Multi-hop for GLOSA systems: Evaluation and results from a field experiment

Green Light Optimal Speed Advisory (GLOSA) systems contribute to the reduction of CO2 emissions and fuel consumption by giving speed advice to drivers based on current and future traffic light signal phase timings so they can avoid unneeded stopping and acceleration. These systems have been well investigated by means of simulations and real-world tests. In previous work we have shown that simulations tend to overestimate the communication quality to be expected in urban environments and that in a real-world test, IEEE 802.11p-based GLOSA cannot always reach the required information distance. Although multi-hop information dissemination can help alleviate this problem, it has not yet received much attention from the research community in the context of GLOSA systems. In this paper we present results from extensive field tests with almost 200 traffic light approaches. We find that two-hop dissemination of signal phase and timing information from traffic lights increases the maximum information distance by around 35% and is able to support continuous updates even in challenging environments.