Faculty and students win at IPSN 2018


April 13, 2018

Carnegie Mellon University had a strong showing at this year’s International Conference on Information Processing in Sensor Networks (IPSN) in Porto, Portugal. Professors Bob Iannucci, Swarun Kumar, and Anthony Rowe teamed up with ECE Ph.D. students Artur Balanuta, Adwait Dongare, and Akshay Gadre, along with Anh Luong and Revathy Narayanan from CyLab, to present their paper, “Charm: Exploiting Geographical Diversity Through Coherent Combining in Low-Power Wide-Area Networks.” The team won Best Paper for their research on allowing wireless base stations to collaboratively decode weak signals from low-power devices (see abstract below). 

Carnegie Mellon teams also came in first and second place in the Microsoft Localization Competition and won Best Demo for research relating to augmented reality.

Low-Power Wide-Area Networks (LPWANs) are an emerging wireless platform which can support battery-powered devices lasting 10-years while communicating at low data-rates to gateways several kilometers away. Not all such devices will experience the promised 10 year battery life despite the high density of LPWAN gateways expected in cities. Transmission from devices located deep within buildings or in remote neighborhoods will suffer severe attenuation forcing the use of slow data-rates to reach even the closest gateway, thus resulting in battery drain.

This paper presents Charm, a system that enhances both the battery life of client devices and the coverage of LPWANs in large urban deployments. Charm allows multiple LoRaWAN gateways to pool their received signals in the cloud, coherently combining them to detect weak signals that are not decodable at any individual gateway. Through a novel hardware and software design at the gateway, Charm carefully detects which chunks of the received signal need to be sent to the cloud, thereby saving uplink bandwidth. We present a scalable solution to decoding weak transmissions at city-scale by identifying the set of gateways whose signals need to be coherently combined over time. In evaluations over a test network and from simulations using traces from a large LoRaWAN deployment in Pittsburgh, Pennsylvania, Charm demonstrates a gain of up to 3x in range and 4x in client battery-life.