Opportunism in Multiuser Relay Channels: Scheduling, Routing and Spectrum Reuse

TL;DR

This paper analyzes the spectral efficiency of opportunistic scheduling in multiuser relay channels, revealing how multiuser diversity, routing, and spectrum reuse can significantly enhance performance in large systems.

Contribution

It introduces a large-system analysis of spectral efficiency using extreme-value theory, providing accurate formulas and insights into the benefits of relay-assisted multiuser communication.

Findings

Opportunistic scheduling yields significant spectral efficiency gains.

Routing and spectrum reuse further enhance multiuser diversity benefits.

Relay-assisted communication outperforms direct multiuser links under certain conditions.

Abstract

In order to understand the key merits of multiuser diversity techniques in relay-assisted cellular multihop networks, this paper analyzes the spectral efficiency of opportunistic (i.e., channel-aware) scheduling algorithms over a fading multiuser relay channel with $K$ users in the asymptotic regime of large (but finite) number of users. Using tools from extreme-value theory, we characterize the limiting distribution of spectral efficiency focusing on Type I convergence and utilize it in investigating the large system behavior of the multiuser relay channel as a function of the number of users and physical channel signal-to-noise ratios (SNRs). Our analysis results in very accurate formulas in the large (but finite) $K$ regime, provides insights on the potential performance enhancements from multihop routing and spectrum reuse policies in the presence of multiuser diversity gains from opportunistic scheduling and helps to identify the regimes and conditions in which relay-assisted multiuser communication provides a clear advantage over direct multiuser communication.