Precise, high coverage, location system

Patent metadata

Field	Value
Publication number	US-9949083-B1
Application number	US-201615296349-A
Country	US
Kind code	B1
Filing date	Oct 18, 2016
Priority date	Oct 18, 2016
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A system and method for improved location tracking of a target device based on location estimates for multiple types of location technologies/sensor types. A received signal strength location estimate of a target device based on wireless transmissions made by the target device received at a plurality of receiver devices at known locations in a location region. A first search area for the target device is derived based on the received signal strength location estimate. An ultrasound based area in which the target device is estimated to be is derived based on reception by the target device of a particular ultrasound beacon in the location region. An intersection of the first search area and the ultrasound based area is computed to produce a second search area. A location estimate of the target device in the second search area is computed based at least on the received signal strength location estimate.

First claim

What is claimed is:

1. A method comprising:
obtaining a received signal strength location estimate of a target device based on wireless transmissions made by the target device that are received at a plurality of receiver devices at known locations in a location region;
deriving a first search area for the target device based on the received signal strength location estimate;
deriving an ultrasound based area in which the target device is estimated to be based on reception by the target device of a particular ultrasound beacon in the location region;
computing an intersection of the first search area and the ultrasound based area to produce a second search area;
computing a first angle-of-arrival location estimate of the target device in the second search area based on a wireless signal received from the target device at each of a plurality of antennas of the plurality of receiver devices; and
computing a location estimate of the target device in the second search area based at least on the received signal strength location estimate and the first angle-of-arrival location estimate.

2. The method of claim 1 , further comprising:
determining whether the first angle-of-arrival location estimate is accurate;
when it is determined that the first angle-of-arrival location estimate is accurate, combining the received signal strength location estimate with the first angle-of-arrival location estimate to produce the location estimate of the target device.

3. The method of claim 2 , wherein when it is determined that the first angle-of-arrival location estimate does not have sufficient accuracy, further comprising:
generating a second angle-of-arrival location estimate on a reduced search area compared to that used for the first angle-of-arrival location estimate; and
combining the received signal strength location estimate with the second angle-of-arrival location estimate to produce the location estimate of the target device.

4. The method of claim 1 , wherein the received signal strength location estimate is a first location measurement of the target device and a second location measurement is based on the ultrasound based area, and further includes: a third location measurement of the target device based on short-range low energy wireless beacon sensors, and a fourth location measurement of the target device based on a detection event from a radio frequency identification (RFID) reader position in the location region to detect the target device on opposite sides of a wall, and wherein computing the location estimate comprises computing a fused location estimate based on a weighted combination of the first location measurement and the third location measurement.

5. The method of claim 4 , wherein when deriving the ultrasound based area in which the target device is estimated to be determines that the target device is not estimated to be in the ultrasound based area, further comprising:
determining whether the fourth location measurement of the target device indicates that the target device is on a same side of a building structure as the RFID reader.

6. The method of claim 5 , wherein when the fourth location measurement of the target device indicates that the target device is on an opposite side of the building structure from the fused location estimate, computing the location estimate comprises modifying the fused location estimate as being on a line from the fused location estimate normal to the building structure but on a correct side of the building structure.

7. The method of claim 4 , wherein when the deriving the ultrasound based area in which the target device is estimated to be in determines that the target device is estimated to be in the ultrasound based area, further comprising:
determining whether the fused location estimate is in the ultrasound based area; and
if the fused location estimate is in the ultrasound based area, using the fused location estimate without modification.

8. The method of claim 5 , wherein if the fused location estimate is not in the ultrasound based area but is on a same side of the building structure as the ultrasound based area, further comprising:
determining whether the fused location estimate is on the same side of the building structure as the RFID reader.

9. The method of claim 8 , further comprising:
modifying the fused location estimate to be at a point that is on a correct side of the building structure approximately mid-way between intersections with the building structure of perpendicular lines from the fused location estimate and a centroid of the ultrasound based area, when it is determined that the fused location estimate is not on the same side of the building structure as the RFID reader; and
modifying the fused location estimate to be at a point on a boundary of the ultrasound based area and on a line between the fused location estimate and the centroid of the ultrasound based area when it is determined that the fused location estimate is on the same side of the building structure as the RFID reader.

10. The method of claim 8 , wherein if the fused location estimate is not in the ultrasound based area but is on an opposite side of the building structure as the ultrasound based area, further comprising:
modifying the fused location estimate to be at a point that is on a correct side of the building structure approximately mid-way between intersections with the building structure of perpendicular lines from the fused location estimate and the centroid of the ultrasound based area, when it is determined that the fused location estimate is not on the same side of the building structure as the RFID reader; and
not modifying the fused location estimate when it is determined that the fused location estimate is on the same side of the building structure as the RFID reader.

11. An apparatus comprising:
a network interface unit configured to enable communications over a network;
a processor coupled to the network interface unit, and configured to:
obtain a received signal strength location estimate of a target device based on wireless transmissions made by the target device that are received at a plurality of receiver devices at known locations in a location region;
derive a first search area for the target device based on the received signal strength location estimate;
derive an ultrasound based area in which the target device is estimated to be based on reception by the target device of a particular ultrasound beacon in the location region;
compute an intersection of the first search area and the ultrasound based area to produce a second search area;
compute a first angle-of-arrival location estimate of the target device in the second search area based on a wireless signal received from the target device at each of a plurality of antennas of the plurality of receiver devices; and
compute a location estimate of the target device in the second search area based at least on the received signal strength location estimate and the first angle-of-arrival location estimate.

12. The apparatus of claim 11 , wherein the processor is configured to:
generate a second angle-of-arrival location estimate on a reduced search area compared to a size of the second search area for the first angle-of-arrival location estimate; and
combine the received signal strength location estimate with the second angle-of-arrival location estimate to produce the location estimate of the target device.

13. The apparatus of claim 11 , wherein the received signal strength location estimate is a first location measurement of the target device and a second location measurement is based on the ultrasound based area, and w

Assignees

• Cisco Tech Inc

Inventors

• Kirby Shaun
• Muller Justin J
• Chundury Jagadish
• To Victor T
• Pandey Santosh G

Classifications

• H04W4/023 Primary

  using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds · CPC title

• G01S5/12

  by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial · CPC title

• G01S1/725

  Marker, boundary, call-sign or like beacons transmitting signals not carrying directional information · CPC title

• G01S15/06

  Systems determining the position data of a target · CPC title

• H04B5/0062

  Electricity · mapped topic