An outage-based method for planning wireless sensor mesh networks

The coverage area of wireless sensor networks (WSN) can be extended using the mesh topology, where intermediate nodes can act as routers to create a multi-hop path between a sensor node and the gateway. The mesh topology is specially useful to deploy WSN over large areas, to support the demand for novel applications to smart grid and smart cities. Multi-hop paths can significantly reduce the overall network capacity, because a same packet is re-transmitted stealing transmission time of the wireless channel of all nodes that are in the same contention domain. Thus, to improve the network capacity, short paths in terms of hops are desirable. However, when the number of hops is reduced, packets have to traverse longer distances without regeneration, increasing the probability of packet loss due to large and small scale propagation effects of the wireless channel. Lost packets need to be retransmitted also stealing time of the wireless channel. In this paper, we formulate a wireless capacity model for WSN that uses a Nakagami-m fading model, to evaluate retransmissions due to packet outage, and a contention model required to evaluate multi-hop paths in WSN. Using our model, we propose a method to the optimal planning of routes in WSN mesh topologies with or without outage constraints.