Unbounded Contention Resolution in Multiple-Access Channels

TL;DR

This paper introduces new protocols for contention resolution in radio networks that are optimal up to a small constant factor, effective without prior knowledge of user count, and validated through extensive simulations.

Contribution

The paper presents novel, optimal protocols for unbounded contention resolution in radio networks without requiring user count knowledge or collision detection.

Findings

Protocols are proven to be optimal up to a small constant factor.

Extensive simulations confirm the tightness of complexity bounds.

Proposed protocols have small, predictable complexity across various system sizes.

Abstract

A frequent problem in settings where a unique resource must be shared among users is how to resolve the contention that arises when all of them must use it, but the resource allows only for one user each time. The application of efficient solutions for this problem spans a myriad of settings such as radio communication networks or databases. For the case where the number of users is unknown, recent work has yielded fruitful results for local area networks and radio networks, although either a (possibly loose) upper bound on the number of users needs to be known, or the solution is suboptimal, or it is only implicit or embedded in other problems, with bounds proved only asymptotically. In this paper, under the assumption that collision detection or information on the number of contenders is not available, we present a novel protocol for contention resolution in radio networks, and we recreate a protocol previously used for other problems, tailoring the constants for our needs. In contrast with previous work, both protocols are proved to be optimal up to a small constant factor and with high probability for big enough number of contenders. Additionally, the protocols are evaluated and contrasted with the previous work by extensive simulations. The evaluation shows that the complexity bounds obtained by the analysis are rather tight, and that both protocols proposed have small and predictable complexity for many system sizes (unlike previous proposals).