On the spectrum efficiency of mesh and star topology wide area wireless sensor networks

Wireless sensor networks (WSNs) are meant to monitor natural and man-made phenomena, made of simple low cost sensors interconnected via low data rate communication links to survey wide areas. In this paper, we investigate the trade-off arising from spectrum occupation and packet delivery time in professionally installed wide area WSNs (WA-WSNs). We study two types of network topologies, namely star and mesh topologies, based on the recent IEEE 802.15.4k and multi-channel multi-radio IEEE 802.15.4g standards, respectively. We perform extensive packet level simulations of the mesh topology network, while keeping the star network as a benchmark. Our contribution is threefold. First, we address connectivity in the mesh network by deploying additional relay nodes, when necessary, to enable also each node with at least two independent route alternatives. Second, our simulation results show that the mesh topology requires 20% more spectrum to deliver the whole set of sensed data to the traffic sink compared with the star topology network under delivery time constraints. Finally, we show that only 10% of the nodes in the mesh network actually need additional spectrum and multiple radio transceivers to keep the delay bounded by that of the star topology.