Safety Message Broadcast Reliability Enhancement MAC protocol in VANETs

Recently, Vehicular Ad-hoc Networks (VANETs) have been considered as an important part of the Intelligent Transportation System. Data transmission in VANET can be safety message and non-safety message transmissions. While the safety message transmission typically requires bounded delay and a high packet delivery ratio, the non-safety message transmission demands sufficiently high throughput. In this paper, a MAC protocol for Safety message broadcast Reliability Enhancement in VANETs, named SRE-MAC protocol, is proposed to ensure both the reliability of safety message transmission and the high throughput for non-safety data transmission. In particular, the proposed SRE-MAC employs a time slot allocation of TDMA and a random-access technique of CSMA schemes for accessing the control channel. To evaluate our proposed SRE-MAC protocol, some extensive simulations are conducted. The simulation results show that the proposed SRE-MAC protocol achieves higher performance in terms of safety packet delivery ratio and throughput of non-safety packets, as compared to the IEEE 1609.4 and the VER-MAC protocol.