| Ad Hoc NetWork is a kind of Multi-hop MANET (Mobile Ad Hoc Network) without fixed infrastructure. Every mode in the Network has the function of random mobile access. This mode has dual roles, which can both act as the terminal and a router. The access properties of the node decides that the MAC layer protocol is suitable for using CSMA/CA access mechanism, this mechanism mainly solves some questions:carrier sense and the method of Collision Avoidance, hidden terminal, exposure terminal and fair access channels and so on. Whether node can effectively avoid conflict or not, the fair access channel is mainly decided by the performance of the algorithm, this paper mainly analyzes the theory of existing algorithm and its insufficiency and has improvement optimization to retreats algorithm on the basis of the existing research.To start with, in this paper, we briefly introduce the development of the Ad Hoc Network, the key technologies and the MAC protocols research situation at home and abroad and so on.Secondly, the paper has a brief introduction to the MAC layer access mechanism and its common agreement, and mainly analyses access control method, the MAC layer function, retreats mechanism and the existing problems in the Ad Hoc network.Then, this paper expounds the principle of commonly used BEB retreats algorithm, MILD retreats algorithm, EIED retreats algorithm in the Ad Hoc network MAC layer, and simulates and analyzes the principle of three retreats algorithm and their performance through different scenes.Finally, this paper proposes two improved Ad Hoc network MAC layer retreats algorithm, expounds their basic principle, analyzes the influence of main parameters in algorithm to Network Performance from the theoretical level, and uses OPNET software to simulate and verify the performance of two retreats algorithms and compare with their performances, so as to provide the reference for the evaluation improvement of algorithm performance in actual network environment. |
PDF Full Text Request