Spectrum Sharing in mmWave Cellular Networks via Cell Association, Coordination, and Beamforming

TL;DR

This paper presents a comprehensive framework for spectrum sharing in mmWave cellular networks, analyzing how beamforming, coordination, and infrastructure sharing impact performance and feasibility.

Contribution

It develops a mathematical framework to evaluate spectrum sharing benefits, considering beamforming, coordination, and infrastructure sharing, with detailed performance analysis.

Findings

Spectrum sharing is feasible with minimal coordination at high mmWave frequencies.

Directional beamforming at user equipment reduces interference issues.

Large antenna arrays lessen the need for coordination and simplify sharing.

Abstract

This paper investigates the extent to which spectrum sharing in mmWave networks with multiple cellular operators is a viable alternative to traditional dedicated spectrum allocation. Specifically, we develop a general mathematical framework by which to characterize the performance gain that can be obtained when spectrum sharing is used, as a function of the underlying beamforming, operator coordination, bandwidth, and infrastructure sharing scenarios. The framework is based on joint beamforming and cell association optimization, with the objective of maximizing the long-term throughput of the users. Our asymptotic and non-asymptotic performance analyses reveal five key points: (1) spectrum sharing with light on-demand intra- and inter-operator coordination is feasible, especially at higher mmWave frequencies (for example, 73 GHz), (2) directional communications at the user equipment substantially alleviate the potential disadvantages of spectrum sharing (such as higher multiuser interference), (3) large numbers of antenna elements can reduce the need for coordination and simplify the implementation of spectrum sharing, (4) while inter-operator coordination can be neglected in the large-antenna regime, intra-operator coordination can still bring gains by balancing the network load, and (5) critical control signals among base stations, operators, and user equipment should be protected from the adverse effects of spectrum sharing, for example by means of exclusive resource allocation. The results of this paper, and their extensions obtained by relaxing some ideal assumptions, can provide important insights for future standardization and spectrum policy.