SYSTEMS AND METHODS FOR TIME SYNCHRONIZATION

• US 20140085136A1
• Filed: 09/25/2012
• Published: 03/27/2014
• Est. Priority Date: 09/25/2012
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Alpert, Yaron, Rochberger, Haim
• Granted Patent: US 9,651,672 B2
• Time in Patent Office: Days
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/005 compensating for timing error by adjustment in the receiver
• CPC Class Codes: H04W 56/0075 based on arrival time vs. expected arrival time

Abstract

A method and system for time synchronization in a mobile device are disclosed. The method includes negotiating a synchronization schedule. The synchronization schedule defines a plurality of synchronization times for receiving synchronization messages. The method further includes transitioning the mobile device from a first state to a second state to receive a synchronization message. The mobile device uses less power in the first state than the second state and the mobile device cannot receive the synchronization message when in the first state. The method further includes synchronizing a clock component in response to receiving the synchronization message.

Claims

1. A method for time synchronization in a mobile device, the method comprising:

negotiating a synchronization schedule, the synchronization schedule defining a plurality of synchronization times for receiving synchronization messages;

transitioning the mobile device from a first state to a second state to receive a synchronization message of the synchronization messages, wherein the mobile device uses less power in the first state than the second state and wherein the mobile device cannot receive the synchronization message when in the first state; and

synchronizing a clock component in response to receiving the synchronization message.

2. The method of claim 1, wherein the synchronization schedule comprises a schedule expiration and wherein no synchronization request message is sent by the mobile device between negotiation and the schedule expiration.

3. The method of claim 1, wherein the synchronization message is received from a radio access network.

4. The method of claim 3, wherein the radio access network comprises a portion of a mobile data network.

5. The method of claim 1, wherein negotiating the synchronization schedules comprises:

suggesting the synchronization schedule to a synchronization component; and

receiving an indication that the synchronization schedule is accepted.

6. The method of claim 1, further comprising determining a time synchronization schedule.

7. The method of claim 6, wherein determining comprises determining a time synchronization schedule based on use requirements of a mobile device.

8. The method of claim 1, wherein a time of the plurality of times comprises a time window, wherein transitioning comprises transitioning from the first state to the second state for at least the length of the time window.

9. The method of claim 1, further comprising determining that time synchronization will be needed.

10. The method of claim 9, wherein negotiating comprises negotiating in response to determining that time synchronization will be needed.

11. The method of claim 9, wherein determining comprises determining that the mobile device will be entering the first state.

12. The method of claim 1, further comprising determining one or more times at which synchronization will be needed.

13. The method of claim 1, further comprising determining that time synchronization will no longer be needed.

14. The method of claim 13, further comprising notifying a synchronization server that the synchronization schedule is no longer needed.

15. The method of claim 13, wherein determining comprises determining that the mobile device is too busy to enter the first state.

16. A mobile device for user communication, the mobile device comprising:

a clock configured to keep time;

a receiver configured to receive wireless signals;

a state component to periodically wake the mobile device at predetermined times to receive clock correction signals through the receiver;

an update component to update the clock based on the received clock correction signals to correct for clock drift; and

a location component to acquire a location signal, wherein the time required to acquire the location signal is reduced based on an accuracy of the clock.

17. The mobile device of claim 16, wherein the state component is configured to wake the mobile device by transitioning the receiver from a sleep state to an awake state.

18. The mobile device of claim 16, wherein the state component is configured to wake the mobile device by transitioning a software process from an idle state to an active state.

19. The mobile device of claim 16, wherein the location component comprises a global positioning component that obtains a global positioning location in response to the update component updating the clock.

20. The mobile device of claim 19, wherein the global positioning component provides location information corresponding to the global positioning location to a client component.

21. The mobile device of claim 20, wherein the state component transitions the mobile device to a sleep state in response to the global positioning component providing the location information to the client component.

22. The mobile device of claim 21, wherein the client component comprises an application running on the mobile device.

23. A computer-readable storage medium comprising program code to perform a method for efficient time synchronization, the method comprising:

negotiating a synchronization schedule, the synchronization schedule defining a plurality of synchronization times for receiving synchronization messages, wherein the synchronization schedule comprises a schedule expiration; and

receiving the synchronization messages at the plurality of synchronization times, wherein no synchronization request message is sent by the mobile device between negotiation and the schedule expiration.

24. The computer-readable storage medium of claim 23, the method further comprising sending a notification that synchronization is no longer needed.

25. A method for time synchronization, the method comprising:

negotiating a synchronization schedule with a mobile device, the synchronization schedule defining a plurality of times for sending a synchronization message; and

sending a synchronization message at each of the plurality of times.

26. The method of claim 25, wherein the synchronization schedule comprises a schedule expiration.

27. The method of claim 26, further comprising recycling the synchronization schedule at the schedule expiration.

28. The method of claim 27, wherein recycling comprises using a time-shifted version of the synchronization schedule to send the synchronization messages.