An analysis of pilot contamination on multi-user MIMO cellular systems with many antennas

This paper considers a two-cell cellular system with multiple antennas at the base station (BS) and single antenna user terminals. In such a scenario, the presence of channel state information (CSI) at the BS is essential for efficient system performance. In reciprocal TDD systems, CSI can be obtained via uplink training. Since only finite time-frequency resources are available, such uplink training generally must be performed using non-orthogonal resources (for different users), leading to pilot contamination between users who train simultaneously. In particular, we analyze the rate of convergence of SINR (in presence of pilot contamination) as the number of antennas (M) at the BS increases to an infinite limit. The effect of SNR and the fading coefficients of the user channels on this rate of convergence is also determined.