Labeling for UWB Ranging in Weak NLOS Conditions

A stepwise feature labeling method for UWB ranging is presented, which allows better separation of LOS and NLOS components in the training data. The packet-by-packet range error evaluation is used as input of the labeling function instead of the conventionally used double-sided two-way ranging result which relies on a cycle of three packets. To assess the packet-wise error, a two-step synchronization scheme is proposed. First, the clock model between anchor and tag is estimated by a least-squares approach. Second, the remaining bias is corrected by determining the time-shift between the channel impulse responses recorded by both nodes. The evaluation of measurement data shows a significant improvement in classification between LOS and NLOS, as well as slightly improved ranging accuracy when used to train a binary classifier.