Patent ID: 6745038
Filing Date: 2004-06-01
Classification: G01S,H04B,H04W

Abstract:
A method of intra-piconet device location, comprising:a) a master device periodically polling a plurality of slave devices of a piconet over a period of time to obtain range information for each slave device of the plurality of slave devices corresponding to a plurality of carrier frequencies over a carrier-frequency range, wherein the range information for each slave device comprises received signal strength indicator (RSSI) values; b) developing a (RSSI) vs. carrier-frequency curve of each slave device of the plurality of slave devices representative of a plurality of RSSI values corresponding to the plurality of carrier frequencies over the period of time contained in the range information; c) identifying one or more periodicities occurring in the RSSI vs. carrier-frequency curve of each slave device of the plurality of slave devices; d) for each slave device of the plurality of slave devices identifying a frequency separation &Dgr;f corresponding to the one or more periodicities; and e) using the frequency separation &Dgr;f in determining a path-length difference, d=a+bâˆ’c, between a direct path distance c from a slave device of the plurality of slave devices to the master device and an indirect path distance, a+b, from the slave device to the master device, wherein d is proportional to &Dgr;f.