Wideband Signal Based Near-Field Electromagnetic Ranging for Indoor Localization

The near-field electromagnetic ranging (NFER) technology exploits the near-field phase behavior of low frequency signals to measure the distance and can provide better ranging performance than the high frequency signal based methods in the cluttered environments. However, the currently existing NFER system uses the mono-frequency signals and can not obtain same ranging accuracy at different distances. In addition, low signal-to-noise ratio (SNR) seriously impacts the ranging accuracy. In this paper, we proposed a wideband signal based NFER system to improve the ranging performance. Instead of the mono-frequency signals, the proposed wideband system transmits the wideband signals. We use frequency domain phase measurement (FDPM) to detect the phase difference between received electric field signal and magnetic field signal. Then the least squares method is used to estimate the distance. Simulation results show that the proposed wideband NFER system can improve the ranging performance at low SNR environment and within a wide range of distances.