Listening window adjustments for power savings in bluetooth low energy (BLE) communications

• US 9,668,209 B1
• Filed: 06/29/2016
• Issued: 05/30/2017
• Est. Priority Date: 06/29/2016
• Status: Active Grant

• Current Assignee: Silicon Laboratories Finland Oy (Silicon Laboratories Incorporated)
• Original Assignee: Silicon Laboratories Finland Oy (Silicon Laboratories Incorporated)
• Inventors: Knaappila, Jere M.
• Primary Examiner(s): Le, Thanh
• Application Number:
  US15/196,244
• Time in Patent Office: 335 Days
• 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 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
• CPC Class Codes: H04W 52/0209 in terminal devices terminal devices per se H04W88/02
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Systems and methods are disclosed for listening window adjustments for power savings in BLE (Bluetooth low energy) communications. BLE devices determine time differences between assumed transmission times and actual receive times for packets transmitted by another BLE device. The BLE device then adjusts a listening window using the time differences, for example, to reduce the size of the listening window based upon the time differences. The adjusted listening window is then used by the BLE device to listen for and receive additional packets from the other BLE device.

Claims

1. A method for BLE (Bluetooth Low Energy) packet communications, comprising:

communicating packets between a first BLE device and a second BLE device using a defined time interval between packet communications;

listening at the first BLE (Bluetooth Low Energy) device within a listening window for a packet transmitted from the second BLE device;

receiving within the listening window a packet at the first BLE device transmitted from the second BLE device;

determining a time difference between an assumed transmission time for the packet based upon the defined time interval and an actual receive time for the packet;

adjusting the listening window for first BLE device using the time difference; and

operating the first BLE device to listen within the adjusted listening window for one or more additional packets transmitted from the second BLE device.

2. The method of claim 1, wherein the adjusting reduces a size for the listening window based upon the time difference.

3. The method of claim 1, wherein the listening window comprises a clock drift component, and wherein the adjusting removes the clock drift component to reduce the size for the listening window.

4. The method of claim 1, wherein the communicating occurs within a connection event between the first BLE device and the second BLE device, and wherein a defined Inter Frame Space (T_IFS) between packet communications for the connection event represents the defined time interval.

5. The method of claim 4, wherein the listening window further comprises a base component configured to account for the defined T_IFS and allowed deviation in the T_IFS.

6. The method of claim 1, wherein the communicating occurs between multiple connection events between the first BLE device and the second BLE device, and wherein a connection interval between connection events represents the defined time interval.

7. The method of claim 6, wherein the listening window further comprises a base component configured to account for the defined connection interval and allowed deviation in the connection interval.

8. The method of claim 1, further comprising determining a plurality of time differences for a plurality of received packets and then adjusting the listening window based upon the plurality of time differences.

9. The method of claim 8, further comprising generating an average for the plurality of time differences and using the average to adjust the listening window.

10. The method of claim 8, wherein the adjusting reduces a size for the listening window based upon the plurality of time differences.

11. The method of claim 1, further comprising determining a distance between the first BLE device and the second BLE device and adjusting the listening window based upon the distance.

12. The method of claim 11, further comprising determining that the distance exceeds a predetermine threshold before adjusting the listening window based upon the distance.

13. The method of claim 11, further comprising determining the distance between the first BLE device and the second BLE device using the time difference.

14. A BLE (Bluetooth Low Energy) device, comprising:

network interface circuitry including a radio configured to transmit and receive packet communications; and

one or more processors configured to execute instructions stored in a non-transitory computer readable medium that cause the one or more processors to;

communicate packets with another BLE device through the network interface circuitry using a defined time interval between packet communications;

listen within a listening window for a packet transmitted from the other BLE device;

receive within the listening window a packet from the other BLE device;

determine a time difference between an assumed transmission time for the packet based upon the defined time interval and an actual receive time for the packet;

adjust the listening window using the time difference; and

listen within the adjusted listening window for one or more additional packets transmitted from the other BLE device.

15. The BLE device of claim 14, wherein the adjustment is configured to reduce a size for the listening window based upon the time difference.

16. The BLE device of claim 14, wherein the listening window comprises a clock drift component, and wherein the adjustment is configured to remove the clock drift component to reduce the size for the listening window.

17. The BLE device of claim 14, wherein the defined time interval is a defined Inter Frame Space (T_IFS) between packet communications within a connection event with the other BLE device.

18. The BLE device of claim 17, wherein the listening window further comprises a base component configured to account for the defined T_IFS and allowed deviation in the T_IFS.

19. The BLE device of claim 14, wherein the defined time interval is a connection interval between connection events with respect to the other BLE device.

20. The BLE device of claim 19, wherein the listening window further comprises a base component configured to account for the defined connection interval and allowed deviation in the connection interval.

21. The BLE device of claim 14, wherein the one or more processors are further configured to determine a plurality of time differences for a plurality of received packets and then adjust the listening window based upon the plurality of time differences.

22. The BLE device of claim 21, wherein the one or more processors are further configured to generate an average for the plurality of time differences and use the average to adjust the listening window.

23. The BLE device of claim 21, wherein the adjustment is configured to reduce a size for the listening window based upon the plurality of time differences.

24. The BLE device of claim 14, wherein the one or more processors are further configured to determine a distance to the other BLE device and adjust the listening window based upon the distance.

25. The BLE device of claim 24, wherein the one or more processors is further configured to determine that the distance exceeds a predetermine threshold before adjustments are made to the listening window based upon the distance.

26. The BLE device of claim 24, wherein the one or more processors are further configured to determine the distance to the other BLE device using the time difference.