Method and system for media synchronization in QoS-enabled wireless networks

• US 20070025325A1
• Filed: 07/29/2005
• Published: 02/01/2007
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kumar, Rajneesh
• Granted Patent: US 7,486,658 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/286 Time to live
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 21/6437 Real-time Transport Protocol [RTP]
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A method and system directed to negotiating and triggering media stream synchronization at the link layer in a QoS-enabled 802.11 WLAN, or other wireless, network. In one implementation, the present invention allows for improved performance of streaming network applications, such as video conferencing, over wireless links. In one implementation, the present invention also provides an optional mechanism whereby a mobile station can signal a need for on-the-fly throttling, if an application on the mobile detects that there is a need for better synchronization of two streams, such as a lower priority stream to a higher priority stream.

Claims

1. In a QoS-enabled wireless network comprising an access point including a link-layer synchronization mechanism enabled to synchronize corresponding traffic streams, a method for synchronizing a first stream and a second stream, the method comprising:

transmitting, to the access point, a first link-layer QoS request for the first stream; and

transmitting, to the access point,.a second link-layer QoS request for the second stream, wherein the second QoS request identifies the first stream and includes at least one synchronization parameter.

2. The method of claim 1 wherein the at least one synchronization parameter comprises a first threshold value indicating the maximum time a packet in the first stream is allowed to lag behind a corresponding packet in the second stream.

3. The method of claim 2 wherein the at least one synchronization parameter comprises a second threshold value indicating the maximum time a packet in the second stream is allowed to lag behind a corresponding packet in the first stream.

4. The method of claim 2 wherein the at least one synchronization parameter comprises a clock basis indicator.

5. The method of claim 4 wherein the clock basis indicator is one selected from a group consisting of a time stamp appended to packets in the stream, and the arrival time of the packets in the streams at the access point.

6. The method of claim 1 further comprising

monitoring, at a mobile station, synchronization of the first and second streams;

and

conditionally transmitting, to the access point, a throttle trigger identifying either the first or the second stream, wherein the throttle trigger is operative to cause the access point to modulate operation of the link layer mechanism relative to the identified stream.

7. The method of claim 1 wherein the throttle trigger is transmitted if packets in the first stream lag behind corresponding packets in the second stream by a magnitude greater than a threshold value.

8. The method of claim 1 wherein the first link-layer QoS request comprises at least one QoS parameter.

9. The method of claim 1 wherein the second link-layer QoS request comprises at least one QoS parameter.

10. The method of claim 1 wherein the first link-layer QoS request identifies the identifies the second stream and includes at least one synchronization parameter.

11. In a QoS-enabled wireless network comprising an access point including a link layer synchronization mechanism enabled to synchronize corresponding traffic streams, an apparatus for synchronizing a first stream and a second stream, comprising

a wireless network interface;

a processor;

a memory;

a wireless network interface driver-application, stored in the memory, comprising instructions operable to cause the processor and the wireless network interface to

transmit, to the access point, a first link-layer QoS request for the. first stream; and

transmit, to the access point, a second link-layer QoS request for the second stream, wherein the second QoS request identifies the first stream and includes at least one synchronization parameter.

12. The apparatus of claim 11 wherein the at least one synchronization parameter comprises a first threshold value indicating the maximum time a packet in the first stream is allowed to lag behind a corresponding packet in the second stream.

13. The apparatus of claim 12 wherein the at least one synchronization parameter comprises a second threshold value indicating the maximum time a packet in the second stream is allowed to lag behind a corresponding packet in the first stream.

14. The apparatus of claim 12 wherein the at least one synchronization parameter comprises a clock basis indicator.

15. The apparatus of claim 14 wherein the clock basis indicator is one selected from a group consisting of a time stamp appended to packets in the stream, and the arrival time of the packets in the streams at the access point.

16. The apparatus of claim 11 further comprising a client application, stored in the memory, comprising instructions operable to cause the processor to

monitor synchronization of the first and second streams;

and

cause the wireless network interface driver application to transmit, to the access point, a throttle trigger identifying either the first or the second stream, wherein the throttle trigger is operative to cause the access point to modulate operation of the link layer mechanism relative to the identified stream.

17. In a QoS-enabled wireless network comprising an access point including a link layer synchronization mechanism enabled to synchronize corresponding traffic streams, an apparatus for synchronizing a first stream and a second stream, comprising

means for wirelessly communicating with an access point associated with a QoS-enabled wireless network;

for transmitting, to the access point, a first link-layer QoS request for the first stream; and

for transmitting, to the access point, a second link-layer QoS request for the second stream, wherein the second QoS request identifies the first stream and includes at least one synchronization parameter.

18. An apparatus for synchronizing traffic streams over a wireless link, comprising

a wireless network interface for communication with a mobile station;

a processor;

a memory; and

an access point application comprising a link-layer QoS module and a link layer synchronization module, the access point application, physically stored in the memory, comprising instructions operable to cause the processor and the apparatus to

receive a first link-layer QoS request identifying a first stream

receive a second link-layer QoS request identifying a second stream, and including synchronization parameters comprising an identifier corresponding to the first stream, and a synchronization constraint; and

enforce the synchronization constraint on the first and second streams.

19. The apparatus of claim 18 wherein the synchronization constraint comprises a first threshold value indicating the maximum time a packet in the first stream is allowed to lag behind a corresponding packet in the second stream.

20. The apparatus of claim 19 wherein the synchronization constraint further comprises a second threshold value indicating the maximum time a packet in the second stream is allowed to lag behind a corresponding packet in the first stream.

21. The apparatus of claim 18 wherein the synchronization parameters include a clock basis indicator.

22. The apparatus of claim 21 wherein the clock basis indicator is one selected from a group consisting of a time stamp appended to packets in the stream, and the arrival time of the packets in the streams at the access point.

23. The apparatus of claim 18 wherein the access point application further comprises instructions operable to cause the processor and the apparatus to

upon receipt of a throttle trigger identifying either the first or the second stream, modulate operation of the link layer QoS mechanism relative to the identified stream.

24. In a QoS-enabled access point including a link layer synchronization mechanism enabled to synchronize corresponding traffic streams, a method for synchronizing a first stream and a second stream, the method comprising:

receiving, from a mobile station, a first link-layer QoS request identifying a first stream

receiving, from the mobile station, a second link-layer QoS request identifying a second stream, and including synchronization parameters comprising an identifier corresponding to the first stream, and a synchronization constraint; and

enforcing the synchronization constraint on the first and second streams.

25. The method of claim 24 wherein the synchronization constraint comprises a first threshold value indicating the maximum time a packet in the first stream is allowed to lag behind a corresponding packet in the second stream.

26. The method of claim 25 wherein the synchronization constraint further comprises a second threshold value indicating the maximum time a packet in the second stream is allowed to lag behind a corresponding packet in the first stream.

27. The method of claim 24 wherein the synchronization parameters include a clock basis indicator.

28. The method of claim 27 wherein the clock basis indicator is one selected from a group consisting of a time stamp appended to packets in the stream, and the arrival time of the packets in the streams at the access point.

29. The method of claim 24 further comprising

upon receipt of a throttle trigger identifying either the first or the second stream, modulating operation of the link layer QoS mechanism relative to the identified stream.

30. An apparatus for synchronizing traffic streams over a wireless link, comprising

means for communicating with a first network;

means for wirelessly communicating with a mobile station;

for receiving a first link-layer QoS request identifying a first stream;

for receiving a second link-layer QoS request identifying a second stream, and including synchronization parameters comprising an identifier corresponding to the first stream, and a synchronization constraint; and

means for enforcing the synchronization constraint on the first and second streams.