Using network time protocol in voice over packet transmission

• US 7,602,815 B2
• Filed: 09/04/2003
• Issued: 10/13/2009
• Est. Priority Date: 09/04/2003
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Sillett, Roderick, Houghton, Philip
• Primary Examiner(s): TIEU, BINH KIEN
• Application Number:
  US10/654,798
• Publication Number:
  US 20050063358A1
• Time in Patent Office: 2,231 Days
• Field of Search: 370298-299, 370/301, 370/304, 370/324, 370/326, 370/350, 370/352, 370/356, 370516-517, 370503-514, 709/208, 709/219, 709/221, 709/228, 709231-232, 709/244, 713/375, 713/400, 713600-601
• US Class Current: 370/506
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• 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 69/28 Timers or timing mechanisms used in protocols

Abstract

One or more methods and systems of effectively transmitting voice and voice band data from one node to another are presented. In one embodiment, the system comprises an NTP time server generating absolute times to computing devices such as residential voice over internet protocol (VoIP) gateways. The NTP time server generates absolute times in response to NTP time requests made by one or more computing devices such as residential VoIP gateways. In one embodiment, the method comprises determining an adequate rate for requesting absolute times from an NTP server, making periodic requests to the NTP server, obtaining the absolute times from the NTP server, and generating an adjustment parameter for use by a computing device such as a residential VoIP gateway.

Claims

1. A method comprising:

requesting absolute time from a server by a first computing device, wherein said server uses a Network Time Protocol (NTP);

receiving said absolute time by said first computing device;

inputting an adjustment parameter derived from said absolute time into a circuitry of said first computing device to synchronize said first computing device to a second computing device, wherein a rate at which said requesting is performed is varied based on a particular synchronization accuracy desired at said first computing device and at said second computing device; and

transmitting time sensitive data from said first computing device to said second computing device.

2. The method of claim 1 wherein said time sensitive data comprises voice.

3. The method of claim 2 wherein said time sensitive data comprises voice band data.

4. The method of claim 3 wherein said voice band data comprises fax data.

5. The method of claim 1 wherein said first and said second computing devices comprise residential voice over IP gateways.

6. The method of claim 1 wherein said circuitry comprises a frequency oscillator.

7. The method of claim 6 wherein said frequency oscillator comprises a numerically controlled oscillator.

8. A method of synchronizing a transmitting computing device to a receiving computing device of a packet switched telecommunication network comprising:

requesting an absolute time from a network time protocol (NTP) server;

receiving said absolute time;

inputting an adjustment parameter into a frequency controlling hardware of said transmitting computing device or said receiving computing device;

storing into said adjustment parameter from a memory of said transmitting computing device or said receiving computing device; and

recalling said adjustment parameter from a memory of said transmitting computing device or said receiving computing device.

9. The method of claim 8 wherein said storing occurs at a rate determined by a user.

10. The method of claim 8 wherein said storing occurs at a rate determined by a variability of the adjustment parameter over time.

11. The method of claim 8 wherein said recalling occurs after power cycling or power shut down.

12. A method of synchronizing a transmitting computing device to a receiving computing device of a packet switched telecommunication network comprising:

requesting an absolute time from a network time protocol (NTP) server;

receiving said absolute time; and

inputting an adjustment parameter into a frequency controlling hardware of said transmitting computing device or said receiving computing device, wherein said frequency controlling hardware comprises a numerically controlled oscillator; and

re-evaluating the rate of said requesting said absolute time from said network time protocol (NTP) server.

13. A method of synchronizing a transmitting computing device to a receiving computing device of a packet switched telecommunication network comprising:

requesting an absolute time from a network time protocol (NTP) server;

receiving said absolute time; and

inputting an adjustment parameter into a frequency controlling hardware of said transmitting computing device or said receiving computing device, said transmitting or receiving computing devices comprising residential voice over IP gateways; and

storing and recalling said adjustment parameter into and from a memory of said transmitting computing device or said receiving computing device.

14. The method of claim 13 wherein said storing occurs at a rate determined by a user.

15. The method of claim 13 wherein said storing occurs at a rate determined by a variability of the adjustment parameter over time.

16. The method of claim 13 wherein said recalling occurs after power cycling or power shut down.

17. A system comprising:

a first computing device comprising;

a first processor; and

a first memory storing a first software, said first processor and said first memory used for running and executing said first software for first requesting a first absolute time from a network time protocol (NTP) server, said first computing device receiving said first absolute time in response to said first requesting; and

wherein a second computing device executes a second software for second requesting a second absolute time from said NTP server, said second computing device receiving said second absolute time in response to said second requesting, resulting in synchronization of said first computing device to said second computing device, said synchronization reducing clock drift between said first computing device and said second computing device such that voice band data transmitted between said first computing device and said second computing device is received with a higher signal to noise ratio, said voice band data transmitted through a packet switched network, said NTP server executing a third software for generating said first and said second absolute times, wherein a first rate at which said first requesting is performed is varied based on a first synchronization accuracy of said first computing device and wherein a second rate at which said second requesting is performed is varied based on a second synchronization accuracy of said second computing device.

18. The system of claim 17 wherein said voice band data comprises fax data.

19. The system of claim 17 wherein said voice band data comprises modem data.

20. The system of claim 17 wherein said voice band data comprises voice.

21. A computing device for transmitting and receiving voice band data, said computing device comprising:

a memory for storing a software;

a processor for executing said software for synchronizing said computing device to a server using a Network Time Protocol (NTP); and

a frequency oscillator for receiving an adjustment parameter from said server for adjusting a phase of said frequency oscillator wherein a rate at which said receiving occurs is varied based on maintaining a particular synchronization accuracy.

22. The computing device of claim 21 wherein said voice band data comprises fax data.

23. The computing device of claim 21 wherein said voice band data comprises modem data.

24. The computing device of claim 21 wherein said voice band data comprises voice.

25. A computing device comprising:

a memory for storing a software program;

a circuitry; and

a processor for executing said software program to perform, at least;

requesting absolute time from a server by said computing device, wherein said server uses a Network Time Protocol (NTP);

receiving said absolute time by said computing device; and

inputting an adjustment parameter derived from said absolute time into a circuitry of said computing device to synchronize said computing device, wherein a rate at which said requesting is performed is varied based on a particular synchronization accuracy desired at said computing device.

26. The computing device of claim 25 wherein said circuitry comprises a frequency oscillator.

27. The computing device of claim 26 wherein said frequency oscillator comprises a numerically controlled oscillator.

28. A method of synchronizing a computing device in a packet switched telecommunication network comprising:

requesting an absolute time from a server using a Network Time Protocol (NTP);

receiving said absolute time;

inputting an adjustment parameter into a frequency controlling hardware of a frequency oscillator of said computing device to adjust a phase of said frequency oscillator; and

storing and recalling said adjustment parameter into and from a memory of said computing device.

29. The method of claim 28 wherein said computing device comprises a residential voice over IP gateway.

30. The method of claim 28 wherein said storing occurs at a rate determined by a user.

31. The method of claim 28 wherein said storing occurs at a rate determined by a variability of the adjustment parameter over time.

32. The method of claim 28 wherein said recalling occurs after power cycling or power shut down.

33. The method of claim 28 wherein said frequency oscillator comprises a numerically controlled oscillator.