| Explosive growth in Information Technology has enabled many innovative application areas such as large-scale outdoor vehicular networks for vehicle-to-vehicle communications. By providing time-sensitive and location-aware information, vehicular networks can contribute to a safer and more efficient driving experience. However, the performance of vehicular networks is easily impaired by high mobility, intermittent connectivity, and unreliability of the wireless channel. In this dissertation, a novel flexible adaptive distributed cooperative medium access control (ADC-MAC) protocol is proposed to support robust and real-time data communications in vehicular networks. ADC-MAC exploits spatial and user diversities to maximize the system throughput and overall application QoS as well as the service range of vehicular networks. This is accomplished by adaptively selecting the most suitable transmission mode and the best relay node for assistance during data transmissions in accordance with cross-layer information, including channel conditions in the physical layer and QoS requirements in the application layer. Three different transmission modes are available in ADC-MAC: direct transmission (DT), cooperative relay (CR) transmission, and two-hop relay (TR) transmission. Both Markov chain based theoretical analysis and simulation experiments show that the ADC-MAC protocol outperforms existing schemes under the same network scenarios. |
