DTB-MAC: Dynamic Token-Based MAC Protocol for reliable and efficient beacon broadcasting in VANETs

Abstract

Abstract-Most applications developed for vehicular environments rely on broadcasting as the main mechanism to disseminate their messages. However, in IEEE 802.11p, which is the most widely accepted MAC protocol for vehicular communications, all transmissions remain unacknowledged if broadcasting is used. Furthermore, safety message transmission requires a strict delay limit and a high reliability, which is an issue for random access MAC protocols like IEEE 802.11p. Therefore, transmission reliability becomes the most important issue for broadcast-based services in vehicular environments. In this paper, we propose a hybrid MAC protocol, referred as Dynamic Token-Based MAC Protocol (DTB-MAC). DTB-MAC uses both a token passing mechanism and a random access MAC protocol to prevent channel contention as much as possible, and to improve the reliability of safety message transmissions. Our proposed protocol tries to select the best neighbouring node as the next transmitter, and when it is not possible, or when it causes a high overhead, the random access MAC protocol is used instead. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance compared with IEEE802.11p in terms of channel utilization and beacon delivery ratio.

Supporting Beacon and Event-Driven Messages in Vehicular Platoons through Token-Based Strategies

“…In this paper, we consider a token passing protocol for safety data exchange within the platoon. While previous work [ 5 , 6 ] introduced the token passing method for periodic beacon exchange only, this paper extends the protocol to incorporate event-driven messages. We propose and evaluate three different methods to integrate event-driven data into our protocol, and we also consider the issue of relaying event-driven packets to improve the successful reception of such packets throughout the platoon.…”