Impact of User Mobility on Optimal Linear Receivers in Cellular Networks

TL;DR

This paper investigates how user mobility affects the performance of optimal linear receivers in multi-cellular MIMO systems, demonstrating that massive MIMO remains advantageous even with channel time variations.

Contribution

It introduces an optimal linear receiver design accounting for user mobility and derives bounds and deterministic equivalents for its performance.

Findings

OLR outperforms known linear receivers in high interference environments

Massive MIMO remains beneficial despite channel time variations

Proposed bounds and deterministic equivalents facilitate performance analysis

Abstract

We consider the uplink of non-cooperative multi-cellular systems deploying multiple antenna elements at the base stations (BS), covering both the cases of conventional and very large number of antennas. Given the inevitable pilot contamination and an arbitrary path-loss for each link, we address the impact of time variation of the channel due to the relative movement between users and BS antennas, which limits system's performance even if the number antennas is increased, as shown. In particular, we propose an optimal linear receiver (OLR) maximizing the received signal-to-interference-plus-noise (SINR). Closed-form lower and upper bounds are derived as well as the deterministic equivalent of the OLR is obtained. Numerical results reveal the outperformance of the proposed OLR against known linear receivers, mostly in environments with high interference and certain user mobility, as well as that massive MIMO is preferable even in time-varying channel conditions.