Research On Resource Location Mechanism And Relay Cooperative Scheme In Wireless P2P Networks

With the continuous development of wireless communication, demand on communication service is becoming higher and higher. The problem of single-point bottleneck in traditional client/service communication model is exposed increasingly, and sharing resource among mobile users through P2P mode becomes the inevitable trend of development in wireless communication system. Consequently, in wireless scenario, how to construct distributed P2P networks effectively is the research focus in wireless communication field, and objective resource location and rapid transmission are the key technologies in it. In this paper, resource location mechanisms and relay cooperative methods are considered, and some correspond solutions are proposed. The main works are as follows:(1)In order to reduce bandwith comsuption during resource location, the mechnisms of resource location in structured P2P model are considered, and a dynamic topology-aware wireless P2P protocol is proposed. The node, wanting to enter the existing system, gets node identify which is connected with its physical position from the best node after analyzing its local topology, and instatanous topology-aware wireless P2P network is realized. A central node collects the topology changing information, and topology awareness is transformed to Traveling Salesman Problem. The optimization solution is got through Simulated Annealing method, and the dynamic topology awareness is realized finally. For the random left or death of the central node, a protocol on how to exchange information between member node and central node is presented, based on which the member with most powerful ability and least service is chosen as the new central node in distributed mode.(2) Based on Bloom Filter, a method supporting semantic location in wireless P2P network is proposed. According to the statistical properties of local resources, member nodes extract their interests respectively, and a small-world model is constructed based on their common interests, and a double-layer semantic search model is constructed. When some objective resource is being located, its similarity to local resource interest is used to determine that it should be located in unstructured P2P semantic layer or structured semantic layer adaptively, which not only improves search efficiency, but also supports semantic location more widely.(3) For relay cooperative in wireless networks, relay selection and power allocation in two-hop amplify-and-forward system and cooperative dirversity system are considered repectively, and a scheme of optimal power allocation and best relay selection is presented. Optimal power allocation and best relay selection are combined, when total power is constant, the closed form of optimal power proportion at the source node is got. Meanwhile, the signal-to-noise under optimal power allocation is taken as criterion to determine which relay is the best one, and it is chosen out in pure distributed mode based on opportunistic relay theory.(4) Under the condition that all relays can work synchronously, for multiple-relay single-channel amplify-and-forward system, a power allocation scheme is proposed to make signal-to-noise increases with the number of relay monotonously. Mimicking the theory of Maximal Ratio Combination in orthogonal multi-channel diversity collaboration system, the maximal achievable signal-to-noise can be got in independent relay channel acts as power amplification factor for the corresponding relay when it transmits signal, and it is realized that signal-to-noise is increasing with the amount of relay monotonously.