QUALITY-OF-SERVICE-AWARE MULTICAST ROUTING FOR MULTIMEDIA APPLICATIONS IN MOBILE AD HOC NETWORKS
Supervisor - Prof. Cem Ersoy
Keywords - Mobile ad hoc networks, multicast routing, quality of service, wireless communications
Abstract - The conceptual shift in the expectations of wireless users towards multimedia and group-oriented computing has a significant impact on today’s networks in terms of need for mobility, quality of service (QoS) and multicast routing. Mobile ad hoc networks can provide users with these features. However, it is imperative for them to combine QoS and multicast routing strategies in order to utilize the wireless medium efficiently.
This work defines the ad hoc QoS multicast (AQM) routing protocol, which achieves multicast efficiency by tracking the availability of resources for each node within its neighbourhood. Computation of free bandwidth is based on reservations made for ongoing sessions and the requirements reported by the neighbours. The QoS status is announced at session initiation and updated periodically to the extent of QoS provision. Nodes are prevented from applying for membership if there is no QoS path for the session. When nodes wish to join a session with certain service requirements, a three-phase process ensures that the QoS information is updated and used to select the most appropriate routes. The allowed maximum hop count of the session is taken into account in order to satisfy the delay requirements of the multimedia applications. To cope with the continuous nature of streaming multimedia, AQM nodes check the availability of bandwidth within their neighbourhood not only for themselves but within a virtual tunnel of nodes. Objection queries are issued prior to reservation to avoid excessive resource usage due to allocations made by nodes which cannot detect each other directly. A priority queue determines the transmission order of data packets according to their traffic classes to support even those applications with more stringent QoS requirements. AQM evolves the initial multicast tree into a mesh during data flow to improve robustness. New performance metrics are introduced to evaluate the efficiency of AQM regarding the satisfaction level of session members. Simulation results show that, by applying novel QoS management techniques, AQM significantly improves multicast efficiency for members as well as for sessions.
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