Area spectral efficiency and area energy efficiency analysis in massive MIMO systems

We consider the downlink multi-user multi-cell massive MIMO systems, and our system model accounts for channel estimation, pilot contamination, and uniformly random user location distribution. An equivalent channel model is investigated which indicates that the users in various cells come through the same `fast fading´ when they reuse the same training signal in uplink pilot transmission phase. Assuming that the number of antennas at base station (BS) is large, under the proposed equivalent channel model, we derive the asymptotic approximations of area spectral efficiency (ASE) with zero-forcing (ZF) and regularized zero-forcing (RZF) techniques which are proven to be accurate via simulation results. Furthermore, with a realistic power consumption model considering not only transmit power but also the precoding processing part, we analyze the performance of area energy efficiency (AEE). In particular, AEE shows quasiconcave with the number of antennas, and it indicates that we can obtain the optimal number of antennas with the existing convex methods.