Research On Key Technologies Of Adaptively Service Discovery In Mobile Ad Hoc Networks

With the development of computer science, communication technology and mobile equipment, mobile ad hoc network (MANET) are being applied widely in many field. Sevice discovery is one of the most important technology in MANET, meanwhile, it's the foundation of many other MANET applications, impacting property and efficiency of network. There is no fix infrastructure for communication in MANET,so that network's topology and request pattern changes frequently as a result of mobility and diversity of terminals, which set up a barrier to provide high efficient, reliable and stability service discovery. Till now the researches about service discovery protocols (SDPs) adapted to changes of network on MANET was not deep enough, they were lack of adaptive mechanism, and can't adjust to network scale, topology and request patterns dynamically.We do the research from network divided, directory deployment and SDP. The network divided aim to control the number and scale of the clusters, provide SDP infrastructure. We propose adaptive clustering problem, and get a linear feasible solution by theoretical analysis, and propose adaptive clustering algorithm. The Algorithm control the number and scale of the clusters in the proper range by add, merger, divide event, and approximate to the expect of solution. Dynamic deployment aim to make the location of directory adapt to network's topology and request pattern, so that we propose adaptive directory deployment problem. By analysing MANET environment, we formulate the relocate process as Markov Decision Process (MDP), with the cost-efficient strategy as policy function, and solve that by Q-learning algorithm. Depand on the theoretical analysis, we design adaptive service discovery for MANET (AMSDP). The SDP execute adaptive clustering algorithm at bottom layer, maintain optimize cluster structure, in which directory is relocated. SDP rely on overlay structure among clusters and cluster heads.Then we analysis the cost of AMSDP.We have carried out simulations to evaluate the performance of AMSDP on C++, and chosen to compare with another adaptive SDP. The result of experiments show that AMSDP not only reduce the number of packets, incurred by service discovery, but also increase the ratio of hit, and shortern the average waiting time, reach the cost efficient strategy.