Mitigating Pilot Contamination Through Location-Aware Pilot Assignment in Massive MIMO Networks

TL;DR

This paper introduces a location-aware pilot assignment method for massive MIMO networks with Rician fading, effectively reducing pilot contamination by leveraging user location data to optimize pilot sequences and improve uplink sum rate.

Contribution

The paper presents a novel pilot assignment scheme that utilizes user location information to minimize LOS interference, enhancing network performance for finite antenna arrays.

Findings

LOS interference converges to zero as antennas increase

Proposed scheme outperforms random assignment in uplink sum rate

LOS interference metric effectively predicts pilot assignment performance

Abstract

We propose a novel location-aware pilot assignment scheme to mitigate pilot contamination in massive multiple-input multiple-output (MIMO) networks, where the channels are subjected to Rician fading. Our proposed scheme utilizes the location information of users as the input to conduct pilot assignment in the network. Based on the location information, we first determine the line of sight (LOS) interference between the intended signal and the interfering signal. Our analysis reveals that the LOS interference converges to zero as the number of antennas at the base station (BS) goes to infinity, whereas for finite number of antennas at the BS the LOS interference indeed depends on specific pilot allocation strategies. Following this revelation, we assign pilot sequences to all the users in the massive MIMO network such that the LOS interference is minimized for finite number of antennas at the BS. Our proposed scheme outperforms the random pilot assignment in terms of achieving a much higher uplink sum rate for reasonable values of the Rician K-factor. Moreover, we propose a new performance metric, which measures the strength of the LOS interference and demonstrate that it is a good metric to analyze the performance of pilot assignment schemes. Theoretical analysis is provided and verified through numerical simulations to support the proposed scheme.