EDCA mechanism and mobility support evaluation in IEEE 802.11s WMNs

IEEE 802.11s Wireless Mesh Networks (WMNs) constitute a cost-effective solution for broadband ubiquitous Internet access. The IEEE 802.11s standard employs the Enhanced Distributed Channel Access (EDCA) as the Medium Access Control (MAC) mechanism in order to provide differentiated channel access and Quality of Service (QoS) guarantees for multimedia flows. Under EDCA, traffic is distinguished into four Access Categories (ACs) that have different priority levels, corresponding to Voice, Video, Best Effort and Background, respectively. In this paper, we evaluate the performance of the EDCA in IEEE 802.11s WMNs by simulating pedestrian users moving at low speed for a variety of demanding multimedia applications, such as Real-Time Gaming, video, Voice over IP (VoIP), as well as, web browsing. It should be noted that we have applied IEEE 802.11n as the underlying PHY Layer of the considered IEEE 802.11s network. Our results show that the ACs defined in EDCA do not perform satisfactory resulting in the inappropriateness of the EDCA mechanism for multimedia applications support in WMNs. Furthermore, an additional shortcoming of the IEEE 802.11s amendment that emerged through our simulation results is its inefficiency to support mobility since the velocity of the users significantly impacts the provided QoS.