Car Ad Hoc Network Routing Protocols

The communication between vehicles which is based on Ad Hoc networks (VANET) is researched in many laboratories, but many shortages are existed in the protocols of this communication system. The protocol of GPSR is used in the city environment, and it also has shortages such as routings breaking and redundancy. In order to improve the GPSR protocol, the thesis gives us some solution formulas.For the routings breaking in the intersection, a fixed node is placed in the center of it, the vehicles which are crossing the intersection would recive and send the information by this fixed node. The routings breaking could be avoided by the fixed node. The routings redundancy is another shortage, to counter this shortage, when a packet is sent from source node to destination node in the first time, the GPSR protocol is used still, but the packet would be monitored, and the number of the hops that from source node to destination node also would be marked in the packet. Next time, when the same soruce node needs to send packet to the same destination node, then a more concise and effective routing would be selected.The thesis uses NS2 to simulate the VANET, in the simulation, a unified scene is built, and the parameters of the simulation are routing load,packet delivery rate,average end-end delay and number of hops. The advance GPSR protocol has less hops,smaller average end-end delay,smaller routing load and higher packet delivery rate than original GPSR protocol.