A Routing Protocol for Delay-Sensitive Applications in Mobile Ad Hoc Networks

The Ad hoc On Demand Distance Vector (AODV) routing protocol is intended for use by mobile nodes in ad hoc networks. To provide quality of service, extensions can be added to the messages used during route discovery. These extensions specifythe service requirements which must be met by nodes rebroadcasting a route request (RREQ) or returning a route reply (RREP) for a destination. In order to provide quality delivery to delay sensitive applications such as voice and video, it is extremely important that mobile ad hoc networks provide quality of service (QoS) support in terms of bandwidth and delay. In spite of using IEEE 802.11 as medium access control (MAC), most of the ad hoc routing protocols do not consider contention time which occurs in the medium reservation. Large contention times can be more critical than hop counts in determining the end-to-end delay. Most existing routing protocols for mobile ad hoc networks are designed to search for the shortest path with minimum hop counts. However, the shortest routes do not always provide the best performance, especially when there are congested nodes along these routes. In this paper we propose an on demand delay based quality of service (QoS) routing protocol (AODV-D) to ensure that delay does not exceed a maximum value for mobile ad hoc networks. This protocol will take into consideration MAC layer channel contention information and the number of packets in the interface queue in addition to minimum hops.