Millimeter-Wave Massive MIMO Systems Relying on Generalized Sub-Array-Connected Hybrid Precoding

Abstract

In this paper, we consider a generalized sub-array-connected (GSAC)\narchitecture for arbitrary radio frequency (RF) chain and antenna\nconfigurations, where the number of RF chains connected to a sub-array and the\nnumber of antennas in each sub-array can be arbitrary. Our design objective is\nto improve the energy-efficiency of the hybrid precoder of millimeter-wave\nmassive multiple input multiple output (MIMO) systems. We firstly propose a\nsuccessive interference cancellation based hybrid precoding algorithm to\nmaximize the achievable rate for any given RF chain and antenna configuration.\nThis algorithm firstly decomposes the total achievable rate optimization\nproblem into multiple sub-rate optimization problems, then it successively\nmaximizes these sub-rates. Since the number of RF chains is limited, we can\nafford using an exhaustive search scheme to evaluate all configurations and\nidentify the one having the best energy efficiency. Moreover, to rely on an\nattractive limited feedback, we also propose a beamsteering codebook for our\nhybrid precoding aided GSAC architecture. Our simulation results demonstrate\nthat the proposed scheme achieves a similar rate as the corresponding optimal\nunconstrained precoder. Furthermore, we show that the energy-efficiency of the\nproposed scheme is better than that of the existing schemes in the\nfully-connected and sub-array-connected architectures.\n