Elimination of Phase Offsets for Microwave Ranging Using OFDM Signals

Precise microwave ranging is critical in localization, sensing, and other applications. However, phase offsets caused by imperfections in devices, particularly in commercial networks such as WiFi, pose challenges for accurate ranging. For precise ranging, this letter proposes a novel approach to eliminate the phase offsets in orthogonal frequency-division multiplexing (OFDM) signals without changing the hardware. It includes a comprehensive mathematical derivation aimed at eliminating phase offsets. We then integrated orthogonal matching pursuit (OMP) and particle swarm optimization (PSO) algorithm for ranging. We implemented the method using software-defined radio (SDR) and conducted extensive testing in an indoor environment. The results indicate that our method's performance is on par with that of ranging operations conducted under perfectly synchronized conditions between transceivers.