Apparatus, system and method of determining a time synchronization function (TSF) based on fine time measurement (FTM) messages

1. An apparatus comprising a memory and a processor, the processor configured to cause a wireless station to:

determine a first Time Synchronization Function (TSF) value of a local TSF of said wireless station at arrival of a first Fine Timing measurement (FTM) message from a responder station;

determine a second TSF value of the local TSF at arrival of a second FTM message from the responder station, the second FTM message comprising a first Time of Departure (TOD) value of the first FTM message;

process a third FTM message from the responder station, the third FTM message comprising a second TOD value of the second FTM message; and

apply to the local TSF a TSF correction based at least on the first TSF value, the second TSF value, the first TOD value, and the second TOD value, the TSF correction based on a first difference value and a second difference value, the first difference value comprising a difference between the second and first TSF values, the second difference value comprises a difference between the second and first TOD values.

2. The apparatus of claim 1 , wherein the processor is configured to cause the wireless station to determine a timing of an FTM burst period based on said local TSF, and to communicate the first, second, and third FTM messages during the FTM burst period.

3. The apparatus of claim 1 , wherein the first and second FTM messages comprise messages within a single burst duration.

4. The apparatus of claim 1 , wherein the first FTM message is within a first burst duration, and the second FTM message is within a second burst duration subsequent to the first burst duration.

5. The apparatus of claim 1 comprising a radio to receive the first, second, and third FTM messages.

6. The apparatus of claim 1 comprising one or more antennas.

7. A system of wireless communication comprising:

one or more antennas;

a radio;

a memory; and

a processor configured to cause a wireless station to:

determine a first Time Synchronization Function (TSF) value of a local TSF of said wireless station at arrival of a first Fine Timing measurement (FTM) message from a responder station;

determine a second TSF value of the local TSF at arrival of a second FTM message from the responder station, the second FTM message comprising a first Time of Departure (TOD) value of the first FTM message;

process a third FTM message from the responder station, the third FTM message comprising a second TOD value of the second FTM message; and

apply to the local TSF a TSF correction based at least on the first TSF value, the second TSF value, the first TOD value, and the second TOD value, the TSF correction based on a first difference value and a second difference value, the first difference value comprising a difference between the second and first TSF values, the second difference value comprises a difference between the second and first TOD values.

8. The system of claim 7 , wherein the processor is configured to cause the wireless station to determine a timing of an FTM burst period based on said local TSF, and to communicate the first, second, and third FTM messages during the FTM burst period.

9. The system of claim 7 , wherein the first and second FTM messages comprise messages within a single burst duration.

10. The system of claim 7 , wherein the first FTM message is within a first burst duration, and the second FTM message is within a second burst duration subsequent to the first burst duration.

11. The system of claim 7 , wherein said radio is configured to receive the first, second, and third FTM messages.

12. A method to be performed at a wireless station, the method comprising:

determining a first Time Synchronization Function (TSF) value of a local TSF of said wireless station at arrival of a first Fine Timing measurement (FTM) message from a responder station;

determining a second TSF value of the local TSF at arrival of a second FTM message from the responder station, the second FTM message comprising a first Time of Departure (TOD) value of the first FTM message;

processing a third FTM message from the responder station, the third FTM message comprising a second TOD value of the second FTM message; and

applying to the local TSF a TSF correction based at least on the first TSF value, the second TSF value, the first TOD value, and the second TOD value, the TSF correction based on a first difference value and a second difference value, the first difference value comprising a difference between the second and first TSF values, the second difference value comprises a difference between the second and first TOD values.

13. The method of claim 12 comprising determining a timing of an FTM burst period based on said local TSF, and communicating the first, second, and third FTM messages during the FTM burst period.

14. The method of claim 12 , wherein the first and second FTM messages comprise messages within a single burst duration.

15. The method of claim 12 , wherein the first FTM message is within a first burst duration, and the second FTM message is within a second burst duration subsequent to the first burst duration.

16. The method of claim 12 comprising receiving the first, second, and third FTM messages.

17. A product comprising one or more tangible computer-readable non-transitory storage media comprising computer-executable instructions operable to, when executed by at least one computer processor, enable the at least one computer processor to cause a wireless station to:

determine a first Time Synchronization Function (TSF) value of a local TSF of said wireless station at arrival of a first Fine Timing measurement (FTM) message from a responder station;

determine a second TSF value of the local TSF at arrival of a second FTM message from the responder station, the second FTM message comprising a first Time of Departure (TOD) value of the first FTM message;

process a third FTM message from the responder station, the third FTM message comprising a second TOD value of the second FTM message; and

apply to the local TSF a TSF correction based at least on the first TSF value, the second TSF value, the first TOD value, and the second TOD value, the TSF correction based on a first difference value and a second difference value, the first difference value comprising a difference between the second and first TSF values, the second difference value comprises a difference between the second and first TOD values.

18. The product of claim 17 , wherein the instructions, when executed, cause the wireless station to determine a timing of an FTM burst period based on said local TSF, and communicate the first, second, and third FTM messages during the FTM burst period.

19. The product of claim 17 , wherein the first and second FTM messages comprise messages within a single burst duration.

20. The product of claim 17 , wherein the first FTM message is within a first burst duration, and the second FTM message is within a second burst duration subsequent to the first burst duration.

21. The product of claim 17 , wherein the instructions, when executed, cause the wireless station to receive the first, second, and third FTM messages.