Enhancing Contention Resolution ALOHA using Combining Techniques

TL;DR

This paper introduces an enhanced ALOHA protocol called ECRA that uses combining techniques to improve contention resolution, significantly outperforming existing asynchronous and synchronous schemes in spectral efficiency and packet loss rate.

Contribution

The paper presents a novel ECRA scheme that incorporates combining techniques for asynchronous ALOHA, along with a tight approximation of packet loss rate suitable for low channel loads.

Findings

ECRA outperforms recent protocols in spectral efficiency.

ECRA achieves lower packet loss rates.

ECRA demonstrates improved throughput over traditional schemes.

Abstract

Recently, random access protocols have acquired a new wave of interest, not only from the satellite communication community, but also from researchers active in fields like Internet of Things and machine-to-machine. Asynchronous (slot- and frame-wise) ALOHA-like random access protocols, are very attractive for such applications, enabling low complexity transmitters and avoiding time synchronization requirements. Evolutions of ALOHA employ time diversity through proactive replication of packets, but the time diversity is not fully exploited at the receiver. Combining techniques, as selection combining and maximal-ratio combining, are beneficial and are adopted in the enhanced contention resolution ALOHA (ECRA) scheme, presented here. A tight approximation of the packet loss rate for asynchronous random access, including ECRA, well suited for the low channel load region is derived. Finally, ECRA is evaluated in terms of spectral efficiency, throughput and packet loss rate in comparison with recent protocols, showing that it is able to largely outperform both slotted synchronous and asynchronous schemes.