Carnegie Mellon University

Hamerschlag Hall

February 19, 2020

Gadre to Present at NSDI 2020

Third-year ECE Ph.D. candidate Akshay Gadre will present a new project on Frequency Configuration for Low-Power IoT Devices at USENIX Symposium on Networked Systems Design and Implementation (NSDI). NSDI focuses on the design principles, implementation, and practical evaluation of networked and distributed systems. The goal is to bring together researchers from across the networking and systems community to foster a broad approach to addressing overlapping research challenges.

Advised by Swarun Kumar, assistant professor of electrical and computer engineering, Gadre focuses on Low-Power Wide-Area Networks (LP-WANs). LP-WANs aim to provide wireless connectivity at extremely low data rates (kbps) over distances of several miles to devices powered by a 10-year battery. Today's LP-WANs struggle to cope with the scale of future IoT deployments and the significant signal attenuation posed by urban environments. Kumar’s research lab, WiTech, has developed new solutions for allowing LP-WANs to scale more efficiently, achieve even longer range in urban settings and save battery life, including solutions that avoid a battery altogether. 


Low-power Wide-Area Networks (LP-WANs) are seen as a leading candidate to network the Internet-of-Things at city-scale. Yet, the battery life and performance of LPWAN devices varies greatly based on their operating frequency. In multipath-rich urban environments, received signal power varies rapidly with a low-power transmitter’s frequency, impacting its transmission time, data rate and battery life. However, the low bandwidth of LP-WANs means that there are hundreds of operating frequencies to choose from. Among them, we show how choosing a select few of these frequencies(≤3.55%) effectively triples the battery life when compared to the rest for LP-WAN devices. This paper presents Chime, a system enabling LP-WAN base stations to identify an optimal frequency of operation after the client sends one packet at one frequency. Chime achieves this by analyzing the wireless channels of this packet across many base stations to disentangle multipath and ascertain an optimal frequency that maximizes client battery life and minimizes interference. We implement Chime on a campus-scale test-bed and achieve a median gain of 3.4 dB in SINR leading to a median increase in battery life of 230% (∼1.4-5.7 years), data rate by 3.3× and reduction in interference of 2.8× over commodity LP-WANs.