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The Scientific World Journal
Volume 2014, Article ID 584164, 9 pages
Research Article

Vehicle Density Based Forwarding Protocol for Safety Message Broadcast in VANET

School of Information Science and Engineering, Central South University, Changsha 410083, China

Received 7 March 2014; Accepted 14 May 2014; Published 10 July 2014

Academic Editor: Zhongmei Zhou

Copyright © 2014 Jiawei Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In vehicular ad hoc networks (VANETs), the medium access control (MAC) protocol is of great importance to provide time-critical safety applications. Contemporary multihop broadcast protocols in VANETs usually choose the farthest node in broadcast range as the forwarder to reduce the number of forwarding hops. However, in this paper, we demonstrate that the farthest forwarder may experience large contention delay in case of high vehicle density. We propose an IEEE 802.11-based multihop broadcast protocol VDF to address the issue of emergency message dissemination. To achieve the tradeoff between contention delay and forwarding hops, VDF adaptably chooses the forwarder according to the vehicle density. Simulation results show that, due to its ability to decrease the transmission collisions, the proposed protocol can provide significantly lower broadcast delay.