Research On Routing And Broadcasting Technologies In Mobile Ad Hoc Networks

Design of routing protocols is a challenging work in the research of wireless ad hoc networks. Wireless ad hoc networks represent a volatile network environment which is characterized by node mobility, limited wireless bandwidth and node ability. Performance of routing protocols in wireless ad hoc networks is mainly decided by two closely related aspects: first, whether these protocols could acclimatize themselves to these characters; second, whether they can adapt to a volatile and uncertain environment. Most of the researches in this realm focused on the first aspect while few efforts have been put on the second one. In different scenarios factors related with these characteristics will affect the performance of routing protocols in different way. So it is critical to understand the influence of different factors precisely for the purpose of achieving best cost efficiency. Most of the routing protocols depend on broadcasting to disseminate the route request message. But broadcast can always incur broadcast storm problems and consume considerable amount of network resources. How to suppress the broadcast storm problem is a hot topic in recent years. But few efforts have been focused on demand-oriented broadcasting optimization and evaluation. Moreover, there is still no proper metric to evaluate the cost efficiency of broadcast schemes.In this thesis the research work is focused on solving the problems mentioned above and could be concluded in the following aspects:①Established an analytical model to evaluate how the fast nodes affect the performance of routing protocols and proved that node mobility is not the dominating factor that leads to route failure.②Established an analytical model to evaluate how node mobility, traffic load and network size affect the performance of routing protocols, the analytical results revealed that it is the MAC layer property of 802.11 based WLAN contributes the most to route failure.③Established a new meteic to evaluate the cost efficiency of broadcast schemes.④Established analytical models to evaluate the performance of counter-based and distance-based broadcast scheme, revealed that SRB is far from sufficient in the evaluation of cost efficiency and evaluations on the performance of broadcast schemes should be based on a more comprehensive view.⑤Established a RE-oriented broadcast performance evaluation model, revealed that multiple rounds of broadcast with low RE could also achieve high coverage ability and in some circumstances better cost efficiency.