Indoor positioning with rake receivers

• US 8,879,607 B2
• Filed: 08/12/2011
• Issued: 11/04/2014
• Est. Priority Date: 08/12/2011
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Mobile Communications AB (Sony Group Corp.)
• Inventors: Skarp, Carl Filip Erik
• Primary Examiner(s): Vlahos, Sophia
• Application Number:
  US13/208,388
• Publication Number:
  US 20130039391A1
• Time in Patent Office: 1,180 Days
• Field of Search: 342/350, 342/453, 342/353, 342/458, 455/456.1, 455/456.3, 455/404.2, 455/456, 455/3, 455/456.5, 455/456.6, 701/408, 375/144, 375/148, 375/340
• US Class Current: 375/148
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 4/029 Location-based management or tracking services

Abstract

A method and a system for storing a constant path loss exponent corresponding to free space; transmitting a signal; receiving the signal via a rake receiver of a user device; identifying a maximum received signal strength based on a signal strength associated with the signal relative to fingers of the rake receiver; storing a current maximum received signal strength value; determining whether the current maximum received signal strength value is a first maximum received signal strength value; calculating a current indoor position of the user device based on the constant path loss exponent and the current maximum received signal strength value when a determination is that the current maximum received signal strength value is the first maximum received signal strength value; and outputting the current indoor position.

Claims

1. A method comprising:

storing a constant path loss exponent corresponding to free space;

receiving a signal via a rake receiver of a user device;

identifying a maximum received signal strength, during an instant t, based on a signal strength associated with the signal relative to fingers of the rake receiver;

storing a current maximum received signal strength value based on the identifying;

determining whether the current maximum received signal strength value is a first time stamped maximum of maximum received signal strength values that are stored corresponding to a sequence of samples of signal strengths received;

calculating a current indoor position of the user device based on the constant path loss exponent and the current maximum received signal strength value when a determination is that the current maximum received signal strength value is the first time stamped maximum of maximum received signal strength values, wherein the constant path loss exponent is used regardless of a type of multipath environment in which the user device resides; and

outputting the current indoor position.

2. The method of claim 1, further comprising:

transmitting the signal;

storing previously identified maximum received signal strength values, wherein the determining comprises;

comparing the current maximum received signal strength value to one or more previously identified maximum received signal strength values; and

determining whether a difference in maximum received signal strength value, based on the comparing, indicates receipt by the user device of a direct signal component of the signal or a reflective signal component of the signal.

3. The method of claim 2, further comprising:

calculating the current indoor position of the user device based on the constant path loss exponent and the compared, current maximum received signal strength value when the difference indicates that the compared, current maximum received signal strength value corresponds to the direct signal component of the signal; and

recalculating one or more previous indoor positions of the user device based on the current indoor position of the user device associated with the compared, current maximum received signal strength value.

4. The method of claim 3, further comprising:

recalculating the one or more previous indoor positions of the user device based on at least one of accelerometer data, gyroscope data, or compass data pertaining to the user device.

5. The method of claim 2, further comprising:

storing previous indoor positions of the user device;

determining, based on the comparing, that the difference in maximum received signal value indicates receipt by the user device of the reflective signal component of the signal; and

selecting one or more of the previous indoor positions as one or more reference indoor positions in response to determining that the difference in maximum received signal strength value indicates receipt by the user device of the reflective signal component of the signal.

6. The method of claim 5, further comprising:

calculating a current indoor position of the user device based on the constant path loss exponent, the selected one or more previous indoor positions, and at least one of accelerometer data, gyroscope data, or compass data pertaining to the user device.

7. The method of claim 5, further comprising:

calculating a current indoor position of the user device based on a weighting system associated with the difference in maximum received signal strength value.

8. The method of claim 2, further comprising:

storing at least one of a threshold difference value, a range of difference values, or a maximum received signal strength signature; and

determining whether the difference in maximum received signal strength value indicates receipt by the user device of the direct signal component of the signal or the reflective signal component of the signal based on the at least one of the threshold difference value, the range of difference values, or the maximum received signal strength signature.

9. A user device comprising:

a rake receiver;

one or more memories that store instructions; and

one or more processors that execute the instructions to;

receive a signal via the rake receiver;

identify a maximum received signal strength, during an instant t, based on a signal strength associated with the signal relative to fingers of the rake receiver;

store a current maximum received signal strength value based on an identified maximum received signal strength;

determine whether the current maximum received signal strength value is a first time stamped maximum of maximum received signal strength values that are stored corresponding to a sequence of samples of signal strengths received; and

calculate a current indoor position of the user device based on a path loss exponent corresponding to free space and the current maximum received signal strength value when a determination is that the current maximum received signal strength value is the first time stamped maximum of maximum received signal strength values, wherein the path loss exponent is used by the user device regardless of a type of multipath indoor environment.

10. The user device of claim 9, wherein when calculating the current indoor position, the one or more processors further execute the instructions to:

calculate the current indoor position based on a triangulation algorithm.

11. The user device of claim 9, wherein the one or more processors further execute the instructions to:

store previously identified maximum received signal strength values, wherein when determining, the one or more processors further execute the instructions to;

compare the current maximum received signal strength value to one or more previously identified maximum received signal strength values; and

determine whether a difference in maximum received signal strength value, based on a comparison, indicates receipt by the user device of a direct signal component of the signal or a reflective signal component of the signal.

12. The user device of claim 11, wherein the one or more processors further execute the instructions to:

calculate the current indoor position of the user device based on the path loss exponent and the compared, current maximum received signal strength value when the difference indicates that the compared, current maximum received signal strength value corresponds to the direct signal component of the signal; and

recalculate one or more previous indoor positions of the user device based on the current indoor position of the user device associated with the compared, current maximum received signal strength value.

13. The user device of claim 12, wherein when recalculating, the one or more processors further execute the instructions to:

recalculate the one or more previous indoor positions of the user device based on at least one of accelerometer data, gyroscope data, or compass data pertaining to the user device.

14. The user device of claim 11, wherein the one or more processors further execute the instructions to:

store previous indoor positions of the user device;

determine, based on a comparison, that the difference in maximum received signal value indicates receipt by the user device of the reflective signal component of the signal; and

select one or more of the previous indoor positions as one or more reference positions in response to determining that the difference in maximum received signal strength value indicates receipt by the user device of the reflective signal component of the signal.

15. The user device of claim 14, wherein the one or more processors further execute the instructions to:

calculate a current indoor position of the user device based on the path loss exponent, the selected one or more previous indoor positions, and at least one of accelerometer data, gyroscope data, or compass data pertaining to the user device.

16. The user device of claim 9, wherein the path loss exponent is a dynamic value based on at least one of a measurement of temperature, humidity, or pressure of air pertaining to an indoor environment of the user device, or a signal frequency.

17. A non-transitory, computer-readable storage medium storing instructions that are executable by a processor of a device, which causes the device to:

identify a maximum received signal strength, during an instant t, based on a signal received via a rake receiver;

store a current maximum received signal strength value based on an identified maximum received signal strength;

determine whether the current maximum received signal strength value is a first time stamped maximum of maximum received signal strength values that are stored corresponding to a sequence of samples of signal strengths received; and

calculate one or more distances relative to one or more wireless nodes of an indoor positioning system based on a constant path loss exponent corresponding to free space and the current maximum received signal strength value when a determination is that the current maximum received signal strength value is the first time stamped maximum of maximum received signal strength values, wherein the constant path loss exponent is used regardless of a type of multipath environment in which the device resides.

18. The non-transitory, computer-readable storage medium of claim 17, further storing instructions that are executable by the processor of the device, which causes the device to:

store previously identified maximum received signal strength values;

compare the current maximum received signal strength value to one or more previously identified maximum received signal strength values; and

determine whether a difference in maximum received signal strength value, based on a comparison, indicates that the signal includes a direct signal component of the signal or a reflective signal component of the signal.

19. The non-transitory storage medium of claim 18, further storing instructions that are executable by the processor of the device, which causes the device to:

calculate a current indoor position of the device based on the constant path loss exponent and the compared, current maximum received signal strength value when the difference indicates that the compared, current maximum received signal strength value corresponds to the direct signal component of the signal; and

recalculate one or more previous indoor positions of the device based on the current indoor position of the device associated with the compared, current maximum received signal strength value.

20. The non-transitory storage medium of claim 18, further storing instructions that are executable by the processor of the device, which causes the device to:

store previous indoor positions of the device;

determine, based on a comparison, that the difference in maximum received signal value indicates receipt by the device of the reflective signal component of the signal; and

select one or more of the previous indoor positions as one or more reference indoor positions when the difference in maximum received signal strength value indicates receipt by the device of a reflective signal component of the signal; and

calculate a current indoor position of the device based on the constant path loss exponent, the selected one or more previous indoor positions, and at least one of accelerometer data, gyroscope data, or compass data pertaining to the device, wherein the current indoor position is calculated based on triangulation.

21. A method comprising:

storing a constant path loss exponent corresponding to free space;

receiving a signal via a rake receiver of a user device;

identifying a maximum received signal strength, during an instant t, based on a signal strength associated with the signal relative to fingers of the rake receiver;

storing a current maximum received signal strength value based on the identifying;

determining whether the current maximum received signal strength value indicates a significant increase in signal strength or a significant decrease in signal strength, relative to maximum received signal strength values that are stored corresponding to a sequence of samples of signal strengths received, based on a threshold value;

calculating a current indoor position of the user device based on the constant path loss exponent and the current maximum received signal strength value when a determination is that the current maximum received signal strength value indicates the significant increase in signal strength, wherein the constant path loss exponent is used regardless of a type of multipath environment in which the user device resides; and

calculating a current indoor position of the user device based on the constant path loss exponent, selected one or more previous indoor positions, and at least one of accelerometer data, gyroscope data, or compass data pertaining to the user device, when a determination is that the current maximum received signal strength value indicates the significant decrease in signal strength.