QoS-based on-demand segmented backup routing in mobile ad hoc networks

Several real-time applications (e.g., video conferencing, remote control systems) demand guarantees on the message delivery latency. Supporting these QoS connections requires the existence of a routing mechanism, which computes paths that satisfy QoS delay constraints (e.g., end-to-end delays or failure recovery delays). In mobile ad hoc network, wireless links tend to frequently fail as nodes move in and out of transmission range of one another. Providing fault tolerance with QoS guarantees in such a network is challenging. The proposed new algorithm, also called a segmented backup routing (SBR), constructs a set of segmented backup paths. Each segmented backup path, protects a segment of the primary path rather than the entire path. The most important points that are made in this algorithm are two. First, one is able to identify backup paths for any selected primary path, as long as there exists a pair of node disjoint paths from source to destination. In other words, if there are two node disjoint paths, one is not forced to use either of them to be the primary path. This has the advantage that the primary path may be selected based on QoS considerations rather than a consideration of fault tolerance. The second advantage is that there are multiple backup paths, each of which protects breakdown of one or more nodes on the primary path. A backup path may be selected based on QoS considerations. In this paper, we have primarily focused on end-to-end delay as the QoS parameter. We apply our scheme to the AODV protocol.