BigBand: GHz-Wide Sensing and Decoding on Commodity Radios

Abstract

The goal of this paper is to make sensing and decoding GHz of spectrum simple, cheap, and low power. Our thesis is simple: if we can build a technology that captures GHz of spectrum using commodity Wi-Fi radios, it will have the right cost and power budget to enable a variety of new applications such as GHz-widedynamic access and concurrent decoding of diverse technologies. This vision will change today s situation where only expensive power-hungry spectrum analyzers can capture GHz-wide spectrum. Towards this goal, the paper harnesses the sparse Fourier transform to compute the frequency representation of a sparse signal without sampling it at full bandwidth. The paper makes the following contributions. First, it presents BigBand, a receiver that can sense and decode a sparse spectrum wider than its own digital bandwidth. Second, it builds a prototype of its design using 3 USRPs that each samples the spectrum at 50 MHz, producing a device that captures 0.9 GHz -- i.e., 6x larger bandwidth than the three USRPs combined. Finally, it extends its algorithm to enable spectrum sensing in scenarios where the spectrum is not sparse.