可重构智能表面辅助的毫米波信道估计算法

Channel Estimation Algorithm for Reconfigurable Intelligent Surface Aided Millimeter Wave Systems

针对可重构智能表面(RIS)辅助的毫米波通信中信道状态信息难以获取问题,该文给RIS的部分器件配备射频链,以分开估计基站(BS)/用户(UE)到RIS之间的信道。根据该结构,提出一种低复杂度的信道估计算法。该算法首先采用解耦原子范数最小化(ANM)方法将信道的离开角和到达角的2维角度估计问题转化为两个1维的角度估计的半正定规划(SDP)问题;其次,利用交替方向乘子算法(ADMM)对该SDP问题进行求解,采用动量梯度下降法对信道矩阵参数进行更新以避免矩阵求逆运算,并通过对迭代步长和信道矩阵参数的联合优化以获得更加精准的信道估计值;最后利用信号的2维角度和信道矩阵参数得到路径增益估计。仿真结果表明,该算法达到了优良的信道估计性能,且在确保信道估计性能的系统参数设置下,该算法的复杂度较低。

As the channel status information is difficult to obtain in Reconfigurable Intelligent Surface(RIS)aided millimeter wave communication.The radio frequency chain is provided in some passive elements of RIS to assist channel estimation and estimate the channel between Base Station(BS)/User Equipment(UE)and RIS.Inspired by the structure,a low complexity channel estimation method is proposed.First,the two-dimensional angle estimation problem is transformed into two one-dimensional angle estimation Semi-positive definite programming(SDP)problem by the Atomic Norm Minimization(ANM)method.Second,an Alternating Direction Method of Multipliers(ADMM)algorithm is proposed to solve the Semi-Definite Programming(SDP)problem.Based on the ADMM algorithm,the algorithm applies momentum gradient descent method to avoid the inverse operation of the matrix,and improves the channel estimation accuracy by joint optimizing between a iteration step and channel parameters.Finally,the path gain estimation is obtained by using the signal angle and channel matrix.Simulation results show that the proposed algorithm has better channel estimation performance,and based on the system parameter set,the proposed algorithm has a low complexity.