An Experimental Investigation of Multi-Hop V2V Communication Delays using WSMP

Even though there is an ongoing push by the U.S. government to adopt the Dedicated Short-Range Communications (DSRC) technology for intelligent transportation systems (ITS) applications, there is not sufficient real-world experimental data available that testifies the reliability of this technology when multi-hop communication is taken into consideration. The current protocol standards for DSRC, as defined by IEEE 1609.3, is purposefully not designed to provide support for multi-hop communication using WAVE short message protocol (WSMP). Instead, the WAVE protocol stack provides an alternate option for multi-hop communication using IP-based communication. However, most off-the-shelf DSRC devices only support WSMP-based broadcasts. Hence, the routing and forwarding services on WSMP are unavailable. Our current research attempts to implement the multi-hop forwarding services on top of WSMP as a cross-layer implementation. In this paper, we examined the challenges and performances of multi-hop vehicle-to-vehicle (V2V) communication in terms of packet drop rate and intra-nodal forwarding delay. Field experimental results with three vehicles show that nodal processing delays within the relay node consistently range from approximately 1 to 5.6 milliseconds. Our results further illustrate the effect of line-of-sight and inter-nodal distances on packet transmission success.