Reliable Transporting and Optimal Routing on Rate-Based for Ad Hoc Networks

Owing to the inflexibility of the structure, the conventional layered protocols suffer from the inability to distinguish between losses due to route failures and congestion. Recently, in efforts to overcome the challenges of dynamic environment in ad hoc networks, there have been increased interests in protocols that rely on interactions between different layers. In this paper, we propose a cross-layer architecture combining the three layers of data link, network, and transport in order to provide reliable transporting and optimal routing on rate-based, termed as RTOR. In accordance with the rate computed at MAC layer, a path with the optimal rate is selected at network layer. While the flow control and reliability is performed by the determination of transmission rate and SACKs at transport layer, respectively. The transport protocol herein is not a variant of TCP but a rehash. In flow control, the transmission rate is adjusted by rate feedback instead of AIMD congestion windows. In reliability, SACK blocks appended to feedback packet are used rather than implication of packet lost by duplicate ACKs. In addition, choosing a path with the optimal rate can balance the network load in an appropriate degree. The evaluation results clearly indicate the significant performance improvement that RTOR provides over default TCP, TCP-ELFN, and ATP.