A Reconfigurable MIMO System for High-Precision FMCW Local Positioning

In this paper, a highly accurate local positioning system is presented that is based on linear frequency-modulated continuous-wave signals in the 5.8-GHz industrial–scientific–medical band. The developed system allows for much higher operating distances than leading ultra-wideband local positioning systems, while it provides the same or even better accuracy. This is achieved by a novel multiple–input multiple–output (MIMO) measurement concept that enables the receiving unit to control the beam patterns of the receiving and the transmitting antenna arrays by a coherent combination of the received signals. In this way, interfering multipath components are suppressed, leading to a significantly reduced ranging error. Furthermore, the angle of arrival and the angle of departure are determined from the MIMO datasets using super-resolution direction-finding techniques. For position determination, both range and angle information are exploited. Extensive measurements with the MIMO system in different indoor environments show that the position error can be reduced by up to 80% compared to an equivalent single-antenna setup.