Before revision:  To take into account the probabilistic nature of the NLoS identifiers , our proposed cooperative localization employs an interacting multiple model (IMM) estimator .
After revision:  To take into account the probabilistic nature of the NLoS identifiers , our proposed cooperative localization employs an interacting multiple model (IMM) estimator in our localization filter. We also propose a bias compensation method for NLoS UWB measurements.