ITS-G5 Performance improvement and Evaluation for Vulnerable Road User Safety Services

Cooperative intelligent transportation system (C-ITS) allows to improve safety of vehicles through communications between vehicles and infrastructure. C-ITS may also improve the safety of vulnerable road users (VRUs), but work on this issue is still in an early stage. ITS-G5 (IEEE 802.11p), the main technology for vehicle-to-vehicle time-critical communications, allows to deliver safety information over a rather long range with low latency, but obstacles in the link path and a large amount of vehicles sending at the same time may reduce performance. In this study, the authors assess and optimise the performance of ITS-G5 for time-critical safety conflict scenarios between vehicles and VRUs. The authors have tested various non-line-of-sight (NLOS) scenarios in urban environments and line-of-sight (LOS) simulations to support C-ITS message prioritisation and scalability with different amount of vehicles. Example use cases with NLOS include pedestrians crossing streets from behind objects, and low-visibility scenarios, e.g. when VRU is behind a vehicle, behind a queue of vehicles, between vehicles, behind trees/bushes or behind a building. The LOS simulations utilise fuzzy weighted queueing mechanism for congestion control to overcome the packet losses and for data prioritisation. Based on these results, the applicability of ITS-G5 for VRU applications is assessed and performance improved.