MOBILE TIME-SYNC DISTRIBUTION

Abstract

This technology allows time synchronization in wireless networks with mobile stations. A wireless network controller transmits instructions to access points (“APs”) within the wireless network to monitor transmissions for time synchronization. One or more second APs observe fine time measurement (“FTM”) exchanges between a first AP and a mobile station. A particular second AP determines whether to perform a time synchronization with the first AP based on the detection of the FTM exchange or a determination that the station is moving toward the second AP. For time synchronization, the second AP determines the time that the first AP transmitted the FTM exchange and the time of transmission from the first AP to the second AP. The second AP synchronizes a second AP clock to the summation of the time of the transmission of the FTM exchange and the time of transmission from the first AP to the second AP.

Description

Claims

1. A method performed by a computing device, comprising: performing, by the computing device, a first time synchronization with a first access point (AP) with which the computing device is connected;synchronizing a local clock of the computing device with a first clock of the first AP based at least in part on the first time synchronization;determining that the computing device is to transition from being connected to the first AP to being connected to a second AP;based at least in part on transitioning from the first AP to the second AP, performing a second time synchronization with the second AP; andsynchronizing the local clock with a second clock of the second AP such that the local clock and second clock are time synchronized.

2. The method of claim 1, wherein determining that the computing device is to transition from being connected to the first AP to being connected to the second AP comprises: determining a first round trip transmission time between the first AP and the computing device;determining a second round trip transmission time between the second AP and the computing device; anddetermining that the second round trip transmission time is less than the first round trip transmission time.

3. The method of claim 1, wherein synchronizing the local clock with the second clock comprises: determining a first time at which a time measurement exchange was transmitted by the computing device;determining a second time at which particular time measurement exchange was received at the second AP; andadjusting a time value of the local clock based at least in part on the first time and the second time.

4. The method of claim 3, wherein the second time is calculated based upon a location mapping of the computing device in a wireless network established at least in part by the second AP.

5. The method of claim 3, wherein the time measurement exchange is a fine time measurement (“FTM”) exchange in accordance with IEEE 802.1AS timing and synchronization standard.

6. The method of claim 1, wherein the computing device is a mobile station.

7. The method of claim 1, wherein: the first AP establishes a first wireless network to which first computing devices are connected;the first AP performs time synchronizations with the first computing devices such that the first computing devices are synced with the first AP;the second AP establishes a second wireless network to which second computing devices are connected; andthe second AP performs time synchronizations with the second computing devices such that the second computing devices are synced with the second AP,wherein second computing devices have different local times than the first computing devices.

8. A computing device comprising: one or more processors; andone or more non-transitory computer-readable media storing computer-executable instructions that, when executed by the one or more processors, causes the one or more processors to perform operations comprising: performing, by the computing device, a first time synchronization with a first access point (AP) with which the computing device is connected;synchronizing a local clock of the computing device with a first clock of the first AP based at least in part on the first time synchronization;determining that the computing device is to synchronize with a second AP;performing a second time synchronization between the computing device and the second AP; andsynchronizing the local clock with a second clock of the second AP such that the local clock, the first clock, and the second clock are time synchronized.

9. The computing device of claim 8, wherein determining that the computing device is to synchronize with the second AP comprises: determining a first round trip transmission time between the first AP and the computing device;determining a second round trip transmission time between the second AP and the computing device; anddetermining that the second round trip transmission time is less than the first round trip transmission time.

10. The computing device of claim 8, wherein synchronizing the local clock with the second clock comprises: determining a first time at which a time measurement exchange was transmitted by the computing device;determining a second time at which particular time measurement exchange was received at the second AP; andadjusting a time value of the local clock based at least in part on the first time and the second time.

11. The computing device of claim 10, wherein the second time is calculated based upon a location mapping of the computing device in a wireless network established at least in part by the second AP.

12. The computing device of claim 10, wherein the time measurement exchange is a fine time measurement (“FTM”) exchange in accordance with IEEE 802.1AS timing and synchronization standard.

13. The computing device of claim 8, wherein the computing device is a mobile station.

14. The computing device of claim 8, wherein: the first AP establishes a first wireless network to which first computing devices are connected;the first AP performs time synchronizations with the first computing devices such that the first computing devices are synced with the first AP;the second AP establishes a second wireless network to which second computing devices are connected; andthe second AP performs time synchronizations with the second computing devices such that the second computing devices are synced with the second AP,wherein second computing devices have different local times than the first computing devices.

15. One or more non-transitory computer-readable media storing computer executable instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: performing, by a computing device a first time synchronization with a first access point (AP) with which the computing device is connected;synchronizing a local clock of the computing device with a first clock of the first AP based at least in part on the first time synchronization;determining that the computing device is to synchronize with a second AP;performing a second time synchronization between the computing device and the second AP; andsynchronizing the local clock with a second clock of the second AP such that the local clock, the first clock, and the second clock are time synchronized.

16. The one or more non-transitory computer-readable media of claim 15, wherein determining that the computing device is to synchronize with the second AP comprises: determining a first round trip transmission time between the first AP and the computing device;determining a second round trip transmission time between the second AP and the computing device; anddetermining that the second round trip transmission time is less than the first round trip transmission time.

17. The one or more non-transitory computer-readable media of claim 15, wherein synchronizing the local clock with the second clock comprises: determining a first time at which a time measurement exchange was transmitted by the computing device;determining a second time at which particular time measurement exchange was received at the second AP; andadjusting a time value of the local clock based at least in part on the first time and the second time.

18. The one or more non-transitory computer-readable media of claim 17, wherein the second time is calculated based upon a location mapping of the computing device in a wireless network established at least in part by the second AP.

19. The one or more non-transitory computer-readable media of claim 17, wherein the time measurement exchange is a fine time measurement (“FTM”) exchange in accordance with IEEE 802.1AS timing and synchronization standard.

20. The one or more non-transitory computer-readable media of claim 15, wherein: the first AP establishes a first wireless network to which first computing devices are connected;the first AP performs time synchronizations with the first computing devices such that the first computing devices are synced with the first AP;the second AP establishes a second wireless network to which second computing devices are connected; andthe second AP performs time synchronizations with the second computing devices such that the second computing devices are synced with the second AP,wherein second computing devices have different local times than the first computing devices.