Performance study of IEEE 802.11p for vehicle to vehicle communications using OPNET : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Telecommunications and Network at Massey University, Auckland, New Zealand
IEEE 802.11p is the recently finalised protocol located at the bottom of the Dedicated Short Range Communication (DSRC) protocol suite, which supports Intelligent Transportation System (ITS) applications for both road safety and added value communication purposes. It has evolved from widely applied Wireless Local Area Network (WLAN) standards and it cooperates with peculiar higher layer protocols in order to carry out inter-vehicle communication. In this thesis, we focus on the performance study of road safety communication as being the vital application in ITS, which is very necessary not only because IEEE 802.11p is a relatively new protocol but also because it heavily relies on broadcast mode, thus distinguishing itself from other 802.11 counterparts. With the aid of OPNET, a powerful commercial simulator, different scenarios have been deployed in which one or more variable factors are involved, such as vehicle number, data packet size, communication distance, vehicle fleet topology, etc., in order to find out their impacts on DSCR and characteristics of 802.11p.
After analysing results data collected from hundreds of simulations, we found out that 802.11p represented a desirable performance in terms of latency and priority-oriented services throughout our simulation scenarios. However, packet collision caused by either media contention or hidden nodes turned out to be a relatively serious issue of vehicle communication and 802.11p seems in shortage of an effective mechanism to deal with it. What we can only hope is that under practical application, the media should always be lightly occupied and that there are few ACs with high priorities trying to contend resources simultaneously at any given time. Meanwhile, our analyses indicate that current 802.11p protocol might still need further modifications in order to address its inherent issues and enhance the communication performance.