Efficient Range Estimation in Beat Radio Interferometry

The beat radio interferometry (BRI) is a novel ranging scheme that achieves high accuracy with low-cost devices. A major problem with BRI is the lack of an efficient range estimation method that is valid in general measurement configurations and accommodates large-scale scenarios. In this paper, we present a new model of BRI and reveal that range estimation in it is equivalent to single tone frequency estimation. Such a revelation has two natural outcomes: the first is the Cramer-Rao lower bound (CRLB) of BRI range estimation; the second is an efficient fast Fourier transform (FFT)-based method that works in arbitrary measurement configurations and large-scale scenarios. Simulation results show that the FFT-based method asymptotically attains the CRLB and is orders of magnitude faster than currently available methods.