Performance of Car to Car Safety Broadcast Using Cellular V2V and IEEE 802.11P

Low delay, high reliability and fast exchange of safety broadcast messages are critical to future Intelligent Transport Systems (ITS) systems. This paper presents a cross layer analysis based on Raptor Q codes for transmitting emergency DENM (Decentralized Environmental Notification Message) messages with interference from other vehicles transmitting periodic CAM (Cooperative Awareness message) safety messages. The performance is compared for Cellular Vehicle to Vehicle (C-V2V) Communications and IEEE 802.11p technologies in a realistic highway environment. The end-to-end delay and Packet Reception Ratio (PRR) are used as the performance metrics to demonstrate the latency and reliability problems of standard repetition codes that are addressed using raptor Q codes. Coverage improvements of up to 240m is seen by using C-V2V with raptor Q codes for higher density of vehicles as compared to standard IEEE 802.11p/WAVE with repetition codes. IEEE 802.11p suffers from preamble channel estimation which effects the reliability.