A Novel GNSS Repeater Architecture for Indoor Positioning Systems in ISM Band

For indoor positioning using customary Global Navigation Satellite Systems (GNSS) receivers, the use of GNSS repeaters can be considered. However, regulations and provisions limit the use of GNSS repeaters. In order to circumvent these limitations, we propose a novel repeater architecture that transmits the Global Positioning System (GPS) signals in 433 MHz ISM band by frequency down-conversion. In addition, a receiver front end is proposed to upconvert GPS signals back to 1575.42 MHz, which allows any off-the-shelf GPS receiver to be used for indoor positioning. Measurement results with the RF hardware show that when the GPS signals are downconverted and then upconverted back to its original frequency, GPS signal fidelity and positioning accuracy are preserved.