CAREER: Pushing the Limits of Low-Power Wide-Area Networks

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Future smart cities will have to provide Internet connectivity to millions of energy-starved Internet-of-Things devices - even those several miles away from the nearest wireless base station. To this end, recentyears have seen novel Low-Power Wide Area Networks (LP-WANs) deployed, such as LoRa and NB-IoT.Unfortunately, today’s LP-WAN technologies require a battery to power these devices, which impactstheir maintenance cost and reliability. This proposal aims to develop a city-scale LP-WAN architecturethat offloads connectivity, sensing and even the source of energy to the more capable base stations andcloud infrastructure. We develop an architecture where base stations actively collaborate to enable fasterand more reliable connectivity to low-power devices, sense their location and surroundings and provideenergy they require to operate in the first place. The proposed work has a detailed integrated education andoutreach program including course projects that leverage a live testbed and summer labs for K-12 studentsin Greater Pittsburgh. The proposed work will be deployed initially to network existing smart sensors atCMU and later scale to surrounding city infrastructure, through extensive collaborations with the City ofPittsburgh, forming a first-of-its-kind university-led programmable LP-WAN deployment.The proposed work enables Low-Power Wide-Area Networking in dense smart-city deployments alongthree axes: (1) Long-Range Wireless Charging: First, the proposal investigates a system at the base stationsthat beams power to battery-free clients at unknown locations. We explore base station and client designs toperform wireless charging over large distances, orders-of-magnitude higher than prior work. (2) PushingLP-WAN Speed and Scaling Limits: Next, the proposed work explores a solution to decode collisions fromeven the weakest of LP-WAN signals that cannot be detected at any single base station. The proposal argueswhy power starved LP-WAN clients motivate the need for even mundane PHY-layer functions at the client:radio configuration, decoding and rate adaptation - to be offloaded to the more capable infrastructure.The proposal then explores intelligent ways for base stations to collaborate at the cloud, despite limitedbackhaul bandwidth. (3) City-Scale Wireless Sensing: Finally, the proposed work investigates novel sensingsolutions that use RF signal measurements received both from city-wide low-power radios as well asCubeSats in Low-Earth Orbit, collated at the edge and cloud. We evaluate how such a system can senseproperties such as structural health and atmospheric moisture at city-scale, without requiring dedicatedsensors on low-power devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.