Power-control-based broadcast scheme for emergency messages in VANETs

In Vehicle Ad hoc Networks (VANETs), multi-hop broadcast is a key technique to disseminate emergency information such as Event-driven safety messages to warn drivers in case of dangerous events. When multiple vehicles receive an emergency message, packet collisions may occur if they rebroadcast the message simultaneously. In this paper we propose a power-control broadcast scheme based on studying the IEEE 802.11p and IEEE 1609 WAVE standards for vehicular communications. Transmission strategy is adjusted based on vehicles´ situation and the receive power of recently broadcast packet from a sender node, and re-dissemination power in short-range for reliable broadcast is adapted based on the observed channel status. We evaluated the performance of the proposed scheme by simulation with NS-2. The results demonstrate high delivery ratio and fast emergency messages dissemination while avoiding congestion simultaneously.