Cooperative Communication in Vehicular Ad-Hoc Networks

The realization of autonomous vehicles presents many challenges that have created several new and active research areas. Among these challenges is the need for the reliable transmission of important data between vehicles to provide each autonomous vehicle with information, such as its geographical location and any objects/hazards in its vicinity. Localisation data is generally obtained from GPS satellites, but there are number of scenarios where the GPS signal is not available due to tall buildings, bridges, tunnels, etc. In this case, localization data must be obtained from an alternative source, such as a nearby vehicle. However, the communication link between vehicles may also be weak, so it would be more desirable to utilize other vehicles to help deliver this information to the target vehicle. The idea of using other vehicles to cooperate in the transmission of data is known as cooperative communication, where vehicles are used as relays between the intended source and destination vehicles.

In this proposal, cooperative communication using relays is proposed as a solution to mitigate the harsh effects of vehicular channels and maximise throughput under varying conditions. Throughout, the research is focussed on abiding by the IEEE 802.11p standard for Wireless Access in Vehicular Environments (WAVE) with specific attention being paid to having practical applications in the Intelligent Transport Systems (ITS) sector. By studying the wireless vehicular channel, we know severe signal degradation occurs from multiple sources including Doppler, multipath fading and shadowing. Due to the highly mobile nature of vehicular ad-hoc networks (VANETs), many existing techniques become suboptimal as the network topology changes rapidly. It is hoped to be shown that through the efficient use of relay selection, relay processing protocols and signal recombination that the overall system performance can be optimised even when the direct link between the transmitter and the receiver is weak. This project will focus on the creation and possible repurposing of algorithms to achieve these tasks, while being mindful of the strict latency requirements imposed by the WAVE standard.