Context-Aware Channel Coordination for DSRC

Vehicular communication could be the much anticipated breakthrough against the unabated fatal and near fatal accidents that continue to threaten the public safety on our roads. The same technology is also expected to concurrently support a range of non-safety applications including real-time traffic information, mobile entertainment, and access to the Internet. The standard has specified an explicit multi-channel structure whereby safety and non-safety transmissions will occur at different channels. Consequently, a vehicle with a conventional single-radio transceiver will need to continuously switch between the safety and the non-safety modes of operation. The interval spent in the safety mode (safety interval) at each cycle is a critical parameter that directly limits the availability of the technology for commercial use. Using simulation, we show that the safety interval required to satisfy the reliability of safety applications is a function of traffic density on the road. Given that in most roads traffic density is expected to vary during the day, we propose dynamic adjustment of the safety interval based on the traffic context. To further motivate the concept of traffic aware vehicular communications, we evaluate the performance of three dynamic channel coordination algorithms using empirical traffic data collected from the roads around the city of Sydney, Australia. A key finding is that, the time-of-day is an effective context that can prevent a vehicular radio from keep running in the safety mode unnecessarily, thereby enhancing the commercial opportunity of the technology. We further demonstrate that the use of the location context can dramatically improve the performance of the basic time-of-day algorithms.