Codebook beam transmission method, device, storage medium and equipment for dynamic beam squint compensation

Abstract

The present invention relates to the field of wireless communication technology, and discloses a codebook beam transmission method, device, storage medium and equipment for dynamic beam squint compensation, including: a codebook composed of a number of beams covers the entire dynamic area, and the center direction of each beam is determined based on the codebook structure and half-power beam width of adjacent and non-overlapping beams; for each beam, a beam optimization problem is established to maximize the minimum beam gain within the bandwidth in the center direction, and limit the fluctuation range of the beam gain with frequency to eliminate the beam squint in the center direction; a digital beam is obtained according to the optimal solution, and the digital beam is split into two analog beams; two groups of beams adjacent to the position are selected according to the position information of the dynamic user, and the bandwidth is dynamically allocated so that the two groups of beams transmit the same signal on different frequency bands. The beneficial effects of the present invention are: it can compensate for beam squint in dynamic conditions and improve the spectrum efficiency of the transmission system.

Description

Technical Field

[0001] The present invention relates to a codebook beam transmission method, device, storage medium and equipment for dynamic beam squint compensation, and in particular to a codebook beam transmission method, device, storage medium and equipment for effectively compensating dynamic beam squint based on frequency band allocation, belonging to the field of wireless communication technology. Background Art

[0002] 5G is the fifth generation of wireless mobile communications. Compared with the fourth generation LTE (Long Term Evolution), its data transmission rate can be increased by nearly 100 times. Millimeter waves can provide GHz spectrum bandwidth, which can increase data transmission rate and is considered one of the key technologies of 5G. However, the signals in the 5G millimeter wave band are very different from the signals in the traditional sub-6GHz band and will experience severe propagation losses. Large-scale antenna beamforming technology plays a key role in compensating for signal attenuation and maintaining a stable communication link.

[0003] The design of phased array antennas faces challenges in ultra-wideband communication systems. In the same beam direction, the beam gains of different frequencies are also different. In particular, the beam gains of the maximum and minimum frequencies are greatly reduced compared to the beam gain of the carrier frequency. This is beam squint, which reduces the available bandwidth of the phased array antenna system. Some existing methods for eliminating or reducing beam squint consider compensating for beam squint in the case of static targets. However, a beam that has been compensated for beam squint in a static situation will still produce new squint in a dynamic situation, so it is necessary to consider the compensation of beam squint in a dynamic situation. Summary of the invention

[0004] The object of the present invention is to provide a codebook beam transmission method for effectively compensating for dynamic beam squint based on frequency band allocation, which can effectively compensate for dynamic beam squint.

[0005] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0006] On the one hand, the present invention provides a codebook beam transmission method for dynamic beam squint compensation, comprising the following steps:

[0007] Step S1, based on the premise that the beam center direction is not skewed and the codebook structure is adjacent and not superimposed, the center direction and left and right boundaries of each beam are determined, and the beam with the maximum gain in the beam center direction is obtained from the carrier frequency;

[0008] Step S2, optimizing the design of each beam that is offset in the center direction to compensate for squint, based on maximizing the minimum beam gain within the bandwidth in the center direction of the beam, limiting the fluctuation range of the beam gain with frequency, and obtaining the optimal solution X, where X represents a matrix;

[0009] Step S3, obtaining a digital beam according to the optimal solution X, splitting the digital beam into two analog beams, and using a double phase shifter array structure based on switch switching to realize the conversion from analog beam to digital beamforming;

[0010] Step S4, for a high-speed moving target user, two groups of simulated beams closest to the target user are selected, and different frequency bands are allocated to transmit the same data signal to achieve dynamic beam squint compensation;

[0011] In combination with the first aspect, further, the codebook beam transmission method of the present invention further includes step S5: based on the implementation of the codebook beam transmission of the frequency band allocation, modifying the data stream.

[0012] In combination with the first aspect, further, the step S1 specifically includes: determining the center direction and left and right boundaries of each beam on the premise that there is no beam squint in the center direction (that is, the half-power beam width in the frequency domain in the center direction of the beam is just the bandwidth size) and the beams are adjacent and non-overlapping codebook structure.

[0013] The specific method for determining the center direction and left and right boundaries of each beam in the codebook is:

[0014] In a given spatial range, the spatial direction of each beam in the codebook is determined by the fluctuation of the beam gain in a fixed range, so that each beam is adjacent in space and does not overlap; θ represents the sine of the transmitting angle of the antenna array base station. Given the mobile range of the target user θ∈[-1,1], the mobile range is the direction of the codebook space composed of several beams in the entire dynamic area to cover this range. The given system bandwidth frequency range is The carrier center frequency is f c , then the bandwidth is B = f max -f min ; Consider the codebook design that is symmetrical relative to the antenna array base station transmission angle θ = 0. Taking θ∈[0,1] as an example, the beam codebook is expressed as

[0015] in, is a single beam in the codebook, is a column vector, j represents the imaginary unit, i = 1, ..., N, N represents the number of beams in the codebook, θ i,o is the codebook beam w i The beam center direction, [·] T represents the transpose of the vector, M is the number of antennas; let the beam w i The 3dB beam spatial range is [θ i,l ,θ i,r ],θ i,l represents the beam w iThe left edge of the coverage area, θ i,r represents the beam w i Right edge of the coverage area; quickly obtain the phase shift β of the simulated beam that achieves the maximum beam gain in the center direction through the center frequency fc of the carrier m =2πf c c -1 (m-1)dθ o , m = 1, ..., M, where c is the speed of light, d is the distance between adjacent antennas, and for any θ o , the 3dB beamwidth of this beam This type of method is hereafter referred to as the fast beam generation method;

[0016] According to the relationship between θ and f in the beam gain expression of rapid beam generation, f represents an arbitrary frequency. If Then the beam center direction θ o The signal gain at all frequencies is within the 3dB beam range, that is, at θ o There is no beam deviation in the direction. According to the requirement that the codebook beam coverage is adjacent and non-overlapping, that is, θ i,l =θ i-1,r ,θ i,r =θ i+1,l , and so on, we get All beam center directions Θ1 = {θ 1,o ,…,θ i,o}, and use the method of fast generation of beam phase shift to obtain the beam codebook for Then the beam needs to be designed to satisfy the o There is no beam deviation in the direction, that is, θ o The signal gain of all frequencies in the direction is within 3dB, and the designed 3dB beam width δ 3dB With θ o Related, beam width must be met at this time The beam codebook is obtained by analogy The corresponding beam center direction θ2 = {θ i+1,o ,…,θ N,o};

[0017] The above algorithm is initialized according to whether the number of codebook beams in the space θ∈[-1,1] is an even number or an odd number; take θ∈[0,1] as an example to illustrate that when the number of codebook beams is an even number, then θ 1,l = 0, and because is definitely true, so the first beam It is definitely true; when the number of codebook beams in the space θ∈[-1,1] is an odd number, then θ 1,o =0.

[0018] In combination with the first aspect, further, step S2 specifically includes: for the beam center direction θ2={θ i+1,o ,…,θ N,o} beam codebook The beams in the system are optimized and designed to compensate for beam squint.

[0019] Define θ n,o is the beam w n The central direction of i+1≤n≤N; consider each w n The optimization process is the same. For the convenience of description, the optimized variable w n Abbreviated as w, the corresponding beam center direction θ n,o Abbreviated as θ o In order to satisfy the beam center direction θ o The signal gain of all frequencies within the bandwidth is within 3dB, and the optimization problem needs to meet the condition where a(f,θ o ) is the steering vector of the uniform linear array, [·] H represents the conjugate transpose of a matrix or vector. Based on this condition, the following optimization problem is established:

[0020]

[0021]

[0022]

[0023] Among them, w and γ are the beams and parameters that need to be optimized, w m represents the mth element in the simulated beam vector W; according to the expression w H a(f,θ0)a H (f,θ0)w=tr(a(f,θ0)a H (f,θ0)·ww H ), tr(a(f,θ0)a H (f,θ0)·ww H ) represents the matrix a(f,θ0)a H (f,θ0)·ww H Let X = ww H , then X is a semi-positive definite matrix, and the rank of matrix X is rank(X) = 1. The original optimization problem becomes a semi-positive definite programming (SDP) problem, and the optimization variable is changed from w to X.

[0024] SDP:

[0025]

[0026]

[0027]

[0028] Since the constraint rank(X) = 1 is non-convex, the SDR (Semidefinite Relaxation) problem is obtained by relaxing the semidefinite programming, that is, removing the rank constraint.

[0029] SDR:

[0030]

[0031]

[0032]

[0033] The optimal solution X for the SDR problem is obtained through software tools.

[0034] In combination with the first aspect, further, step S3 specifically includes:

[0035] Since the rank of the optimal solution X of the SDR problem is not 1, it is impossible to directly obtain the simulated beam vector w using the eigenvalue; τ represents the sum of the elements on the τ-th diagonal of the matrix X, and -(M-1)≤τ≤(M-1), τ>0 represents the upper right diagonal of the matrix X, τ<0 represents the lower left diagonal of the matrix X, and τ=0 represents the main diagonal of the matrix X; Σ τ Specifically expressed as

[0036]

[0037] The M×M Toeplitz matrix represented by is 1 only on the τth diagonal and the rest are 0. τ Then, the digital beam vector v = [v0, v1, ..., v M-1 ] T ;

[0038]

[0039] Among them, the plural Represents the plural v m The conjugate of f(x) is given by Σ τis a polynomial function of degree M-1 consisting of coefficients. Let f(x) = 0, according to the polynomial coefficients Σ τ Find the root x of the polynomial m , and then according to the root z of the following polynomial function y(x) m , the coefficients of the following polynomial are obtained as v = [v0, v1, …, v M-1 ] T ;

[0040] where z m Can take value x m or

[0041] According to the above method, we can get the digital beam vector v = [ν0, v1, ..., ν m ,…,v M-1 ] T , the amplitude and phase of each element in v are controlled by the phase of the two phase shifters of each antenna. Assume Then the phase of the two phase shifters connected to antenna m is and And meet According to Euler's formula, we can get and These phases are respectively used to simulate the beam and The beam codebook is obtained by this process method Each beam in the CNN is actually composed of two simulated beams, that is, two simulated beams constitute a group of beams, respectively using beam codebooks and It means that w i+1,a and w i+1,b is a set of beams.

[0042] Considering that when the beam center θ o <θ i+1,o When using fast analog beam generation, only one set of phase shifters is required, while θ o ≥θ i+1,o The designed beam needs to use two sets of phase shifters. Therefore, a double phase shifter array structure based on switch switching is used to realize the conversion from analog beamforming to digital beamforming. o <θ i+1,o When the switch is open, only one set of phase shifters is activated. o ≥θ i+1,o When , the switch is closed and the two sets of phase shifters are activated, realizing a digital beam composed of two analog beams.

[0043] In combination with the first aspect, further, step S4 specifically includes:

[0044] When the target user is in a high-speed motion state, such as in trains, high-speed trains, drones, etc., the base station transmitter cannot obtain accurate instantaneous channel state information due to the high-speed motion, and therefore cannot quickly generate an instantaneous beam. Based on the predictability of its motion direction, when the target user position is within the base station transmission angle range θ∈[θ i,o ,θ i+1,o ) (the base station transmission angle can also represent the user direction), in order to eliminate dynamic beam squint, two groups of beams w corresponding to the beam center directions adjacent to the user position are selected from the codebook. i and w i+1 , the two groups of beams send the same data signal, but use different frequency bands to divide the bandwidth. The beam group w i-1 Frequency range Beam group w i Frequency range And because θ i-1,r =θ i,l ,so By analogy, if the target user moves quickly within the range of θ∈[-1, 1], the beam squint generated by the dynamics can be eliminated.

[0045] Note that the beam group w i and w i+1 Probably the codebook from the fast beamforming method It may also come from the beam codebook When from the beam codebook When Each beam in is actually composed of two groups of simulated beams, namely and In the beam group, two simulated beams in the same direction send the same signal and use the same frequency band, while simulated beams in different directions send the same signal but use different frequency bands.

[0046] In combination with the first aspect, further, step S5 specifically includes:

[0047] For K users, K data streams are copied into 4K data streams. The base station selects two adjacent groups of beams in the direction of the target users to transmit four identical data streams on two different frequency bands. However, the four data streams are sent by two groups of beams in different beam directions. Therefore, 2K pilot signals need to be sent for 4K data streams.

[0048] In a second aspect, the present invention provides a codebook beam transmission device for dynamic beam squint compensation, comprising:

[0049] A beam spatial direction determination module is used to determine the spatial direction of each beam in the codebook based on a fixed fluctuation range of the beam gain in the frequency band domain in the beam center direction, so that each beam space is adjacent and non-overlapping, and there is no beam deflection in the center direction;

[0050] The optimal solution acquisition module is used to optimize the design of each beam that is offset in the center direction to compensate for squint, based on maximizing the minimum beam gain within the bandwidth in the center direction of the beam, limiting the fluctuation range of the beam gain with frequency, and obtaining the optimal solution X, where X represents a matrix;

[0051] A digital beamforming module is used to obtain a digital beam according to the optimal solution X, split the digital beam into two analog beams, and realize the conversion from analog beam to digital beamforming by using a double phase shifter array structure based on switch switching;

[0052] The frequency band allocation module is used to select two sets of analog beams closest to the direction of the target user moving at high speed, and allocate different frequency bands to transmit the same data signal to achieve dynamic beam squint compensation;

[0053] In combination with the second aspect, it also includes a data stream modification module, which is used to modify the data stream based on the implementation of codebook beam transmission based on frequency band allocation.

[0054] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned steps of codebook beam transmission for dynamic beam squint compensation.

[0055] In a fourth aspect, the present invention provides a computer device, comprising:

[0056] Memory for storing computer programs;

[0057] A processor is used to execute the computer program to implement the steps of the above-mentioned codebook beam transmission method for dynamic beam squint compensation.

[0058] In a fifth aspect, the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned codebook beam transmission method for dynamic beam squint compensation.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention can effectively compensate for dynamic beam squint and improve the available bandwidth and throughput of the system in dynamic scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a flow chart of the codebook beam transmission method of the present invention;

[0062] Figure 2 A schematic diagram of the structure of a double phase shifter antenna array based on switch switching provided by the present invention;

[0063] Figure 3 A schematic diagram of beam gain performance of a broadband system in a dynamic target scenario using a codebook formed by a fast beam generation method through single beam transmission;

[0064] Figure 4 A schematic diagram of beam gain performance of a broadband system in a dynamic target scenario when a codebook formed by a fast beam generation method is applied to a dual-beam transmission form with dynamic frequency band segmentation of the present invention;

[0065] Figure 5 A schematic diagram of beam gain performance of a broadband system in a dynamic target scenario when a codebook formed by the beamforming method of the present invention is applied in a single beam transmission form;

[0066] Figure 6 The figure is a schematic diagram of beam gain performance of a broadband system in a dynamic target scenario when a codebook formed by the beamforming method of the present invention is applied to a dual-beam transmission form with dynamic frequency band segmentation of the present invention. DETAILED DESCRIPTION

[0067] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0068] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0069] Example 1

[0070] like Figure 1 As shown, this embodiment provides a codebook beam transmission method for dynamic beam squint compensation, comprising the following steps:

[0071] Step S1 of this embodiment: determine the spatial direction of each beam in the codebook based on a fixed fluctuation range of the beam gain in the frequency band domain in the beam center direction, so that the beams are spatially adjacent and non-overlapping, and there is no beam deflection in the center direction.

[0072] In a specific implementation of the present embodiment, step S1 of the present embodiment specifically includes: determining the center direction and left and right boundaries of each beam on the premise that there is no beam squint in the center direction (i.e., the half-power beam width in the frequency domain in the center direction of the beam is just the bandwidth size) and the beams are adjacent and non-overlapping codebook structures.

[0073] The specific method for determining the center direction and left and right boundaries of each beam in the codebook is:

[0074] In a given spatial range, the spatial direction of each beam in the codebook is determined by the fluctuation of the beam gain in a fixed range, so that each beam is adjacent in space and does not overlap; θ represents the sine of the transmitting angle of the antenna array base station. Given the mobile range of the target user θ∈[-1,1], the mobile range is the direction of the codebook space composed of several beams in the entire dynamic area to cover this range. The given system bandwidth frequency range is The carrier center frequency is f c , then the bandwidth is B = f max -f min ; Consider the codebook design that is symmetrical relative to the antenna array base station transmission angle θ = 0. Taking θ∈[0,1] as an example, the beam codebook is expressed as

[0075] in, is a single beam in the codebook, is a column vector, j represents the imaginary unit, i = 1, ..., N, N represents the number of beams in the codebook, θ i,o is the codebook beam w i The beam center direction, [·] T represents the transpose of the vector, M is the number of antennas; let the beam w i The 3dB beam spatial range is [θ i,l ,θ i,r ],θ i,l represents the beam w i The left edge of the coverage area, θ i,r represents the beam w i Right edge of the coverage area; quickly obtain the phase shift β of the simulated beam that achieves the maximum beam gain in the center direction through the center frequency fc of the carrier m =2πf c c -1 (m-1)dθ o , m = 1, ..., M, where c is the speed of light, d is the distance between adjacent antennas, and for any θ o , the 3dB beamwidth of this beam This type of method is hereafter referred to as the fast beam generation method;

[0076] According to the relationship between θ and f in the beam gain expression of rapid beam generation, f represents an arbitrary frequency. If Then the beam center direction θ o The signal gain at all frequencies is within the 3dB beam range, that is, at θ o There is no beam deviation in the direction. According to the requirement that the codebook beam coverage is adjacent and non-overlapping, that is, θ i,l =θ i-1,r ,θ i,r =θ i+1,l , and so on, we get All beam center directions Θ1 = {θ 1,o ,…,θ i,o}, and use the method of fast generation of beam phase shift to obtain the beam codebook for Then the beam needs to be designed to satisfy the o There is no beam deviation in the direction, that is, θ o The signal gain of all frequencies in the direction is within 3dB, and the designed 3dB beam width δ 3dB With θ o Related, beam width must be met at this time The beam codebook is obtained by analogy The corresponding beam center direction θ2 = {θ i+1,o ,…,θ N,o};

[0077] The above algorithm is initialized according to whether the number of codebook beams in the space θ∈[-1,1] is an even number or an odd number; take θ∈[0,1] as an example to illustrate that when the number of codebook beams is an even number, then θ 1,l = 0, and because is definitely true, so the first beam It is definitely true; when the number of codebook beams in the space θ∈[-1,1] is an odd number, then θ 1,o =0.

[0078] Step S2 of this embodiment: optimize the design of each beam that is offset in the center direction to compensate for squint, based on maximizing the minimum beam gain within the bandwidth in the center direction of the beam, limiting the fluctuation range of the beam gain with frequency, and obtaining the optimal solution X, where X represents a matrix.

[0079] In a specific implementation of this embodiment, step S2 of this embodiment specifically includes: i+1,o ,…,θ N,o} beam codebook The beams in the system are optimized and designed to compensate for beam squint.

[0080] Define θ n,o is the beam w n The central direction of i+1≤n≤N; consider each w n The optimization process is the same. For the convenience of description, the optimized variable w n Abbreviated as w, the corresponding beam center direction θ n,o Abbreviated as θ o In order to satisfy the beam center direction θ o The signal gain of all frequencies within the bandwidth is within 3dB, and the optimization problem needs to meet the condition where a(f,θ o ) is the steering vector of the uniform linear array, [·] H represents the conjugate transpose of a matrix or vector. Based on this condition, the following optimization problem is established:

[0081]

[0082]

[0083]

[0084] Among them, w and γ are the beams and parameters that need to be optimized, w m represents the mth element in the simulated beam vector W; according to the expression w H a(f,θ0)a H (f,θ0)w=tr(a(f,θ0)a H (f,θ0)·ww H ), tr(a(f,θ0)a H (f,θ0)·ww H ) represents the matrix a(f,θ0)a H (f,θ0)·ww H Let X = ww H , then X is a semi-positive definite matrix, and the rank of matrix X is rank(X) = 1, the original optimization problem becomes a semi-positive definite programming (SDP) problem, and the optimization variable is changed from w to X;

[0085] SDP:

[0086]

[0087]

[0088]

[0089] Since the constraint rank(X) = 1 is non-convex, the SDR problem is obtained by relaxing the semi-positive definite programming, that is, removing the rank constraint.

[0090] SDR:

[0091]

[0092]

[0093]

[0094] The optimal solution X for the SDR problem is obtained through software tools.

[0095] Step S3 of this embodiment: a digital beam is obtained according to the optimal solution X, the digital beam is split into two analog beams, and a double phase shifter array structure based on switch switching is used to realize the conversion from analog beam to digital beam forming.

[0096] In a specific implementation of this embodiment, Figure 2 The schematic diagram of the structure of the double phase shifter antenna array based on switch switching is shown, and step S3 of this embodiment specifically includes:

[0097] Since the rank of the optimal solution X of the SDR problem is not 1, it is impossible to directly obtain the simulated beam vector w using the eigenvalue; τ represents the sum of the elements on the τ-th diagonal of the matrix X, and -(M-1)≤τ≤(M-1), τ>0 represents the upper right diagonal of the matrix X, τ<0 represents the lower left diagonal of the matrix X, and τ=0 represents the main diagonal of the matrix X; Σ τ Specifically expressed as

[0098]

[0099] The M×M Toeplitz matrix represented by is 1 only on the τth diagonal and the rest are 0. τ Then, the digital beam vector v = [v0, v1, ..., v M-1 ] T ;

[0100]

[0101] Among them, the plural Represents the plural v m The conjugate of f(x) is given by Σ τ is a polynomial function of degree M-1 consisting of coefficients. Let f(x) = 0, according to the polynomial coefficients Σ τ Find the root x of the polynomial m, and then according to the root z of the following polynomial function y(x) m , the coefficients of the following polynomial are obtained as v = [v0, v1, …, v M-1 ] T ;

[0102] where z m Can take value x m or

[0103] According to the above method, we can get the digital beam vector v = [ν0, v1, ..., ν m ,…,v M-1 ] T , the amplitude and phase of each element in v are controlled by the phase of the two phase shifters of each antenna. Assume Then the phase of the two phase shifters connected to antenna m is and And meet According to Euler's formula, we can get and These phases are respectively used to simulate the beam and The beam codebook is obtained by this process method Each beam in the CNN is actually composed of two simulated beams, that is, two simulated beams constitute a group of beams, respectively using beam codebooks and It means that w i+1,a and w i+1,b is a set of beams.

[0104] Considering that when the beam center θ o <θ i+1,o When using fast analog beam generation, only one set of phase shifters is required, while θ o ≥θ i+1,o The designed beam needs to use two sets of phase shifters, so a double phase shifter array structure based on switch switching is used to realize the conversion from analog beamforming to digital beamforming, such as Figure 2 As shown, when θ o <θ i+1,o When the switch is open, only one set of phase shifters is activated. o ≥θ i+1,o When , the switch is closed and the two sets of phase shifters are activated, realizing a digital beam composed of two analog beams.

[0105] Step S4 of this embodiment: for a target user moving at a high speed, two groups of simulation beams closest to the target user are selected, and different frequency bands are allocated to transmit the same data signal to achieve dynamic beam squint compensation.

[0106] In a specific implementation of this embodiment, step S4 of this embodiment specifically includes:

[0107] When the target user is in a high-speed motion state, such as in trains, high-speed trains, drones, etc., the base station transmitter cannot obtain accurate instantaneous channel state information due to the high-speed motion, and therefore cannot quickly generate an instantaneous beam. Based on the predictability of its motion direction, when the target user position is within the base station transmission angle range θ∈[θ i,o ,θ i+1,o ) (the base station transmission angle can also represent the user direction), in order to eliminate dynamic beam squint, two groups of beams w corresponding to the beam center directions adjacent to the user position are selected from the codebook. i and w i+1 , the two groups of beams send the same data signal, but use different frequency bands to divide the bandwidth. The beam group w i-1 Frequency range Beam group w i Frequency range And because θ i-1,r =θ i,l ,so By analogy, if the target user moves quickly within the range of θ∈[-1, 1], the beam squint generated by the dynamics can be eliminated.

[0108] Note that the wave group beam w i and w i+1 Probably the codebook from the fast beamforming method It may also come from the beam codebook When from the beam codebook When Each beam in is actually composed of two groups of simulated beams, namely and In the beam group, two simulated beams in the same direction send the same signal and use the same frequency band, while simulated beams in different directions send the same signal but use different frequency bands.

[0109] Because the codebook beam transmission method of the present invention needs to process the data stream to be sent in advance when it is implemented, and copy the same data stream into two, so that the same signal can be sent using different beams and different frequency bands in the subsequent process, the codebook beam transmission method of the present invention also includes step S5: modifying the data stream based on the implementation of the codebook beam transmission of the frequency band allocation. The specific method is as follows:

[0110] For K users, K data streams are copied into 4K data streams. The base station selects two adjacent groups of beams in the direction of the target users to transmit four identical data streams on two different frequency bands. However, the four data streams are sent by two groups of beams in different beam directions. Therefore, 2K pilot signals need to be sent for 4K data streams.

[0111] like Figures 3 to 6 As shown, the simulation of the present invention is described below.

[0112] The present invention is proposed to solve the problem of broadband millimeter-wave beam squint compensation in a MIMO (multiple-input multiple-output) communication system in a dynamic scenario. Since the beam squint problem has the same impact on the available bandwidth and throughput of communication in multi-user MIMO hybrid beamforming transmission and in analog beamforming transmission, in order to facilitate analysis, the present invention is first applied to a simple analog beamforming system for exemplary description.

[0113] The simulation results compare the present invention with another scheme for quickly generating a beamforming codebook through the dual-beam transmission with frequency band allocation proposed by the present invention and the single-beam transmission without frequency band allocation. The beam of the comparison scheme is designed to compensate for beam squint in a static scene, that is, a corresponding beam in the codebook is directly selected for output transmission without frequency band allocation. Figures 3 to 6 The schematic diagram of the beam gain performance of the present invention applied to a broadband system, the simulation conditions are: the number of transmitting antennas M = 64, the antenna array spacing d = λ c / 2, ε = 3dB, carrier frequency f c =28GHz, maximum frequency f max =30GHz, minimum frequency f min =26GHz. Figure 3 and Figure 4 or Figure 5 and Figure 6 It can be seen from the comparison that the dual-beam transmission method of frequency band allocation proposed by the present invention can effectively compensate for dynamic beam deflection. Figure 3 and Figure 5 or Figure 4 and Figure 6 It can be seen from the comparison that the codebook beam formed by the beam optimization method proposed in the present invention is helpful for dynamic beam skew compensation in dynamic beams. In a 4GHz bandwidth system, the beam gain of the maximum and minimum frequencies of the codebook for quickly generating beams and the beam skew compensation design for the transmission method applied to dynamic scenes are significantly reduced compared with the beam gain at the carrier frequency, especially in the large angle direction, such as Figure 3 and Figure 4; However, when the beam gain of the present invention is applied, the fluctuation of the beam gain is very small at different frequencies in the same direction, and the fluctuation of the beam gain in different directions is also greatly reduced. Therefore, in dynamic scenes, no matter in which direction the user is, the beam squint is effectively compensated, such as Figure 6 .

[0114] Example 2

[0115] Based on the same inventive concept as Embodiment 1, this embodiment introduces a codebook beam transmission device for dynamic beam squint compensation, including:

[0116] The beam spatial direction determination module is used to determine the spatial direction of each beam in the codebook based on the fixed fluctuation range of the beam gain in the frequency band domain in the beam center direction, so that the beam spaces are adjacent and non-overlapping, and there is no beam deflection in the center direction.

[0117] The optimal solution acquisition module is used to optimize the design of each beam that is offset in the center direction to compensate for squint, based on maximizing the minimum beam gain within the bandwidth in the center direction of the beam and limiting the fluctuation range of the beam gain with frequency to obtain the optimal solution X, where X represents a matrix.

[0118] The digital beam module is used to obtain a digital beam according to the optimal solution X, split the digital beam into two analog beams, and use a double phase shifter array structure based on switch switching to realize the conversion from analog beam to digital beam forming.

[0119] The frequency band allocation module is used to select two sets of analog beams closest to the direction of the high-speed moving target user, and allocate different frequency bands to transmit the same data signal to achieve dynamic beam squint compensation.

[0120] The data stream modification module is used to modify the data stream based on the implementation of codebook beam transmission based on frequency band allocation.

[0121] Example 3

[0122] Based on the same inventive concept as other embodiments, this embodiment introduces a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above-mentioned codebook beam transmission method for dynamic beam squint compensation are implemented.

[0123] Example 4

[0124] Based on the same inventive concept as other embodiments, this embodiment introduces a computer device, including: a memory for storing a computer program; a processor for executing the computer program to implement the steps of the above-mentioned codebook beam transmission method for dynamic beam squint compensation.

[0125] Example 5

[0126] Based on the same inventive concept as other embodiments, this embodiment introduces a computer program product, including a computer program, which implements the steps of the above-mentioned codebook beam transmission method for dynamic beam squint compensation when executed by a processor.

[0127] In summary of the above embodiments, the present invention first determines the spatial center direction of each beam of the codebook by the fluctuation of the beam gain within a fixed range, so that the beams are spatially adjacent and non-overlapping; for each beam, a beam optimization problem is established to maximize the minimum beam gain within the bandwidth in the center direction, and limit the fluctuation range of the beam gain with frequency to eliminate the beam squint in the center direction; a digital beam is obtained according to the optimal solution, and the digital beam is split into two analog beams, and a double phase shifter array structure based on switch switching is used to realize the conversion from analog beam to digital beamforming; in engineering implementation, for K users, K data streams need to be copied into 4K data streams, and the base station needs to select two groups of beams adjacent to the user direction to transmit 4 identical data streams on two different frequency bands, respectively, and 4K data streams only need to send 2K pilot signals; this codebook beam transmission method based on frequency division that effectively compensates for dynamic beam squint can effectively compensate for beam skew and improve the available bandwidth and throughput of the system.

[0128] In addition, the present invention can be operated offline, the beam can be calculated and stored in advance, and the codebook beam can cover the entire spatial range, so complexity is not a problem. According to different application backgrounds, the present invention can also be applied to other MIMO communication fields related to millimeter wave beamforming after appropriate modification.

[0129] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0130] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0131] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0132] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0133] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A codebook beam transmission method for dynamic beam squint compensation, characterized in that: include: Based on the premise that the beam center direction is not skewed and the codebook structure is adjacent and not superimposed, the center direction and left and right boundaries of each beam are determined; The optimal design of each beam offset in the center direction is performed to compensate for squint, based on maximizing the minimum beam gain within the bandwidth in the center direction of the beam and limiting the fluctuation range of the beam gain with frequency to obtain the optimal solution X, where X represents a matrix; A digital beam is obtained according to the optimal solution X, and the digital beam is split into two analog beams; For high-speed moving target users, two groups of analog beams closest to the target users are selected, and different frequency bands are allocated to transmit the same data signal to achieve dynamic beam squint compensation.

2. The codebook beam transmission method for dynamic beam squint compensation according to claim 1, characterized in that: The codebook beam transmission method also includes implementing codebook beam transmission based on frequency band allocation and modifying the data stream.

3. The codebook beam transmission method for dynamic beam squint compensation according to claim 1, characterized in that: Based on the premise that there is no beam squint in the center direction and the beams are adjacent and non-overlapping, the center direction and left and right boundaries of each beam in the codebook are determined; The specific method for determining the center direction and left and right boundaries of each beam in the codebook is: In a given spatial range, the spatial direction of each beam in the codebook is determined by the fluctuation of the beam gain in a fixed range, so that each beam is adjacent in space and does not overlap; θ represents the sine of the transmitting angle of the antenna array base station. Given the mobile range of the target user θ∈[-1,1], the mobile range is the direction of the codebook space composed of several beams in the entire dynamic area to cover this range. The given system bandwidth frequency range is The carrier center frequency is f c , then the bandwidth is B = f max -f min ; Considering the codebook design symmetric with respect to the antenna array base station transmission angle θ = 0, when θ∈[0,1], the beam codebook is expressed as in, is a single beam in the codebook, is a column vector, j represents the imaginary unit, i = 1, ..., N, N represents the number of beams in the codebook, θ i,o is the codebook beam w i The beam center direction, [·] T represents the transpose of the vector, M is the number of antennas; let the beam w i The 3dB beam spatial range is [θ i,l ,θ i,r ],θ i,l represents the beam w i The left edge of the coverage area, θ i,r represents the beam w i Right edge of coverage area; passing through carrier center frequency f c Get the phase shift β of the simulated beam that achieves the maximum beam gain in the center direction m =2πf c c -1 (m-1)dθ o , m = 1, ..., M, where c is the speed of light, d is the distance between adjacent antennas, and for any θ o , the 3dB beamwidth of this beam According to the relationship between θ and f, f represents any frequency, if Then the beam center direction θ o The signal gain at all frequencies is within the 3dB beam range, that is, at θ o There is no beam deviation in the direction. According to the requirement that the codebook beam coverage is adjacent and non-overlapping, that is, θ i,l =θ i-1,r ,θ i,r =θ i+1,l , and so on, we get All beam center directions Θ1 = {θ 1,o ,…,θ i,o }, and get the beam codebook for Then the beam needs to be designed to satisfy the o There is no beam deviation in the direction, that is, θ o The signal gain of all frequencies in the direction is within 3dB, and the designed 3dB beam width δ 3dB With θ o Related, beam width must be met at this time The beam codebook is obtained by analogy The corresponding beam center direction θ2 = {θ i+1,o ,…,θ N,o }.

4. The codebook beam transmission method for dynamic beam squint compensation according to claim 3, characterized in that: For the beam center direction θ2 = {θ i+1,o ,…,θ N,o } beam codebook The beams in are optimized and designed to compensate for beam squint. The specific method is as follows: Define θ n,o is the beam w n The central direction of i+1≤n≤N; consider each w n The optimization process is the same. For the convenience of description, the optimized variable w n Abbreviated as w, the corresponding beam center direction θ n,o Abbreviated as θ o ; In order to satisfy the beam center direction θ o The signal gain of all frequencies within the bandwidth is within 3dB, and the optimization problem needs to satisfy the condition γ≤w H a(f,θ0)a H (f,θ0)w≤γ10 3 / 10 , where a(f,θ o ) is the steering vector of the uniform linear array, [·] H represents the conjugate transpose of a matrix or vector. Based on this condition, the following optimization problem is established: Among them, w and γ are the beams and parameters that need to be optimized, w m represents the mth element in the simulated beam vector w; according to the expression w H a(f,θ0)a H (f,θ0)w=tr(a(f,θ0)a H (f,θ0)·ww H ), tr(a(f,θ0)a H (f,θ0)·ww H ) represents the matrix a(f,θ0)a H (f,θ0)·ww H Let X = ww H , then X is a semi-positive definite matrix, and the rank of matrix X is rank(X) = 1, the original optimization problem becomes a semi-SDP problem, and the optimization variable is changed from w to X; Since the constraint rank(X) = 1 is non-convex, the SDR problem is obtained by relaxing the semi-positive definite programming, that is, removing the rank constraint. The optimal solution X for the SDR problem is obtained through software tools.

5. The codebook beam transmission method for dynamic beam squint compensation according to claim 4, characterized in that: The method for obtaining the digital beam is: Since the rank of the optimal solution X of the SDR problem is not 1, it is impossible to directly obtain the simulated beam vector w using the eigenvalue; τ represents the sum of the elements on the τ-th diagonal of the matrix X, and -(M-1)≤τ≤(M-1), τ>0 represents the upper right diagonal of the matrix X, τ<0 represents the lower left diagonal of the matrix X, and τ=0 represents the main diagonal of the matrix X; Σ τ Specifically expressed as The M×M Toeplitz matrix represented by is 1 only on the τth diagonal and the rest are 0. τ Then, the digital beam vector v = [v0, v1, ..., v M-1 ] T ; Among them, the plural Represents the plural v m The conjugate of f(x) is given by Σ τ is an M-1 degree polynomial function composed of coefficients; let f(x) = 0, according to the polynomial coefficients Σ τ Find the root x of the polynomial m , according to the polynomial function The root of m Obtain the coefficients of the polynomial, i.e., the digital beam vector v = [v0, v1, …, v M-1 ] T , where z m Value x m or According to the above method, we can get the digital beam vector v = [ν0, v1, ..., ν m ,…,v M-1 ] T , the amplitude and phase of each element in v are controlled by the phase of the two phase shifters of each antenna; assuming Then the phase of the two phase shifters connected to antenna m is and And meet According to Euler's formula, we can get and These phases are respectively used to simulate the beam and The beam codebook is obtained by this process method Each beam in the CNN is actually composed of two simulated beams, that is, two simulated beams constitute a group of beams, respectively using beam codebooks and It means that w i+1,a and w i+1,b is a set of beams.

6. The codebook beam transmission method for dynamic beam squint compensation according to claim 1, characterized in that: For a high-speed moving target user, the specific method of selecting two sets of simulated beams closest to the target user and allocating different frequency bands to transmit the same data is as follows: When the target user is in a high-speed moving state, when the target user position is within the base station transmission angle range θ∈[θ i,o ,θ i+1,o ), in order to eliminate dynamic beam squint, two groups of beams w corresponding to the beam center directions adjacent to the user position are selected from the codebook. i and w i+1 , the two groups of beams send the same data signal, but use different frequency bands to divide the bandwidth. The beam group w i-1 Frequency range Beam group w i Frequency range And because θ i-1,r =θ i,l ,so By analogy, when the target user moves quickly within the range of θ∈[-1, 1], the beam squint generated by the dynamics is eliminated.

7. The codebook beam transmission method for dynamic beam squint compensation according to claim 1, characterized in that: To implement codebook beam transmission based on frequency band allocation, the specific method to modify the data stream is as follows: For K users, K data streams are copied into 4K data streams. The base station selects two adjacent groups of beams in the direction of the target users to transmit four identical data streams on two different frequency bands. However, the four data streams are sent by two groups of beams in different beam directions. Therefore, 2K pilot signals need to be sent for 4K data streams.

8. A codebook beam transmission device for dynamic beam squint compensation, characterized in that: include: A beam spatial direction acquisition module is used to determine the spatial direction of each beam in the codebook based on a fixed fluctuation range of the beam gain in the frequency band domain in the beam center direction, so that each beam space is adjacent and non-overlapping, and there is no beam deflection in the center direction; The optimal solution acquisition module is used to optimize the design of each offset beam to compensate for squint, based on maximizing the minimum beam gain within the central direction bandwidth and limiting the fluctuation range of the beam gain with frequency to obtain the optimal solution X, where X represents a matrix; The digital beam acquisition module is used to select two sets of analog beams closest to the direction of the fast-moving target user and allocate different frequency bands to transmit the same data signal; The data stream modification module is used to modify the data stream based on the implementation of codebook beam transmission based on frequency band division.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the codebook beam transmission method for dynamic beam squint compensation described in any one of claims 1 to 7 are implemented.

10. A computer device, characterized in that: include: Memory for storing computer programs; A processor is used to execute the computer program to implement the steps of the codebook beam transmission method for dynamic beam squint compensation according to any one of claims 1 to 7.

11. A computer program product, comprising a computer program, characterized in that: When the computer program is executed by a processor, the steps of the codebook beam transmission method for dynamic beam squint compensation described in any one of claims 1 to 7 are implemented.

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