Risk-Based Transmission Control for Mitigating Network Congestion in Vehicle-to- Everything Communications

Vehicle-to-Everything (V2X) communication technologies and High-definition (HD) maps are essential to improve the safety of vehicles in areas with limited visibility. V2X- enabled vehicles use periodic beacon messages to update each other on their moving state (position, velocity, heading). However, due to the limited resources of V2X wireless channels, the explosion of data pouring into the network (e.g., from a crowded group of connected vehicles) can exhaust bandwidth and cause severe network congestion. Consequently, the rapid drop of sharing messages can threaten the safety of connected vehicles due to lost tracking. In this work, we present an efficient risk-based transmission control model, namely RTC+, to automatically control the time interval for broadcasting beacon messages of the connected vehicles in V2X networks. RTC+ works at the application layer to minimize interference with algorithms in the low layers (e.g., MAC). Two new algorithms are proposed in RTC+. The first one is RiskSCAN, a robust risk management algorithm to check and determine whether a vehicle suffers the risk of a potential collision with its neighbors. The second is RateCONTR, an adaptive broadcasting rate control to adjust the time interval of sharing messages, particularly when bandwidth is limited to serve all channel requests. The evaluation results show that RTC+ can significantly increase 25% of packet delivery rate while mitigating the collision threats compared with the default time interval in current vehicular network settings.