Entropy based TOA estimation in IR UWB ranging with energy detection receiver under dense multipath environment

To estimate the time of arrival (TOA) of the first path (FP) in ultra wideband (UWB) ranging, we propose an entropy based method. In the energy detection (ED) receiver, thresholding crossing (TC) is used a lot to detect the FP. The threshold should be carefully chosen, or else the false alarm rate will be high. Our method detects the FP from a different angle based on the arrival characteristics of the dense multipath, which is that the FP is always followed by many other strong paths. During a short interval, the TOAs of these paths are definite and the samples which contain these multipath signals can exceed the suboptimal threshold in most cases, while the TOAs of the few TC noise samples before the FP are random. We use the entropy to measure the randomness of the distribution of the last TC sample before the current one. Then the FP is determined by choosing the sample which has very large entropy and is followed by a sample with very low entropy. Simulation results verify its effectiveness with IEEE 802.15.4a Standard.