Sitara: Spectrum Measurement Goes Mobile Through Crowd-Sourcing

Abstract

Software-defined radios (SDRs) are often used in the experimental evaluation of next-generation wireless technologies. While crowdsourced spectrum monitoring is an important component of future spectrum-agile technologies, there is no clear way to test it in the real world, i.e., with hundreds of users each with an SDR in their pocket participating in RF experiments controlled by, and data uploaded to, the cloud. Current fully functional SDRs are bulky, with components connected via wires, and last at most hours on a single battery charge. To address the needs of such experiments, we design and develop a compact, portable, untethered, and inexpensive SDR we call Sitara. Our SDR interfaces with a mobile device over Bluetooth 5 and can function standalone or as a client to a central command and control server. The Sitara offers true portability: it operates up to one week on battery power, requires no external wired connections and occupies a footprint smaller than a credit card. It transmits and receives common waveforms, uploads IQ samples or processed receiver data through a mobile device to a server for remote processing and performs spectrum sensing functions. Multiple Sitaras form a distributed system capable of conducting experiments in wireless networking and communication in addition to RF monitoring and sensing activities. In this paper, we describe our design, evaluate our solution, present experimental results from multi-sensor deployments and discuss the value of this system in future experimentation. CCS CONCEPTS• Networks → Wireless access points, base stations and infrastructure; • Hardware → Digital signal processing; Sensor devices and platforms.

Llocus

“…We build an end-to-end prototype for LLOCUS, that uses a cloudbased compute server as the CC, with a web interface for sending commands to the crowdsourced participants. For the convenience of the participants, instead of the tethered RTL-SDR that we used for collecting dataset A, B, and C, we use a low-power, portable, and untethered SDR, that we have developed [14], with both RF transmit and receive capability, as the crowdsourced client. We build an Android app that runs on the participants' smartphones in the background, and simultaneously maintains a socket with the CC and a Bluetooth connection to the SDR; thus it acts as an intermediary between the CC and the SDRs.…”