Virtual Carrier Sensing Based Random Access in Massive MIMO Systems

TL;DR

This paper introduces a virtual carrier sensing scheme for massive MIMO systems to enhance random access capacity by exploiting spatial resources, reducing interference, and increasing uplink channel efficiency.

Contribution

It proposes a novel VCS-based RA scheme that leverages spatial orthogonality in massive MIMO to improve access capacity without significant interference.

Findings

Significantly increases RA channel resources in massive MIMO.

Provides closed-form expressions for channel availability probability.

Theoretical analysis and simulations confirm performance improvements.

Abstract

The 5th generation mobile communication systems aim to support massive access for future wireless applications. Unfortunately, wireless resource scarcity in random access (RA) is a fundamental bottleneck for enabling massive access. To address this problem, we propose a virtual carrier sensing (VCS) based RA scheme in massive MIMO systems. The essence of the proposed scheme lies in exploiting wireless spatial resources of uplink channels occupied by assigned user equipments (UEs) to increase channel resources for RA. With the proposed scheme, RA UEs are able to exploit the spatial resources that are approximately orthogonal to those of assigned UEs, thus sharing the uplink channel resource with assigned UEs without causing significant interference to them. Specifically, to ensure RA UEs avoid serious interference with assigned UEs, base station (BS) sends tailored virtual carriers to RA UEs on behalf of assigned UEs. RA UEs then conduct VCS to determine whether or not the uplink channel resource is available for RA. Closed-form approximations for probability of channel availability and uplink achievable rate with the proposed scheme are derived. Theoretical analysis and simulation results show that the proposed scheme is able to significantly increase channel resources of RA for massive access.