Reseach On Multi-hop Capacity In Mobile Ad Hoc Network

The mobile Ad hoc network(MANET) is considered as a kind of particular wireless network based on not depending on infrastructure, no center, self organization, strong survivability, dynamic topology, multi hop routing. Because of these characteristics, it has properties of temporary, on demand, automatic and so on and has potential value being used in the military communication and disaster relief. The current theoretical research of MANET has become a branch of wireless communication network research. The problem of MANET capacity has attracted many researchers to study. In order to provide a theoretical for a construction of high quality network, the network model is abstracted and established based on depth analysis of MANET capacity problem. At last, the theoretical expression of capacity and delay is derived.Based on the different mobility models, a system model is constructed according to the characteristics of MANET. This system also includes the establishment of network, interference, and business model. Under the reference point group mobile model(RPGM), the analysis will be divided into two parts. In the first part, when the logical center keeps still, an upper bound on the capacity is derived. Then, a routing strategy is adopted, and a lower capacity bound and its delay performance is derived based on it. In the second part, when the logical center can move across the network. An upper bound on the capacity can also be derived and a routing strategy is proposed to derive a lower capacity bound and its delay performance. At last, the conclusion is discussed and a numerical simulation is made, we obtain the optimal number of groups in order to minimize the ratio of delay and capacity.Then, considering the characteristic of small range shift, a local memory condition is added to the random walk mobility model and the probability of node encounter is derived. Under the two-hop relay routing scheme with redundancy, the closed form of capacity and delay performance is obtained through the success probability of each transmission stage. Meanwhile, considering the influence of adding pure relays into network, we proposed a two-hop pure relay routing scheme with redundancy. The closed form of capacity and delay performance is derived and the optimal number of pure relays is obtained to minimize the ratio of delay and capacity.Finally, the MANET routing protocol is simulated under different mobility models. By using the network simulation software NS2 and Bonn-Motion, the network simulation platform is built. We obtain the performance parameters such as average end-to-end delay, packet delivery under random waypoint model, reference point mobility and random walk mobility model. The difference about the performance parameter is analyzed under different mobility and point out the suitable routing protocol in a certain application scene.