Ad hoc qualiy of service multicast routing with objection queries for admission control

Abstract

AbstractToday's handheld computing devices equipped with novel wireless network technologies can provide their users with features such as mobility, multimedia support and group communication. On the other hand, the administrative effort required to enable all these features increases beyond the level that an ordinary user can manage. Ad hoc networks, being able to quickly organise themselves without user intervention, can overcome this problem. They are also suitable for group‐oriented mobile multimedia communication. However, it is imperative for ad hoc networks to combine quality of service (QoS) and multicast routing strategies in order to utilise the wireless medium efficiently. This article defines the components of an ad hoc QoS multicast routing (AQM) protocol, which addresses this issue. AQM achieves multicast routing 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 allocations reported by neighbours. Current QoS status is announced at the initiation of a new session and updated periodically in the network to the extent of QoS provision. Thus, 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 consisting of request, reply and reserve steps 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. New performance metrics are introduced to evaluate the efficiency of AQM regarding the satisfaction level of individual members as well as the success rate of sessions. Simulation results show that, by applying novel QoS management techniques, AQM significantly improves multicast efficiency for members as well as for sessions. Copyright © 2005 AEIT.