| dc.description.abstract | Safety is the only way home. Even though governments around the world announce the importance of traffic safety, it seems extremely hard to avoid traffic accidents happening repeatedly every year. Rear-end crashes are the most frequently occurring for tragedy and resulting in a substantial number of injuries. People are eager to find clever solutions to such critical problems.
With the techniques of wireless communications growing mature, Inter-Vehicle Communications provide an efficient way to improve traffic safety and prevent congestion through exchanging or disseminating the traffic conditions. Broadcasting techniques are the widely used applications of delivering the emergency messages to drivers; however, they often suffer the broadcast storm, hidden node, interference, and contention problems, which makes the emergency message undelivered or delayed. For this reason, using current techniques to forward emergency messages, it remains difficult to lower the incidence of traffic accidents efficiently.
A novel broadcasting algorithm by event-driven was proposed in the thesis and is categorized as area-based method broadcast. Not only does it overcome the broadcast storm problem effectively, but it is also suitable for cooperative collision avoidance on two-way highway. Its message-relaying decisions are made by receivers based on the position, direction, and speed properties of re-transmitters and itself. Moreover, the time delay is adaptively adjusted in opposite directions to reduce the hidden node problem and result the delivery more efficiently and reliably.
The simulation results show that the proposed algorithm disseminates the emergency messages most efficaciously and steadily, for instance, it can reduce the delay of compared protocols at least 10% and the retransmission rate at most 79% since the delivery on 100 vehicles within 4.5 km is only taking 15.30 ms and 21 retransmissions. Not merely does it have the lower latency and packet loss rate, but also it takes the fewer retransmissions than other flooding based protocols. Consequently, it can help prevent the rear-end crashes. In addition, a sophisticate data format is defined as well for future extensions and developments of vehicular services. | en_US |