Energy-Efficient Hybrid Analog and Digital Precoding for mmWave MIMO Systems


Xinyu Gao, Linglong Dai, Shuangfeng Han, Chih-Lin I, and R. W. Heath, Jr.


submitted to the Journal on Selected Areas of Communications, Special Issue on Special Issue on Energy-Efficient Techniques for 5G Wireless Communication Systems


Millimeter wave (mmWave) MIMO will likely use hybrid analog and digital precoding, which uses a small number of RF chains to avoid power consumption associated with mixed signal components like analog-to-digital components not to mention baseband processing complexity. Most hybrid precoding techniques consider a fully-connected architecture. In this paper, we focus on the more energy-efficient hybrid precoding with subconnected architecture, and propose a successive interference cancelation (SIC)-based hybrid precoding with near-optimal performance and low complexity. Inspired by the idea of SIC for multi-user signal detection, we propose to decompose the total achievable rate optimization problem with non-convex constraints into a series of simple sub-rate optimization problems, each of which only considers one sub-antenna array. Then, we prove that maximizing the achievable sub-rate of each subantenna array is equivalent to simply exploring a precoding vector sufficiently close (in terms of Euclidean distance) to the unconstrained optimal solution. Finally, we propose a lowcomplexity algorithm to realize SIC-based hybrid precoding, which can avoid the need for the singular value decomposition (SVD) and matrix inversion. Calculations shows that the complexity of SIC-based hybrid precoding is only about 10% of that of the recently proposed spatially sparse precoding in typical mmWave MIMO systems. Simulation results verify the near-optimal performance of SIC-based hybrid precoding.