Routing Protocol For Ad Hoc Networks Based On Path Stable Strategy

Mobile Ad Hoc Network (MANET) is a kind of complicated distributed and mulithop wireless networks, which does not relay on a fixed communication infrastructure. Without any central controlling nodes and with good survivability, MANET is widely used in the environment such as military communications, rescue catastrophe recovery or deal with unexpected incidents which could not be supported by exixting infrastructures or temporary needs of communication.Routing is a key technology for Ad Hoc neworks which undertakes to search routes for data packets and transmit them to the destinations. As the key components of routing technology, rouging algorithms and protocols have direct effect on network performances. They are closely related: the former is the core of the later, and the later is the concrete realization of the former. The characteristics such as distributed, multihop, self-organized dynamic topology and limited resources make the existing routing algorithms and protocls of wired networks and centerd wireless networks can not be directly used in Ad Hoc networks. So it is urgently needed to design appropriative routing algorithms and protocols for MANET, and these special characteristics make it an enormous challenging task.Based on AODV routing protocol, this paper analyze the routing technology of Ad Hoc networks. The research focuses on the following aspects:(1) In order to reduce the overhead caused by the optional HELLO message mechanism in AODV, this paper used the MAC layer interception to manage local connectivity. The paper also used adaptive mechanism regulating HELLO sent opportunity to reduce the number of routing control packet.(2) The dominant feature of Ad Hoc networks is dynamic topology, so this paper presented a novel method of using the path efficiency factor to quantitatively figure the stability of the selected routing path. With this new method chapter 4 designed a routing protocol based on path stability to reduce the negative impact on the network performance caused by the topology changes.(3) To further reduce the negative impacts of topology changes and decrease broadcast overhead, chapter 5 presented a new algorithm using MAC layer relay to select next-hop nodes without informing network layer. It had been briefly proved that the stability of 2-hop neighbors would be higher than that of 1-hop neighbors; therefore MAC layer reply would reduce the negative impact of 1-hop neighbors' changes on network performances. At the same time MAC layer would control the flooding range of route request packets and reduce the broadcast overhead.