Vehicle-to-Vehicle Communication and Mobility Management in Vehicular Ad Hoc Networks

• Main Authors: Kuan-Lin Chiu, 邱冠霖
• Other Authors: Ren-Hung Hwang
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/68991529432786345468

博士 === 國立中正大學 === 資訊工程研究所 === 99 === To provide an efficient and stable framework to vehicles is an emerging issue. Since conventional communication schemes in Vehicular Ad Hoc Networks (VANETs) only support short transmission range, vehicles need to switch to different roadside units frequently in order to disseminate data. It is difficult to deliver an emergency message to other vehicles in time and provide real-time multimedia services in VANETs. Fortunately, a new version of Worldwide Interoperability for Microwave Access (WiMAX), known as IEEE 802.16j, can support long transmission range and high mobility using mobile multi-relay node. This dissertation fist develops an efficient framework, termed SIP-Based Safety/Vehicular Information Delivery (SVID), by using WiMAX mobile multi-relay techniques. SVID also introduces several crosslayer mechanisms to maintain the proposed framework and satisfy the characteristics of VANETs. With SVID, Vehicles can communicate with each other and connect to the Internet through a relay vehicle. However, the proposed framework still faces two mobility problems: (1) imbalanced traffic load among relay vehicles; (2) long handover latency for vehicles. In load balancing problem, a SRV may become overloaded once too many vehicles choose it as their relay vehicle. Thus, mechanisms are needed to distribute vehicles to nearby relay vehicles to avoid the overloading problem. This dissertation investigates two threshold-based schemes to help vehicles to select their relay vehicles dynamically to balance the traffic load among SRVs based on Markov chain model. To solve the long handover latency problem, this dissertation presents a cross-layer fast handover scheme, called vehicular fast handover scheme (VFHS), where the physical layer information is shared with the MAC layer, to reduce the handover delay. The key idea of VFHS is to utilize oncoming side vehicles (OSVs) to accumulate physical and MAC layers information of passing through relay vehicles and broadcast the information to vehicles that are temporarily disconnected, referred to as disconnected vehicles (DVs). Simulations are conducted to verify the feasibility and stability of the proposed schemes. The simulation results indicate that the proposed schemes can yield better system performance and low handover latency. The main contribution of this dissertation is to develop an efficient and stable communication framework for VANETs based on the WiMAX relay network.