A heterogeneous RSSI-based localization system for indoor and outdoor sports activities

Abstract

Localization and tracking of players is crucial for monitoring both indoor and outdoor sports activities. The effects of the environment pose a major challenge for an accurate position estimation. In this paper, we present a novel solution based on the received signal strength indication (RSSI) feature provided by off-the-shelf wireless networks. Trilateration is used for estimating the position of targets with a RSSI to distance mapping function based on the path-loss shadowing propagation model. Key to our system is the real-time collection of RSSI measurements for which we designed and implemented a new, channel-hopping, TDMA-based protocol, which coordinates frame transmissions among nodes. A further innovative aspect of our solution is that the nodes are heterogeneous, using Waspmote and IRIS nodes as well as XBee modules. The latter enables a signicant boost in the transmit power, which in turn improves the resolution of the RSSI to distance estimates. Additionally, we address the challenges of fast deployment and testing by using a semi-automatic calibration mechanism for adjusting the distances estimated from RSSI measurements. Our experiments, conducted both indoors and outdoors, show that sub-meter accuracy can be achieved by combing a high transmit power, multiple channels, together with multiple antennas.