Perfect pulses for ambient backscatter communication

Abstract

This paper explains how to construct perfect pulses - antipodal binary waveforms with extraordinary DC-nulling properties. Several methods for employing perfect pulses in digital modulation schemes, with particular emphasis on backscatter (and simply scatter) radio modulation, are demonstrated. These waveforms enable a completely new type of RF information exchange by piggy-backing useful information onto ambient wireless signals using low-powered electronics. A mathematical model of perfect pulses is shared as well as an overview of their spectral properties. Software simulations of perfect pulse enabled communications depict the creation of the channel waveforms, modulation onto a pseudo-random ambient carrier, and retrieval of the intended message data from the noisy and interference laden received signal. A robust receiver system is described which can be implemented via simple post-processing techniques in a software defined system or as a low-cost, low-power RF circuit using commercial-off-the-shelf components. Experimentally retrieved data is used to create a realistic estimate of bit rate errors using an actual FM radio station signal.