Ultra-wide Band Positioning in Sport: How the Relative Height Between the Transmitting and the Receiving Antenna Affects the System Performance

This work presents the performance evaluation of an ultra-wide band (UWB) positioning system for monitoring athletes in sports. Focusing on a five-a-side football scenario, the objective of this paper is to evaluate the performance of the proposed UWB positioning system by considering three different heights of the receiver antenna: 1 m, 1.6 m and 2 m. The system consists of four static UWB receivers placed at the corners of the pitch, while a player is equipped with an UWB transmitter worn on the upper back of the body. The UWB communication link from the on-body transmitter to the receivers can be influenced by the relative height between the transmitting and the receiving antenna. In order to assess the performance of the positioning system, on-field tests have been performed with five players. The players were asked to run at a variable speed while traveling a predefined path inside the pitch. Three metrics have been considered to assess the system performance: the accuracy of the position for each player, the percentage of packets lost by each receiver with respect to the total number of transmitted packets, and the percentage of packets respectively received by one, two, three, and four anchors, with respect to the total number of transmitted packets. The experimental results show that the intermediate height of 1.6 m for the receiver antenna presents the best results: the lowest value of position RMSE (equal to 31 cm), an average of 28% of the lost transmitted packets and an average of 63% of the transmitted packets being received at least by 3 anchors.