A LINK-LIFETIME BASED DYNAMIC SOURCE ROUTING PROTOCOL (LTDSR) FOR MULTIMEDIA OVER MANETS

This paper proposes a link-lifetime based dynamic source routing protocol (LTDSR) to support Soft QoS for multimedia over MANETs, with a series of improved routing mechanisms. First, our research has shown that some routes held in the route cache may become invalid as time passes, due to node mobility. In this work, we introduce a path lifetime based route selection strategy by establishing link lifetimes for routes, so that no node may select already broken routes. A route discovery will be initiated before all the routes in the cache are broken. Second, considering that the routing protocol reacts mistakenly to the transmission failures due to congestion, a cross-layer design framework is explored to establish a shared link-state table with nodes' coordinate and velocity vector; on this basis, the link-state detection mechanism can identify the cause properly when packet loss occurs, and then coordinate with the routing protocol to avoid unnecessary route updating. Our simulation results demonstrate that the LTDSR improves the quality of multimedia playing significantly, in terms of decodable frame ratio, end-to-end frame delay and delay jitter. In addition, the route overhead is greatly reduced.