The Effect of Multiple Access Categories on the MAC Layer Performance of IEEE 802.11p

TL;DR

This paper develops a Markov chain model to analyze how the parallel operation of four access categories in IEEE 802.11p affects MAC layer performance in V2V communications, highlighting the importance of considering all ACs together.

Contribution

It introduces a multi-dimensional DTMC model that captures the joint behavior of all four ACs in IEEE 802.11p, providing analytical insights into their combined MAC performance.

Findings

Performance varies significantly among ACs based on priority.

Analytical model accurately predicts MAC layer performance metrics.

Highlights the necessity of modeling all ACs simultaneously.

Abstract

The enhanced distributed channel access (EDCA) mechanism enables IEEE 802.11p to accommodate differential quality of service (QoS) levels in vehicle-to-vehicle (V2V) communications, through four access categories (ACs). This paper presents multi-dimensional discrete-time Markov chain (DTMC) based model to study the effect of parallel operation of the ACs on the medium access control (MAC) layer performance of ITS-G5 IEEE 802.11p. The overall model consists of four queue models with their respective traffic generators, which are appropriately linked with the DTMCs modeling the operation of each AC. Closed-form solutions for the steady-state probabilities of the models are obtained, which are then utilized to derive expressions for key performance indicators at the MAC layer. An application for a highway scenario is presented to draw insights on the performance. The results show how the performance measures vary among ACs according to their priority levels, and emphasize the importance of analytical modeling of the parallel operation of all four ACs.