Investigation of Massive MIMO in Dense Small Cell Deployment for 5G

Abstract

To meet the challenging capacity requirement of 5G, a set of radio access technologies may be needed, including technologies to improve the spectrum efficiency, to utilize more available spectrum, and network densification, etc. In this paper, we focus on how to combine massive multiple-input and multiple-output (MIMO) and dense small cell (DSC) deployment to boost the system capacity. Under the framework of adjacent channel heterogenous network (HetNet) architecture, clustered small cell deployment with two dimensional active antenna array system (2D AAS) is investigated. The suitable massive MIMO array structure is identified for small cell deployment. Then the coverage issue of clustered small cell deployment with the directional 2D AAS is examined and both packet throughput and area throughput are evaluated with the increasing antenna number as well as the increasing small cell density. Based on the system-level simulation results, the combination of massive MIMO and DSC is revealed to be a promising solution for 5G. Moreover, considering the balance between performance and cost, we further discuss the low-cost massive MIMO scheme for small cell, i.e., hybrid beamforming, and list several challenges to be addressed.