Research On Cross-layer Design Of Protocol Stack In Ad Hoc Network

Ad Hoc network is one kind of acentric self-organized multi-hop wireless network, dynamically organizing networks to communication freely by mobile nodes, without any existing communication infrastructure, and has broad application prospects. But Ad Hoc network facing some problems, such as dynamic topology changes, variable-time quality of wireless channel, limited bandwidth, limited power, etc. The tradition protocol stack has poor performance on these problems. Cross-layer design break the shackles of tradition protocol stack, achieve an overall optimization because of information sharing and interaction between the network layers.This paper first introduced the principle, goal and method of the cross-layer design, and analysed the Multi-rate transmission theory. Then based on the Multi-rate transmission, researched the cross-layer design method focus on the MAC and Routing protocol. The main contributions of this dissertation are as follows:1. Proposed A rate adaptive MAC protocol with congestion aware against multi-rate and congestion problem in multi-hop Ad Hoc networks. The receiver sets the highest feasible transmission rate allowed by the channel condition, and sends the rate and congestion information to the sender, the sender chooses transmission or backoff according to the congestion information of receiver. Simulation results show that the proposed protocol can achieve congestion control, and improve the throughput especially under heavey network load.2. Traditional Ad Hoc network routing protocols are mainly based on the condition"Shortest Path",it can not support multi-rate mechanism well and usually lead to local congestion. This paper propose a synthetical metric routing protocol(SMRP) with cross-layer design. It take rate on physical layer, competition on MAC layer and queue length on network layer into account, and convert them to route cost. Then the route with least total cost is chosed at last. This method can utilize multi-rate support better and avoid local congestion. Simulation results show that SMRP performs better than traditional routing protocols including network throughput, delay, and packet deliver ratio.