Impact of Transmission Power on the Performance of UDP in Vehicular Ad Hoc Networks

With the availability of cheap and robust wireless devices there is demand for new applications in vehicular ad-hoc networks (VANET). The challenge in implementing applications is in understanding of the complex dynamics of highly mobile multi-hop ad hoc networks which is a characteristics of VANET. Studies have been reported that attempt to quantify transport protocol (TCP and UDP) performance in mobile ad-hoc network in general and VANet in particular. However, very little work has been done in looking at the effect of tuning transmission power and its effect on the performance of the transport layer protocols. Our work specifically looks at the result of tuning transmission power and its effect on UDP throughput in VANet. To facilitate this study we first developed a comprehensive integrated simulation tool which accurately simulates both vehicular mobility patterns and wireless network environment and the communication protocols; the former is based on a cellular automata model while the later is developed using JIST/SWANS network simulator. Results show that the major mitigating factor in VANETs multi-hop environment is the number of hops between the source and the destination. Increasing the transmission range results in decreasing the number of hops between source and destination effectively increasing throughput. However, increasing the transmission range beyond a certain point saturates the throughput due to increased interference. We also found that the effect of vehicle densities is only important at lower transmission ranges to provide the required connectivity.