Ultra-wide Band Positioning in Sport: How the On-body Tag Location Affects the System Performance

This paper reports and discusses the results of a measurement campaign of an ultra-wide band positioning (UWB) system for monitoring players in sports. In particular, the present work aims to investigate how the location of the tag worn on the player’s body affects the system performance in a five-a-side football scenario. Four static UWB receivers are placed at the corners of a five-a-side pitch, while a mobile player is equipped with four UWB transmitters arranged on different body locations: left arm, right arm, upper back, and lower back. The player’s body influences the UWB communication link defined between the on-body transmitter and the receivers that are located on the sideline. In order to assess the performance of the positioning system, on-field tests have been performed with a player. The latter was asked to run at a variable speed while traveling a predefined path inside the pitch. Three metrics have been considered to compare the system performance for the different on-body transmitter locations: the position accuracy for each transmitter, the percentage of packets lost by the receivers with respect to the transmitted packets, and the percentage of packets transmitted and, respectively, received by one, two, three, or four receivers. The experimental evaluation shows the upper back location guarantees the best results by achieving the lowest position RMSE that is equal to 0.70 m, an average of 40% of the transmitted packets lost by the receivers and the 42% of the transmitted packets reaching at least 3 anchors.