Hardware implementation and performance analysis of MPTD-CSMA protocol based on field-programmable gate array in VANET

Abstract

Contention-based carrier sense multiple access (CSMA) and contention-free time division multiple access (TDMA) protocol are two typical access protocols of media access control in vehicular ad hoc network (VANET). They all show their unique advantages under specific conditions. TDMA has high transmission reliability, CSMA has a low transmission delay in the communication environment with low packet arrival rate. However, when the arrival rate of information packets increases rapidly, the throughput of CSMA will decrease rapidly and approach zero, which is not suitable for data transmission in the communication environment with a high arrival rate of information packets; while data transmission through a single TDMA protocol will cause high system overhead due to strict synchronous information. Aiming at the defects of the two protocols and the multi-channel communication environment, this study proposes the optimised protocol model multi-priority time division-CSMA (MPTD-CSMA). The optimised protocol model not only ensures the reliability of data communication but also reduces the transmission delay of the system. At the same time, the multi-priority mechanism is added to increase the channel utilisation of the protocol model.