A 3-D Integrated Localization and Sensing Method for UWB Systems Using TOA/TDOA Measurements

The position information of active user equipment (UE) and passive targets forms the basis for numerous wireless applications. Ultra-Wideband (UWB) systems characterized by large signal bandwidths offer temporal resolution and accuracy. In this paper, we introduce an asynchronous 3-D integrated localization and sensing (ILAS) network for UWB systems, utilizing collaborative protocol. A maximum likelihood (ML)based ILAS solution is developed by optimizing the log-likelihood function of hybrid time of arrival (TOA), time sum of arrival (TSOA), and time difference of arrival (TDOA) measurements. The original problem is decomposed into localization and sensing problems. Closed-form ML estimators are derived first using the measurements separately, then weighted averaged in the polar and a modified polar coordinate system. We derive the fundamental limits of the estimators in both coordinate systems to determine the weights. Numerical results confirm the effectiveness of the proposed closed-form ML estimators, which demonstrate performance approaching the Cramr-Rao Lower Bound (CRLB).