Experimental Characterization of Communications in Vehicular Ad Hoc Network Experimental Characterization of Communications in Vehicular Ad Hoc Network

Majority of characterization studies on Vehicular Ad Hoc Network (VANET) are based on simulations that assume little network errors and consistent signal strength. Existing VANET experiments, on the other hand, focus mostly on single-hop communication and they are conducted with external antennas or other built-in equipments in small areas. This thesis surveys the challenges in VANET and conducts experimental study on TCP and UDP communication of a multi-hop VANET in highway and suburban areas. We first introduce VANET in six areas: (1) mobility and network characteristics, (2) enabling technologies, (3) operating environments, (4) application requirements, (5) security, and (6) routing strategies. We then describe signal strength, TCP/UDP throughput, datagram loss, jitter, and round trip time in an experiment that we have conducted using IEEE 802.11b wireless cards on inter-vehicle communication. In this thesis we derive inferences in three major areas: (1) providing adjustable network parameters to manage network instabilities, (2) improving UDP efficiency by detecting out-of-touch receivers early, and (3) using speed, route, and distance to improve routing protocols. This thesis summarizes VANET characteristics and challenges, and also proivdes insights to VANET behavior derived from our experimental study. iii Acknowledgements