Multipath Routing Protocol using Cross-layer based QoS Metrics for IEEE 802. 11e WLAN

Abstract

To achieve Quality of Service (QoS) support for multimedia traffic, IEEE 802.11e specifies Hybrid Coordination Function (HCF) Controlled Channel Access (HCCA) technique. When it is applied in multi-hop networks, the performance results, however, reveal that there is significant degradation of throughput with high delay at high load conditions. This is due to the fact that routing is responsible for the successful packet delivery and QoS Support. In a single path routing protocol, although multiple paths are discovered by the source during the process of discovering a route, the path with the shortest delay is chosen as the best path while discarding the rest. An increased efficiency can be achieved in terms of QoS metrics, balancing the load and tolerance to faults by the use of multipath routing. Apart from using multipath routing, cross-layer based approach is also necessary for the enhancement of QoS in IEEE 802.11e networks. This paper proposes a multipath routing protocol using cross-layer based metrics for improving the QoS of multimedia traffic in IEEE 802.11e networks. Initially a combined cost metric is formed based on traffic contention time, average transmission delay and signal fading values. The path with minimum combined cost is chosen as the primary path from the multiple disjoint paths discovered. In case of failed data transmission, the traffic is re-routed through an alternate path with next minimum cost. Simulated Performance evaluation substantiates the reliability of the proposed protocol in achieving higher delivery ratio and throughput and reducing the delay. General Terms Average Transmission Delay, Multipath Route Discovery Process, Signal Fading Value, Traffic Contention Time.