ALOHA Random Access that Operates as a Rateless Code

TL;DR

This paper introduces a rateless coding-inspired frameless ALOHA protocol for wireless M2M communications, achieving high throughput with adaptive contention periods and practical advantages over existing methods.

Contribution

It proposes a novel frameless ALOHA scheme inspired by rateless coding, with adaptive contention length to optimize throughput in wireless random access.

Findings

High throughput achievable even with few users

Heuristic criteria effectively determine contention termination

Practical implementation benefits over asymptotic approaches

Abstract

Various applications of wireless Machine-to-Machine (M2M) communications have rekindled the research interest in random access protocols, suitable to support a large number of connected devices. Slotted ALOHA and its derivatives represent a simple solution for distributed random access in wireless networks. Recently, a framed version of slotted ALOHA gained renewed interest due to the incorporation of successive interference cancellation (SIC) in the scheme, which resulted in substantially higher throughputs. Based on similar principles and inspired by the rateless coding paradigm, a frameless approach for distributed random access in slotted ALOHA framework is described in this paper. The proposed approach shares an operational analogy with rateless coding, expressed both through the user access strategy and the adaptive length of the contention period, with the objective to end the contention when the instantaneous throughput is maximized. The paper presents the related analysis, providing heuristic criteria for terminating the contention period and showing that very high throughputs can be achieved, even for a low number for contending users. The demonstrated results potentially have more direct practical implications compared to the approaches for coded random access that lead to high throughputs only asymptotically.