SCALABLE ERROR DETECTION AND CROSS-SESSION TIMING SYNCHRONIZATION FOR PACKET-SWITCHED TRANSMISSION

• US 20090154495A1
• Filed: 09/19/2008
• Published: 06/18/2009
• Est. Priority Date: 09/21/2007
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Ojala, Pasi, Lakaniemi, Ari
• Granted Patent: US 8,570,869 B2
• Time in Patent Office: Days
• US Class Current: 370/469
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/008 where the control data relates to payload of a different packet
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control

Abstract

A system and method for providing improved scalable error detection and cross-timing synchronization for packet-switched transmission. In one embodiment, checksum error detection is applied for the core layer and for enhancement layers of the scalable payload in such a way that dropping one or several enhancement layers from the payload does not change the value of the checksum. Only one checksum is transmitted, e.g., in the payload or in the header of the lower-layer protocol. The transmitter modifies the encoded bit stream in such a manner that the entity in the network deploying the scalable payload and removing layers from the packet does not need to recalculate the checksum placed in the payload or packet header, even when the payload size is changed. A prefix/tail bit field is added in the beginning/end of each enhancement layer to make the checksum check match with the common checksum. In another embodiment, the receiver may check the correctness of each received layer simultaneously and, if desired, utilize data only from correctly received layers.

Claims

1. A method for encoding data into a bitstream, comprising:

encoding a core layer and at least one corresponding enhancement layer into the bitstream; and

encoding a single checksum into the bitstream, the single checksum being applicable for use in performing a check of each corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer.

2. The method of claim 1, wherein the single checksum comprises a cyclic redundancy check checksum.

3. The method of claim 1, wherein the single checksum is encoded in a payload header for the encoded core layer and the at least one corresponding enhancement layer.

4. The method of claim 1, wherein the single checksum is encoded in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer.

5. The method of claim 1, wherein the single checksum is encoded in a payload.

6. The method of claim 1, wherein the single checksum is encoded in a packet header.

7. The method of claim 1, further comprising, before encoding the at least one corresponding enhancement layer, adding an additional field to at least one of the at least one corresponding enhancement layer such that any subsequent check involving a corresponding enhancement layer including the additional field will match the single checksum if no data is missing or in error.

8. The method of claim 7, wherein the additional field is added at the beginning of each corresponding enhancement layer.

9. The method of claim 7, wherein the additional field is added at the end of each corresponding enhancement layer.

10. The method of claim 7, wherein the additional field is encoded in a payload.

11. The method of claim 7, wherein the additional field is encoded in a packet header.

12. The method of claim 7, wherein the additional field is encoded in a payload header.

13. The method of claim 1, wherein the core layer and the at least one corresponding enhancement layer are transmitted to a remote device in a plurality of sessions.

14. A computer program product, embodied in a computer-readable storage medium, comprising computer code configured to perform the processes of claim 1.

15. An apparatus, comprising:

an electronic device configured to;

encode a core layer and at least one corresponding enhancement layer into the bitstream; and

encode a single checksum into the bitstream, the single checksum being applicable for use in performing a check of each corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer.

16. The apparatus of claim 15, wherein the single checksum comprises a cyclic redundancy check checksum.

17. The apparatus of claim 15, wherein the single checksum is encoded in a payload header for the encoded core layer and the at least one corresponding enhancement layer.

18. The apparatus of claim 15, wherein the single checksum is encoded in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer.

19. The apparatus of claim 15, wherein the single checksum is encoded in a payload.

20. The apparatus of claim 15, wherein the single checksum is encoded in a packet header.

21. The apparatus of claim 15, wherein the electronic device is further configured to, before encoding the at least one corresponding enhancement layer, add an additional field to at least one of the at least one corresponding enhancement layer such that any subsequent check involving a corresponding enhancement layer including the additional field will match the single checksum if no data is missing or in error.

22. The apparatus of claim 21, wherein the additional field is added at the beginning of each corresponding enhancement layer.

23. The apparatus of claim 21, wherein the additional field is added at the end of each corresponding enhancement layer.

24. The apparatus of claim 21, wherein the additional field is encoded in a payload.

25. The apparatus of claim 21, wherein the additional field is encoded in a packet header.

26. The apparatus of claim 21, wherein the additional field is encoded in a payload header.

27. The apparatus of claim 15, wherein the core layer and the at least one corresponding enhancement layer are transmitted to a remote device in a plurality of sessions.

28. A method of processing encoded data from a bitstream;

processing a core layer and at least one corresponding enhancement layer from the bitstream;

processing a single checksum from the bitstream; and

performing a check of one of the at least one corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer, using the single checksum, wherein the single checksum is usable regardless of the number of corresponding enhancement layers which are used in the check.

29. The method of claim 28, wherein the single checksum comprises a cyclic redundancy check checksum.

30. The method of claim 28, wherein the single checksum is located in a payload header for the encoded core layer and the at least one corresponding enhancement layer.

31. The method of claim 28, wherein the single checksum is located in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer.

32. The method of claim 28, wherein the single checksum is encoded in a payload.

33. The method of claim 28, wherein the single checksum is encoded in a packet header.

34. The method of claim 28, wherein an additional field has been previously added to at least one of the at least one corresponding enhancement layer such that the check involving the respective enhancement layer will match the single checksum if no data is missing or in error.

35. The method of claim 34, wherein the additional field has been added at the beginning of each corresponding enhancement layer.

36. The method of claim 34, wherein the additional field has been added at the end of each corresponding enhancement layer.

37. The method of claim 34, wherein the additional field is encoded in a payload.

38. The method of claim 34, wherein the additional field is encoded in a packet header.

39. The method of claim 34, wherein the additional field is encoded in a payload header.

40. The method of claim 28, wherein the core layer and the at least one corresponding enhancement layer are received from a remote device in a plurality of sessions, and further comprising:

using the performed check to match the core layer with the at least one corresponding enhancement layer; and

synchronizing the plurality of sessions including the core layer and the at least one corresponding enhancement layer.

41. The method of claim 28, wherein checks are performed simultaneously for each corresponding enhancement layer and the core layer, and further comprising using in a subsequent process only those layers which have been correctly received.

42. A computer program product, embodied in a computer-readable storage medium, comprising computer code configured to perform the processes of claim 28.

43. An apparatus, comprising:

an electronic device configured to;

process a core layer and at least one corresponding enhancement layer from the bitstream;

process a single checksum from the bitstream; and

perform a check of one of the at least one corresponding enhancement layer, either alone or in combination with each lower corresponding enhancement layer and the core layer, using the single checksum, wherein the single checksum is usable regardless of the number of corresponding enhancement layers which are used in the check

44. The apparatus of claim 43, wherein the single checksum comprises a cyclic redundancy check checksum.

45. The apparatus of claim 43, wherein the single checksum is located in a payload header for the encoded core layer and the at least one corresponding enhancement layer.

46. The apparatus of claim 43, wherein the single checksum is located in a header of a lower-layer protocol for the encoded core layer and the at least one corresponding enhancement layer.

47. The apparatus of claim 43, wherein the single checksum is encoded in a payload.

48. The apparatus of claim 43, wherein the single checksum is encoded in a packet header.

49. The apparatus of claim 43, wherein an additional field has been previously added to at least one of the at least one corresponding enhancement layer such that the check involving the respective corresponding enhancement layer will match the single checksum if no data is missing or in error.

50. The apparatus of claim 49, wherein the additional field has been added at the beginning of each corresponding enhancement layer.

51. The apparatus of claim 49, wherein the additional field has been added at the end of each corresponding enhancement layer.

52. The apparatus of claim 49, wherein the additional field is encoded in a payload.

53. The apparatus of claim 49, wherein the additional field is encoded in a packet header.

54. The apparatus of claim 49, wherein the additional field is encoded in a payload header.

55. The apparatus of claim 43, wherein the core layer and the at least one corresponding enhancement layer are received from a remote device in a plurality of sessions, and wherein the electronic device is further configured to:

use the performed check to match the core layer with the at least one corresponding enhancement layer; and

synchronize the plurality of sessions including the core layer and the at least one corresponding enhancement layer.

56. The apparatus of claim 43, wherein checks are performed simultaneously for each corresponding enhancement layer and the core layer, and wherein the electronic device is further configured to use in a subsequent process only those layers which have been correctly received.