Architecture for obtaining playback time from a packet sequence number in AAL2 SSCS voice

• US 20040001494A1
• Filed: 07/01/2002
• Published: 01/01/2004
• Est. Priority Date: 07/01/2002
• Status: Abandoned Application

• Current Assignee: Zarlink Semiconductor VN Inc (Microchip Technology Incorporated)
• Original Assignee: Zarlink Semiconductor VN Inc (Microchip Technology Incorporated)
• Inventors: Yik, James, Barrack, Craig I.
• Application Number:
  US10/186,438
• Publication Number:
  US 20040001494A1
• Time in Patent Office: Days
• US Class Current: 370/395.61
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/565 Sequence integrity
• CPC Class Codes: H04L 2012/5656 using the AAL2
• CPC Class Codes: H04L 2012/5671 Support of voice
• CPC Class Codes: H04L 47/50 Queue scheduling

Abstract

Architecture for generating a playback time from a AAL2 SSCS voice packet sequence number in a stream-based application. The architecture comprises an event scheduler engine for initiating control parameters for an interpretive window associated with a packet stream; a sliding window engine for controlling the interpretive window according to the control parameters; and an arrival engine that maps the packet sequence number to an expected playback time in accordance with an association created between the packet sequence number and the expected playback time by the interpretive window.

Claims

1. A method of generating a playback time from a packet, comprising the steps of:

inputting a packet sequence number of the packet into a mapping module, which packet is associated with an arrival time; and

mapping the packet sequence number to expected playback time data utilizing the mapping module, which mapping is based upon an interpretive window, and which expected playback time data is associated with the arrival time.

2. The method of claim 1, wherein the packet in the step of inputting is utilized in an AAL2/SSCS voice architecture.

3. The method of claim 1, wherein the arrival time is a local time that is recorded when the packet was received into the mapping module in the step of inputting.

4. The method of claim 1, wherein the packet sequence number is no more than four bits resolution and the expected playback time data in the step of mapping is more than four bits resolution.

5. The method of claim 1, wherein the packet in the step of inputting has a payload that is different in size from the payload of a subsequent packet received in the step of inputting.

6. The method of claim 1, wherein the packet sequence number in the step of mapping is mapped to one arrival window in a series of arrival windows, which one arrival window corresponds to the expected playback time data, and which each arrival window in the series of arrival windows define a unique range of the arrival times.

7. The method of claim 6, wherein the packet sequence number is utilized to determine which one series of a plurality of series of the arrival windows is selected to obtain the expected playback time data.

8. The method of claim 6, wherein the unique range of arrival times of the arrival window is further defined as a plurality of packet payload times, which packet payload time is a time associated with the size of a payload of the packet.

9. The method of claim 6, wherein a local clock steps the interpretive window through the plurality of series of arrival windows to provide the association between the packet sequence number and the expected playback time data.

10. The method of claim 1, wherein the mapping module in the step of mapping accesses a database, which database includes mapping parameters that are updated according to a location of the interpretive window and associated packet sequence number information.

11. The method of claim 10, wherein the mapping module includes a database request manager that arbitrates access to the database so that a first read-write operation of the database is completed before a second read-write operation of the database is allowed.

12. The method of claim 10, wherein when the packet arrives, the mapping module in the step of mapping accesses the database for the status of the interpretive window, and either discards the packet or determines the expected playback time data based upon the mapping parameters associated with the interpretive window.

13. The method of claim 1, wherein the expected playback time data in the step of mapping includes a translation factor, which translation factor is additive and, includes at least one of a programmable playback delay and a clock differential between a remote clock and a local clock.

14. The method of claim 1, wherein the mapping module in the step of mapping includes a scheduler that triggers for playback one or more packet streams in a time-indexed data structure, which the one or more packet streams are each associated with a respective time index, and which only the one or more packet streams having the associated time index that matches the current time, are played back.

15. The method of claim 14, wherein the time-indexed data structure associates to the time index at least one of a next event, payload size, a next event time index, and a previous event.

16. The method of claim 1, wherein the step of mapping further includes the steps of determining if a change in the size of a payload of the packet has occurred, and in response to a changed payload size,

adjusting translation information utilized to translate the packet sequence number to the expected playback time data;

and

interrupting a scheduler to adjust a frequency at which the interpretive window shifts.

17. The method of claim 16, wherein the changed payload size in the step of detecting is detected by at least one of an arrival engine and a sliding window engine.

18. The method of claim 16, wherein when the packet with the changed payload size arrives substantially in the middle of an associated arrival window, a next event time is queued by the scheduler, which next event time is defined as a current time plus a payload time that is associated with the changed payload size.

19. The method of claim 16, wherein when the packet with the changed payload size arrives either substantially late in an associated arrival window or outside the associated arrival window, the scheduler in the step of interrupting dequeues an event associated with an old payload size, and requeues an event associated with the changed payload size such that the frequency of the interpretive window is adjusted.

20. A method of generating a playback time from a packet sequence number, comprising the steps of:

inputting a packet sequence number of the packet into a mapping module, which packet is associated with an arrival time;

determining if a change in the size of a payload of the packet has occurred; and

mapping the packet sequence number to expected playback time data utilizing the mapping module, which mapping is based upon an interpretive window, and which expected playback time data is associated with the arrival time.

21. The method of claim 20, wherein in response to a change in payload size in the step of determining, performing the further steps of:

adjusting translation information utilized to translate the packet sequence number to the expected playback time data; and

interrupting a scheduler to adjust a frequency at which the interpretive window shifts.

22. The method of claim 20, wherein the step of mapping further comprises the steps of:

providing a series of arrival windows associated with the packet sequence number, which series of arrival windows includes one arrival window that corresponds to the expected playback time data, and which each arrival window in the series of arrival windows defines a unique range of the arrival times, and

clocking the interpretive window through the series of arrival windows to define the association between the packet sequence number and the expected playback time data.

23. The method of claim 20, wherein the packet in the step of inputting conforms to an AAL2/SSCS architecture and the expected playback time data of the packet is of a higher resolution than the packet sequence number.

24. Architecture for generating a playback time from a packet, comprising:

a processing system for receiving the packet, and extracting a packet sequence number therefrom, which packet has an associated arrival time; and

a mapping module for mapping the packet sequence number to expected playback time data, which mapping is based upon an interpretive window, and which expected playback time data is associated with the arrival time.

25. The architecture of claim 24, wherein the packet is utilized in an AAL2/SSCS voice architecture.

26. The architecture of claim 24, wherein the arrival time is a local time that is recorded when the packet was received into the mapping module.

27. The architecture of claim 24, wherein the packet sequence number is no more than four bits resolution and the expected playback time data is more than four bits resolution.

28. The architecture of claim 24, wherein the packet has a payload different in size from a payload of a subsequent packet received.

29. The architecture of claim 24, wherein the packet sequence number is mapped to one arrival window in a series of arrival windows, which one arrival window corresponds to the expected playback time data, and which each arrival window in the series of arrival windows defines a unique range of the arrival times.

30. The architecture of claim 29, wherein the packet sequence number is utilized to determine which one series of a plurality of series of the arrival windows is selected to obtain the expected playback time data.

31. The architecture of claim 29, wherein the unique range of arrival times of the arrival window is further defined as a plurality of packet payload times, which packet payload time is a time associated with the size of a payload of the packet.

32. The architecture of claim 29, wherein a local clock steps the interpretive window through the plurality of series of arrival windows to provide the association between the packet sequence number and the expected playback time data.

33. The architecture of claim 24, wherein the mapping module accesses a database, which database includes mapping parameters that are updated according to a location of the interpretive window and associated packet sequence number information.

34. The architecture of claim 33, wherein the mapping module includes a database request manager that arbitrates access to the database so that a first read-write operation of the database is completed before a second read-write operation of the database is allowed.

35. The architecture of claim 33, wherein when the packet arrives, the mapping module accesses the database for a status of the interpretive window, and either discards the packet or determines the expected playback time data based upon the mapping parameters associated with the interpretive window.

36. The architecture of claim 24, wherein the expected playback time data includes a translation factor, which translation factor is additive and, includes at least one of a programmable playback delay and a clock differential between a remote clock and a local clock.

37. The architecture of claim 24, wherein the mapping module includes a scheduler that triggers for playback one or more packet streams in a time-indexed data structure, which the one or more packet streams are each associated with a respective time index, and which only the one or more packet streams having the associated time index that matches the current time, are played back.

38. The architecture of claim 37, wherein the time-indexed data structure associates to the time index at least one of a next event, payload size, a next event time index, and a previous event.

39. The architecture of claim 24, wherein the mapping module determines if a change in the size of a payload of the packet has occurred, and in response to a changed payload size, adjusts translation information utilized to translate the packet sequence number to the expected playback time data, and interrupts a scheduler engine to adjust a frequency at which the interpretive window shifts.

40. The architecture of claim 39, wherein the changed payload size is detected by at least one of an arrival engine and a sliding window engine.

41. The architecture of claim 39, wherein when the packet with the changed payload size arrives substantially in the middle of an associated arrival window, a next event time is queued by the scheduler, which next event time is defined as a current time plus a payload time that is associated with the changed payload size.

42. The architecture of claim 39, wherein when the packet with the changed payload size arrives either substantially late in an associated arrival window or outside the associated arrival window, the scheduler engine dequeues an event associated with an old payload size, and requeues an event associated with the changed payload size such that the frequency of the interpretive window is adjusted.

43. Architecture for generating a playback time from a packet sequence number of a packet in a stream-based application, comprising:

an event scheduler engine for initiating control parameters for an interpretive window associated with a packet stream;

a sliding window engine for controlling the interpretive window according to the control parameters; and

an arrival engine that maps the packet sequence number to an expected playback time in accordance with an association created between the packet sequence number and the expected playback time by the interpretive window.

44. The architecture of claim 43, wherein at least one of the sliding window engine and the arrival engine signals the event scheduler engine when a change in the payload size of the packet is detected.

45. The architecture of claim 44, wherein in response to detected change in payload size, translation information utilized to translate the packet sequence number to the expected playback time data is adjusted, and the signaled event scheduler engine adjusts a frequency at which the interpretive window shifts.

46. The architecture of claim 43, wherein a series of arrival windows are generated in association with the packet sequence number, which series of arrival windows includes one arrival window that corresponds to the expected playback time, and which each arrival window in the series of arrival windows defines a unique range of the arrival times.

47. The architecture of claim 43, wherein the packet conforms to an AAL2/SSCS architecture and the expected playback time of the packet is of a higher resolution than the packet sequence number.

48. The architecture of claim 43, further comprising a database request manager that arbitrates access to a database of mapping parameters to update the mapping parameters, which database request manager that arbitrates so that a first read-write operation of the database is completed before a second read-write operation of the database is allowed.

49. The architecture of claim 48, wherein both the arrival engine and the sliding window engine access the database to update the mapping parameters according to the packet sequence number and a location of the interpretive window.