Performance and channel load evaluation for contextual pedestrian-to-vehicle transmissions

Communication between pedestrians' mobile devices and vehicles can play a vital role in improving traffic safety. Enabling such communication is challenging in areas where pedestrian density is high, since transmissions from all pedestrians could lead to high channel load, co-channel interference, and degraded communication performance. To understand these challenges, we first introduce a high-density pedestrian simulation scenario modeled after the Times Square neighborhood in New York City. We then evaluate the channel load in terms of Channel Busy Percentage (CBP) under several contextual safety message trigger policies and different transmission rates. The study uses the Network Simulator 3 (ns-3) with mobility traces generated from a calibrated Simulation of Urban MObility (SUMO) model. The results show that higher transmission rates (5Hz) for all pedestrians lead to high packet error rates, which raises questions about whether application performance requirements can be met at such rates. The results also show that context-aware trigger policies can significantly reduce channel load and lower latency (inter-packet gaps).