Efficient Communication System based on Multiple Access Techniques for VANETs

Abstract

Road traffic accidents are perceived as a serious problem in societies and one of the main reasons for fatalities, disability, and injuries that inflict humans all over the world. To minimize the hazard and ruthlessness of a road traffic accident a series of new safety applications can be achieved by employing wireless communication among vehicles travelling near each other or among vehicles and particularly installed Road side units (RSUs) , a technology widely known as a Vehicular Ad Hoc Network (VANET) . Most of the vehicular ad hoc network supported safety applications mainly rely on transmitting safety messages either by the means of vehicles or Road-Side Units, whether it is a periodical action or in the case of an unexpected event, such as detecting unsafe road condition or hard brake cases. This thesis presents a multi-channel Time Division Multiple Access (TDMA) protocol and Code Division Multiple Access (CDMA) protocol which are designed specifically for supporting high priority safety applications in a vehicular ad hoc network scenario. Computer simulations are performed by the use of MATLAB. The scenario of a virtual city is simulated and various metrics for performance are evaluated, comprising protocol overheads, good network mode, channel usage, fairness of protocol, potential transmission collision, and delay delivery of the safety message. The Cross-Layer design‟s performance in a multi-channel vehicular ad hoc network is evaluated in a highway scenario, principally in connection with delaying end-to-end package delivery. Queuing packages in each relay vehicle are considered in end-to-end delay analysis. Furthermore, the numerical results are provided to study the impact of different parameters, where CDMA provides a smaller transmission collision rate that leads to a significant rise in efficiency, where the E2E delay in TDMA has 37.026 sec and the CDMA has 36.3 sec. The scheme has a 94% packet delivery ratio in CDMA while has 92% in TDMA. The tested techniques can be seen as a promising tool for Medium Access Control in vehicular ad hoc networks, which is able to achieve various unconventional safety applications to boost the standards of public safety and enhance safety for passengers, pedestrians and drivers on roads