follows:

[0158]

[0159] Auxiliary parameters representing KKT conditions; i and i′ are labels of the constraints.

[0160] By solving the above formula, we can get the candidate solution μ k and P c According to C1-C7, we get μ k and P c Therefore, compare the values ​​of the objective function Φ1 at the KKT candidate solution and the boundary point, and then select μ k and P c The maximum sum and its corresponding solution are taken as the final solution.

[0161] b. Power allocation problem of private flows

[0162] Given the rate division and power allocation of public flows, the optimization problem degenerates into the power allocation problem of private flows. According to the monotonicity of logarithms and the expression of spectral efficiency, the sub-optimization problem is:

[0163]

[0164] st

[0165]

[0166] C4:l3=P c ,P1,P2≥0

[0167]

[0168] C7:l6=P c -P k -P k′ -P Δ ≥0

[0169] Since constraints C3-C7 are k and P k′ is convex, so the KKT equation is:

[0170]

[0171] in Auxiliary parameters representing KKT conditions; i1 and i′ are labels of the restriction conditions.

[0172] According to the above formula, P k and P k′ The candidate solution (P k ,P k′ ), P k and P k′ The boundary points of can be obtained by constraints C3-C7, which are respectively represented as the left boundary points and right boundary point Calculate the value and boundary points of the objective function Φ2 under KKT conditions, and then select the point with the largest Φ2 value as the final solution.

[0173] c. Aircraft Scheduling Problem

[0174] When the rate division and power allocation are fixed, the original optimization problem is simplified to the aircraft pairing problem, namely:

[0175]

[0176] stC5,C6,C8

[0177] Function Φ3 for channel gain ‖h k ‖ and ‖h k′ The partial derivative of ‖ is:

[0178]

[0179] From the above formula, we can see that It shows that as ‖h k ‖ and ‖h k′ As the value of ‖ increases, the function ψ3 shows an upward trend. Therefore, we consider selecting the receiving aircraft with the largest channel gain and the second largest channel gain for transmission. Let these two receiving aircraft be u max ,u max′ ; In order to get u max and u max′ The order of arrangement, assuming:

[0180]

[0181] in, and Respectively represent u max and u max′ The channel gain.

[0182] when When max ,u max′ ) is the optimal strategy of the system; when δ<0, choose (u max ,u max′ ) as the pairing method for the final aircraft.

[0183] In order to jointly solve the above three sub-optimization problems, a joint iterative algorithm is proposed as follows:

[0184] Step 1, initialization: set the number of candidate receiving aircraft U, select the receiving aircraft pair (u k ,u k' ), the public part rate μ of the receiving aircraft k and μ k' , the power allocated to the public flow and the kth receiving aircraft, the power allocated to the private flow of the k′th receiving aircraft The power of AWGN noise σ 2 and the corresponding precoding vector w k , w k′ .

[0185] Step 2, three-layer iteration: In order to obtain the optimal solution to the optimization problem, a three-layer iteration algorithm is used, as shown below:

[0186] (1) Common flow layer: Determine the common sub-part μ k , μ k′ The rate of the public flow P c Power;

[0187] (2) Private flow layer: Allocate power to P k and P k′ two private streams;

[0188] (3) Receive information aircraft pairing layer: select the optimal aircraft pairing strategy for the aircraft efficient data transmission system.

[0189] Computation: Computational and spectral efficiency.

[0190] Step 3, comparison process: compare the sum spectral efficiency with the sum spectral efficiency of the previous iteration.

[0191] Step 4, output: output parameters such as maximum and spectrum efficiency, optimal receiving information aircraft pairing, common part rate of receiving information aircraft, power allocation scheme of common stream and optimal receiving information aircraft pairing.

[0192] Through the above joint iterative algorithm, all parameters including aircraft pairing and power allocation are determined.

[0193] Figure 1 The system is an efficient data transmission system for aircraft with adjustable rate. The system includes 1 signal transmitting aircraft and U (U ≥ 3) aircraft waiting for service, where the signal transmitting aircraft serves k aircraft during the transmission process. The signal transmitting aircraft is configured as N T (N T ≥2) transmitting antennas, and each waiting service aircraft is equipped with 1 receiving antenna. The transmitting aircraft sends a pilot signal, and the waiting service aircraft calculates and feeds back the received signal-to-noise ratio. The transmitting aircraft selects K (K≥2) aircraft with the largest signal-to-noise ratio for transmission, and improves the spectrum efficiency of the aircraft efficient data transmission system through multi-user diversity.

[0194] Figure 2The total spectrum efficiency of the system, the spectrum efficiency of the kth aircraft and the k'th aircraft under different signal-to-noise ratios are compared. As can be seen from the figure, with the increase of the signal-to-noise ratio, all curves show an upward trend. The figure shows the performance of the spectrum efficiency of the system under the algorithm proposed by the present invention.

[0195] Figure 3 This is a comparison chart of the system and spectrum efficiency of the system using the rate division and power allocation coefficient method of a fixed common stream and the joint iterative algorithm of the present invention. The results show that the curve of the optimal rate and power allocation scheme obtained by the joint iterative algorithm adopted by the present invention is higher than that of the fixed scheme, which shows the superiority of the proposed joint iterative algorithm, and it can obtain higher system and spectrum efficiency than the fixed scheme.

[0196] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for efficient data transmission of an aircraft with adjustable rate, characterized in that: The method is directed to an aircraft data transmission system including an information transmitting aircraft and a plurality of information receiving aircraft; the method includes: Step 1: The transmitting aircraft splits the message. Suppose the message to be transmitted by the receiving aircraft k is K represents the total number of aircraft receiving information. The transmitting aircraft will receive the kth aircraft u k Messages to be transmitted The public part messages of K receiving aircraft are then combined into a public message x c , and encode it into a common stream s c ;s c Contains part of the message that needs to be transmitted by each aircraft, and the private part message x k Then they are encoded into K private streams, namely {s1,s2,…,s k ,…,s K }; Public and private streams α It is expressed as: where α=k,c, represents the expectation, * represents the conjugate; x α Indicates a public message or a private part of a message, w α represents the coherent beamforming vector, (·) T This means to find the transpose: Where N T Represents the total number of transmitting antennas of the aircraft, n t (1≤n t ≤N T ) represents the ntth transmitting antenna of the aircraft, Represents the nth t coherent beamforming elements on the transmit antennas, Represents 1×N t dimensional complex space; α Designed for: Where h represents the channel matrix between the transmitting aircraft and the receiving aircraft. and(·) H denote the pseudo-inverse and conjugate transpose of a matrix respectively; Step 2: The message transmitting aircraft allocates power to the public flow and the private flow to achieve power reuse. The transmitted signal s after power allocation is expressed as: Where P c represents the power allocated to the common flow, P k represents the power allocated to the kth private flow, P j represents the power allocated to the jth (j∈K, j≠k) private flow, s j represents the jth (j∈K, j≠k) private flow; Step 3, Definition is the information transmitting aircraft and the kth information receiving aircraft u k The channel matrix between them, then the received signal y of the kth receiving information aircraft is k for: Where z k The variance is σ 2 Additive white Gaussian noise AWGN; Step 4: The kth receiving aircraft u k Using serial interference cancellation, the public stream is first decoded and the private stream is treated as noise; the decoded public stream γ c,k The signal-to-noise ratio is: Where w c represents the coherent beamforming vector of the common stream, w j represents the coherent beamforming vector of the jth (j∈K) private stream; Step 5: The kth receiving aircraft u k Successfully decoded public stream s c After that, the decoded common stream is sent from the received signal y k Remove it; then, for u k Decode the private stream of u j The private stream of (j∈K,j≠k) is treated as noise; the signal-to-noise ratio of the private stream decoded by the kth receiving aircraft is γ p,k for: Step 6: The public flow and private flow rates that can be achieved by the kth receiving aircraft are: R c,k =log2(1+γ c,k ) R p,k =log2(1+γ p,k ) Set the rate of the public flow to: R c =min{R c,k } The common partial rate μ of the kth aircraft k satisfy: The spectral efficiency of the kth aircraft is expressed as: Step 7: Construct the spectrum efficiency model ψ of the aircraft data transmission system sum for: For the above and spectral efficiency models ψ sum An optimization problem is constructed and solved to obtain the optimal pairing of receiving aircraft, the common part rate of receiving aircraft, the common flow and the power allocation scheme of the optimal pairing of receiving aircraft.

2. The method for efficient data transmission of an aircraft with adjustable rate according to claim 1, characterized in that: For the above and spectral efficiency models ψ sum Construct an optimization problem, where the objective function of the optimization problem is expressed as: in represents the power allocated to the public flow and the private flow of the kth receiving aircraft and the k′th receiving aircraft; (u k ,u k' )(0≤k′≤K, k′≠k) represents the two selected information receiving aircraft that communicate with the information transmitting aircraft.

3. The method for efficient data transmission of an aircraft with adjustable rate according to claim 2, characterized in that: The constraints of the objective function include: C1:l1=R c -m k -m k′ ≥0 C2:l2=μ k ,m k′ ≥0 C3: C4:l3=P c ,P k ,P k′ ≥0 C5: C6: C7:l6=P c -P k -P k′ -P Δ ≥0 C8: Where R c =min{R c,k ,R c,k′ },μ k , μ k′ denote the common part rate of the kth receiving aircraft and the k′th receiving aircraft respectively. In order to ensure that each aircraft can successfully decode the common stream, the common stream R c The rate is no greater than the common flow rate R that can be achieved by the kth and k′th receiving aircraft. c,k and R c,k′ The minimum value of P Σ is the total transmission power of the transmitting aircraft, P c represents the power allocated to the common flow, P k ,P k′ denote the private flow powers allocated to the kth information receiving aircraft and the k′th information receiving aircraft respectively; represents the spectrum efficiency of the k′th receiving aircraft, and represents the minimum required rate of the kth receiving aircraft and the k′th receiving aircraft; P Δ represents the minimum power difference between the public flow and the private flow; According to the feedback signal-to-noise ratio, a pairing set of aircraft receiving information is obtained from the candidate A pair of receiving aircraft is selected for message transmission.

4. The method for efficient aircraft data transmission with adjustable rate according to claim 3, characterized in that: The optimization problem is decomposed into three sub-optimization problems for solution, where: The first sub-optimization problem is the rate division and power allocation problem of the common flow. This problem aims to maximize the objective function μ k , μ k′ and P c is the target, and the constraints are C1 to C7; The second sub-optimization problem is the power allocation problem of private flows. This problem aims to maximize the objective function P k ,P k′ is the target, and the constraints are C1-C7; The third sub-optimization problem is the aircraft scheduling problem, which aims to find the pairing of receiving information aircraft (u k ,u k' ) is the target, and the constraints are C5, C6, and C8.

5. The method for efficient aircraft data transmission with adjustable rate according to claim 4, characterized in that: In the first sub-optimization problem, the KKT condition is introduced to solve the problem, which is expressed as follows: Auxiliary parameters representing KKT conditions; i and i′ are labels of constraints; By solving the above formula, we can get μ k and P c Candidate solution μ k and P c ; According to C1-C7, we get μ k and P c Therefore, compare the values ​​of the objective function Φ1 at the KKT candidate solution and the boundary point, and then select μ k and P c The maximum sum and its corresponding solution are taken as the final solution.

6. The method for efficient aircraft data transmission with adjustable rate according to claim 4, characterized in that: In the second sub-optimization problem, the KKT condition is introduced to solve the problem, which is expressed as follows: According to the above formula, P k and P k′ The candidate solution (P k ,P k′ ), P k and P k′ The boundary points of can be obtained by constraints C3-C7, which are respectively represented as the left boundary points and right boundary point Calculate the value and boundary points of the objective function Φ2 under KKT conditions, and then select the point with the largest Φ2 value as the final solution.

7. The method for efficient aircraft data transmission with adjustable rate according to claim 4, characterized in that: In the third sub-optimization problem, the receiving aircraft with the largest channel gain and the second largest channel gain are selected for transmission. Let these two receiving aircraft be u max ,u max′ ; In order to get u max and u max′ The order of arrangement, assuming: in, and Respectively represent u max and u max′ The channel gain of when When max ,u max′ ) is the optimal strategy of the system; when δ<0, choose (u max ,u max′ ) as the pairing method for the final aircraft.

8. The method for efficient aircraft data transmission with adjustable rate according to claim 4, characterized in that: The three sub-optimization problems are solved by the following joint iterative algorithm: Step 1, initialization: set the number of candidate receiving aircraft U, select the receiving aircraft pair (u k ,u k' ), the public part rate μ of the receiving aircraft k and μ k' , the power allocated to the public flow and the kth receiving aircraft, the power allocated to the private flow of the k′th receiving aircraft The power of AWGN noise σ 2 and the corresponding precoding vector w k , w k′ ; Step 2, three-layer iteration: In order to obtain the optimal solution to the optimization problem, a three-layer iteration algorithm is used, as shown below: (1) Common flow layer: Determine the common sub-part μ k , μ k′ The rate of the public flow P c Power; (2) Private flow layer: Allocate power to P k and P k′ two private streams; (3) Receive information aircraft pairing layer: select the optimal aircraft pairing strategy for the aircraft efficient data transmission system; Computation: Computational and spectral efficiency; Step 3, comparison process: compare the sum spectral efficiency with the sum spectral efficiency of the previous iteration; Step 4, output: output the maximum and spectrum efficiency, the optimal receiving information aircraft pairing, the common part rate of the receiving information aircraft, the power allocation scheme parameters of the common stream and the optimal receiving information aircraft pairing.

9. A terminal device comprising a processor, a memory and a computer program stored in the memory; characterized in that: When the processor executes the computer program, the rate-adjustable aircraft efficient data transmission method according to any one of claims 1-8 is implemented.

10. A computer-readable storage medium, wherein a computer program is stored in the medium; characterized in that: When the computer program is executed by a processor, the rate-adjustable aircraft efficient data transmission method according to any one of claims 1 to 8 is implemented.

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