On the Effective Capacities of Distributed and Co-located Large-Scale Antenna Systems

Effective capacity analysis is a powerful tool to investigate the impact of physical layer designs on the link layer delay-sensitive QoS performance, which is important for real-time multimedia applications. In this paper, we rigorously analyze the effective capacities of downlink large-scale antenna systems. The main focus is to establish the fundamental effective capacity in a very-large MIMO system, and to characterize the performance difference between co-located and distributed antenna layouts. To that end, we first analytically derive the closed-form effective capacities for two widely used linear precoding schemes, conjugate beamforming and zero-forcing beamforming. We then analyze the asymptotic average effective capacities when the number of BS antennas and the number of users grow unboundedly with a fixed ratio. The effective capacity gain of the distributed antenna layout over the co-located layout is established via theoretical analysis.