An Experimental Study on Improving Accuracy of Phase-Based Ranging in Indoor Environments

A high-accuracy phase-based ranging (PBR) algorithm is described for Bluetooth Low Energy (BLE) channel sounding. The received I/Q signals are weighted with a side-lobe suppression window and then transformed by IFFT into time-domain signals to tentatively estimate the distance. The time-domain signals are weighted with a window function shifted at the tentatively estimated distance to suppress long-time delayed paths. The weighted time-domain signals are transformed back to the subcarrier signals, which are then used in the search-range-limited MUSIC algorithm. Our enhanced PBR scheme achieved the ranging accuracy within a median error of about 0.35 m in indoor multi-path environments.