A Load Balancing and Congestion-Avoidance Routing Mechanism for Teal-Time Traffic over Vehicular Networks Chenn-Jung Huang, I-Fan Chen, Kai-Wen Hu, Hung-Yen Shen (Department of Computer Science and Information Engineering National Dong Hwa University, Hualien, Taiwan cjhuang@mail.ndhu.edu.tw, {even0709, drive55555}@gmail.com, lukelock@gmail.com) You-Jia Chen, Dian-Xiu Yang (Department of Computer Science and Information Engineering National Taiwan University, Taipei, Taiwan {youjiachen1985, youngsc13}@gmail.com) Abstract: With the growth up of internet in mobile commerce, researchers have reproduced various mobile applications that vary from entertainment and commercial services to diagnostic and safety tools. Resource management for real-time traffic has widely been recognized as one of the most challenging problems for seamless access to vehicular networks. In this paper, a novel load balancing and congestion-avoidance routing mechanism over short communication range is proposed to satisfy the stringent QoS requirement of real-time traffic in vehicular ad hoc networks. Fuzzy logic systems are used to select the intermediate nodes on the routing path via inter-vehicle communications, and H-infinity technique is used to adjust the membership functions employed in the fuzzy logic systems to adapt to the volatile characteristics of the vehicular networks. Notably, a prediction of the remaining connection time among each vehicle and its neighbors is derived to assisting in the determination of the intermediate nodes on the routing path. The experimental results verify the effectiveness and feasibility of the proposed schemes, in terms of several performance metrics such as packet delivery ratio, end-to-end delay, control overhead, throughputs, call blocking probability and call dropping probability. Keywords: vehicular ad hoc network (VANET), fuzzy logic, routing enhancement, H-infinity Categories: C.2, C.2.2 1 Introduction In recent years, the research on the intelligent transportation systems (ITSs) has been progressing intensively. ITS is a broad range of diverse technologies applied to make the roads safer, more efficient, more reliable, and less damaging to the environment, without having to physically alter existing infrastructure. The range of technologies involved includes the advanced information technologies, sensor technology, automatic control theory, operations research, artificial intelligence and cross- disciplines such as transportation, engineering, finance, electronic commerce and automobile manufacturing. The key in ITS is the interface between the driver/the traveler, the vehicle, and the roadway that can work as a single integrated environment through advanced communications, allowing for better management and use of the available transportation resources. One major problem in ITS is the analysis Journal of Universal Computer Science, vol. 15, no. 13 (2009), 2506-2527 submitted: 31/10/08, accepted: 13/6/09, appeared: 1/7/09 © J.UCS