IEEE 802.15.4a UWB-IR ranging with bilateral transmitter power control methodology for multipath effects mitigation

IEEE 802.15.4a Ultra Wideband Impulse Radio (UWB-IR) measures the distance using the time-of-arrival (TOA) of the leading path signal. Multipath propagation in indoor environments can adversely affect the signal to noise ratio (SNR) resulting errors in leading path detection. In this paper, the multipath effects mitigation is in focus and method for bilateral transmitter power control. Measurements for SNR status of the 802.15.4a UWB-IR propagation in indoor buildings are reported. Relevant aspects of power control are discussed on practical issues, using an automatic control framework, which is integrated into the symmetric double-sided two-way (SDS-TW) ranging protocol. We evaluate the resulting performance and compare with existing non-power control techniques in Line-of-Sight (LOS) condition. Experimental results show that, with power control, ranging error below sub 10cm occurs in more than 90% of the 4800 measurements from 2.5m to 30m; without power control, ranging error below sub 10cm occurs in less than 20%. The use of transmitter power controlled ranging method is capable of mitigating the uncertain multipath effects, improving the ranging accuracy and stability in indoor multipath environments.