Congestion-Controlled-Coordinator-Based MAC for Safety-Critical Message Transmission in VANETs

Abstract

Vehicular ad hoc networks (VANETs) provide the communication framework for the dissemination of safety-critical messages such as beacons and emergency messages. The communication channel witnesses significant network load generated by frequently exchanged beacons. Under high-density situations, it leads to a serious scalability problem in VANETs. Moreover, contention-based medium access control (MAC) protocols suffer from a great number of packet collisions, and as a result, the reliability and latency of safety messages are severely affected. Because of the periodic nature of beacons, time-division multiple access (TDMA) can be a good choice over contention-based MAC. In this paper, we propose congestion-controlled-coordinator-based MAC (CCC-MAC), which is a time-slot-based medium access protocol that addresses beacons and emergency messages. Basically, the network is virtually partitioned into a number of segments. Within a segment, medium access is accomplished by using a time-slot-scheduling mechanism supervised by a local coordinator vehicle. A significant number of vehicles can be supported under the proposed configuration. In fact, the proposed scheduling mitigates channel congestion by reducing the transmission time of beacons through the use of multiple data rates. Bandwidth utilization is also improved by reusing the unoccupied time slots. Finally, CCC-MAC ensures fast and reliable propagation of emergency messages by employing a pulse-based reservation mechanism.In the simulations, we demonstrate the ability of CCC-MAC to scale well in different vehicular density scenarios. Moreover, it outperforms existing MAC-layer protocols with respect to packet reception probability and latency of safety messages.Index Terms-Beacon, dedicated short-range communications (DSRC), emergency message, IEEE 802.11p, vehicular ad hoc network (VANET).

Adaptive beaconing for collision avoidance and tracking accuracy in vehicular networks

“…However, the beaconing latency and high beacon reception probability still cannot be guaranteed when the vehicle density is high. To improve the safety message reliability and to ensure bounded delay, conflict-free MAC (Medium Access Control) protocols, such as TDMA (Time-Division Multiple-Access) [15,16] and SDMA (Space-Division Multiple-Access)/LDMA (Location-Division Multiple-Access) [17,18] , have been proposed in the literatures. In Ref.…”

“…In Ref. [16], a time slotbased mechanism to access channels was proposed, which utilized a multi-rate beacon transmission time control mechanism to mitigate channel congestion. In Ref.…”

Distributed spatial reuse distance control for basic safety messages in SDMA-based VANETs

“…On the other hand, [24] utilizes channel occupancy statistics to control the transmission range while dynamically changing the packet generation rate according to the position error estimation. Other relevant techniques can be found in [25][26][27][28][29][30][31] for safety message performance enhancement.…”

A multi-hop broadcast protocol design for emergency warning notification in highway VANETs

“…In particular, safety applications are enabled by the the transmission of two main types of messages [5]. Periodic single-hop safety messages are used to support cooperative awareness applications enabling vehicles to maintain safe driving environment [7][8][9], whereas warning messages propagate event-driven notifications to all vehicles within a certain geographical area [10]. As the warning messages have to be transmitted *Correspondence: muhammadawais.javed@uon.edu.au School of Electrical Engineering and Computer Science, The University of Newcastle, 2308 Callaghan, Australia to locations potentially out of the transmission range of any individual vehicle, multi-hop transmissions are necessary to support this class of traffic.…”