Most of geographic routing approaches in wireless ad hoc and sensor networks do not take into consideration the medium access control (MAC) and physical layers when designing a routing protocol. In this paper, we focus on a cross-layer framework design that exploits the synergies between network, MAC, and physical layers. In the proposed CoopGeo, we use a beaconless forwarding scheme where the next hop is selected through a contention process based on the geographic position of nodes. We optimize this Network-MAC layer interaction using a cooperative relaying technique with a relay selection scheme also based on geographic information in order to improve the system performance in terms of reliability.

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Abstract

In this paper, we propose SBRM (Score-Based Routing Mechanism), a hybrid forwarding protocol based on the use of a modified contention-based forwarding coupled with carry then forward mechanism. Our solution combines different forwarding schemes and takes profit from advantages of each mechanism. Every node calculates its own Score to decide if it will be the next forwarder. The Score computation takes into account the sender and destination locations, the location of the forwarder node itself, its direction, speed and the road traffic density. A score function is defined to minimize the packet delay and to avoid spatial and temporal holes.Keywords-Vehicular ad hoc networks, routing, contention-based forwarding, carry then forward.