Hybrid precoding method and device for time modulation antenna array OFDM (Orthogonal Frequency Division Multiplexing) system

Abstract

The invention provides a hybrid precoding method and hybrid precoding equipment for a time modulation antenna array OFDM (Orthogonal Frequency Division Multiplexing) system. The method comprises the following steps: generating hybrid pre-coding parameters based on channel state information, wherein the hybrid pre-coding parameters comprise a pulse duty ratio, starting time and a baseband pre-coding matrix of a single-pole double-throw radio frequency switch of a time modulation antenna array; performing baseband pre-coding processing on the user data through a baseband pre-coder; generating an active interference cancellation signal, and performing OFDM modulation after the active interference cancellation signal is superposed with the baseband pre-coding signal; the antenna array is controlled by the single-pole double-throw radio frequency switch to transmit signals, and sideband radiation interference is suppressed. According to the method, effective compromise is obtained between beam forming gain and sideband radiation interference avoidance by adopting regularization processing, the pulse starting time of the single-pole double-throw radio frequency switch is adjusted to control the maximum harmonic interference phase, so that the system obtains the minimum maximum harmonic interference under the condition of statistical significance, and by introducing an active interference elimination signal, the maximum harmonic interference can be effectively eliminated. And other higher harmonic interferences caused by the subcarriers are further counteracted.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of wireless communication technology, and in particular to a hybrid precoding method and device for a time-modulated antenna array OFDM system. Background Art

[0002] The time-modulated antenna array (TMAA) uses periodic pulse signals to control the RF switch to generate the array beam pointing. Compared with the traditional phase shifter solution, it has the advantages of low cost, low insertion loss and miniaturization of the feed network. However, the harmonic interference caused by the periodic switch will cause sideband radiation problems. Currently, similar related technologies for sideband radiation suppression are mostly based on the background of narrowband wireless communications. For broadband multi-carrier communications, the existing technical solutions overcome the harmonic interference problem between subcarriers by idling some sub-channels. In fact, TMAA has rich high-order harmonic components, and idle sub-channels cannot completely avoid the sideband radiation problem. In addition, too many idle sub-channels will also lead to a decrease in the system's frequency band utilization efficiency. Therefore, the development of a hybrid precoding method and device for a time-modulated antenna array OFDM system that can effectively overcome the defects in the above-mentioned related technologies has become a technical problem that needs to be solved urgently in the industry. Summary of the Invention

[0003] In view of the above problems existing in the prior art, an embodiment of the present invention provides a hybrid precoding method and device for a time-modulated antenna array OFDM system.

[0004] In the first aspect, an embodiment of the present invention provides a hybrid precoding method for a time-modulated antenna array OFDM system, including: generating hybrid precoding parameters based on channel state information, including a pulse duty cycle, a start time, and a baseband precoding matrix of a single-pole double-throw radio frequency switch of the time-modulated antenna array; performing baseband precoding processing on user data through a baseband precoder; generating an active interference cancellation signal, superimposing it with the baseband precoding signal, and performing OFDM modulation; controlling the antenna array transmit signal through a single-pole double-throw radio frequency switch to suppress sideband radiation interference.

[0005] Based on the content of the above method embodiment, the hybrid precoding method for a time-modulated antenna array OFDM system provided in an embodiment of the present invention, wherein generating hybrid precoding parameters based on channel state information includes:

[0006] Step 1: Construct the transmit subchannel frequency response matrix T based on the channel frequency response matrix H. And extract the eigenvector group G corresponding to its first L largest eigenvalues;

[0007] Step 2: Solve the SOCP optimization problem for all column vectors g[i], i∈[0,L-1] of the eigenvector group G:

[0008]

[0009] Step 3: According to g RF [i], i∈[0,L-1] The results are normalized to obtain the fundamental wave simulation precoding matrix And calculate the pulse duty cycle of each SPDT switch

[0010]

[0011] Step 4: Simulate the precoding matrix based on the fundamental wave Calculate the digital baseband precoding matrix F BB ,in

[0012] Where L is the number of RF links; Used to extract the real part of the matrix; (·) H To take the conjugate transpose sign; g RF [i] is the optimal solution of the SOCP problem constructed by the i-th column vector g[i] of the eigenvector group G; argmax(·) is the independent variable parameter that makes the function take the maximum value; γ is the regularization parameter; ρ i,j represents the duty cycle of the single-pole double-throw RF switch of the j-th RF link corresponding to the i-th antenna; ||·||2 is the symbol for taking the 2-norm; (·) T is the transposed symbol; min(·) is the symbol for taking the minimum value of the vector; max(·) is the symbol for taking the maximum value of the vector; Δ is the subcarrier spacing; k is the kth information transmission subchannel; K is the number of information transmission subchannels, and h[kΔ] is the frequency response of the kΔth subchannel.

[0013] Based on the content of the above method embodiment, the hybrid precoding method of the time modulated antenna array OFDM system provided in the embodiment of the present invention is characterized in that the OFDM system uses K subchannels with a subcarrier spacing of Δ as information transmission channels. At the same time, for the k∈[0,K-1]th transmission subchannel, the system uses the current subchannel and the adjacent left and right subchannels. The idle sub-channels generate active interference cancellation signals to cancel harmonic interference.

[0014] Based on the content of the above method embodiment, the hybrid precoding method for the time-modulated antenna array OFDM system provided in the embodiment of the present invention, wherein the pulse start time of the single-pole double-throw radio frequency switch is adjusted, considering that the interference with the greatest impact on the information transmission subchannel is caused by the harmonic components of the adjacent left and right transmission subchannels, and reducing such interference by adjusting the pulse start time τ, includes:

[0015] Step 1: According to Calculate the qth harmonic initial precoding matrix assuming τ = 0

[0016] Step 2: Calculate the coefficient matrix A of harmonic interference caused by the harmonic components of adjacent left and right transmission sub-channels;

[0017] Step 3: Define vector v = vec(exp(jπΔ(τ / T0))), construct the optimization problem min||A·v||2, and solve vector v by block coordinate descent method;

[0018] Step 4: Update the start time matrix τ according to the vector v;

[0019] Step 5: Modify the qth harmonic precoding matrix Each element of the matrix is defined as:

[0020]

[0021] Where vec(·) is the matrix straightening operation; exp(·) is the natural exponential function; τ is the start time matrix of the single-pole double-throw RF switch group, where τ i,j is the pulse start time of the jth link corresponding to the ith antenna; T0 is the OFDM symbol duration; sinc(·) is the symbol of the Singer function.

[0022] Based on the content of the above method embodiment, the hybrid precoding method for a time-modulated antenna array OFDM system provided in the embodiment of the present invention is characterized in that generating an active interference cancellation signal includes:

[0023] Step 1: Send information according to the system and Calculate the harmonic interference in the system's transmit subchannel I = [I[0], I[1], ..., I[K-1]] T ,in,

[0024]

[0025] Step 2: Introduce active interference cancellation signal Construct the interference cancellation signal optimization problem:

[0026]

[0027] , using convex optimization tools to solve the interference cancellation signal C, including:

[0028]

[0029] Where I[k] is the sum of all harmonic interferences suffered by the kth transmission subchannel; P c is the total power of the interference cancellation signal; μ is the distribution weight of the total power of the interference cancellation signal; P TX is the total power of the transmitted signal; k The set of interference cancellation signals whose harmonic components have an impact on the kth information transmission subchannel, that is, the mth harmonic component of the nth interference cancellation signal has an impact on the kth information transmission subchannel, where m = kΔ-n and |·| is the absolute value symbol; Φ k N is the set of transmission subchannel signals whose harmonic components interfere with the kth information transmission subchannel, that is, the qth harmonic component of the pth transmission subchannel signal interferes with the kth information transmission subchannel; c is the total number of subcarriers; ||·|| F is the symbol of the F norm; s[p] is the transmitted signal of the p-th transmitting subchannel; e[n] is the complex weight of C[n].

[0030] Based on the contents of the above method embodiments, the hybrid precoding method of the time-modulated antenna array OFDM system provided in the embodiments of the present invention, wherein the interference cancellation signal is superimposed with the baseband precoding signal and then OFDM modulation is performed, including: performing an inverse fast Fourier transform on the superimposed signal; adding a cyclic prefix to the transformed signal and converting it into a serial signal, and then converting it into an analog signal through digital-to-analog conversion; using a radio frequency link to convert the analog signal into a radio frequency signal, amplifying and filtering it, and then transmitting it through the time-modulated antenna array.

[0031] Based on the contents of the above method embodiments, the hybrid precoding method of the time-modulated antenna array OFDM system provided in the embodiments of the present invention, wherein the antenna array transmits signals by using a single-pole double-throw radio frequency switch, includes: in a millimeter-wave OFDM system, using a single-pole double-throw switch to control multiple transmitting antennas and corresponding multiple radio frequency links.

[0032] In the second aspect, an embodiment of the present invention provides a time-modulated antenna array OFDM transmission system, including: a hybrid precoding parameter generator for generating precoding parameters; a baseband precoder for precoding the baseband; an interference cancellation signal generator for generating an interference cancellation signal; an IFFT module for performing an inverse fast Fourier transform on the signal; an inserted CP circuit for reducing inter-symbol interference and inter-carrier interference; a parallel-to-serial conversion circuit for converting parallel data into serial data; a DAC circuit for converting a digital signal into an analog signal; a radio frequency link for modulating the baseband signal into a radio frequency signal and performing amplification, filtering and other processing; a time-modulated antenna array for performing analog precoding based on a single-pole double-throw radio frequency switch and transmitting a radio frequency signal; and a main controller for loading a corresponding program to implement the time-modulated antenna array OFDM hybrid precoding method as described in any of the aforementioned method embodiments.

[0033] In the third aspect, an embodiment of the present invention provides a hybrid precoding device for a time-modulated antenna array OFDM system, including: a first main module, used to generate hybrid precoding parameters based on channel state information, including the pulse duty cycle, start time and baseband precoding matrix of the time-modulated antenna array single-pole double-throw RF switch; a second main module, used to implement baseband precoding processing of user data through the baseband precoder; a third main module, used to generate an active interference cancellation signal, which is superimposed with the baseband precoding signal and then subjected to OFDM modulation; a fourth main module, used to control the antenna array transmission signal through the single-pole double-throw RF switch to suppress sideband radiation interference.

[0034] In a fourth aspect, an embodiment of the present invention provides an electronic device, including:

[0035] At least one processor, at least one memory and a communication interface; wherein,

[0036] The processor, memory and communication interface communicate with each other;

[0037] The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the hybrid precoding method of the time-modulated antenna array OFDM system provided by any one of the various implementations of the first aspect.

[0038] In a fifth aspect, an embodiment of the present invention provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions enable a computer to execute the hybrid precoding method of a time-modulated antenna array OFDM system provided by any one of the various implementation methods of the first aspect.

[0039] The hybrid precoding method and device for a time-modulated antenna array OFDM system provided in an embodiment of the present invention adjust the pulse duty cycle of a single-pole double-throw radio frequency switch and design a hybrid precoding scheme. Regularization processing is used to achieve an effective compromise between beamforming gain and avoiding sideband radiation interference. The maximum harmonic interference phase is controlled by adjusting the pulse start moment of the single-pole double-throw radio frequency switch, so that the system obtains the minimum maximum harmonic interference under statistically significant conditions. By introducing an active interference cancellation signal, other high-order harmonic interference caused by the subcarrier is further offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 A schematic flow chart of a hybrid precoding method for a time-modulated antenna array OFDM system provided in an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of the structure of a hybrid precoding device for a time-modulated antenna array OFDM system provided by an embodiment of the present invention;

[0043] Figure 3 A schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention;

[0044] Figure 4 A schematic diagram of the structure of a time-modulated antenna array OFDM transmission system provided in an embodiment of the present invention;

[0045] Figure 5 A schematic diagram of the subcarrier usage and allocation effect in the hybrid precoding method for the time-modulated antenna array OFDM system provided by an embodiment of the present invention;

[0046] Figure 6 A schematic diagram illustrating the effect of parameter control of a single single-pole double-throw RF switch provided by an embodiment of the present invention;

[0047] Figure 7 This is a schematic diagram showing the simulation comparison effects of the hybrid precoding method for the time-modulated antenna array OFDM system provided by an embodiment of the present invention and related technical solutions. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention can be combined with each other arbitrarily to form a feasible technical solution. This combination is not subject to the constraints of the sequence of steps and / or structural composition mode, but must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present invention. If there are step numbers in the following embodiments, they are only set for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0049] The embodiment of the present invention provides a hybrid precoding method for a time-modulated antenna array OFDM system, see Figure 1 The method includes: generating hybrid precoding parameters based on channel state information, including a pulse duty cycle, a start time, and a baseband precoding matrix of a single-pole double-throw radio frequency switch of a time-modulated antenna array; performing baseband precoding processing on user data through a baseband precoder; generating an active interference cancellation signal, superimposing it with the baseband precoding signal, and performing OFDM modulation after that; and controlling the antenna array to transmit a signal through a single-pole double-throw radio frequency switch to suppress sideband radiation interference.

[0050] Based on the content of the above method embodiment, as an optional embodiment, the hybrid precoding method for a time-modulated antenna array OFDM system provided in the embodiment of the present invention, wherein generating hybrid precoding parameters based on channel state information includes:

[0051] Step 1: Construct the transmit subchannel frequency response matrix T based on the channel frequency response matrix H. And extract the eigenvector group G corresponding to its first L largest eigenvalues;

[0052] Step 2: Solve the SOCP optimization problem for all column vectors g[i], i∈[0,L-1] of the eigenvector group G:

[0053]

[0054] Step 3: According to g RF [i], i∈[0,L-1] The results are normalized to obtain the fundamental wave simulation precoding matrix And calculate the pulse duty cycle of each SPDT switch

[0055]

[0056] Step 4: Simulate the precoding matrix based on the fundamental wave Calculate the digital baseband precoding matrix F BB ,in

[0057] In the formula, L is the number of RF links; Used to extract the real part of the matrix; (·) H To take the conjugate transpose sign; g RF [i] is the optimal solution of the SOCP problem constructed by the i-th column vector g[i] of the eigenvector group G; argmax(·) is the independent variable parameter that makes the function take the maximum value; γ is the regularization parameter; ρ i,j represents the duty cycle of the single-pole double-throw RF switch of the j-th RF link corresponding to the i-th antenna; ||·||2 is the symbol for taking the 2-norm; (·) T is the transposed symbol; min(·) is the symbol for taking the minimum value of the vector; max(·) is the symbol for taking the maximum value of the vector; Δ is the subcarrier spacing; k is the kth information transmission subchannel; K is the number of information transmission subchannels, and h[kΔ] is the frequency response of the kΔth subchannel.

[0058] Specifically, assume that the system uses M transmit antennas and L RF links to transmit wireless signals, and the receiving user uses a single antenna for reception. Each RF link is connected to all transmit antennas via an adder through a single-pole double-throw switch, where the parameter ρ of the single-pole double-throw switch is i,j ∈[0,1] and τ i,j ∈[0,T0] respectively controls the duty cycle and start time of the single-pole double-throw switch of the j-th RF link corresponding to the i-th transmitting antenna. T0 is the duration of the OFDM symbol. The number of OFDM subcarriers in the system is N c , using K subcarriers with adjacent number intervals of Δ as information transmission channels. The overall information transmission subcarriers are allocated and distributed as follows Figure 5 As shown. The transmitter hybrid precoding includes the digital baseband precoding matrix

[0059] F BB =[F BB [0],F BB [1],...,F BB [K-1]] and fundamental wave analog precoding matrix based on single-pole double-throw switch control The elements in the precoding matrix and SPDT switch parameter ρ i,j The corresponding relationship is:

[0060]

[0061] For the harmonic interference caused by TMAA, the qth harmonic precoding matrix caused by single-pole double-throw is The elements of this matrix are related to each element ρ in the SPDT switch duty cycle parameter ρ and the start time parameter τ i,j and τ i,j The corresponding relationship is The SPDT RF switch parameter control demonstration diagram is as follows Figure 6 shown.

[0062] The system is set to use the pilot channel estimation to obtain the channel frequency response matrix of all antennas H=[h[0],h[1],...,h[N c -1]], then the signal to interference and noise ratio of the k∈[0,K-1]th information transmission channel is:

[0063]

[0064] where Φ k is the set of transmission subchannel signals whose harmonic components interfere with the kth information transmission subchannel, that is, the qth harmonic component of the pth transmission subchannel signal interferes with the kth information transmission subchannel; σ 2 is the Gaussian white noise power of the sub-channel. Set the system transmission power under harmonic interference The total system transmit power is P, which is evenly distributed to each subchannel. The following describes a specific algorithm to achieve the maximum average subchannel signal-to-interference-and-noise ratio under the total power constraint:

[0065]

[0066] The fundamental wave analog precoding matrix and RF switch pulse duty cycle parameters are calculated based on the channel state information. The transmit sub-channel frequency response matrix is constructed according to the overall channel frequency response matrix H:

[0067]

[0068] and calculate is a matrix The eigenvector group corresponding to the first L largest eigenvalues of Used to extract the real part of a matrix.

[0069] For each column vector g[i] of the obtained matrix G, construct the SOCP optimization problem g RF [i] Use convex optimization tools to obtain a feasible solution, normalize it, and construct the fundamental wave simulation precoding matrix At the same time, calculate the corresponding single-pole double-throw RF switch duty cycle parameters where ||·|| ∞ Take the ∞ norm symbol. Then simulate the precoding matrix based on the fundamental wave The digital baseband precoding matrix F can be calculated BB ,in

[0070] Based on the content of the above method embodiment, as an optional embodiment, the hybrid precoding method of the time modulated antenna array OFDM system provided in the embodiment of the present invention, the pulse start time adjustment of the single-pole double-throw radio frequency switch, considering that the interference with the greatest impact on the information transmission subchannel is caused by the harmonic components of the adjacent left and right transmission subchannels, reduces such interference by adjusting the pulse start time τ, including:

[0071] Step 1: According to Calculate the qth harmonic initial precoding matrix assuming τ = 0

[0072] Step 2: Calculate the coefficient matrix A of harmonic interference caused by the harmonic components of adjacent left and right transmission sub-channels;

[0073] Step 3: Define vector v = vec(exp(jπΔ(τ / T0))), construct the optimization problem min||A·v||2, and solve vector v by block coordinate descent method;

[0074] Step 4: Update the start time matrix τ according to the vector v;

[0075] Step 5: Modify the qth harmonic precoding matrix Each element of the matrix is defined as:

[0076]

[0077] Where vec(·) is the matrix straightening operation; exp(·) is the natural exponential function; τ is the start time matrix of the single-pole double-throw RF switch group, where τ i,j is the pulse start time of the jth link corresponding to the ith antenna; T0 is the OFDM symbol duration; sinc(·) is the symbol of the Singer function.

[0078] Specifically, the RF switch pulse start time is calculated based on the hybrid precoding matrix to suppress the adjacent maximum harmonic interference. Considering that the interference with the information transmission subchannel that is most affected is caused by the harmonic components of the adjacent left and right transmission subchannels, this type of interference is reduced by adjusting the pulse start time τ:

[0079] according to And the corresponding ρ calculation assumes that τ = 0 when the qth harmonic initial simulation precoding matrix vector

[0080] Constructing an optimization problem Solve for v, the maximum adjacent harmonic interference matrix of all transmit subchannels When k=0, When k∈[1,K-2], When k=K-1,

[0081]

[0082] Where conj(·) is used to obtain the complex conjugate of the vector; diag(·) is a function that generates a diagonal matrix. is the matrix Kronecker product operation; K is the number of information transmission subchannels; k is the kth information transmission subchannel; is the initial harmonic interference matrix of the qth harmonic interference assuming τ = 0, where each element of the matrix is given by the formula

[0083] Calculated.

[0084] This optimization problem is solved using the block coordinate descent method, that is, each step of the calculation only updates a certain element of v. Construct the matrix B = A H A, set the convergence threshold ε, initialize the vector v, set the number of iterations t = 1, and perform the element update calculation of v in turn After all elements of v are updated, the value of ||A·v||2 is calculated. If it is less than the threshold ε, the iteration is stopped; if it is greater than the threshold ε, the number of iterations t is increased by 1 and the element update calculation of v is performed again until the value of ||A·v||2 is less than the threshold ε or the number of iterations t reaches a certain value.

[0085] After obtaining the solution of the optimization problem, the inverse transformation is performed using the formula v = vec(exp(jπΔ(τ / T0))) to obtain the starting time parameter τ of the single-pole double-throw switch and update

[0086] Based on the content of the above method embodiment, as an optional embodiment, the hybrid precoding method for a time-modulated antenna array OFDM system provided in the embodiment of the present invention, wherein generating an active interference cancellation signal includes:

[0087] Step 1: Send information according to the system and Calculate the harmonic interference in the system's transmit subchannel I = [I[0], I[1], ..., I[K-1]] T ,in,

[0088]

[0089] Step 2: Introduce active interference cancellation signal Construct the interference cancellation signal optimization problem:

[0090]

[0091] , using convex optimization tools to solve the interference cancellation signal C, including:

[0092]

[0093] Where I[k] is the sum of all harmonic interferences suffered by the kth transmission subchannel; P c is the total power of the interference cancellation signal; μ is the distribution weight of the total power of the interference cancellation signal; P TX is the total power of the transmitted signal; k The set of interference cancellation signals whose harmonic components have an impact on the kth information transmission subchannel, that is, the mth harmonic component of the nth interference cancellation signal has an impact on the kth information transmission subchannel, where m = kΔ-n and |·| is the absolute value symbol; Φ k N is the set of transmission subchannel signals whose harmonic components interfere with the kth information transmission subchannel, that is, the qth harmonic component of the pth transmission subchannel signal interferes with the kth information transmission subchannel; c is the total number of subcarriers; ||·|| F is the symbol of the F norm; s[p] is the transmitted signal of the p-th transmitting subchannel; e[n] is the complex weight of C[n].

[0094] Specifically, the active interference cancellation signal is calculated to cancel other high-order harmonic interferences in the current transmission symbol. Further cancel out the high-order sideband radiation interference. For each transmitting subchannel k∈[0,K-1], the system uses the interference cancellation signal C[kΔ] of the current subchannel and the adjacent left and right subchannels. Idle sub-channel signals cancel out interference signals

[0095] The harmonic components of the

[0096] Assuming that the transmitted OFDM signal is s = [s[0], s[1], ..., s[K-1]], then the interference of all channels is I = [I[0], I[1], ..., I[K-1]] T , construct the interference cancellation signal optimization problem:

[0097]

[0098] in μ is the distribution weight of the total power of the interference cancellation signal, Ψ k is the set of all subchannels whose harmonic components interfere with the kth information transmission subchannel, that is, the mth harmonic component of the nth subchannel interferes with the kth information transmission subchannel. Considering that the power of the interference cancellation signal is much smaller than the power of the information transmission subchannel, and the power of the higher harmonics caused by the RF switch is even smaller, the interference of the harmonics of the cancellation signal on other transmission subchannels can be approximately ignored, that is, a certain subchannel cancellation signal only affects several adjacent information transmission subchannels, that is, it satisfies m = kΔ-n and

[0099] Specific methods for calculating feasible solutions and power allocation for interference cancellation signals:

[0100]

[0101] Constructing a band matrix For any i∈[0,K-1], when hour, The other D[i,j] are all 0. The interference cancellation signal optimization problem is transformed into a QCQP problem with total power constraint: in e=[e[0],e[1],...,e[N c -1]] T , this problem can be solved by using convex optimization tools to obtain a feasible solution of e, thereby obtaining the interference cancellation signal C.

[0102] Based on the content of the above method embodiment, as an optional embodiment, the hybrid precoding method of the time-modulated antenna array OFDM system provided in the embodiment of the present invention, which is superimposed with the baseband precoding signal and then subjected to OFDM modulation, includes: performing an inverse fast Fourier transform on the superimposed signal; adding a cyclic prefix to the transformed digital signal, converting the digital-to-analog signal into an analog signal after parallel-to-serial conversion; converting the serial analog signal into an RF signal through a RF link, amplifying and filtering it, and then transmitting it through the time-modulated antenna array.

[0103] Based on the content of the above method embodiment, as an optional embodiment, the hybrid precoding method of the time-modulated antenna array OFDM system provided in the embodiment of the present invention, wherein the antenna array transmits signals by a single-pole double-throw radio frequency switch, includes: in a millimeter-wave OFDM system, using a single-pole double-throw switch to control multiple transmitting antennas and corresponding multiple radio frequency links.

[0104] For details, please refer to Figure 7Experimental results comparing the bit error rate (BER) of OFDM 64QAM symbols transmitted using this method with other methods under the same system parameters are presented. Existing hybrid precoding (WHP) schemes rely solely on adjusting the pulse duty cycle of a single-pole, double-throw (SPDT) RF switch for hybrid precoding. This results in a sharp deterioration in performance under medium and high signal-to-noise ratio (SNR) conditions. This is because increased signal power also increases the power of higher-order harmonics. Although a spare subcarrier scheme is used to isolate nearby harmonic components, the impact of higher-order harmonics also causes a sharp deterioration in BER performance. The Enhanced-WHP (EWHP) scheme implemented in this invention not only shares the advantages of existing schemes but also utilizes the time-modulated antenna array pulse start time to control the phase of the maximum harmonic interference, minimizing the interference from adjacent maximum harmonics. This significantly improves BER performance compared to existing schemes. Finally, the EWHP with AIC algorithm implemented in this invention combines EWHP with active interference cancellation (AIC), effectively addressing the sideband radiation problem of higher-order harmonics using no more than one percent of the transmitted signal energy as an interference cancellation signal, further improving BER performance.

[0105] The hybrid precoding method for a time-modulated antenna array OFDM system provided in an embodiment of the present invention adjusts the pulse duty cycle of a single-pole double-throw radio frequency switch and designs a hybrid precoding scheme. Regularization processing is used to achieve an effective compromise between beamforming gain and avoiding sideband radiation interference. The maximum harmonic interference phase is controlled by adjusting the pulse start moment of the single-pole double-throw radio frequency switch, so that the system obtains the minimum maximum harmonic interference under statistically significant conditions. By introducing an active interference cancellation signal, other high-order harmonic interference caused by the subcarrier is further offset.

[0106] The embodiment of the present invention provides a time modulation antenna array OFDM transmission system, see Figure 4 The system includes: a hybrid precoding parameter generator for generating precoding parameters; a baseband precoder for precoding the baseband; an interference cancellation signal generator for generating an interference cancellation signal; an IFFT module for performing an inverse fast Fourier transform on the signal; an inserted CP circuit for reducing inter-symbol interference and inter-carrier interference; a parallel-to-serial conversion circuit for converting a parallel digital signal into a serial digital signal; a DAC circuit for converting a digital signal into an analog signal; a radio frequency link for modulating the baseband signal into a radio frequency signal and performing amplification and filtering processing; a time-modulated antenna array for performing analog precoding based on a single-pole double-throw radio frequency switch and transmitting a radio frequency signal; and a master controller (bottom-layer device, implicitly disclosed) for loading a corresponding program to implement the hybrid precoding method of the time-modulated antenna array OFDM system as described in any of the aforementioned method embodiments.

[0107] Specifically, an embodiment of the present invention provides a time-modulated antenna array OFDM transmission system, including: a hybrid precoding parameter generator, a baseband precoder, an interference cancellation signal generator, an IFFT module, a parallel-to-serial conversion circuit, a CP insertion circuit, a DAC, a radio frequency link, and a time-modulated antenna array based on a single-pole double-throw radio frequency switch, characterized in that: the base station transmitter uses the obtained channel state information to input the hybrid precoding parameter generator to generate baseband precoding parameters and parameter information required by the single-pole double-throw switch group, and the transmitter inputs user data into the baseband precoder and the interference cancellation signal generator respectively. The output end of the baseband precoder is added to the output end of the interference cancellation signal generator and then connected to the IFFT module, the cyclic prefix insertion circuit, the serial-to-parallel conversion circuit, the DAC, and the radio frequency link in sequence, and finally transmits the signal through the transmitting antenna array after passing through the single-pole double-throw radio frequency switch component.

[0108] The hybrid precoding parameter calculation method for the time-modulated antenna array OFDM system of the present invention is characterized in that: the system calculates the single-pole double-throw radio frequency switch control parameters and baseband precoding parameters based on the user's channel state information and takes the system sub-channel signal-to-noise ratio and maximum as the optimization target. The main difference from the existing design is that: while controlling the pulse duty cycle parameters of the radio frequency switch to maximize the fundamental wave beamforming gain of the device, the interference of its maximum harmonic on the adjacent sub-channel is reduced by controlling the pulse start time of the radio frequency switch. The interference cancellation signal generation method of the time-modulated antenna array OFDM system: using an active interference cancellation signal to suppress the sideband radiation interference of the time-modulated antenna array OFDM system to make it almost negligible.

[0109] The implementation basis of each embodiment of the present invention is to implement programmed processing through a device with processor functions. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention can be encapsulated into various modules. Based on this reality, on the basis of the above embodiments, an embodiment of the present invention provides a hybrid precoding device for a time-modulated antenna array OFDM system, which is used to execute the hybrid precoding method for a time-modulated antenna array OFDM system in the above method embodiment. Figure 2 The device includes: a first main module, which is used to generate hybrid precoding parameters based on channel state information, including the pulse duty cycle, start time and baseband precoding matrix of the single-pole double-throw radio frequency switch of the time-modulated antenna array; a second main module, which is used to implement baseband precoding processing of user data through the baseband precoder; a third main module, which is used to generate an active interference cancellation signal, and perform OFDM modulation after superimposing it with the baseband precoding signal; and a fourth main module, which is used to control the antenna array to transmit signals through the single-pole double-throw radio frequency switch to suppress sideband radiation interference.

[0110] The hybrid precoding device of the time modulation antenna array OFDM system provided by the embodiment of the present invention adopts Figure 2 Several modules in the system are designed by adjusting the pulse duty cycle of the single-pole double-throw RF switch of the time-modulated antenna array and designing a hybrid precoding scheme. Regularization processing is used to achieve an effective compromise between beamforming gain and avoiding sideband radiation interference. The maximum harmonic interference phase is controlled by adjusting the pulse starting moment of the single-pole double-throw RF switch, so that the system can minimize the maximum harmonic interference under statistically significant conditions. By introducing active interference cancellation signals, other high-order harmonic interference caused by subcarriers is further offset.

[0111] It should be noted that the device in the device embodiment provided by the present invention can not only be used to implement the method in the above-mentioned method embodiment, but also can be used to implement the method in other method embodiments provided by the present invention. The only difference is that the corresponding functional modules are set, and its principle is basically the same as the principle of the above-mentioned device embodiment provided by the present invention. As long as those skilled in the art refer to the specific technical solutions in other method embodiments on the basis of the above-mentioned device embodiment, obtain the corresponding technical means and the technical solutions composed of these technical means by combining technical features, they can improve the device in the above-mentioned device embodiment on the premise of ensuring the practicality of the technical solution, thereby obtaining the corresponding device type embodiment for implementing the methods in other method type embodiments.

[0112] The method of the embodiment of the present invention is implemented by electronic devices, so it is necessary to introduce the relevant electronic devices. Based on this purpose, the embodiment of the present invention provides an electronic device, such as Figure 3 As shown, the electronic device includes: at least one processor, a communications interface, at least one memory, and a communications bus, wherein the at least one processor, the communications interface, and the at least one memory communicate with each other via the communications bus. The at least one processor can call logic instructions in the at least one memory to execute all or part of the steps of the methods provided in the aforementioned method embodiments.

[0113] In addition, the logic instructions in the at least one memory mentioned above can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each method embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0114] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0115] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course can also be implemented by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiment.

[0116] The flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present invention. Based on this understanding, each box in the flowchart or block diagram can represent a module, program segment or part of the code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, or sometimes in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0117] It should be noted that the terms "include", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements. Any "predetermined threshold", "preset threshold" or similar expressions that do not indicate a specific value can be determined by a person of ordinary skill in the art through simple experiments or corresponding debugging.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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. However, 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 various embodiments of the present invention.

Claims

1. A hybrid precoding method for a time-modulated antenna array OFDM system, characterized in that: include: Generate hybrid precoding parameters based on channel state information, including the pulse duty cycle, start time, and baseband precoding matrix of the single-pole double-throw radio frequency switch of the time-modulated antenna array; Performing baseband precoding processing on user data through a baseband precoder; Generate active interference cancellation signal, superimpose it with baseband precoded signal and perform OFDM modulation; The antenna array transmits signals through a single-pole double-throw RF switch to suppress sideband radiation interference.

2. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: Generating hybrid precoding parameters based on channel state information includes: Step 1: Construct the transmit subchannel frequency response matrix T based on the channel frequency response matrix H. And extract the eigenvector group G corresponding to its first L largest eigenvalues; Step 2: Solve the SOCP optimization problem for all column vectors g[i], i∈[0,L-1] of the eigenvector group G: Step 3: According to g RF [i], i∈[0,L-1] The results are normalized to obtain the fundamental wave simulation precoding matrix And calculate the pulse duty cycle of each SPDT switch Step 4: Simulate the precoding matrix based on the fundamental wave Calculate the digital baseband precoding matrix F BB ,in Where L is the number of RF links; Used to extract the real part of the matrix; (·) H To take the conjugate transpose sign; g RF [i] is the optimal solution of the SOCP problem constructed by the i-th column vector g[i] of the eigenvector group G; argmax(·) is the independent variable parameter that makes the function take the maximum value; γ is the regularization parameter; ρ i,j represents the duty cycle of the single-pole double-throw RF switch of the j-th RF link corresponding to the i-th antenna; ||·||2 is the symbol for taking the 2-norm; (·) T is the transposed symbol; min(·) is the symbol for taking the minimum value of the vector; max(·) is the symbol for taking the maximum value of the vector; Δ is the subcarrier spacing; k is the kth information transmission subchannel; K is the number of information transmission subchannels, and h[kΔ] is the frequency response of the kΔth subchannel.

3. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: The OFDM system uses K sub-channels with a sub-carrier spacing of Δ as information transmission channels; at the same time, for the k∈[0,K-1]th transmission sub-channel, the system uses the current sub-channel and the adjacent left and right sub-channels. The idle sub-channels generate active interference cancellation signals to cancel harmonic interference.

4. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: The pulse start time adjustment of the SPDT RF switch takes into account that the interference with the greatest impact on the information transmission subchannel is caused by the harmonic components of the adjacent left and right transmission subchannels. Such interference is reduced by adjusting the pulse start time τ, including: Step 1: According to Calculate the qth harmonic initial precoding matrix assuming τ = 0 Step 2: Calculate the coefficient matrix A of harmonic interference caused by the harmonic components of adjacent left and right transmission sub-channels; Step 3: Define vector v = vec(exp(jπΔ(τ / T0))), construct the optimization problem min||A·v||2, and solve vector v by block coordinate descent method; Step 4: Update the start time matrix τ according to the vector v; Step 5: Modify the qth harmonic precoding matrix Each element of the matrix is defined as: Where vec(·) is the matrix straightening operation; exp(·) is the natural exponential function; τ is the start time matrix of the single-pole double-throw RF switch group, where τ i,j is the pulse start time of the jth link corresponding to the ith antenna; T0 is the OFDM symbol duration; sinc(·) is the symbol of the Singer function.

5. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: Generating an active interference cancellation signal includes: Step 1: Send information according to the system and Calculate the harmonic interference in the system's transmit subchannel I = [I[0], I[1], ..., I[K-1]] T ,in, Step 2: Introduce active interference cancellation signal Construct the interference cancellation signal optimization problem: The interference cancellation signal C is solved using convex optimization tools, including: Where I[k] is the sum of all harmonic interferences suffered by the kth transmission subchannel; P c is the total power of the interference cancellation signal; μ is the distribution weight of the total power of the interference cancellation signal; P TX is the total power of the transmitted signal; k The set of interference cancellation signals whose harmonic components have an impact on the kth information transmission subchannel, that is, the mth harmonic component of the nth interference cancellation signal has an impact on the kth information transmission subchannel, where m = kΔ-n and |·| is the absolute value symbol; Φ k N is the set of transmission subchannel signals whose harmonic components interfere with the kth information transmission subchannel, that is, the qth harmonic component of the pth transmission subchannel signal interferes with the kth information transmission subchannel; c is the total number of subcarriers; ||·|| F is the symbol of the F norm; s[p] is the transmitted signal of the p-th transmitting subchannel; e[n] is the complex weight of C[n].

6. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: The interference cancellation signal is superimposed on the baseband precoding signal and then subjected to OFDM modulation, including: performing inverse fast Fourier transform on the superimposed signal; adding a cyclic prefix to the transformed signal and converting it into a serial signal, and then converting it into an analog signal through digital-to-analog conversion; using a radio frequency link to convert the analog signal into a radio frequency signal, amplifying and filtering it, and then transmitting it through a time-modulated antenna array.

7. The hybrid precoding method for a time-modulated antenna array OFDM system according to claim 1, wherein: The method of controlling the time modulation antenna array to transmit signals by using a single-pole double-throw radio frequency switch includes: in a millimeter wave OFDM system, using a single-pole double-throw switch to control multiple transmitting antennas and corresponding multiple radio frequency links.

8. A time-modulated antenna array OFDM hybrid precoding system, characterized in that: include: A hybrid precoding parameter generator, configured to generate precoding parameters; A baseband precoder, used for precoding the baseband; an interference cancellation signal generator, used for generating an interference cancellation signal; IFFT module, used to perform inverse fast Fourier transform on the signal; Insert the CP circuit to reduce inter-symbol interference and inter-carrier interference; the parallel-to-serial conversion circuit is used to convert parallel data into serial data; the DAC circuit is used to convert digital signals into analog signals; the radio frequency link is used to modulate the baseband signal into a radio frequency signal and perform other processing such as amplification and filtering; A time-modulated antenna array for analog precoding and transmitting radio frequency signals based on a single-pole double-throw radio frequency switch; a master controller for loading a corresponding program to implement the hybrid precoding method of the time-modulated antenna array OFDM system according to any one of claims 1 to 7.

9. A hybrid precoding device for a time-modulated antenna array OFDM system, characterized in that: include: The first main module is used to generate hybrid precoding parameters based on channel state information, including the pulse duty cycle, start time and baseband precoding matrix of the single-pole double-throw radio frequency switch of the time-modulated antenna array; The second main module is used to implement baseband precoding processing on user data through a baseband precoder; The third main module is used to generate an active interference cancellation signal, which is superimposed with the baseband precoding signal and then modulated by OFDM. The fourth main module is used to control the antenna array to transmit signals through a single-pole double-throw RF switch to suppress sideband radiation interference.

10. An electronic device, characterized in that: include: At least one processor, at least one memory and a communication interface; wherein, The processor, memory and communication interface communicate with each other; The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the method according to any one of claims 1 to 7.

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