Adaptive Multimode Hybrid Precoding for Single-RF Virtual Space Modulation With Analog Phase Shift Network in MIMO Systems

摘要

In this paper, we propose a novel transmission approach, namely, analog precoding-aided virtual space modulation (APAVSM), and its corresponding multimode hybrid precoder designs in the multiple-input multiple-output system. We consider the system equipped with a single radio frequency chain and a phase shift network. Our proposed designs can attain benefits of both beamforming and spatial modulation, and therefore enable the significant signal-to-noise power ratio enhancement with efficient degrees of freedom utilization and low cost. We elaborate APAVSM and formulate the multimode hybrid precoder design problem. To solve the problem, we impose restrictions on the number of candidate modes for selection, and propose the hybrid precoder design approach in which two non-convex max-min problems are solved sequentially by iterative approaches. To trade off between error rate and complexity, we propose alternative designs by reducing the dimensionality and/or relaxing constraints. Moreover, by the concept of beamspace, heuristic algorithms are proposed with extremely low complexities. We offer complexity analyses for proposed design approaches. Simulations in Ralyigh fading and millimeter-wave (mmWave) channels are used to evaluate the proposed designs. Results show that our designs can outperform the existing SM-MIMO systems, and provide the feasible operation in mmWave channels with severe path loss. Moreover, the superiority of proposed designs to the conventional precoding-aided MIMO systems is numerically demonstrated.