Analysis And Management Of Link Under Vehicular Ad Hoc Networks Environment

In the various types of Mobile Ad Hoc communication networks, VANET is the mostpromising one. It is a dispensible part of the future intelligent transportation system (ITS).VANET has many particular characteristics, e.g. dynamic topologies, high speed and regularmovement, limited bandwidth and etc. Specifically, wireless link quality is one of the majorfactors that affect VANET’s performance. We are motivated to analyze the link quality ofVANET by taking its unique network features into account. In general, there are three kinds oflinks in VANET, including single-hop links, multi-hop links, and heterogeneous links. Theresearches in this thesis are carried out accordingly, regarding these three types of links.Firstly, the thesis introduces some related research background, and state-of-art ofVANET. Secondly, it takes a briefly introduce on network structure, functions, features andchallenges of VANET. After that, VANET with single-hop links, multi-hop links andheterogeneous links are studied respectively:(1) Single-hop link analysis in VANET mainly focues on the access delay analysis andoptimal access algorithm design. It applies p-consistent CSMA mathematical model toestimate the access delay of IEEE802.11p, approximately. Then, we formulate theproblem in the non-cooperative game framework, and propose a multi-business accesscontrol algorithm. Finally, it validates the access algorithm by using OMNET simulator.(2) Multi–hop link analysis in VANET concentrates on the design and improvement ofrouting protocol. We briefly introduce some typical routing protocols of VANET, andfocus on AODV. Besides, we present the main process and key logical modules of AODVand determine its development scheme, which applies linux-based Netfilter framework.On the other hand, an improved AODV protocol is proposed in this text, which isimproved by adjusting HELLO period at real time. At the end, by building a testenvironment and comparing AODV and improved AODV’s package-drop-ratio, wedemonstrate that the improved routing algorithm achieves a satisfying performance.(3) Heterogeneous link management in VANET aims mostly at the design of vertical handoff algorithm. Firstly, we introduce the vertical handoff issues in heterogeneous networks.Secondly, we put the vertical handoff problems of VANET in optimal stopping theoreticalframework. And then propose a vehicular heterogeneous network mathematical model. Itsutility function is defined as a satisfactory function combining cost and bandwidth of eachnetwork. The analysis is conducted for the utility of three handoff schemes. Finally, weget a conclusion that the optimal stop-based handoff scheme outperforms the other twoschemes by simulation.