An Analytical Approach to Relay Access Delay in Multihop Relay Chain of VANETs

On the demand of many applications, vehicle to vehicle (V2V) communications have attracted many researchers’ attentions. In the developments of traffic safety applications based on VANET, the dissemination delay is critical. The dissemination delay of safety messages in the form of text has been studied thoroughly. In contrast, the dissemination delays of video or audio safety messages are just emerging and there are still a lot of things to be done. Considering the poor communication environment of multimedia safety messages dissemination in V2V, the analysis of multimedia message dissemination delay has great significance in the traffic safety applications. By extending and integrating previous achievements of analyzing MAC access delay in video stream dissemination, we proposed a method for modeling the relay access delay of IEEE 802.11p in the multihop relay chain of VANETs. Simulation results showed that the cumulative distribution function, the expectation, and the standard deviation of the relay access delays can be calculated effectively. In addition, the impacts of the number of hops and the length of packets on the relay access delays have been properly evaluated. Our study would open these research issues for discussion, which will contribute to the design and implementation of traffic safety.