Delay analysis of a reliable broadcast scheme for I2V/V2I communications

Cooperative intelligent transport system (C-ITS) is an emerging paradigm. It aims at wirelessly increasing the awareness of vehicles of their neighborhood traffic via cooperative awareness messages for safety and non-safety purposes. Toward an efficient C-ITS realization, this paper presents a simple, yet effective, broadcast scheme for I2V/V2I communications. In this scheme, road information or safety related messages are reported from the C-ITS to vehicles via road side units (RSUs) using acknowledged radio broadcasts. Vehicles report any newly observed road status and/or safety related information piggybacked in their acknowledgments. The RSUs report these messages to the rest of the vehicles under its coverage via repeated broadcasts using adaptive inter-broadcast interval based on vehicle density and estimated average channel quality. The scheme aims at decreasing unnecessary vehicle-to-vehicle (V2V) broadcasts, which leads to potentially decreasing the risk of broadcast storms. The paper introduces a comprehensive analysis of the delay performance of the proposed scheme considering practical physical channel conditions. The analysis, supported by validating simulation results, indicates the applicability of the proposed scheme as it can achieve low information transfer latency for high density roads.