The Research And Improvement Of Routing Protocols Based On On-Demand Algorithms In Mobile Ad Hoc Networks

MANET (Mobile Ad hoc Network) is a multi-hop temporary autonomous system and is made up of some mobile nodes equipped with wireless transmitter-receiver set. For the characteristics as independence of fixed communication infrastructure and without central control node, Ad hoc network has a wide and deep application in emergency events, military and civilian fields, multi-media applications and so on. MANET has been gradually growing from a branch of the wireless communication field to a relatively independent field. It has attracted more attention increasingly by communications industry.Due to the features such as self-organizing, dynamical topological structure and wireless-connection, traditional routing protocols can't be adopted effectively in mobile Ad hoc network. The routing protocol issues in this network environment is becoming a mainly topic and a hot point problem in the research of Ad hoc network.In this paper, the background of the research is firstly introduced, including the network infrastructure, technique characteristics, research and development status. Some analyses and comparisons are performed for characteristics, pros and cons in different kinds of Ad hoc routing protocols in existence. As a type of on-demand routing protocols and the research object in this paper, AODV protocol is deeply analyzed. And its mechanism is also introduced in detail.Considering the shortcomings of AODV such as instability of routing path, low efficiency in path-rediscovery when the link breaks up and lack of security solution, we propose an improved AODV scheme-IAODV, which is based on the comprehensive stabilization and path redundancy mechanisms. We also optimize the process in congestion control, local path reparation and neighbor maintenance to improve the efficiency and enhance the feasibility and expansibility of IAODV. In addition, a secure routing solution is proposed for this IAODV protocol. Both the routing security and network performance are ensured by the combination of symmetric encryption technology and public-key authentication technology.Simulation with different scenes is completed in this paper by the popular simulation platform-NS2. The methods and processes in the simulation of IAODV are described. The performance comparison between IAODV and AODV is analyzed according to the different parameters like packet delivery ratio, end-to end delay, routing cost. After all this,the conclusion shows that the performance of IAODV is superior to the AODV.