Cross layer approach for effective multi hop broadcast in VANET

Cooperative communication in VANET has become the de-facto in enabling technology to improve safety and efficiency on inter-vehicle communication (IVC). The safety related messages broadcast on emergency must have a minimum delay and high reliability. This paper proposes a cross-layer approach to efficiently broadcast the safety messages by minimizing the message redundancy and maintaining low end-to-end communication delays. We propose a scheme to select a one-hop neighbor relay as a potential forwarder for relaying the broadcast messages to improve the transmission reliability in a platoon of vehicles. The relay selection metrics compose of vehicular density, velocity, and the geographical location. The selected relay controls the broadcast messages with minimum overhead and with minimum bandwidth consumption. Similarly, a multimedia emergency message needs high priority with a shorter transmission delay. To provide the service differentiation to different traffic classes, we adopt 802.11e MAC. The cross layer is further extended to the transport layer to dynamically adapt the data transmission rate based on the physical channel state. The extensive simulation analysis conducted reveals that the proposed cross-layer scheme effectively propagates the critical broadcast messages with lesser packet latency and higher packet delivery ratio.