Flexible access cross-domain efficient anti-interference transmission method

Abstract

The invention discloses a flexible access cross-domain efficient anti-interference transmission method, which comprises the following steps of: dividing a communication transmission process into a training stage and a data transmission stage, and dividing the training stage into a plurality of mini time slots; in each mini time slot of a training stage, a base station in a cellular network firstly randomly generates a group of flexible access vectors, then constructs a useful signal space for receiving a signal space and broadcasts to all users of a cell where the base station is located; the user constructs an interference leakage matrix and calculates a user beam forming weight; an interference leakage value of the user is set, and the base station performs user selection by using the interference leakage value; determining the spectrum efficiency corresponding to each mini time slot according to the signal to interference plus noise ratio of the receiving end and the beam forming weight of the user; and in the data transmission stage, the base station determines the flexible access vector corresponding to the mini time slot with the maximum spectrum efficiency, and applies the flexible access vector to the communication process of the user screened through the interference leakage value.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a flexible access cross-domain efficient anti-interference transmission method. Background Art

[0002] At present, using effective interference management schemes to improve transmission performance has become one of the key technologies in wireless networks. Among them, the traditional anti-interference transmission scheme divides the signal space into an interference subspace and a null space of the interference subspace, and uses directional access technology to direct the interference signal to the interference subspace and send useful signals in the null space of the interference subspace, thereby achieving interference elimination. For example, the anti-interference transmission scheme is applied to a multi-cell interference multiple access channel network, and the network is grouped to perform assisted interference alignment; however, the traditional scheme often requires perfect channel state information (CSI) to calculate the directional access vector, resulting in a high complexity of the scheme. Summary of the invention

[0003] The purpose of the present invention is to provide a cross-domain efficient anti-interference transmission method with flexible access, which jointly processes the weight of flexible access and the user selection scheme to minimize interference and achieve efficient transmission.

[0004] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0005] A cross-domain efficient anti-interference transmission method with flexible access, comprising:

[0006] The duration of a communication transmission process between a base station and a user in a cellular network is divided into a training phase and a data transmission phase, wherein the training phase is further divided into a plurality of mini time slots;

[0007] During each mini-slot of the training phase:

[0008] The base station in the cellular network first randomly generates a set of flexible access vectors, then constructs a useful signal space of the received signal space based on the flexible access vectors and broadcasts it to all users in the cell where the base station is located;

[0009] Based on the channel matrix between the user and the base station and the useful signal space, the user constructs the interference leakage matrix and calculates the user beamforming weight;

[0010] The interference leakage value of the user is set, and the base station uses the interference leakage value to select the user; the spectrum efficiency corresponding to each mini-time slot is determined by the signal-to-interference-noise ratio at the receiving end and the user beamforming weight;

[0011] During the data transfer phase:

[0012] The base station determines a flexible access vector corresponding to a mini-time slot having the maximum spectrum efficiency, and applies the flexible access vector to a communication process of a user selected by an interference leakage value.

[0013] Furthermore, the duration of a communication transmission process between the base station and the user in the cellular network is a time slot T, which is divided into a training phase and a data transmission phase in a 2:8 manner. The training phase is divided into M mini time slots of length τ, where M is not less than 10 and τ≥0.

[0014] Further, the flexible access vector is expressed as:

[0015]

[0016] And there are:

[0017]

[0018] in, Represents the nth signal received by the jth receiving antenna in the mth mini-time slot c The vector of the BS of a cellular network, and satisfy and Represent the coefficients of flexible access The amplitude and phase of , e is the natural base, i represents the imaginary unit, N R ×1-dimensional complex space; 0<m≤M, M is the total number of mini-slots, N R represents the number of receiving antennas arranged in the base station BS;

[0019] The useful signal space It is expressed as:

[0020]

[0021] Furthermore, based on the channel matrix between the user and the base station and the useful signal space, the user constructs an interference leakage matrix and calculates the user beamforming weight, including:

[0022] Interference leakage matrix Perform singular value decomposition SVD and get:

[0023]

[0024] in is the unitary matrix obtained by singular value decomposition, is the singular value matrix, is the interference leakage matrix The l singular values ​​of is N obtained after singular value decomposition T unit orthogonal column vectors, define That is to get the The beamforming weights for each user.

[0025] Further, Transmit beamforming weights for each user satisfy:

[0026]

[0027] Where 1≤n c '≤N C And n c '≠n c ,|| || 2 represents the square of the two-norm, Indicates the mth mini-slot Users and nth c Channel matrix between ′ base stations; For the The interference leakage matrix of a user is expressed as:

[0028]

[0029] in Represents the nth c The first base station The user and other base stations select the first to The channel matrix between users, N c is the number of cellular networks, N T The number of transmit antennas deployed for the user, N C ≥n c ≥1.

[0030] Furthermore, the user's interference leakage value It is expressed as:

[0031]

[0032] in Represents the interference leakage matrix The minimum singular value obtained by performing a singular value decomposition.

[0033] Further, the base station uses the interference leakage value to select the user, specifically:

[0034] All the cells where the base station BS is located Each user feeds back the calculated interference leakage value to the BS, and the BS selects the user with the smallest interference leakage value. users.

[0035] Further, determining the spectrum efficiency corresponding to each mini-time slot by using the signal to interference noise ratio of the receiving end and the user beamforming weight includes:

[0036] For the nth c The base station in a cellular network receives the signal:

[0037]

[0038] The transmitted signal is is Gaussian white noise with a power spectrum density of N0; the transmission signal and the reception signal are data for training sent and received between the user and the base station during the training phase; For the Users and nth c The channel matrix between base stations, For the The transmit beamforming weights of each user;

[0039] After zero-forcing equalization, the signal-to-interference-and-noise ratio (SINR) at the receiving end is:

[0040]

[0041] in represents the pseudo-inverse, N0 is the power spectral density of Gaussian white noise, ||·|| 2 represents the square of the two-norm, Represents the useful signal in the transmitted signal or received signal. Represents the interference signal in the transmitted or received signal. is the equivalent user channel, that is, the nth c The first base station The transmission channel of the useful signal of each user, is the equivalent interference channel, that is, the nth c The first base station The transmission channel of the interference signal of each user;

[0042] The spectrum efficiency SE corresponding to the mth mini-time slot is:

[0043]

[0044] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor is executed by a computer, the flexible access cross-domain efficient anti-interference transmission method is implemented.

[0045] A computer-readable storage medium stores a computer program; when the computer program is executed by a processor, the flexible access cross-domain efficient anti-interference transmission method is implemented.

[0046] Compared with the prior art, the present invention has the following technical features:

[0047] Compared with the traditional anti-interference transmission system, the present invention achieves higher SE and lower interruption probability with lower computational complexity in the absence of perfect CSI and with a small number of candidate users, thereby realizing cross-domain efficient anti-interference transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A cross-domain, efficient, and anti-interference network model diagram for flexible access;

[0049] Figure 2 This is a graph showing how system spectrum efficiency changes with signal-to-noise ratio under different numbers of users;

[0050] Figure 3 is the cumulative distribution function diagram of signal to interference noise ratio;

[0051] Figure 4 is the probability density function diagram of signal-to-interference-noise ratio;

[0052] Figure 5 This is a graph showing the variation of the outage probability with the signal-to-noise ratio under different numbers of users;

[0053] Figure 6 The figure is a comparison chart of the spectrum efficiency of the efficient anti-interference transmission scheme and the traditional anti-interference transmission scheme under different numbers of users. DETAILED DESCRIPTION

[0054] The present invention proposes a flexible access solution that does not require perfect CSI and complex channel estimation, that is, it uses randomly generated flexible access weights instead of the directional access vector that needs to be calculated. In order to solve the problem of reduced system performance when the number of users is small, the cross-domain idea is introduced to improve the spectrum efficiency (SE) by selecting the most appropriate weights in different networks, thereby making up for the performance of the scheme when the number of users is insufficient. In addition, the cumulative distribution function (CDF) and probability density function (PDF) of the signal-to-interference-plus-noise ratio (SINR) of the system under the flexible access cross-domain efficient anti-interference transmission scheme are derived. At the same time, closed expressions for the interruption probability and symbol error rate are given based on CDF and PDF.

[0055] The present invention proposes a flexible access cross-domain efficient anti-interference transmission method, which jointly processes the weight of flexible access and service users with the goal of maximizing SE, thereby improving system SE and reducing system interruption probability by minimizing interference.

[0056] The present invention is based on the principle of wireless communication and aims at uplink multi-user cellular network communication. It uses flexible access weights to replace the directional access vector that needs to be calculated in the traditional communication network (the transmitting end pre-processes the transmitted signal to eliminate the channel influence, thereby increasing the complexity and overhead of the receiver receiving the signal) to achieve efficient communication.

[0057] See also Figure 1 The network targeted by the present invention includes N c A cellular network is constructed in which a base station BS is deployed at the center of each cell and N R (N R ≥2) receiving antennas, nth c (N C ≥n c ≥1) cellular network has U nc (U nc ≥2) users, each user deploys N T (N T ≥2) transmitting antennas; in one transmission process, select K nc (U nc ≥K nc ≥1) users communicate, assuming that the signal interference within the cell is ignored.

[0058] The duration of a communication transmission process between a base station and a user in a cellular network is a time slot of T (T ≥ 0), and the time slot is divided into a training phase and a data transmission phase, wherein the training phase occupies 20% of the entire time slot, and the data transmission phase occupies 80% of the entire time slot, and the training phase is divided into M (not less than 10) mini time slots of length τ (τ ≥ 0) to generate and estimate the random access vector; the following is based on the nth c A cellular network is used as an example for explanation.

[0059] Step 1: The prior art requires a large amount of calculations during the data training phase to obtain a directional access vector; different from the traditional method, this solution proposes a randomly generated flexible access vector, which can reduce the complexity of the algorithm.

[0060] No.n c The BS of a cellular network randomly generates a set of flexible access vectors:

[0061]

[0062] The subscript m (0<m≤M) represents the mth mini-slot, 1≤j≤N R , the coefficient of flexible access Represents the nth signal received by the jth receiving antenna in the mth mini-time slot c The vector of the BS of a cellular network, and satisfy represents the power of the flexible access coefficient, and Represent the coefficients of flexible access The amplitude and phase of , e is the natural base, i represents the imaginary unit, N R ×1-dimensional complex space.

[0063] In order to ensure constant power, assume:

[0064]

[0065] BS divides the received signal space formed by the received signals fed back by each user to the base station into the interference subspace and the null space of the interference subspace. The division of space into interference space and useful space is a measure to reduce interference. Through the preprocessing of beamforming vectors, the useful signal is propagated in the useful space as much as possible, and the interference signal is propagated in the interference channel, thereby reducing the impact of the interference signal and improving the spectrum efficiency SE of the system.

[0066] The null space of the interference subspace is used to transmit useful signals, also called useful signal space, and the interference subspace and useful signal space Respectively expressed as:

[0067]

[0068] BS broadcasts the interference subspace to all users and useful signal space

[0069] Step 2, Build For the Users and nth c The channel matrix between base stations:

[0070]

[0071] in Indicates the mth mini-slot Users and nth c The nth base station r The channel vector between the root receiving antennas; in this scheme, the right subscript of the matrix represents the matrix dimension, such as the matrix dimension of the above formula is NR×NT , the same below.

[0072] The user constructs the interference leakage matrix and calculates the user beamforming weight; The interference leakage matrix of a user is defined as:

[0073]

[0074] in It is expressed as:

[0075]

[0076] in Represents the nth c The first base station The user and other base stations select the first to The channel matrix between users (users with the smallest interference leakage value).

[0077] No. Transmit beamforming weights for each user satisfy:

[0078]

[0079] in Useful signal space 1≤n c '≤N C And n c '≠n c ,|| || 2 represents the square of the 2-norm.

[0080] For design And realize the equivalent interference channel The null space of the interference subspace The approximate uncorrelation between them is considered, and the interference leakage matrix Perform singular value decomposition (SVD) and get:

[0081]

[0082] in is the unitary matrix obtained by singular value decomposition, is the singular value matrix, is the interference leakage matrix The singular values ​​of is the unit orthogonal column vector obtained after singular value decomposition, since The corresponding decomposed smallest singular value, and the singular value can reflect the correlation of space to a certain extent, so the definition That is to get the The beamforming weights for each user.

[0083] Step 3: Set the square of the minimum singular value obtained by SVD as the interference leakage value of the user It is expressed as:

[0084]

[0085] Step 4: Interference leakage value As an indicator for BS to select users; all Each user feeds back the calculated interference leakage value to the BS; the BS selects the user with the smallest interference leakage value. users; at this time, the BS is subject to minimal interference from users in other cells, thus achieving efficient transmission.

[0086] For the nth c The base station in a cellular network receives the signal:

[0087]

[0088] The transmitted signal is is Gaussian white noise with a power spectrum density of N0; the transmitted signal and received signal are data for training sent and received between the user and the base station during the training phase.

[0089] After zero-forcing equalization, the signal-to-interference-and-noise ratio (SINR) at the receiving end is:

[0090]

[0091] in represents the pseudo-inverse, N0 is the power spectral density of Gaussian white noise, ||·|| 2 represents the square of the two-norm, Represents the useful signal (the signal expected to be received) in the transmitted signal or received signal. Represents the interference signal in the transmitted or received signal, U means useful, I means interference, and equ means equivalent. is the equivalent user channel, that is, the nth c The first base station The transmission channel of the useful signal of each user, is the equivalent interference channel, that is, the nth c The first base station The transmission channel of the interference signal of each user.

[0092] The spectrum efficiency SE corresponding to the mth mini-time slot is:

[0093]

[0094] Step 5: BS compares the spectrum efficiency SE determined in all M mini-time slots; then, BS selects the mini-time slot with the largest SE; in the data transmission phase, BS uses the flexible access vector in the mini-time slot for the K with the smallest interference leakage value selected in step 4. nc The communication process of a user.

[0095] Therefore, the spectral efficiency of the entire system can be expressed as:

[0096]

[0097] in represents the expectation, and the spectral efficiency of the entire system is represented by the ergodic situation obtained after the expectation is calculated; see Figure 6 As shown in the example, compared with the traditional solution, the system spectrum efficiency of this solution is significantly improved under different numbers of users.

[0098] The interruption probability and symbol error rate are very important indicators for measuring communication systems. C =3,

[0099] N T =2 as an example, the statistical characteristics of SINR are derived and analyzed.

[0100] At this time, SINR is expressed as:

[0101]

[0102] Where P is the transmit power and N0 is the noise power at the receiving end.

[0103] Considering the numerator of SINR, due to and is a unit vector and is independent of and The mathematical statistical properties are consistent.

[0104] Assumptions The elements obey Rayleigh distribution, then is an exponential variable. To simplify the mathematics, let:

[0105]

[0106] but The CDF and PDF of are:

[0107]

[0108] For the denominator of SINR, and They can be considered to follow the same distribution. Rewritten as:

[0109]

[0110] right Perform SVD decomposition and get:

[0111]

[0112] According to the above formula, It can be written as:

[0113]

[0114] in Represents a unitary matrix The elements of the first row and second column of express The minimum singular value of . Therefore, we get:

[0115]

[0116] Similarly, we have:

[0117]

[0118] Use the average value to approximate have to:

[0119]

[0120] definition in is a second-order Wishart matrix, so the interference leakage matrix The mathematical statistical characteristics of the minimum singular value of are:

[0121]

[0122] According to the knowledge related to order statistics, due to the existence of Users waiting for service, The probability density of is:

[0123]

[0124] According to the isotropy between users, and have similar mathematical statistical characteristics. Therefore, we get:

[0125]

[0126] The PDF is:

[0127]

[0128] set up but

[0129]

[0130] therefore, The CDF and PDF of are expressed as:

[0131]

[0132] Assume that the threshold of the outage probability is given by γ thr If , then the interruption probability is expressed as:

[0133]

[0134] The symbol error rate is expressed as:

[0135]

[0136] where binary phase shift keying (BPSK) modulation is used and Q(·) is a Gaussian Q function.

[0137] 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, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such 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 be included in the protection scope of the present application.

Claims

1. A flexible access cross-domain efficient anti-interference transmission method, characterized in that: include: The duration of a communication transmission process between a base station and a user in a cellular network is divided into a training phase and a data transmission phase, wherein the training phase is further divided into a plurality of mini time slots; During each mini-slot of the training phase: The base station in the cellular network first randomly generates a set of flexible access vectors, then constructs a useful signal space of the received signal space based on the flexible access vectors and broadcasts it to all users in the cell where the base station is located; Based on the channel matrix between the user and the base station and the useful signal space, the user constructs the interference leakage matrix and calculates the user beamforming weight; The interference leakage value of the user is set, and the base station uses the interference leakage value to select the user; the spectrum efficiency corresponding to each mini-time slot is determined by the signal-to-interference-noise ratio at the receiving end and the user beamforming weight; During the data transfer phase: The base station determines a flexible access vector corresponding to a mini-time slot having the maximum spectrum efficiency, and applies the flexible access vector to a communication process of a user selected by an interference leakage value.

2. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: The duration of a communication transmission process between the base station and the user in the cellular network is a time slot T, which is divided into a training phase and a data transmission phase in a 2:8 manner. The training phase is divided into M mini time slots of length τ, where M is not less than 10 and τ≥0.

3. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: The flexible access vector is expressed as: And there are: in, Represents the nth signal received by the jth receiving antenna in the mth mini-time slot c The vector of the BS of a cellular network, and satisfy and Represent the coefficients of flexible access The amplitude and phase of , e is the natural base, i represents the imaginary unit, N R ×1-dimensional complex space; 0<m≤M, M is the total number of mini-slots, N R represents the number of receiving antennas arranged in the base station BS; The useful signal space It is expressed as:

4. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: The user constructs an interference leakage matrix and calculates the user beamforming weight based on the channel matrix between the user and the base station and the useful signal space, including: Interference leakage matrix Perform singular value decomposition SVD and get: in is the unitary matrix obtained by singular value decomposition, is the singular value matrix, is the interference leakage matrix The l singular values ​​of is N obtained after singular value decomposition T unit orthogonal column vectors, define That is to get the The beamforming weights for each user.

5. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: No. Transmit beamforming weights for each user satisfy: Where 1≤n c '≤N C And n c '≠n c ,|| || 2 represents the square of the two-norm, Indicates the mth mini-slot users and n′ c The channel matrix between base stations; For the The interference leakage matrix of a user is expressed as: in Represents the nth c The first base station The user and other base stations select the first to The channel matrix between users, N c is the number of cellular networks, N T The number of transmit antennas deployed for the user, N C ≥n c ≥1.

6. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: User's interference leakage value It is expressed as: in Represents the interference leakage matrix The minimum singular value obtained by performing a singular value decomposition.

7. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: The base station uses the interference leakage value to select users, specifically: All the cells where the base station BS is located Each user feeds back the calculated interference leakage value to the BS, and the BS selects the user with the smallest interference leakage value. users.

8. The cross-domain efficient anti-interference transmission method with flexible access according to claim 1 is characterized in that: The determining the spectrum efficiency corresponding to each mini-time slot by using the signal to interference noise ratio of the receiving end and the user beamforming weight includes: For the nth c The base station in a cellular network receives the signal: The transmitted signal is is Gaussian white noise with a power spectrum density of N0; the transmission signal and the reception signal are data for training sent and received between the user and the base station during the training phase; For the Users and nth c The channel matrix between base stations, For the The transmit beamforming weights of each user; After zero-forcing equalization, the signal-to-interference-and-noise ratio (SINR) at the receiving end is: in represents the pseudo-inverse, N0 is the power spectral density of Gaussian white noise, ||·|| 2 represents the square of the two-norm, Represents the useful signal in the transmitted signal or received signal. Represents the interference signal in the transmitted or received signal. is the equivalent user channel, that is, the nth c The first base station The transmission channel of the useful signal of each user, is the equivalent interference channel, that is, the nth c The first base station The transmission channel of the interference signal of each user; The spectrum efficiency SE corresponding to the mth mini-time slot is:

9. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; when the processor is executed by a computer, it implements the cross-domain efficient and anti-interference transmission method with flexible access according to any one of claims 1-8.

10. A computer-readable storage medium, wherein a computer program is stored in the medium; when the computer program is executed by a processor, the cross-domain efficient and anti-interference transmission method with flexible access is implemented according to any one of claims 1-8.

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