Research On Improvement Of Backup Route Protocol In Ad Hoc Networks

Mobile Ad Hoc Networks (MANET) is a kind of multi-hop, self-configuring network of mobile routers with receiving and sending equipments connected by wireless links. In MANET, multi-hop nature, limited storage capacity as well as unstable topology in MANET, the research on QoS support in MANET is a challenge.The paper proposes a routing protocol QoS-CA-AODV (QoS-Congestion Aware AODV) based on the expected transmission efficiency and the residual load of the node considering the characteristics of mobile Ad Hoc networks. This protocol can effectively improve QoS performance with heavy load and routes breaking up in the main path of networks.In the presence of the primary route breaks, reinitiating route discovery process will affect network performance in Ad Hoc network. The proposed routing protocol QoS-CA-AODV attempts to construct an alternate route in case a link break occurs, which can well adapt to high loads of network scenarios. Through cross-layer design between network layer and MAC layer, the protocol provides the network layer with the two path quality information which can be aware of network congestion status: the expected transmission efficiency and the residual load of node, integrates them to form routing decision-making function, and determines which backup node to choose to deliver data packets based on this function.This paper has realized the QoS-CA-AODV protocol in the NS2, compared with the QoS-MAODV and QoS-AODV protocols and analyzed their performance. The results show that either under different CBR rate or under various network sizes the proposed protocol could performs better than the other two protocols in terms of throughput, PDF(packet delivery fraction),delay and route cost and satisfy network QoS demands.