IRS多分区辅助太赫兹多子阵列波束成形设计

Design of beamforming for IRS multi-partition-aided THz multi-subarray

在智能反射表面(IRS)辅助太赫兹(THz)通信系统中,为突破信道稀疏性对系统空间多路复用增益的限制,提出收发端采用宽间隔多子阵列混合波束成形架构,设计IRS多分区辅助THz多子阵列的传输方案。首先,基于频谱效率最大化原则,构建一个含有多变量耦合和非凸约束的非凸目标函数;然后,将优化问题解耦成2个易于求解的子问题,即IRS反射系数矩阵设计问题和收发端混合波束成形矩阵设计问题;最后,采用黎曼流形优化算法计算IRS反射系数矩阵,并通过数理推导得到混合波束成形矩阵的闭式解。仿真结果表明,与基准方案相比,所提方案可以获得更好的频谱效率。

In the IRS-aided THz communication system,in order to break the channel sparsity limitation on the system spatial multiplexing gain,a hybrid beam forming architecture with wide-spaced multi-subarrays at the transceiver/transmitter side was proposed and the transmission scheme of IRS multi-partition-aided THz multi-subarrays was designed.Firstly,a non-convex objective function with multivariate coupling and non-convex constraints was constructed based on the principle of maximizing spectrum efficiency.Then,the optimization problem was decoupled into two easy-to-solve sub-problems,namely,the reflection coefficient matrix design of IRS and the hybrid beamforming matrix design at the transceiver/receiver.Finally,the Riemannian manifold optimization algorithm was used to calculate the reflection coefficient matrix of IRS,and the closed solution of the hybrid beamforming matrix design at the transceiver/receiver was obtained through mathematical derivation.Simulation results show that compared with the baseline scheme,the proposed scheme can achieve better spectrum efficiency.