Power optimization in visible light communication positioning

Patent metadata

Field	Value
Publication number	US-9948394-B1
Application number	US-201715458791-A
Country	US
Kind code	B1
Filing date	Mar 14, 2017
Priority date	Mar 14, 2017
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

Embodiments of apparatuses and methods of power optimization in VLC positioning are disclosed. In one embodiment, a mobile device may include image sensors configured to receive visible light communication signals, a memory configured to store the visible light communication signals, and a transceiver configured to receive positioning assistance data of a venue, and a controller configured to: decode one or more light fixtures within a field of view of the mobile device to obtain corresponding light fixture identifications, determine a motion of the mobile device with respect to the one or more light fixtures based on the light fixture identifications and the positioning assistance data of the venue, and switch the image sensors of the mobile device to a reduced duty cycle state based on the motion of the mobile device with respect to the one or more light fixtures within the field of view of the mobile device.

First claim

We claim:

1. A method of power optimization in visible light communication (VLC) positioning of a mobile device, comprising:
receiving positioning assistance data of a venue, wherein the positioning assistance data includes identifications and positions of light fixtures in the venue;
decoding one or more light fixtures within a field of view of the mobile device to obtain corresponding light fixture identifications;
determining a motion of the mobile device with respect to the one or more light fixtures based on the light fixture identifications and the positioning assistance data of the venue; and
switching image sensors of the mobile device to a reduced duty cycle state based on the motion of the mobile device with respect to the one or more light fixtures within the field of view of the mobile device.

2. The method of claim 1 , further comprising:
monitoring angles of arrival of light from the one or more light fixtures in field of view of the mobile device; and
determining a position of the mobile device using decoded light fixture identifications and the angles of arrival of light from the one or more light fixtures in field of view of the mobile device.

3. The method of claim 2 , further comprising:
in the reduced duty cycle state, for each light fixture in the field of view of the mobile device,
measuring light pixels of the each light fixture for at least one image sensor frame, and
determining the field of view for the each light fixture based on the light pixels measured for the at least one image sensor frame.

4. The method of claim 3 , further comprising:
predicting a subsequent field of view of the each light fixture based on current field of view of the each light fixture, motion of the mobile device, and orientation of the mobile device.

5. The method of claim 4 , further comprising:
determining whether to use the each light fixture identification for positioning based on a comparison of a predicted field of view of the mobile device and a measured field of view of the mobile device.

6. The method of claim 4 , further comprising:
comparing two frames of the light pixels of the each light fixture; and
determining validity of each light fixture identification decoded based on similarity of the two frames of the light pixels.

7. The method of claim 2 , wherein determining the position of the mobile device comprises:
measuring angles of arrival of light from the one or more light fixtures;
computing corresponding distances between the mobile device and the one or more light fixtures using the angles of arrival of light from the one or more light fixtures; and
determining the position of the mobile device using the distances from the one or more light fixtures with a triangulation method.

8. The method of claim 2 , further comprising:
predicting identifications of neighboring light fixtures outside the field of view of the mobile device using a direction of motion of the mobile device and the positioning assistance data of the venue.

9. The method of claim 1 , wherein switching image sensors of the mobile device to the reduced duty cycle state comprises:
operating the image sensors of the mobile device with a programmable duty cycle, wherein the programmable duty cycle is determined based on the motion of the mobile device, a number of light fixtures in the field of view of the mobile device, and distances between the one or more light fixtures.

10. The method of claim 9 , further comprising:
detecting that an orientation of the mobile device has changed substantially from a previous orientation of the mobile device with respect to the one or more light fixtures; and
switching the image sensors of the mobile device to a full duty cycle state to decode the one or more light fixtures within the field of view of the mobile device to obtain an updated set of light fixture identifications.

11. The method of claim 1 , wherein in the reduced duty cycle state,
measuring an angle of arrival of light from the one or more light fixtures and stopping VLC signal decode for a programmable duration.

12. A mobile device, comprising:
image sensors configured to receive visible light communication signals;
a memory configured to store the visible light communication signals;
a transceiver configured to receive positioning assistance data of a venue, wherein the positioning assistance data includes identifications and positions of light fixtures in the venue;
a controller configured to:
decode one or more light fixtures within a field of view of the mobile device to obtain corresponding light fixture identifications;
determine a motion of the mobile device with respect to the one or more light fixtures based on the light fixture identifications and the positioning assistance data of the venue; and
switch the image sensors of the mobile device to a reduced duty cycle state based on the motion of the mobile device with respect to the one or more light fixtures within the field of view of the mobile device.

13. The mobile device of claim 12 , wherein the controller is further configured to:
monitor angles of arrival of light from the one or more light fixtures in field of view of the mobile device; and
determine a position of the mobile device using decoded light fixture identifications and the angles of arrival of light from the one or more light fixtures in field of view of the mobile device.

14. The mobile device of claim 13 , wherein in the reduced duty cycle state, for each light fixture in the field of view of the mobile device, the controller is further configured to:
measure light pixels of the each light fixture for at least one image sensor frame; and
determine the field of view for the each light fixture based on the light pixels measured for the at least one image sensor frame.

15. The mobile device of claim 14 , wherein the controller is further configured to:
predict a subsequent field of view of the each light fixture based on current field of view of the each light fixture, motion of the mobile device, and orientation of the mobile device.

16. The mobile device of claim 15 , wherein the controller is further configured to:
determine whether to use the each light fixture identification for positioning based on a comparison of a predicted field of view of the mobile device and a measured field of view of the mobile device.

17. The mobile device of claim 15 , wherein the controller is further configured to:
compare two frames of the light pixels of the each light fixture; and
determine validity of each light fixture identification decoded based on similarity of the two frames of the light pixels.

18. The mobile device of claim 13 , wherein the controller is further configured to:
measure angles of arrival of light from the one or more light fixtures;
compute corresponding distances between the mobile device and the one or more light fixtures using the angles of arrival of light from the one or more light fixtures; and
determine the position of the mobile device using the distances from the one or more light fixtures with a triangulation method.

19. The mobile device of claim 13 , wherein the controller is further configured to:
predict identifications of neighboring light fixtures outside the field of view of the mobile device using a direction of motion of the mobile device and the positioning assistance data of the venue.

20. The mobile device of claim 12 , wherein the controller is further configured to:
operate the image sensors of the mob

Assignees

• Qualcomm Inc
• Quacomm Incorporated

Inventors

• Bitra Suresh Kumar
• Agrawal Meghna

Classifications

• G01S2201/01

  adapted for specific applications or environments · CPC title

• G01S1/7038 Primary

  Signal details · CPC title

• G01S1/7034

  Mounting or deployment thereof · CPC title

• G01S5/16

  using electromagnetic waves other than radio waves · CPC title

• H04B10/1149

  Arrangements for indoor wireless networking of information · CPC title