Wireless Access in Vehicular Environments Using Bit Torrent and Bargaining

Publication Date

9-2008

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Electrical and Computer Engineering

Department

Electrical and Computer Engineering

Supervisory Committee Chair

R. Jacob Baker

Abstract

Wireless Access in Vehicular Environment (WAVE) technology has emerged as a state-of-the-art solution to vehicular communications. The major challenges in WAVE arise due to the fast changing communication environment and short durations of communications due to the high mobility and speed of vehicles. As a result, it is difficult to broadcast a large amount of data in such a network for Vehicle-to-Roadside and/or Vehicle-to-Vehicle communications.

Considering channel adaptations and fairness in their achieved utility, the vehicles use different bargaining methods to exchange data. The bargaining solutions proposed include the Nash Bargaining Algorithm, the Kalai-Smorodinsky Bargaining Solution, and the Egalitarian Bargaining Solution. These three solutions are based on the fairness criteria. Nash Bargaining Solution will try to maximize the product of the gains of two vehicles sharing information. Kalai-Smorodinsky Bargaining Solution will try to keep the ratio of gain constant with their utilities and Egalitarian Bargaining Solution will try to make their gains equal. We propose a solution based on the idea of BitTorrent to distribute data from roadside unit to vehicles and bargaining to exchange information between vehicles. For RSUs, depending on the traffic pattern, distribution of packets to the OBUs is optimized considering the different priorities of the packets and the different traffic intensity at day and night time. During traffic hours, there are plenty of chances for the vehicles to exchange information, so the RSU would distribute different priorities of data evenly. On the other hand, during late night when there is little traffic, RSU would distribute higher priority data first.

To study the theory that has been proposed, a two-lane highway traffic scenario was considered with two vehicles moving in opposite directions. Each vehicle is equipped with a transceiver. The maximum transmission range is 80 meters be- tween the vehicles. The vehicle speed is uniformly random between 80-120 km/hr. The experiment was carried out using MATLAB. While the vehicles were in motion, the different solutions of the bargaining game (i.e., Nash, Kalai-Smorodinsky, and Egalitarian solutions) were applied in succession. Simulation results illustrate that the proposed methods can ensure fairness among the OBUs and adapt to different traffic scenarios with different vehicular traffic intensity.

Therefore, by using BitTorrent and Bargaining, we can solve the problem in WAVE regarding the inconsistency of complete data transfer due to the high mobility and speed of the vehicles.

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