Traffic Differentiation in Dense Collision-free WLANs using CSMA/ECA

TL;DR

This paper investigates how CSMA/ECA, a collision-free MAC protocol, enhances traffic differentiation in dense WLANs, outperforming EDCA by reducing collisions and preventing starvation of low priority traffic.

Contribution

It analyzes the mechanisms of collision-free schedule construction in CSMA/ECA and evaluates its performance in dense scenarios with multiple traffic priorities.

Findings

CSMA/ECA effectively constructs collision-free schedules in dense networks.

It prevents starvation of low priority traffic in high contention scenarios.

Performance improvements over EDCA in throughput and delay are demonstrated.

Abstract

The ability to perform traffic differentiation is a promising feature of the current Medium Access Control (MAC) in Wireless Local Area Networks (WLANs). The Enhanced Distributed Channel Access (EDCA) protocol for WLANs proposes up to four Access Categories (AC) that can be mapped to different traffic priorities. High priority ACs are allowed to transmit more often than low priority ACs, providing a way of prioritising delay sensitive traffic like voice calls or video streaming. Further, EDCA also considers the intricacies related to the management of multiple queues, virtual collisions and traffic differentiation. Nevertheless, EDCA falls short in efficiency when performing in dense WLAN scenarios. Its collision-prone contention mechanism degrades the overall throughput to the point of starving low priority ACs, and produce priority inversions at high number of contenders. Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA) is a compatible MAC protocol for WLANs which is also capable of providing traffic differentiation. Contrary to EDCA, CSMA/ECA uses a contention mechanism with a deterministic backoff technique which is capable of constructing collision-free schedules for many nodes with multiple active ACs, extending the network capacity without starving low priority ACs, as experienced in EDCA. This work analyses traffic differentiation with CSMA/ECA by describing the mechanisms used to construct collision-free schedules with multiple queues. Additionally, evaluates the performance under different traffic conditions and a growing number of contenders. (arXiv's abstract field is not large enough for the paper's abstract, please download the paper for the complete abstract.)