CN117200844A - Intelligent metasurface-assisted beamforming design methods, media, equipment and systems - Google Patents
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Abstract
Description
技术领域Technical field
本发明属于无线通讯领域,具体涉及一种智能超表面辅助的波束赋形设计方法、存储介质、计算机设备及装置。The invention belongs to the field of wireless communications, and specifically relates to an intelligent metasurface-assisted beamforming design method, storage medium, computer equipment and device.
背景技术Background technique
近年来,智能超表面(Reconfigurable intelligent surface,RIS)作为一种新涌现的动态电磁参数的调控技术,其低成本、低能耗、可编程和易部署的特点能很好的改善未来无线通信将面临的超复杂、高成本和高能耗的困境,这极大的重塑了无线通信环境。RIS本身是一种具有可编程二维超材料,其由大量的无源发射单元组成,每个单元能够独立的对入射信号施加一个可控的幅度和相位。RIS技术最重要的特性是它可以调节电磁波响应,重塑收发设备之间的无线信道,改善终端设备的接收信号强度以及实现干扰管理。In recent years, intelligent metasurface (Reconfigurable intelligent surface, RIS) is a new emerging dynamic electromagnetic parameter control technology. Its low cost, low energy consumption, programmability and easy deployment can greatly improve the future wireless communication will face. The dilemma of ultra-complexity, high cost and high energy consumption has greatly reshaped the wireless communication environment. RIS itself is a programmable two-dimensional metamaterial, which consists of a large number of passive emission units. Each unit can independently impose a controllable amplitude and phase on the incident signal. The most important feature of RIS technology is that it can adjust electromagnetic wave response, reshape the wireless channel between transceiver devices, improve the received signal strength of terminal devices, and achieve interference management.
在现有技术中,为了充分发挥智能反射面灵活调控信号传播环境的能力,需要快速准确的计算出智能超表面相移矩阵,但是基于传统的波束赋形算法的计算时间很长,由于用户的移动性,基站需要实时的计算出不同位置的用户所对应的相移矩阵,这就导致在实际应用中,当出现RIS单元较大时,传统的波束赋形设计算法会出现在线计算过长的弊端,从而出现因为相移矩阵和用户位置不同步而导致性能变差,影响用户体验。In the existing technology, in order to give full play to the ability of intelligent reflective surfaces to flexibly control the signal propagation environment, it is necessary to quickly and accurately calculate the phase shift matrix of intelligent metasurfaces. However, the calculation time based on traditional beamforming algorithms is very long, due to the user's For mobility, the base station needs to calculate the phase shift matrices corresponding to users at different locations in real time. This results in that in practical applications, when the RIS unit is large, the traditional beamforming design algorithm will take too long to calculate online. Disadvantages, resulting in poor performance due to the phase shift matrix and the user's position being out of sync, affecting the user experience.
发明内容Contents of the invention
本发明的目的是为了克服以上现有技术存在的不足,提供了一种智能超表面辅助的波束赋形设计方法,该方法通过“梯度上升”因子加速迭代更新,能够在最短的时间内快速准确的计算出相移矩阵,从而克服了传统的波束赋形设计算法因在线计算时间过长,出现的相移矩阵和用户位置不同步而导致性能变差的问题。The purpose of the present invention is to overcome the shortcomings of the above existing technologies and provide an intelligent metasurface-assisted beamforming design method. This method accelerates iterative updates through the "gradient rise" factor and can be quickly and accurately in the shortest time. The phase shift matrix is calculated, thereby overcoming the problem of poor performance caused by the traditional beamforming design algorithm's long online calculation time and the phase shift matrix being out of sync with the user's position.
本发明的第二个目的是提供一种存储介质。A second object of the present invention is to provide a storage medium.
本发明的第三个目的是提供一种计算机设备。A third object of the present invention is to provide a computer device.
本发明的第四个目的是提供一种智能超表面辅助的波束赋形设计系统。The fourth object of the present invention is to provide an intelligent metasurface-assisted beamforming design system.
为了实现上述目的,本发明可通过采用如下技术方案达到:In order to achieve the above objects, the present invention can be achieved by adopting the following technical solutions:
一种智能超表面辅助的波束赋形设计方法,包括以下步骤:An intelligent metasurface-assisted beamforming design method includes the following steps:
S1、获取智能超表面辅助的通信系统的信道信息,所述智能超表面辅助的通信系统包括基站、智能超表面和用户设备,然后通过所述计算出所述智能超表面辅助的通信系统中基站到用户设备的等效的信道状态信息;所述信道信息包括所述基站到智能超表面反射端的信道状态信息矩阵、所述智能超表面反射端到用户设备的信道状态信息矩阵;S1. Obtain the channel information of the intelligent metasurface-assisted communication system. The intelligent metasurface-assisted communication system includes a base station, an intelligent metasurface and a user equipment, and then calculate the base station in the intelligent metasurface-assisted communication system through the calculation. Equivalent channel state information to user equipment; the channel information includes a channel state information matrix from the base station to the smart metasurface reflector, and a channel state information matrix from the smart metasurface reflector to user equipment;
S2、设置初始的随机的相移矩阵,通过所述初始的随机的相移矩阵更新出预编码矩阵;所述相移矩阵在每一次迭代时均会发生变化,此时,所述预编码矩阵也会更新;迭代时,所述预编码矩阵的更新表达式如下:S2. Set an initial random phase shift matrix, and update the precoding matrix through the initial random phase shift matrix; the phase shift matrix will change in each iteration. At this time, the precoding matrix will also be updated; during iteration, the update expression of the precoding matrix is as follows:
其中,W表示基站端的预编码矩阵,h表示的是基站到用户设备的等效的信道矩阵,hH表示矩阵h的共轭转置矩阵,τ是利用二次转化技术引入的额外变量,m≥0是功率限制的拉格朗日乘法器,IN表示的是一个N×N的单位矩阵,α是由拉格朗日对偶变换引入的辅助向量;Among them, W represents the precoding matrix at the base station, h represents the equivalent channel matrix from the base station to the user equipment, h H represents the conjugate transpose matrix of the matrix h, τ is an additional variable introduced using the secondary transformation technology, m ≥0 is a power-limited Lagrangian multiplier, I N represents an N×N identity matrix, and α is an auxiliary vector introduced by the Lagrangian dual transformation;
S3、根据步骤S2得到的预编码矩阵,构造包含相移矩阵的目标函数,利用所述目标函数反解更新相移矩阵,得到更新后的相移矩阵;S3. According to the precoding matrix obtained in step S2, construct an objective function including a phase shift matrix, use the inverse solution of the objective function to update the phase shift matrix, and obtain an updated phase shift matrix;
所述更新后的相移矩阵的表达式如下:The expression of the updated phase shift matrix is as follows:
其中,PjF(·)表示投影,q针对θ引入了一个额外的变量用来求解θ,q≠θ,ρ是一个惩罚参数,表示拉格朗日变量,t是迭代次数;Among them, P jF (·) represents the projection, q introduces an additional variable for θ to solve θ, q≠θ, ρ is a penalty parameter, represents the Lagrangian variable, t is the number of iterations;
S4、交替迭代更新相移矩阵和预编码矩阵,得到更新后的相移矩阵和预编码矩阵;S4. Alternately and iteratively update the phase shift matrix and precoding matrix to obtain the updated phase shift matrix and precoding matrix;
S5、设置梯度上升因子,通过所述梯度上升因子对步骤S4所述更新后的预编码矩阵和相移矩阵进行更新,得到优化后的预编码矩阵和相移矩阵;S5. Set the gradient rising factor, and update the updated precoding matrix and phase shift matrix described in step S4 by using the gradient rising factor to obtain the optimized precoding matrix and phase shift matrix;
S6、设置收敛精度条件;将步骤S5得到的优化后的预编码矩阵和相移矩阵构造成函数,判断所述函数是否满足所述收敛精度条件,当满足收敛精度条件时,结束迭代并输出此时的相移矩阵;若不满足收敛精度条件时,则继续回到步骤S4,再次更新,直到满足收敛精度条件为止。S6. Set the convergence accuracy condition; construct the optimized precoding matrix and phase shift matrix obtained in step S5 into a function, determine whether the function satisfies the convergence accuracy condition, and when the convergence accuracy condition is met, end the iteration and output this phase shift matrix; if the convergence accuracy condition is not met, continue to return to step S4 and update again until the convergence accuracy condition is met.
优选的,步骤S5所述梯度上升因子的表达式如下:Preferably, the expression of the gradient rising factor in step S5 is as follows:
其中,λ表示梯度上升因子,a是设定的参数值,at表示第t-1次迭代的参数值,而at +1表示第t次迭代的参数值;Among them, λ represents the gradient ascent factor, a is the set parameter value, a t represents the parameter value of the t-1th iteration, and a t +1 represents the parameter value of the t-th iteration;
所述设定的参数值a的更新表达式如下:The update expression of the set parameter value a is as follows:
优选的,步骤S5中所述优化后的预编码矩阵表示如下:Preferably, the optimized precoding matrix described in step S5 is expressed as follows:
Wt+1=Wt+λ*(Wt-Wt-1)W t+1 =W t +λ*(W t -W t-1 )
其中,λ表示梯度上升因子,W表示基站端的预编码矩阵,Wt-1表示的是第t-1次的迭代值,Wt表示第t次迭代的预编码矩阵,而Wt+1表示第t+1次迭代的预编码矩阵。Among them, λ represents the gradient rising factor, W represents the precoding matrix at the base station, W t-1 represents the t-1 iteration value, W t represents the precoding matrix of the t iteration, and W t+1 represents The precoding matrix of the t+1 iteration.
优选的,步骤S5中所述优化后的相移矩阵表示如下:Preferably, the optimized phase shift matrix described in step S5 is expressed as follows:
θt+1=θt+λ*(θt-θt-1)θ t+1 =θ t +λ*(θ t -θ t-1 )
其中,λ表示梯度上升因子,θ表示智能超表面的相位矩阵,并按照列向量进行排布,θt-1表示的是第t-1次的迭代智能超表面的相位矩阵值,θt表示第t次迭代的智能超表面的相位矩阵值,而θt+1表示第t+1次迭代的智能超表面的相位矩阵值。Among them, λ represents the gradient rising factor, θ represents the phase matrix of the smart metasurface, and is arranged according to the column vector, θ t-1 represents the phase matrix value of the t-1th iteration of the smart metasurface, θ t represents The phase matrix value of the smart metasurface at the t-th iteration, and θ t+1 represents the phase matrix value of the smart metasurface at the t+1-th iteration.
优选的,步骤S4的具体步骤如下:Preferably, the specific steps of step S4 are as follows:
首先根据输入的相移矩阵,利用步骤S2的方法计算出相应的预编码矩阵,然后根据所述相应的预编码矩阵采用步骤S3方法计算出优化更新的相移矩阵,最终得到更新后的预编码矩阵和相移矩阵。First, according to the input phase shift matrix, the corresponding precoding matrix is calculated using the method of step S2, and then the optimized and updated phase shift matrix is calculated according to the corresponding precoding matrix using the method of step S3, and finally the updated precoding is obtained. matrix and phase shift matrix.
优选的,步骤S6中所述优化后的预编码矩阵和相移矩阵构造成函数f1的表达如下:Preferably, the optimized precoding matrix and phase shift matrix described in step S6 are constructed into a function f1 expressed as follows:
f1(W,Θ)=log2(1+SNR)f 1 (W,Θ)=log 2 (1+SNR)
其中,SNR表达式为Among them, the SNR expression is
其中,W表示为预编码矩阵,h表示的是基站到用户设备的等效的信道矩阵,hH表示矩阵h的共轭转置矩阵,δ2为噪声,G1为RIS辅助通信系统中网络设备侧到RIS反射端的信道状态信息矩阵,G2为RIS反射端到用户设备的信道状态信息矩阵,Θ是相位矩阵。Among them, W represents the precoding matrix, h represents the equivalent channel matrix from the base station to the user equipment, h H represents the conjugate transposed matrix of the matrix h, δ 2 represents the noise, and G 1 represents the network in the RIS-assisted communication system. The channel state information matrix from the device side to the RIS reflection end, G 2 is the channel state information matrix from the RIS reflection end to the user equipment, and Θ is the phase matrix.
优选的,所述收敛精度条件表示如下:Preferably, the convergence accuracy condition is expressed as follows:
f1(iter)-f1(iter-1)<σf 1 (iter)-f 1 (iter-1)<σ
其中,iter表示迭代次数,σ为收敛精度,f1为最大信息传送速率函数。Among them, iter represents the number of iterations, σ is the convergence accuracy, and f 1 is the maximum information transfer rate function.
一种存储介质,用于存储非暂时性计算机指令,当所述非暂时性计算机指令被运行时,执行所述的智能超表面辅助的波束赋形设计方法。A storage medium is used to store non-transitory computer instructions. When the non-transitory computer instructions are executed, the intelligent metasurface-assisted beamforming design method is executed.
一种计算机设备,包括处理器和存储器,所述存储器上存储有非暂时性计算机指令,当所述非暂时性计算机指令被处理器运行时,执行所述的智能超表面辅助的波束赋形设计方法。A computer device, including a processor and a memory. Non-transitory computer instructions are stored on the memory. When the non-transitory computer instructions are executed by the processor, the intelligent metasurface-assisted beamforming design is executed. method.
一种智能超表面辅助的波束赋形设计系统,用于实现所述的智能超表面辅助的波束赋形设计方法,所述系统包括:An intelligent metasurface-assisted beamforming design system, used to implement the intelligent metasurface-assisted beamforming design method, the system includes:
信道状态信息获取模块,用于获取基站-智能超表面反射端信道状态信息、基站-用户设备信道状态信息以及不同波束下的智能反射面-用户设备信道状态信息;The channel state information acquisition module is used to obtain the base station-intelligent metasurface reflector channel state information, the base station-user equipment channel state information, and the intelligent reflector-user equipment channel state information under different beams;
相移矩阵生成模块,用于根据所述信道状态信息获取模块获取的信道数据,采用加入梯度上升因子的波束赋形算法交替优化预编码矩阵和相移矩阵,加速预编码矩阵和相移矩阵的迭代更新,生成满足收敛条件的相移矩阵;A phase shift matrix generation module, configured to alternately optimize the precoding matrix and the phase shift matrix by using a beamforming algorithm adding a gradient rising factor based on the channel data obtained by the channel state information acquisition module, and accelerate the generation of the precoding matrix and the phase shift matrix. Update iteratively to generate a phase shift matrix that meets the convergence conditions;
网路设备调控智能超表面相位模块,用于通过所述相移矩阵生成模块生成智能超表面的相位,所述智能超表面辅助的通信系统中的基站通过RF链路控制智能超表面的控制器调节每个单元的电压或者电流信号,使得智能超表面的每个单元的电压或者电流信号发生改变,进而达到改变所述智能超表面中每个单元的反射系数。The network device regulates the intelligent metasurface phase module, which is used to generate the phase of the intelligent metasurface through the phase shift matrix generation module. The base station in the intelligent metasurface-assisted communication system controls the controller of the intelligent metasurface through the RF link. The voltage or current signal of each unit is adjusted to change the voltage or current signal of each unit of the smart metasurface, thereby changing the reflection coefficient of each unit in the smart metasurface.
本发明相对于现有技术具有如下的优点:The present invention has the following advantages over the prior art:
(1)本发明的智能超表面辅助的波束赋形设计方法通过“梯度上升”因子加速迭代更新,加快收敛,从而减少了算法的响应时间,能够在最短的时间内快速准确的计算出相应的相移矩阵,从而克服了传统的波束赋形设计算法因在线计算时间过长,出现的相移矩阵和用户位置不同步而导致性能变差的问题,提升了效率。(1) The intelligent metasurface-assisted beamforming design method of the present invention accelerates iterative updates and convergence through the "gradient rising" factor, thereby reducing the response time of the algorithm and being able to quickly and accurately calculate the corresponding Phase shift matrix, thereby overcoming the problem of poor performance of traditional beamforming design algorithms due to too long online calculation time and the phase shift matrix and user position being out of sync, and improving efficiency.
(2)本发明的智能超表面辅助的波束赋形设计方法适用于各种RIS的通信场景,在当前和未来的通信系统中有着良好的应用前景,具有较高的工程应用价值。(2) The intelligent metasurface-assisted beamforming design method of the present invention is suitable for various RIS communication scenarios, has good application prospects in current and future communication systems, and has high engineering application value.
附图说明Description of the drawings
图1为本发明实施例1提供的一种智能超表面辅助的波束赋形设计方法的方法流程图;Figure 1 is a method flow chart of an intelligent metasurface-assisted beamforming design method provided in Embodiment 1 of the present invention;
图2为本发明实施例1提供的智能超表面辅助的通信系统的结构示意图;Figure 2 is a schematic structural diagram of an intelligent metasurface-assisted communication system provided in Embodiment 1 of the present invention;
图3为本发明实施例1提供的一种智能超表面辅助的波束赋形设计方法的算法的频谱效率变化曲线图;Figure 3 is a spectrum efficiency change curve diagram of an algorithm of an intelligent metasurface-assisted beamforming design method provided in Embodiment 1 of the present invention;
图4为本发明实施例1提供的一种智能超表面辅助的波束赋形设计方法的算法的响应时间对比曲线图;Figure 4 is a response time comparison graph of an algorithm of an intelligent metasurface-assisted beamforming design method provided in Embodiment 1 of the present invention;
图5本发明实施例4提供的一种智能超表面辅助的波束赋形设计系统的结构示意图;Figure 5 is a schematic structural diagram of an intelligent metasurface-assisted beamforming design system provided in Embodiment 4 of the present invention;
图6为本发明实施例4提供的相移矩阵生成模块的工作流程图。Figure 6 is a work flow chart of the phase shift matrix generation module provided in Embodiment 4 of the present invention.
具体实施方式Detailed ways
为使本发明实施例的目的、技术方案和优点更加清楚,下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例是本发明的一部分实施例,而不是全部的实施例,基于本发明中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例,都属于本发明保护的范围。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 These are some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention. .
实施例1Example 1
如图1和图2所示,一种智能超表面辅助的波束赋形设计方法,该方法包括以下步骤:As shown in Figures 1 and 2, an intelligent metasurface-assisted beamforming design method includes the following steps:
S1、获取智能超表面辅助的通信系统的信道信息,所述智能超表面辅助的通信系统包括基站、智能超表面和用户设备,然后通过所述计算出所述智能超表面辅助的通信系统中基站到用户设备的等效的信道状态信息;所述信道信息包括所述基站到智能超表面反射端的信道状态信息矩阵G1、所述智能超表面反射端到用户设备的信道状态信息矩阵G2;S1. Obtain the channel information of the intelligent metasurface-assisted communication system. The intelligent metasurface-assisted communication system includes a base station, an intelligent metasurface and a user equipment, and then calculate the base station in the intelligent metasurface-assisted communication system through the calculation. Equivalent channel state information to the user equipment; the channel information includes the channel state information matrix G 1 from the base station to the smart metasurface reflector, and the channel state information matrix G 2 from the smart metasurface reflector to the user equipment;
具体的,所述智能超表面辅助的通信系统中基站到用户设备的等效的信道状态信息h表示如下:Specifically, the equivalent channel state information h from the base station to the user equipment in the intelligent metasurface-assisted communication system is expressed as follows:
h=G2 HΘG1 (1)h=G 2 H ΘG 1 (1)
其中,h表示的为基站到用户设备的等效的信道,G1表示基站到智能超表面反射端的信道状态信息矩阵,G2表示智能超表面反射端到用户设备的信道状态信息矩阵。Among them, h represents the equivalent channel from the base station to the user equipment, G 1 represents the channel state information matrix from the base station to the smart metasurface reflector, and G 2 represents the channel state information matrix from the smart metasurface reflector to the user equipment.
S2、设置初始的随机的相移矩阵,通过所述初始的随机的相移矩阵更新出预编码矩阵;所述相移矩阵在每一次迭代时均会发生变化,此时,所述预编码矩阵也会更新。S2. Set an initial random phase shift matrix, and update the precoding matrix through the initial random phase shift matrix; the phase shift matrix will change in each iteration. At this time, the precoding matrix Will also be updated.
具体的,步骤S2的具体过程如下:Specifically, the specific process of step S2 is as follows:
S21、首先设置初始的随机的相移矩阵,所述相移矩阵为一个N维的矩阵,且所述N维的矩阵的对角线为智能超表面中每个单元的反射系数;S21. First set an initial random phase shift matrix. The phase shift matrix is an N-dimensional matrix, and the diagonal of the N-dimensional matrix is the reflection coefficient of each unit in the smart metasurface;
所述N维的相移矩阵表示如下:The N-dimensional phase shift matrix is expressed as follows:
Θ=diag{θ} (2)Θ=diag{θ} (2)
其中,Θ表示RIS相移矩阵,θ=[θ1,θ2,…θN]T, 表示的是幅度系数,θ表示的是每个单元的反射系数,θ表示的是所有单元组成的列向量,维度为Nx1,Θ是θ的对角形式,维度为NxN。Among them, Θ represents the RIS phase shift matrix, θ = [θ 1 , θ 2 ,...θ N ] T , represents the amplitude coefficient, θ represents the reflection coefficient of each unit, θ represents the column vector composed of all units, the dimension is Nx1, Θ is the diagonal form of θ, and the dimension is NxN.
S22、设置网络设备侧的预编码矩阵为W,噪声为δ2,则用户接收端的信噪比SNR表示如下:S22. Set the precoding matrix on the network device side to W and the noise to δ 2 . Then the signal-to-noise ratio SNR at the user receiving end is expressed as follows:
则最大信息传送速率f1表示为:Then the maximum information transfer rate f 1 is expressed as:
f1(W,Θ)=log2(1+SNR) (4)f 1 (W, Θ)=log 2 (1+SNR) (4)
S23、设置发射功率P,引入额外变量τ利用二次技术把SNR构造优化W,τ的函数;S23. Set the transmission power P, introduce an additional variable τ, and use quadratic technology to optimize the SNR structure W, a function of τ;
具体的,由于此时已经初始化Θ,需要求得预编码矩阵W,因此把初始化的Θ代入最大信息传送速率函数f1,为了更方便求解此时的变量预编码矩阵W,引入新的额外变量τ,这样函数f1就改写为了函数f2,此时f2与编码矩阵W,额外变量τ相关。所述关于W,τ的优化函数f2表示如下:Specifically, since Θ has been initialized at this time, it is necessary to obtain the precoding matrix W. Therefore, the initialized Θ is substituted into the maximum information transmission rate function f 1. In order to more conveniently solve the variable precoding matrix W at this time, new additional variables are introduced. τ, so that function f 1 is rewritten as function f 2. At this time, f 2 is related to the encoding matrix W and the additional variable τ. The optimization function f 2 with respect to W, τ is expressed as follows:
f2(W,τ)=|hW|2-τ(|hW|2+δ2) (5)f 2 (W,τ)=|hW| 2 -τ(|hW| 2 +δ 2 ) (5)
预编码矩阵W满足条件如下:The precoding matrix W satisfies the following conditions:
tr(WWH)≤P (6)tr(WW H )≤P (6)
其中,WH表示W的转置。Among them, W H represents the transpose of W.
S24、然后根据步骤S24得到的关优化函数可以推导出功率限制的拉格朗日乘法器;所述拉格朗日乘法器的表达如下:S24. Then a power-limited Lagrangian multiplier can be derived based on the optimization function obtained in step S24; the Lagrangian multiplier The expression is as follows:
其中,m≥0是功率限制的拉格朗日乘法器,m为辅助变量。Among them, m≥0 is the power-limited Lagrangian multiplier, and m is the auxiliary variable.
S25、根据公式(7)计算出W,去更新相移矩阵,并结合公式(5)和(6)计算出当最大信息传送速率f1最大时的预编码矩阵、额外变量τ。S25. Calculate W according to formula (7) to update the phase shift matrix, and calculate the precoding matrix and additional variable τ when the maximum information transmission rate f 1 is maximum by combining formulas (5) and (6).
所述预编码矩阵的表示如下:The precoding matrix is expressed as follows:
其中,W表示基站端的预编码矩阵,h表示的是基站到用户设备的等效的信道矩阵,hH表示矩阵h的共轭转置矩阵,τ是利用二次转化技术引入的额外变量,m≥0是功率限制的拉格朗日乘法器,IN表示的是一个N×N的单位矩阵,α是由拉格朗日对偶变换引入的辅助向量。Among them, W represents the precoding matrix at the base station, h represents the equivalent channel matrix from the base station to the user equipment, h H represents the conjugate transpose matrix of the matrix h, τ is an additional variable introduced using the secondary transformation technology, m ≥0 is a power-limited Lagrangian multiplier, IN represents an N×N identity matrix, and α is an auxiliary vector introduced by the Lagrangian dual transformation.
所述额外变量τ表示如下:The additional variable τ is expressed as follows:
其中,α为额外参数,数值等于α=SNR。Among them, α is an additional parameter, and the value is equal to α=SNR.
综上所述,迭代时,所述预编码矩阵的更新表达式如公式(8)所示。To sum up, during iteration, the update expression of the precoding matrix is as shown in formula (8).
S3、根据步骤S2得到的预编码矩阵,将函数f1构造包含相位矩阵的目标函数Υ(q,θ,κU,κI),利用所述目标函数反解更新相移矩阵,得到更新后的相移矩阵;S3. According to the precoding matrix obtained in step S2, construct the objective function Y(q, θ, κ U , κ I ) including the phase matrix from the function f 1 , and use the inverse solution of the objective function to update the phase shift matrix to obtain the updated The phase shift matrix;
具体的,步骤S3的具体过程如下:Specifically, the specific process of step S3 is as follows:
S31、根据步骤S2得的预编码矩阵,令辅助变量ν=diag(G2 H)G1W,计算出额外变量ρ;所述额外变量ρ的表示如下:S31. According to the precoding matrix obtained in step S2, let the auxiliary variable ν = diag (G 2 H ) G 1 W and calculate the additional variable ρ; the additional variable ρ is expressed as follows:
S32、根据步骤S31,推导出额外变量Δ, S32. According to step S31, derive the additional variable Δ,
Δ=|ρ|2υυH (11)Δ=|ρ| 2 υυ H (11)
其中,Δ和均为便于辅助计算所引入的额外变量。Among them, Δ and All are additional variables introduced to facilitate auxiliary calculations.
S33、重新构造目标函数,并设置约束条件;S33. Reconstruct the objective function and set constraints;
具体的,由于已知了预编码矩阵W,需要求解的是Θ,因而将预编码矩阵W代入函数f1进行变形,并转变为关于θ的函数,重新构造的目标函数f3具体表示如下:Specifically, since the precoding matrix W is known and what needs to be solved is Θ, the precoding matrix W is substituted into the function f 1 for deformation and transformed into a function about θ. The reconstructed objective function f 3 is specifically expressed as follows:
其中,f3为f1变换的关于θ的目标函数。Among them, f 3 is the objective function about θ transformed by f 1 .
所述约束条件表示如下:The constraints are expressed as follows:
S34、针对θ引入了一个额外的变量q,且设置q≠θ;因此得出:S34. An additional variable q is introduced for θ, and q≠θ is set; therefore:
其中,约束条件为s.t.q=θ,θi∈[0,2π],ρ>0是一个惩罚参数。Among them, the constraint conditions are stq=θ, θ i ∈[0,2π], ρ>0 is a penalty parameter.
S35、构造新的函数Υ(q,θ,κU,κI),所述新的函数Υ(q,θ,κU,κI)表示如下:S35. Construct a new function Y(q,θ,κ U ,κ I ). The new function Y(q,θ,κ U ,κ I ) is expressed as follows:
其中,κR=[κR,1,…,κR,N]T,κI=[κI,1,…,κI,N]T是拉格朗日变量,Re{q-θ}=0,Im{q-θ}=0, Among them, κ R =[κ R,1 ,…,κ R,N ] T ,κ I =[κ I,1 ,…,κ I,N ] T is a Lagrangian variable, Re{q-θ} =0, Im{q-θ}=0,
然后,对于公式(16)的对偶问题进行变换,表示如下:Then, the dual problem of formula (16) is transformed and expressed as follows:
S36对步骤S35得到的函数公式(16)进行迭代,得到更新后的相移矩阵θt+1;所述θt+1表示如下:S36 iterates the function formula (16) obtained in step S35 to obtain the updated phase shift matrix θ t+1 ; the θ t+1 is expressed as follows:
其中,t是迭代次数。in, t is the number of iterations.
对公式(18)进行优化,最终更新后的相移矩阵表示如下:After optimizing formula (18), the final updated phase shift matrix is expressed as follows:
其中,PjF(·)表示投影,q针对θ引入了一个额外的变量用来求解θ,q≠θ,ρ是一个惩罚参数,表示拉格朗日变量,t是迭代次数。Among them, P jF (·) represents the projection, q introduces an additional variable for θ to solve θ, q≠θ, ρ is a penalty parameter, represents the Lagrangian variable, and t is the number of iterations.
S4、交替迭代更新相移矩阵和预编码矩阵,得到更新后的相移矩阵和预编码矩阵;S4. Alternately and iteratively update the phase shift matrix and precoding matrix to obtain the updated phase shift matrix and precoding matrix;
步骤S4的步骤如下:The steps of step S4 are as follows:
首先根据输入的相移矩阵,利用步骤S2的方法计算出相应的预编码矩阵,然后根据所述相应的预编码矩阵采用步骤S3方法计算出优化更新的相移矩阵,最终得到更新后的预编码矩阵和相移矩阵。First, according to the input phase shift matrix, the corresponding precoding matrix is calculated using the method of step S2, and then the optimized and updated phase shift matrix is calculated according to the corresponding precoding matrix using the method of step S3, and finally the updated precoding is obtained. matrix and phase shift matrix.
S5、设置梯度上升因子,通过所述梯度上升因子对步骤S4所述更新后的预编码矩阵和相移矩阵进行更新,得到优化后的预编码矩阵和相移矩阵;S5. Set the gradient rising factor, and update the updated precoding matrix and phase shift matrix described in step S4 by using the gradient rising factor to obtain the optimized precoding matrix and phase shift matrix;
所述梯度上升因子的表达式如下:The expression of the gradient ascent factor is as follows:
其中,λ表示梯度上升因子,a是设定的参数值,at表示第t-1次迭代的参数值,而at +1表示第t次迭代的参数值。Among them, λ represents the gradient ascent factor, a is the set parameter value, a t represents the parameter value of the t-1th iteration, and a t +1 represents the parameter value of the t-th iteration.
所述设定的参数值a的更新表达式如下:The update expression of the set parameter value a is as follows:
具体的,所述优化后的预编码矩阵表示如下:Specifically, the optimized precoding matrix is expressed as follows:
Wt+1=Wt+λ*(Wt-Wt-1) (22)W t+1 =W t +λ*(W t -W t-1 ) (22)
其中,λ表示梯度上升因子,W表示基站端的预编码矩阵,Wt-1表示的是第t-1次的迭代值,Wt表示第t次迭代的预编码矩阵,而Wt+1表示第t+1次迭代的预编码矩阵。Among them, λ represents the gradient rising factor, W represents the precoding matrix at the base station, W t-1 represents the t-1 iteration value, W t represents the precoding matrix of the t iteration, and W t+1 represents The precoding matrix of the t+1 iteration.
具体的,步骤S5中所述优化后的相移矩阵表示如下:Specifically, the optimized phase shift matrix described in step S5 is expressed as follows:
θt+1=θt+λ*(θt-θt-1) (23)θ t+1 =θ t +λ*(θ t -θ t-1 ) (23)
其中,λ表示梯度上升因子,θ表示智能超表面的相位矩阵,并按照列向量进行排布,θt-1表示的是第t-1次的迭代智能超表面的相位矩阵值,θt表示第t次迭代的智能超表面的相位矩阵值,而θt+1表示第t+1次迭代的智能超表面的相位矩阵值。Among them, λ represents the gradient rising factor, θ represents the phase matrix of the smart metasurface, and is arranged according to the column vector, θ t-1 represents the phase matrix value of the t-1th iteration of the smart metasurface, θ t represents The phase matrix value of the smart metasurface at the t-th iteration, and θ t+1 represents the phase matrix value of the smart metasurface at the t+1-th iteration.
S6、设置收敛精度条件;将步骤S5得到的优化后的预编码矩阵和相移矩阵构造成函数,判断所述函数是否满足所述收敛精度条件,当满足收敛精度条件时,结束迭代并输出此时的相移矩阵;若不满足收敛精度条件时,则继续回到步骤S4,再次更新,直到满足收敛精度条件为止。S6. Set the convergence accuracy condition; construct the optimized precoding matrix and phase shift matrix obtained in step S5 into a function, determine whether the function satisfies the convergence accuracy condition, and when the convergence accuracy condition is met, end the iteration and output this phase shift matrix; if the convergence accuracy condition is not met, continue to return to step S4 and update again until the convergence accuracy condition is met.
具体的,步骤S6中所述优化后的预编码矩阵和相移矩阵构造成函数f1的表达如下:Specifically, the optimized precoding matrix and phase shift matrix described in step S6 are constructed into function f1, which is expressed as follows:
f1(W,Θ)=log2(1+SNR)f 1 (W,Θ)=log 2 (1+SNR)
其中,SNR表达式为Among them, the SNR expression is
其中,W表示为预编码矩阵,h表示的是基站到用户设备的等效的信道矩阵,hH表示矩阵h的共轭转置矩阵,δ2为噪声,G1为RIS辅助通信系统中网络设备侧到RIS反射端的信道状态信息矩阵,G2为RIS反射端到用户设备的信道状态信息矩阵,Θ是相位矩阵。Among them, W represents the precoding matrix, h represents the equivalent channel matrix from the base station to the user equipment, h H represents the conjugate transposed matrix of the matrix h, δ 2 represents the noise, and G 1 represents the network in the RIS-assisted communication system. The channel state information matrix from the device side to the RIS reflection end, G 2 is the channel state information matrix from the RIS reflection end to the user equipment, and Θ is the phase matrix.
所述收敛精度条件表示如下:The convergence accuracy conditions are expressed as follows:
f1(iter)-f1(iter-1)<σf 1 (iter)-f 1 (iter-1)<σ
其中,iter表示迭代次数,σ为收敛精度。Among them, iter represents the number of iterations, and σ is the convergence accuracy.
如图3所示,在设置频率为28Ghz,用户为单天线,基站天线数目为4,RIS单元数为20*20,RIS单元尺寸为0.5λ*0.5λ,σ=1e-4,电脑的运行内存12GB的条件下,本实施例提出的算法与和分式规划算法提升频谱效率基本一致,和ADMM算法相比,本实施例提出的算法提升频谱效率较大。As shown in Figure 3, when the set frequency is 28Ghz, the user is a single antenna, the number of base station antennas is 4, the number of RIS units is 20*20, the RIS unit size is 0.5λ*0.5λ, σ=1e-4, the operation of the computer Under the condition of 12GB of memory, the algorithm proposed in this embodiment is basically consistent with the fractional planning algorithm in improving spectral efficiency. Compared with the ADMM algorithm, the algorithm proposed in this embodiment improves the spectral efficiency significantly.
如图4所示,图4具体评估了本实施例提出的算法与分式规划算法、ADMM算法的收敛性能,图中,随着RIS的单元数增加,ADMM算法和分式规划算法的响应时间显著增加,但是本实施例提出的算法远低于前两者的响应时间,这是因为本实施例在算法中增加了梯度下降因子,此设置会使总的迭代次数大幅度减少,这样响应时间也会大幅度降低。As shown in Figure 4, Figure 4 specifically evaluates the convergence performance of the algorithm proposed in this embodiment, the fractional planning algorithm, and the ADMM algorithm. In the figure, as the number of units in the RIS increases, the response times of the ADMM algorithm and the fractional planning algorithm increase. Significant increase, but the response time of the algorithm proposed in this embodiment is much lower than the first two. This is because this embodiment adds a gradient descent factor in the algorithm. This setting will greatly reduce the total number of iterations, so that the response time It will also be significantly reduced.
具体的,经过多次试验,当梯度下降因子设置为合适的固定值时,本实施例的算法依然比ADMM算法的收敛速度更快、时间更短。Specifically, after many experiments, when the gradient descent factor is set to an appropriate fixed value, the algorithm of this embodiment still converges faster and in a shorter time than the ADMM algorithm.
实施例2Example 2
一种存储介质,用于存储非暂时性计算机指令,当所述非暂时性计算机指令被运行时,执行实施例1所述的智能超表面辅助的波束赋形设计方法。A storage medium used to store non-transitory computer instructions. When the non-transitory computer instructions are executed, the intelligent metasurface-assisted beamforming design method described in Embodiment 1 is executed.
实施例3Example 3
一种计算机设备,包括处理器和存储器,所述存储器上存储有非暂时性计算机指令,当所述非暂时性计算机指令被处理器运行时,执行实施例1所述的智能超表面辅助的波束赋形设计方法。A computer device, including a processor and a memory. Non-transitory computer instructions are stored on the memory. When the non-transitory computer instructions are executed by the processor, the intelligent metasurface-assisted beam described in Embodiment 1 is executed. Shape design method.
实施例4Example 4
如图5所示,一种智能超表面辅助的波束赋形设计系统,包括:As shown in Figure 5, an intelligent metasurface-assisted beamforming design system includes:
信道状态信息获取模块,用于获取基站-智能超表面反射端信道状态信息、基站-用户设备信道状态信息以及不同波束下的智能反射面-用户设备信道状态信息;The channel state information acquisition module is used to obtain the base station-intelligent metasurface reflector channel state information, the base station-user equipment channel state information, and the intelligent reflector-user equipment channel state information under different beams;
相移矩阵生成模块,用于根据所述信道状态信息获取模块获取的信道数据,采用加入梯度上升因子的波束赋形算法交替优化预编码矩阵和相移矩阵,加速预编码矩阵和相移矩阵的迭代更新,生成满足收敛条件的相移矩阵;A phase shift matrix generation module, configured to alternately optimize the precoding matrix and the phase shift matrix by using a beamforming algorithm adding a gradient rising factor based on the channel data obtained by the channel state information acquisition module, and accelerate the generation of the precoding matrix and the phase shift matrix. Update iteratively to generate a phase shift matrix that meets the convergence conditions;
网路设备调控智能超表面相位模块,用于通过所述相移矩阵生成模块生成智能超表面的相位,所述智能超表面辅助的通信系统中的基站通过RF链路控制智能超表面的控制器调节每个单元的电压或者电流信号,使得智能超表面的每个单元的电压或者电流信号发生改变,进而达到改变所述智能超表面中每个单元的反射系数。The network device regulates the intelligent metasurface phase module, which is used to generate the phase of the intelligent metasurface through the phase shift matrix generation module. The base station in the intelligent metasurface-assisted communication system controls the controller of the intelligent metasurface through the RF link. The voltage or current signal of each unit is adjusted to change the voltage or current signal of each unit of the smart metasurface, thereby changing the reflection coefficient of each unit in the smart metasurface.
具体的,所述收敛精度条件表示如下:Specifically, the convergence accuracy condition is expressed as follows:
f1(iter)-f1(iter-1)<σf 1 (iter)-f 1 (iter-1)<σ
其中,iter表示迭代次数,σ为收敛精度,f1为最大信息传送速率函数。Among them, iter represents the number of iterations, σ is the convergence accuracy, and f 1 is the maximum information transfer rate function.
需要说明的是,上述实施例方法中的全部或部分流程,可以通过计算机程序来指令相关的硬件来完成,计算机程序可存储于计算机可读取存储介质中,该计算机程序在执行时,可包括如上述各方法的实施例的流程。其中,计算机可读取存储介质可包括非易失性和/或易失性存储器。非易失性存储器可包括只读存储器(ROM)、可编程ROM(PROM)、电可编程ROM(EPROM)、电可擦除可编程ROM(EEPROM)或闪存。易失性存储器可包括随机存取存储器(RAM)或者外部高速缓冲存储器。It should be noted that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed, the computer program can include The procedures of the above method embodiments are as follows. Wherein, the computer-readable storage medium may include non-volatile and/or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory.
可以理解的是,RAM具备多种形式,诸如同步DRAM(SDRAM)、增强型SDRAM(ESDRAM)、存储器总线(Rambus)直接RAM(RDRAM)、直接存储器总线动态RAM(DRDRAM)、存储器总线动态RAM(RDRAM)、静态RAM(SRAM)、动态RAM(DRAM)等。It can be understood that RAM has many forms, such as synchronous DRAM (SDRAM), enhanced SDRAM (ESDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), memory bus dynamic RAM ( RDRAM), static RAM (SRAM), dynamic RAM (DRAM), etc.
上述实施例为本发明较佳的实施方式,但本发明的实施方式并不受上述实施例的限制,其他的任何未背离本发明的精神实质与原理下所作的改变、修饰、替代、组合、简化,均应为等效的置换方式,都包含在本发明的保护范围之内。The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, etc. may be made without departing from the spirit and principles of the present invention. All simplifications should be equivalent substitutions, and are all included in the protection scope of the present invention.
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