Comprehensive QoS analysis of enhanced distributed channel access in wireless local area networks

Wireless information networks satisfy the users’ desirable requirements for mobility and relocation and thus have experienced tremendous growth in recent years. The Enhanced Distributed Channel Access (EDCA) is a promising Medium Access Control (MAC) protocol for provisioning of Quality-of-Service (QoS) in Wireless Local Area Networks (WLANs). This protocol specifies three important QoS schemes including Arbitrary Inter-Frame Space (AIFS), Contention Window (CW) and Transmission Opportunity (TXOP). Analytical models of EDCA reported in the literature have been primarily developed for the AIFS, CW, and TXOP schemes, separately. This paper proposes a comprehensive analytical model to accommodate the integration of these three QoS schemes in WLANs with finite buffer capacity under unsaturated traffic loads. The important QoS performance metrics in terms of throughput, delay, delay jitter, and frame loss probability are derived. The accuracy of the model is validated through extensive simulation experiments. Performance results reveal that the TXOP can support QoS differentiation, improve the system performance significantly and outperform AIFS and CW owing to its unique burst transmission property. Furthermore, the results demonstrate that the buffer size has considerable impact on the QoS of EDCA, highlighting the importance of taking the buffer size into account for design and analysis of MAC protocols.