Localized routing with guaranteed delivery and a realistic physical layer in wireless sensor networks

Routing is the problem of sending a packet from a source node to a destination node in the network. Existing solutions for sensor networks assume a unit disk graph model, where messages between nodes are received correctly if and only if the distance between them is up to the transmission radius, which is equal for all nodes. Sensor networks require localized solutions, where nodes make decisions based on their own positions, the positions of their neighbouring nodes and the position of the destination. Existing localized routing algorithms include greedy routing and GFG (with guaranteed delivery) for the unit disk graph model and expected progress routing for a physical layer model. In a physical layer model, the packet reception probability depends on the distance between nodes. We propose to combine the expected progress routing with face routing to define a localized routing algorithm that guarantees delivery under realistic physical layer models. The proposed localized routing protocol is called EFE (Expected progress–Face–Expected progress). We have implemented the proposed algorithm and compared it with the shortest weighted path scheme. They both assume an ideal medium access layer, where packets between two neighbouring nodes are delivered in the number of attempts equal to the expected hop count between them (which is the expected number of transmissions and acknowledgments). The experiments show that localized EFE is efficient compared to the globalized shortest path algorithm, especially for dense networks.