Systems and methods for synchronizing timing between wireless networking devices

Patent metadata

Field	Value
Publication number	US-9426763-B2
Application number	US-201414253842-A
Country	US
Kind code	B2
Filing date	Apr 15, 2014
Priority date	Apr 17, 2013
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

Systems and methods are provided for synchronizing a timing of one or more access points in an area. The systems and methods utilize a timestamp frame exchange between the one or more access points based on a timestamp refresh interval that is changed after each timestamp frame exchange is performed.

First claim

What is claimed is:

1. A method for synchronizing a timing of a first device with a second device in communication with the first device, comprising:
moving, by the first device, to a channel associated with the second device when a timestamp refresh interval expires;
transmitting, by the first device, a timestamp request frame from the first device to the second device when the timestamp refresh interval expires;
receiving, by the first device, a timestamp response frame, the timestamp response frame including a time value representative of an internal clock of the second device;
updating, by the first device, a clock of the first device based on the time value in the timestamp response frame;
moving, by the first device, to an original channel after receiving the timestamp response frame; and
selecting, by the first device, a new timestamp refresh interval.

2. The method of claim 1 , wherein the selecting the new timestamp refresh interval comprises randomly selecting the new timestamp refresh interval, wherein the new timestamp refresh interval is based on one of a uniform distribution or an exponential distribution.

3. The method of claim 1 , wherein the first device and the second device comprise wireless access points.

4. The method of claim 1 , wherein the receiving the timestamp response frame comprises receiving a frame including the time value of the internal clock of the second device at a start or end of a symbol that includes a start or end of a timestamp, or at a start or end of the timestamp response frame.

5. The method of claim 1 , wherein the timestamp request frame specifies a bandwidth for transmitting the timestamp response frame.

6. The method of claim 1 , further comprising transmitting an acknowledgment frame after receiving the timestamp response frame.

7. The method of claim 6 , wherein the transmitting the acknowledgment frame comprises transmitting the acknowledgment frame a short interframe space (SIFS) after receiving the timestamp response frame.

8. A method for synchronizing a timing of a first device with a second device in communication with the first device, comprising:
moving, by the first device, to a channel associated with the second device when a timestamp refresh interval expires;
transmitting, by the first device, a timestamp indication frame from the first device to the second device when the timestamp refresh interval expires, the timestamp indication frame including a time value representative of an internal clock of the first device;
receiving, by the first device, an acknowledgment frame from the second device;
moving, by the first device, to an original channel after receiving the acknowledgment frame; and
selecting, by the first device, a new timestamp refresh interval.

9. The method of claim 8 , wherein the selecting the new timestamp refresh interval comprises randomly selecting the new timestamp refresh interval, wherein the new timestamp refresh interval is based on one of a uniform distribution or an exponential distribution.

10. The method of claim 8 , wherein the first device and the second device comprise wireless access points.

11. A wireless access point, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
determine when a timestamp refresh interval expires,
move to a channel associated with a different wireless access point based on the determination that the timestamp refresh interval has expired,
transmit a timestamp request frame when the timestamp refresh interval expires,
receive a timestamp response frame including a time value representative of an internal clock of a different wireless access point in response to the transmitted timestamp request frame,
store the time value,
update a local clock based on the time value in the timestamp response frame,
move to an original channel after receiving the timestamp response frame, and
select a new timestamp refresh interval.

12. The wireless access point of claim 11 , wherein the one or more processors are further configured to randomly select the new timestamp refresh interval, wherein the new timestamp refresh interval is based on one of a uniform distribution or an exponential distribution.

13. The wireless access point of claim 11 , wherein the timestamp request frame specifies a bandwidth for sending the timestamp response frame.

14. The wireless access point of claim 11 , wherein the wireless network interface is further configured to receive the timestamp response frame by receiving a frame including the time value of the internal clock of the different wireless access point at a start or end of a symbol that includes a start or end of a timestamp, or at a start or end of the timestamp response frame.

15. The wireless access point of claim 11 , wherein the wireless network interface is further configured to transmit an acknowledgment frame after receiving the timestamp response frame.

16. The wireless access point of claim 15 , wherein the wireless network interface is configured to transmit the acknowledgment frame by transmitting the acknowledgment frame a short interframe space (SIFS) after receiving the timestamp response frame.

17. A wireless access point, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
determine when a timestamp refresh interval expires,
move to a channel associated with a different wireless access point based on the determination that the timestamp refresh interval has expired,
transmit a timestamp indication frame to the different wireless access point when the timestamp refresh interval expires, the timestamp indication frame including a time value representative of an internal clock of the wireless access point,
receive an acknowledgment frame from the different wireless access point,
move to an original channel after receiving the acknowledgment frame, and
select a new timestamp refresh interval.

18. The wireless access point of claim 17 , wherein the one or more processors are further configured to randomly selecting the new timestamp refresh interval, wherein the new timestamp refresh interval is based on one of a uniform distribution or an exponential distribution.

19. A first device for wireless communication, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
move to a channel associated with a second device when a timestamp refresh interval expires;
transmit a timestamp request frame from the first device to the second device when the timestamp refresh interval expires;
receive, by the first device, a timestamp response frame, the timestamp response frame including a time value representative of an internal clock of the second device;
update a clock of the first device based on the time value in the timestamp response frame;
move to an original channel after receiving the timestamp response frame; and
select a new timestamp refresh interval.

20. A first device for wireless communication, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
move to a channel associated with a second device when a timestamp refresh interval expires;
transmit a timestamp indication frame from the first device to the second device when the timestamp refresh interval expires, the timestamp indication frame including a time value representative of an internal clock of the first device;
receive, by the first device, an acknowledgment frame from the second device;
move to an origi

Assignees

• Qualcomm Inc

Inventors

• Wentink Maarten Menzo
• Van Nee Didier Johannes Richard
• Aldana Carlos Horacio

Classifications

• H04W56/00

  Synchronisation arrangements · CPC title

• H04J3/0667

  Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864) · CPC title

• H04W36/00

  Hand-off or reselection arrangements · CPC title

• H04W56/001 Primary

  Synchronization between nodes · CPC title