A Research On Using Modified Ant Colony Algorithm To Improve Ad Hoc Routing Protocols

Ad Hoc is a temporary self-organized multi-hop wireless network that can exists without any network infrastructure. All the nodes in the network are completely equal in status, and each node not only provides interactive services for users but also in charge of data switching. As the topology is always changing and does not need any network infrastructure, Ad Hoc has a strong resistance to destruction, and could be quickly set up anywhere anytime. This makes Ad Hoc network widely used in many fields such as disaster recovery, wild exploration, emergency meeting, ocean performance, battlefield command and so on. On the other hand, it also makes general routing protocols are no longer adapt to the changing network topology. After ten years of research and development, a few routing protocol for Ad Hoc has been widely recognized, such as DSDV, AODV, ZRP and so on. But these protocols still can’t satisfy people’s expect on time-lag, packet loss, protocol overhead and node’s energy consumption. To design a routing protocol that can fully adapt to the changing topology is a research hotspot about Ad Hoc in recent years.Ant colony optimization(ACO) is a kind of intelligent optimization algorithm which was derived from simulating ants’foraging behavior. This algorithm can get global optimal solution by accumulating and volatilizing pheromone. ACO has property of positive feeding-back and diversity. Positive feeding-back ensures reinforcement of the excellent features, and diversity can make ACO innovative. These makes ACO fully adapted to solving dynamic shortest path problem. Ad Hoc routing problem is just a dynamic shortest path problem, so ACO may perform perfect on Ad Hoc routing problem.In order to make it more adaptable, we should make some improvements on ACO. By introducing Two-way ant colony optimization mechanism, establishing pheromone threshold mechanism, changing ants’moving rules, ACO was improved. At last, we make ACO combined with regional frequency difference mechanism, introducing an improved Ad Hoc routing protocol. The results of simulation experiments shows that the improved protocol perform better on time-lag, packet loss, protocol overhead and node’s energy consumption.