Researches On Performance Of Wireless Ad Hoc Networks

Wireless Ad hoc network has great application potential in so many fields like intelligent transportation, smart home, intelligent city, emergency saving etc. due to its flexible, on-demand and automatic organization characteristic. Many specific network styles such as wireless sensor network, vehicular Ad hoc network, and wireless mesh network employed Ad hoc technologies.Even though there are ever-growing theoretical achievements on Ad hoc network technologies, it is far from being deployed extensively, i.e. Long distance exists from theoretical to practice. In order to understand and employ Ad hoc network technologies more effectively, we studied its networking performances comprehensively and thoroughly in this dissertation, which we hope can accelerate its progress in application. This dissertation is part of results of the project "adaptive reconfigureable Ad hoc network with sensing function" funded by National Nature and Science Fund Committee, China (Grant No.60772109) and project "research and implementation of wireless Ad hoc experimental platform" funded by National Ministry of Education Fund for Studying Aboard and Returning People. The main issues of this paper are:Chapter 1 mainly discussed the studying background and research object of this paper by introducing Ad hoc network's basic features, research progress and current application situation.Chapter 2 established a measurable system capacity evaluation model of multi-hop networking. Through analyzing the behavior of the nodes in carrier sense multiple access (CSMA) scheme and contemporaneously the hidden nodes (HN)' effect on the current transmission node, we put forward the method-Integrated Consideration of CSMA and HN (ICSHN), by which we obtained the measureable evaluation model of system's maximum sustainable data rate. The model's accuracy is verified by large amount of simulations in various network parameters. This model could be used to evaluate the system capacity in numerical if the relative network parameters are provided.Chaper 3 discussed the popular multimedia traffics and their codec technologies, packaging formats, and transmission features. Based on the packet format analyzing and system measurable model given in chaper 2, we evaluated the capability of voice and video stream on multi-hop transmission circumstances. Finally, their operation performance features under multi-hop transmission are evaluated by simulation through the Evalvid toolset which intergrated into NS2 to do the special quality evaluation of video transmissions.Chaper 4 analyzed the performance features of typical on demand routing protocols in Ad hoc networks. And, aims at amending the defects like unstable connectivity and high delay jitter of these routing protocols, we put forward a robust routing protocol NBC-OPP employing the opportunistic forwording idea. NBC-OPP manifests its superiority over tradional determination routing protocols in simulation. We also studied its comprehensive performances from three different aspects, ie. node density, channel quality and traffic rate, and finally showed the network circumstances which NBC-OPP is skilled at.Chapter 5 summarized the dissertation and pointed out the potential directions for future study.