Ad Hoc QoS Multicast
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Ad Hoc QoS Multicast (AQM) is a Quality of Service (QoS)-aware multicast routing protocol designed for mobile ad hoc networks. It 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 monitored continuously and announced periodically to the extent of QoS provision. Using these features, AQM nodes make their decisions on joining a new multicast session based on the sustainability of their perceived QoS. When nodes wish to join a session with certain service requirements, a three-phase request–reply–reserve 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 along a virtual tunnel of nodes. AQM also evolves the initial multicast tree into a mesh during the course of an ongoing session to achieve a more robust network topology.
