基于混合量化移相器的毫米波大规模MIMO预编码设计

Mixed‑Resolution Phase Shifters⁃Based Precoding Design for the mmWave Massive MIMO Systems

针对毫米波大规模MIMO(Multiple-Input Multiple-Output)系统能量效率低下的问题,提出一种基于混合精度移相器量化的混合预编码设计方法.首先考虑到系统能量效率闭合表达式难以直接求解,通过Dinkelbach方法将能量效率优化问题转换为范数最小化的形式,然后将其进一步解耦为混合预编码矩阵和混合精度移相器量化配比问题,实现非凸能效低范数和的凸优化转化,最后通过引入酉矩阵松弛恒模约束求解混合预编码矩阵,并采用增量搜索算法求解混合量化移相器精度配比向量,从而实现系统能量效率最大化.仿真结果表明,所提出的混合精度量化算法的系统频谱效率优于传统单精度量化算法,且具有更高的系统能量效率.同时,当多数据流传输时,所提出混合精度量化结构的系统性能接近全数字结构.

For the insufficient energy efficiency(EE)in mmWave massive MIMO(Multiple-Input Multiple-Output)systems,a method with mixed-resolution phase shifters is proposed.Considering that the closed expression for EE is diffi⁃cult to solve directly,the EE optimization problem is converted into norm minimization form through the Dinkelbach meth⁃od.Then it is further decoupled into the hybrid precoding matrix and the mixed-resolution ratio problems to realize the con⁃vex optimization transformation of non-convex EE and low norm sum.Finally,in order to maximize the EE of the system,the unitary matrix relaxation constant modulus constraint is introduced to solve the full-resolution hybrid precoding matrix,and the incremental search algorithm is used to solve the optimal mixed-resolution ratio vector.The simulation results show that the spectrum efficiency performance of the proposed mixed-resolution algorithm is better than that of the traditional fi⁃nite-resolution algorithm,and it has higher EE performance.Meanwhile,the system performance of the proposed mixed-res⁃olution quantization structure is close to the full-digital structure when multiple data streams are transmitted.