Robust QoS Control of DSRC Vehicle Networks for Collaborative Road Safety Applications

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Road traffic safety has been a subject of worldwide concern. The annual national lost due to road accidents is tremendously high. During the last decade extensive efforts have been made on road safety systems to actively prevent accidents or passively minimize the consequences of accidents. With the advances in wireless communications and mobile ad hoc networking, the so-called collaborative safety applications (CSA) enabled by vehicular communications is widely regarded as a key to future road safety [19]. Equipped with inter-vehicle communication (IVC) and GPS, vehicles can assist drivers to recognize events that can not be detected by the drivers or local sensors alone. For example, a vehicle broken in highway can use IVC to inform the following vehicles the emergency event and avoid possible collisions. Apart from safety applications, a wide range of non-safety applications can also be deployed over vehicle networks, e.g. efficient route planning to reduce fuel consumption and carbon emission. Dedicated short range communications (DSRC) is a leading technique for IVC. It is regarded as the only technology able to provide a robust medium and affordable enough to build large scale CSA. Small scale field tests have demonstrated the communication capabilities of DSRC for CSA. However, CSA will not be effective unless a large proportion of vehicles are equipped with IVC. For the success of large scale CSA a critical issue is how to provide efficient and robust QoS support over DSRC vehicle networks. The reason is that safety messages generated by CSA have very strict QoS requirements in terms of throughput, reliability and delay. Excessive delay and message losses can nullify proper CSA operations and even produce negative unanticipated consequences. However providing effective and robust QoS support for CSA is very challenging. Existing research work on CSA has been primarily focused on the feasibility study of DSRC from the lower layers (physical and MAC layers) by field test or simulation approaches, while efficient QoS control of DSRC networks for CSA QoS support has not been studied. There is a big gap between the capabilities provided by DSRC at the lower layers and QoS support required by large scale CSA. This project aims to develop solutions for robust and bandwidth-efficient DSRC QoS control schemes to provide QoS support for large scale CSA, which is of utmost importance to practical CSA deployment. We will focus our work on two closely related tasks: (a) development of state of the art offline analytical and optimization tools for QoS support of large scale CSA and service planning purposes. Here offline means global network knowledge available for QoS control decisions. The tools will be developed based on Markov chain, queuing theory and water-filling method; and (b) development of novel online robust and bandwidth efficient congestion control schemes to provide QoS support, where transmit power and message rate are jointly controlled with cross-layer interaction, feedback and vehicle cooperation. Only localized knowledge is available for online QoS control. The insights into QoS support obtained in task (a) will be feed into the online control scheme design in task (b). The proposed research is novel and built upon the expertise of the investigator and his research group in the field of network performance modeling, network protocols design and optimization. To the best of our knowledge, the proposed work is the first of its kind on the robust congestion control and QoS support of DSRC networks. The implications of this research are expected to contribute directly to DSRC network QoS support in both theory and applications sides, which will eventually contribute to realize safe, environment friendly and comfortable driving.