Hybrid Precoding for Broadband Millimeter-Wave Communication Systems With Partial CSI

Millimeter-wave (mm-wave) communication systems can provide significantly higher throughput thanks to its larger bandwidth. However, due to the hardware cost and power consumptions, the hybrid analog/digital implementation tends to be more practical than the conventional full-digital one. In this paper, we propose a novel hybrid multiuser precoding design for the orthogonal frequency-division multiplexing (OFDM)-based broadband mm-wave systems with a fully connected structure and partial channel state information (CSI). Specifically, the joint analog/digital hybrid precoding design is first transformed into a sparse digital precoding problem with a given analog codebook and corresponding effective CSI. In addition, two approaches, i.e., subcarrier grouping and equal power allocation, are proposed to reduce the computational complexity. Finally, a limited feedback strategy via exploiting the dominant channel subspace is proposed to reduce the feedback overhead. Simulation results show that the proposed designs can achieve near-optimal performance of the considered hybrid mm-wave systems.