WideScatter:Toward Wide Area Battery-Free Wireless Sensor Networks

Thesis (Master's)--University of Washington, 2021The vision of ubiquitous battery-free sensing has run into the practical limitations of wireless communication networks. To address this, we design the first wide-area and scalable backscatter network with multiple receivers(RX) and transmitters(TX) base units to communicate with battery-free sensor nodes. Our system circumvents the inherent limitations of backscatter systems - including the limited coverage area, frequency-dependent operability, and sensor node limitations in handling network tasks- by introducing several coordination techniques between the base units starting from a single RX-TX pair to networks with many RX and TX units. We build low-cost RX and TX base units and battery-free sensor nodes with multiple sensing modalities and evaluate the performance of the WideScatter system in various deployments. Our evaluation shows that we can successfully communicate with battery-free sensor nodes across 23400 ft2 of a two-floor educational complex using 5 RX and 20 TXunits, costing $569. Also, we show that the aggregated throughput of the backscatter network increases linearly as the number of RX units and the network coverage grows