An admission control algorithm for multi-hop 802.11e based WLANs

Abstract

Recently, wireless local area network (WLAN) hotspots have been deployed in many areas (e.g., cafes, airports, university campuses). The new IEEE 802.11e standard further provides quality of service (QoS) provisioning by grouping the applications (or traffic) into four different access categories. The coverage area of WLANs can be extended by allowing the neighboring mobile devices to relay data to the access points. This concept is known as multi-hop WLANs. Due to the limited network capacity and the contention-based channel access mechanism, admission control is required to regulate the number of simultaneous flows to maintain QoS. The multi-hop extension of WLANs present further challenges for admission control design due to the location-dependent contention in the network. In this paper, we propose an admission control algorithm for multi-hop 802.11e WLANs. The admission control algorithm first constructs the network's contention graph to break down the network contention situation into areas comprised of maximal cliques. Then, the admission decision is made by analyzing the available capacity of each maximal clique with 802.11e saturation throughput analysis. Simulation results show that our proposed algorithm is effective in providing QoS guarantee to the existing voice and video flows while maintaining a good performance for best effort traffic.