A multi-tag access scheme for indoor UWB localization systems used in medical environments

Ultra wideband (UWB) wireless systems have many advantages in indoor environments with dense multipath. UWB positioning systems are increasingly used in indoor environments to track and locate important assets. Many applications exist in medicine for UWB positioning which includes tracking personnel, assets, and even surgical navigation. We have designed a UWB positioning system with millimeter range accuracy with potential use in surgical navigation. This paper outlines a multi-tag access scheme for our UWB positioning system which integrates a 2.4 GHz physical layer to allow simultaneous tracking of up to 30 UWB tags. A static experiment was performed with two UWB tags while switching between the tags at 20 Hz. Millimeter accuracy was achieved even when tracking two tags. A 10% system latency was experienced when adding the multi-tag overhead, although a 744 Hz system update rate was still achieved. Asynchronous communication between the FPGA and microcontroller at the main control station ensured correct synchronization of the 3-D positioning data and corresponding tag ID. Future work includes a full dynamic experiment with simultaneous tracking of 5-10 tags.