Abstract
In order to ensure traffic safety, the emergency warning message should be transmitted quickly and reliably in vehicular ad hoc networks by multi-hop broadcast. In this article, we propose a traffic flow theory-based dynamic multi-hop broadcast protocol to address the issue of emergency warning message dissemination in vehicular ad hoc networks. The main goal of our protocol is to reduce delay and enhance reliability no matter the traffic density is high or low. First, according to the simulations of the distribution of vehicles under different traffic densities, a method of dynamically dividing the communication range is proposed, which, to a large extent, could find the candidate forwarders by one non-uniform partition. Next, a mechanism of dynamically adjusting the contention window size and boundary is designed, and the minimum waiting time difference is considered. The complete execution process of theory-based dynamic multi-hop broadcast protocol and corresponding retransmission strategies are included for high reliability. Through extensive simulations, we demonstrate the superior performance of our protocol in terms of one-hop delay, one-hop message processing, and delivery ratio compared with other existing schemes.
Highlights
With the development of transportation industry, some serious problems, such as traffic accident and road congestion, are brought into our vision
We propose a traffic flow theory-based dynamic multi-hop broadcast protocol, called TFDMB
A dynamic area partition method is designed where the length of remote area is different under different traffic densities, which helps to find the non-empty remote area by only one non-uniform partition and reduce the delay
Summary
With the development of transportation industry, some serious problems, such as traffic accident and road congestion, are brought into our vision. When the traffic density is high, some protocols usually evenly and iteratively divide the communication range As a result, they waste too much time on repeated and unnecessary partitions, which increases the delay. Some protocols use non-adaptive contention windows (i.e. waiting time intervals), the sizes of which are fixed It results in high collision probability and reduces the reliability. To this end, how to design a dynamic and comprehensive multi-hop broadcast protocol that makes full use of the traffic density both in area partition phase and competitive phase becomes a significant challenge. We design a traffic density–based dynamic competition mechanism, which can adaptively adjust the contention window size and boundary according to the realistic traffic conditions It helps to enhance reliability in dense networks and reduce delay in sparse networks. We evaluate the performance of our protocol by extensive simulations in the fifth section followed by concluding remarks in the final section
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