Method and system for synchronizing platform clocks in a distributed wireless platform

• US 7,356,618 B2
• Filed: 12/31/2003
• Issued: 04/08/2008
• Est. Priority Date: 12/31/2003
• Status: Active Grant

• Current Assignee: Beijing Xiaomi Mobile Software Co., Ltd. (Xiaomi Corp.)
• Original Assignee: Intel Corporation
• Inventors: Egorychev, Sergey A., Chikalov, Igor V., Budnikov, Dmitry N., Kozintsev, Igor V., Lienhart, Rainer W.
• Primary Examiner(s): WON, MICHAEL YOUNG
• Application Number:
  US10/749,989
• Publication Number:
  US 20050228902A1
• Time in Patent Office: 1,560 Days
• Field of Search: 709/221, 709/248, 709/201, 713/375, 713/400, 342/31, 342/385, 348/423.1, 348/425.4, 348/500, 370/503, 370507-514, 370/516, 370/519, 370/520
• US Class Current: 709/248
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators

Abstract

According to one embodiment of the present invention, a novel method and system are disclosed. In one embodiment, a first node records a first node local time of receiving a wirelessly transmitted packet, the first node local time recorded with a monotonically increasing clock of the first node. The first node wirelessly transmits the recorded local time to at least a second node. The second node records a second node local time of receiving the wirelessly transmitted packet and records the first node local time of receiving the wirelessly transmitted packet. The second node updates a second node timing model to synchronize with the first node, the updating based on the second node local time of receiving the wirelessly transmitted packet and the first node local time of receiving the wirelessly transmitted packet. In one embodiment, the method and system further include synchronizing sample numbers of a multimedia stream on the second node with the timing model of the second node, the timing model of the second node having been synchronized with the first node.

Claims

1. A method comprising:

recording a first node local time of receiving a wirelessly transmitted packet at a first node, the first node local time recorded with a monotonically increasing clock of the first node;

recording a second node local time of receiving the wirelessly transmitted packet at a second node, the second node local time recorded with a monotonically increasing clock of the second node;

wirelessly transmitting the first node recorded local time by the first node to at least the second node;

receiving the first node recorded local time at the second node and recording the first node local time of receiving the wirelessly transmitted packet;

synchronizing a second node timing model with a first node timing model, wherein the first and second node timing models are updated at predetermined speeds to provide controlled time interval length adaptation; and

synchronizing the first and second node timing models with a global clock associated with the first node and the second node.

2. The method of claim 1, wherein the wirelessly transmitted packet comprises a beacon transmitted from a wireless access point.

3. The method of claim 1, further including:

synchronizing sample numbers of a multimedia stream on the second node with the second node timing model, the second node timing model having been synchronized with the first node.

4. The method of claim 3, wherein the synchronization of sample numbers in I/O operations is performed by time-stamping IRQs (interrupt reguests) with a global time according to the global clock.

5. The method of claim 1, further including repeating the method of claim 1 to generate an updated second node timing model to synchronize with the first node timing model.

6. The method of claim 1, further including:

recording a third node local time of receiving the wirelessly transmitted packet from the first node at a third node and recording the first node local time of receiving the wirelessly transmitted packet; and

synchronizing a third node timing model with the first node timing model and the second node timing model, and further synchronizing the first, second and third node timing models with the global clock associated with the first node, the second node, and the third node.

7. A machine-readable medium having stored thereon sets of instructions which when executed by a machine cause the machine to:

record a first node local time of receiving a wirelessly transmitted packet at a first node, the first node local time recorded with a monotonically increasing clock of the first node;

record a second node local time of receiving the wirelessly transmitted packet at the second node, the second node local time recorded with a monotonically increasing clock of the second node;

wirelessly transmit the first node recorded local time by the first node to at least a second node;

receive the first node recorded local time at the second node and record the first node local time of receiving the wirelessly transmitted packet;

synchronize a second node timing model with a first node timing model, wherein the first and second node timing models are updated at predetermined speeds to provide controlled time interval length adaptation; and

synchronize the first and second node timing models with a global clock associated with the first node and the second node.

8. The machine-readable medium of claim 7, wherein the wirelessly transmitted packet comprises a beacon transmitted from a wireless access point.

9. The machine-readable medium of claim 7, wherein the sets of instructions when executed further cause the machine to:

synchronize sample numbers of a multimedia stream on the second node with the second node timing model, the second node timing model having been synchronized with the first node.

10. The machine-readable medium of claim 9, wherein the synchronization of sample numbers in I/O operations is performed by time-stamping IRQs (interrupt reguests) with a global time according to the global clock.

11. The machine-readable medium of claim 7, wherein the sets of instructions when executed further cause the machine to:

record a third node local time of receiving the wirelessly transmitted packet from the first node at a third node and recording the first node local time of receiving the wirelessly transmitted packet; and

synchronize a third node timing model with the first node timing model and the second node timing model, and further synchronize the first, second and third node timing models with the global clock associated with the first node, the second node, and the third node.

12. A system comprising:

a first node to record a first node local time of receiving a wirelessly transmitted packet, the first node local time recorded with a monotonically increasing clock of the first node;

a second node to record a second node local time of receiving the wirelessly transmitted packet at the second node, the second node local time recorded with a monotonically increasing clock of the second node;

the first node to wirelessly transmit the first node recorded local time to at least the second node;

the second node to receive the first node recorded local time and record the first node local time of receiving the wirelessly transmitted packet; and

the second node to synchronize a second node timing model with a first node timing model, wherein the first and second node timing models are updated at predetermined speeds to provide controlled time interval length adaptation, and synchronize the first and second node timing models with a global clock associated with the first node and the second node.

13. The system of claim 12, wherein the wirelessly transmitted packet comprises a beacon transmitted from a wireless access point.

14. The system of claim 13, wherein the second node is further to:

synchronize sample numbers of a multimedia stream on the second node with the second node timing model, the second node timing model having been synchronized with the first node.

15. The system of claim 14, wherein the synchronization of sample numbers in I/O operations is performed by time-stamping IRQs (interrupt recquests) with a global time according to the global clock.

16. The system of claim 13, further including:

a third node to record a third node local time of receiving the wirelessly transmitted packet from the first node and record the first node local time of receiving the wirelessly transmitted packet; and

the third node to synchronize a third node timing model with the first node timing model and the second node timing model, and further to synchronize the first, second, and third node timing models with the global clock associated with the first node, the second node, and the third node.