The United States Department of Transportation (USDOT) and the Crash Avoidance Metrics Partnership-Vehicle Safety Communications 2 (CAMP-VSC2) Consortium (Ford, General Motors, Honda, Mercedes-Benz, and Toyota) initiated, in December 2006, a three-year collaborative effort in the area of wireless-based safety applications under the Vehicle Safety Communications-Applications (VSC-A) Project. The VSC-A Project developed and tested Vehicle-to-Vehicle (V2V) communications-based safety systems to determine if Dedicated Short Range Communications (DSRC) at 5.9 GHz, in combination with vehicle positioning, would improve upon autonomous vehicle-based safety systems and/or enable new communications-based safety applications.
A crucial element required for potential deployment of V2V safety systems is the understanding of how DSRC will perform as larger numbers of DSRC radios are added to the system and ensuring that the communication channel can support a large number of vehicles in potentially congested traffic conditions. This is referred to as system scalability. In the VSC-A Project, a preliminary, multiple On-Board Equipment (OBE) testing effort was undertaken utilizing up to sixty DSRC radios which had the following objectives:
Analyze how well the communication channel operates, primarily in terms of Packet Error Rate (PER) and the Inter-Packet Gap (IPG) distribution, in a variety of channel configurations and transmit characteristics.
Gain experience in the set-up and execution of a large-scale DSRC test effort and in the areas of tools development, software tools, efficient logistics, setup, procedures, and analysis to ensure the end results are correct, meaningful, and repeatable.
The multiple OBE scalability testing conducted and the results obtained are described in this paper. Based on the results it is clear that using a dedicated, full-time, safety channel to transmit V2V safety messages provides superior performance over any of the other channel configuration methods employing IEEE 1609.4 channel switching when considering the PER and IPG metrics.