Research On Wireless Multi-hop Ad Hoc Networks Based On Load Balance Key Technology

MANET (Mobile Ad hoc network) is always one of the research hotspots in next generation wireless communication systems research field. It is a base requirement that mobile equipments can be organized by themselves into connected networks, without any aid of infrastructure. An efficient and dynamical communication system can provide convenient communication services freely and highly invulnerably.In this paper, in order to solve the load balance problem of Ad hoc network, works on different MAC protocol performance analyse, theoretical modeling, multi-path routing load balance protocol and cocurrent multipath transfer protocol are represented.The major contributions of this thesis include:(1) On the basis of analysis MAC layer transmission mechanism of wireless network, it has given the simulation performance results of different MAC protocol under wireless multi-hop single channel environment, focusing on hidden terminal and exposed terminal problems. It also has proposed a MAC layer protocol which is used in multi-channel environment. The simulation results show that this new MAC layer protocol can solve hidden terminal and exposed terminal problems and upgrade the network performance. This new multi-channel MAC layer protocol can distribute channels with no collisions, and play a role in load balance. This new protocol also gave a support for the following new routing protocol and the new transport protocol.(2) Based on the previous single-hop Ad hoc network analysis work, it has proposed a mathematical method which modeled IEEE 802.11 MAC state transitions with Markov chain in multi-hop situation. The contrasts between theoretical results and simulation results validate that the analytical model describles the influence factors of transmission performance in multi-hop Ad hoc network accurately. This model is also given an important theoretical support for the load balance problem.(3) In order to achive the load balance object, it has proposed a multi-path routing protocol which is used in k-fold multicast Ad hoc network. This protocol has used node connect degree as one of the conditions to judge nodes' load balance. It has also effectively avoided the appearance of twist routing paths and bottleneck nodes. The simulation result indicated this routing protocol can control the congestion well and increase the network stability.(4) A concurrent multi-path transfer protocol-WCMT-SCTP is propsed in order to match with the multi-path routing protocol. WCMT-SCTP can implement information data be transferred on multi-path concurrently, use the limited bandwidth efficitively. Simulations are conducted to show the performance improvement of tradintional WCMT-SCTP in terms of throughput and the independence of data streams.