Positioning in Inhomogeneous Media

This chapter studies techniques of measuring the straight‐line range between sensor nodes distributed within inhomogeneous media (IHM), which are critical to localization and body scanning applications. It proposes high‐resolution time‐of‐arrival (TOA) estimation in IHM. In IHM, TOA cannot be mapped into the actual range between the transmitter and receiver, as the propagation path of transmitted waveform is not a straight line. The chapter discusses how the range in IHM is computed via a combination of TOA and direction‐of‐arrival (DOA) estimation. TOA estimation in IHM via wideband signals needs to deal with waveform dispersion. The chapter presents a new method that exploits preallocated orthogonal frequency division multiplexing (OFDM) subcarriers to construct a wideband ranging signal. It proposes a novel approach, which reduces the number of unknowns by linear approximation of imposed delays and phases to the allocated OFDM subcarriers in frequency domain.