Cooperative UWB based positioning systems: CDAP algorithm and experimental results

The need for accurate positioning has attracted significant interest in recent years, especially in cluttered environments where signals from satellite navigation systems are not reliable. Positioning systems based on ultrawide bandwidth (UWB) technology have been considered for these environments due to the property of UWB signals to resolve multipath and penetrate obstacles. However, localization techniques based solely on ranging typically lack accuracy and reliability in dense cluttered environments, due to line-of-sight (LOS) blockage and excess propagation delay through material. In this paper, we consider positioning in a typical indoor environment scenario, where ranging is subject to estimation error and excess delay. Beacons are deployed in known locations, and one or more target nodes wish to determine their positions. We consider a range measurement error models based on measured data from real ranging devices. These models are used in a multilateration cooperative algorithm we propose to determine the target position. So we examine the case where multiple targets are present in the same environment and how the position accuracy is affected by the cooperative nodes positions and by the availability of priori information about the environment and network geometry. Using numerical results, we demonstrate the impact of cooperation on the positioning accuracy. It is shown that, depending on the geometric configuration of the nodes, cooperation is not always advantageous.