Method and Arrangement For Harq in Wireless Multi-Carrier Systems

• US 20090013232A1
• Filed: 12/30/2005
• Published: 01/08/2009
• Est. Priority Date: 12/30/2005
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cheng, Jung-Fu, Wan, Lei
• Granted Patent: US 8,205,127 B2
• Time in Patent Office: Days
• US Class Current: 714/748
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1816 with retransmission of the same, encoded, message
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements

Abstract

The present invention relates to automatic repeat request (ARQ) in wireless communication systems wherein a coded message block is spread over a plurality of sub-carriers or components. According to the invention an equalizing HARQ method is introduced. The equalizing HARQ identifies (215) and retransmits (230) the most distorted parts of a received coded message block. In addition, the retransmitted parts can optionally be relocated (225) to components of higher quality, which ensures good retransmission quality for those badly distorted parts in the prior transmission. After a soft-bit combination in a receiving node, the final received codeword experience an equalized quality variation with low multi-state performance loss.

Claims

1. A method of communication in a wireless communication system between a sending node and a receiving node, wherein the communication comprises the sending node transmitting to the receiving node a first coded message block comprising a plurality of parts distributed over a plurality of components, the method characterised by the steps of:

identifying (215) that the received first coded message block could not be correctly decoded, and identifying at least one part of the first coded message which has probably contributed to decoding error, and the component associated to said part;

the receiving node feeding back (220) to the sending node at least an indication that the first coded message block could not be correctly decoded; and

the sending node retransmitting (230) selected parts of the first coded message block in a second coded message block to the receiving node.

2. The communication method according to claim 1, wherein the identifying step comprises determining quality indicators for a plurality of the components used for the transmission of the first coded message block.

3. The communication method according to claim 2, wherein a part of the first coded message block is identified as a part that requires retransmission if the quality indicator of the component associated with that part is below a quality threshold value.

4. The communication method according to claim 2 or 3, wherein the quality indicators are at least partly based on quality measurements performed on the first coded message block or the radio signal associated with the first coded message block.

5. The communication method according to claim 3 or 4, wherein the quality indicators are at least partly based on SINR measurements.

6. The communication method according to claim 3 or 4, wherein the quality indicators are at least partly based on symbol information rates.

7. The communication method according to claim 2 or 3, wherein the quality indicators are at least partly based on channel quality predictions.

8. The communication method according to any of claims 2 to 7, wherein the step of identifying a decoding error (210) comprises error detection coding and the use of cyclic redundancy check bits.

9. The communication method according to any of claims 2 to 7, wherein in the step of identifying a decoding error (210) comprises the use of early stopping methods.

10. The communication method according to any of claims 2 to 9, further comprising a step of determining retransmission settings (225), said determining comprising one of, or a combination of:

component selection, link adaptation, power control and scheduling.

11. The communication method according to claim 10, wherein the link adaptation is based on link adaptation parameters provided in the feedback from the receiving node.

12. The communication method according to claim 11, wherein a change in link adaptation is initiated if one or more of the link adaptation parameters are below corresponding threshold values.

13. The communication method according to claim 10, wherein new coded bits that were not comprised in the first coded message block are added to the second coded message block.

14. The communication method according to any of claims 1 to 13, further comprising a step of combining (235) information from the first coded message block and the second coded message block to facilitate the decoding of the first coded message block.

15. The communication method according to claim 14, wherein the combining is a soft-bit combining.

16. The communication method according to claim 15, wherein the soft-bit combining is selective and the selection of soft-bits of the first coded message block to be excluded from the combining, is based on the quality indicators of their associated components.

17. The communication method according to claim 16, wherein the soft-bits to be excluded are identified as soft-bits with their associated components having quality indicators below an exclusion threshold value.

18. The communication method according to any of claims 1 to 17, wherein the wireless communication system utilizes orthogonal frequency division multiplexing as the radio access technique.

19. A communication method in a sending node in a wireless communication system, the sending node engaged in communication with a receiving node, wherein the communication comprises the sending node transmitting to the receiving node a first coded message block comprising a plurality of parts distributed over a plurality of components, the method characterised by the sending node retransmitting (230) selected parts of the first coded message block in a second coded message block to the receiving node, whereby the retransmission is initiated upon reception of a feedback from the receiving node at least indicating that the first coded message block could not be decoded.

20. The communication method according to claim 19, wherein the feedback from the receiving node comprises explicit repeat request information identifying parts of the first coded message block that require retransmission.

21. The communication method according to claim 19, further comprising an identifying step (215:

a) identifying which parts of the first coded message block that require retransmission, wherein the identification at least partly is based on quality indicators for a plurality of the components used for the transmission of the first coded message block, and said quality indicators determined in a sending node and provided to the sending node by the feedback.

22. The communication method according to claim 21, wherein a part of the first coded message block is identified as a part that requires retransmission if the quality indicator of the component associated to that part is below a quality threshold value.

23. The communication method according to claim 22, wherein the quality threshold value is a pre-determined value.

24. The communication method according to claim 22, wherein the quality threshold value is a dynamic value determined by the sending node.

25. The communication method according to claim 24, wherein the quality threshold value is determined based on information that has been provided the sending node in the feedback.

26. The communication method according to claim 25, wherein the sending node transfer information of the quality threshold value to the receiving node, which whereby can correctly interpret the second coded message block.

27. The communication method according to any of claims 21 to 26, wherein the quality indicators are at least partly based on quality measurements performed on the first coded message block or the radio signal associated with the first coded message block.

28. The communication method according to claim 27, wherein the quality indicators are at least partly based on SINR measurements.

29. The communication method according to claim 27, wherein the quality indicators are at least partly based on symbol information rates.

30. The communication method according to claim 19, further comprising an identifying step (215:

b) identifying which parts of the first coded message block that require retransmission, wherein the identification at least partly is based on quality indicators for a plurality of the components used for the transmission of the first coded message block, and wherein said quality indicators are at least partly based on channel quality predictions.

31. The communication method according to any of claims 19 to 30, further comprising a step of determining retransmission settings (225), said determining comprising one of, or a combination of:

component selection, link adaptation, power control and scheduling.

32. The communication method according to claim 31, wherein the link adaptation is based on link adaptation parameters provided in the feedback from the receiving node.

33. The communication method according to claim 31, wherein the link adaptation is based on predicted link adaptation parameters.

34. The communication method according to claim 32 or 33, wherein a change in link adaptation is initiated if one or more of the link adaptation parameters are below corresponding threshold values.

35. The communication method according to claim 31, wherein new coded bits that were not comprised in the first coded message block are added to the second coded message block.

36. A communication method in a receiving node in a wireless communication system, the receiving node engaged in communication with a sending node, wherein the communication comprises the receiving node receiving from the sending node, a first coded message block comprising a plurality of parts distributed over a plurality of components, the method characterised by the steps of:

identifying (215) that the received first coded message block could not be correctly decoded;

determining (215;

a) at least one part of the first coded message block that should be retransmitted in a second message block in order to facilitate the decoding of the first coded message block; and

feeding back (220) to the sending node at least an indication that the first coded message block could not be correctly decoded, and an indication of which of the at least one part of the first coded message block that should be retransmitted.

37. The communication method according to claim 36, wherein the feedback from the receiving node comprises explicit repeat request information identifying parts of the first coded message block that require retransmission.

38. The communication method according to claim 37, wherein the quality indicators are at least partly based on quality measurements performed on the first coded message block or the radio signal associated with the first coded message block.

39. The communication method according to claim 38, wherein the quality indicators are at least partly based on SINR measurements.

40. The communication method according to claim 38, wherein the quality indicators are at least partly based on symbol information rates.

41. The communication method according to any of claims 38 to 40, wherein a part of the first coded message block is identified as a part that requires retransmission if the quality indicator of the component associated to that part is below a quality threshold value.

42. The communication method according to any of claims 36 to 40, further comprising a step of determining suggested retransmission settings, the suggested retransmission settings being comprised in the feedback to the sending node, said determining comprising one of, or a combination of:

component selection, link adaptation and power control.

43. The communication method according to claim 42, wherein a quality threshold value is included in the feedback to the sending node.

44. The communication method according to claim 42 or 43, wherein a change in link adaptation is suggested if one or more of the link adaptation parameters are below corresponding threshold values.

45. The communication method according to any of claims 36 to 44, further comprising a step of combining (235) information from the first coded message block and the second coded message block to facilitate the decoding of the first coded message block.

46. The communication method according to claim 45, wherein the combining is a soft-bit combining.

47. The communication method according to claim 46, wherein the soft-bit combining is selective and the selection of soft-bits of the first coded message block to be excluded from the combining, is based on the quality indicators of their associated components.

48. The communication method according to claim 47, wherein the soft-bits to be excluded are identified as soft-bits with their associated components having quality indicators below an exclusion threshold value.

49. The communication method according to any of claims 36 to 48, wherein the identification (215) that the received first coded message block could not be correctly decoded is based on error detection decoding.

50. The communication method according to any of claims 36 to 48, wherein the identification (215) that the received first coded message block could not be correctly decoded is based on cyclic redundancy check bits.

51. The communication method according to any of claims 36 to 48, wherein the identification (215) that the received first coded message block could not be correctly decoded is based on early stopping methods for iterative decoders.

52. A sending node adapted for use in a communication system, wherein the sending node is adapted for communication with at least a receiving node, and in the communication the sending node transmits to the receiving node coded message blocks comprising a plurality of parts distributed over a plurality of components, wherein the sending node comprising radio communication means (605) and is characterised by:

a feedback reception module (610), adapted to receive feedback information from a receiving node, said feedback indicating if a coded message block was received in error;

a retransmission settings module (615) in connection with the feedback reception module (610) and adapted to determine which of the parts of a message block that should be retransmitted based at least partly on feedback provided from the feedback reception module (610).

53. The sending node according to claim 52, wherein the feedback module (610) is further adapted to receive quality indicators associated with the components, and the retransmission settings module (615) is adapted to base the determination of retransmitting settings on quality indicators provided by the feedback module (610).

54. The sending node according to claim 52 or 53, wherein the retransmission settings module (615) further comprises, or is in connection with, a link adaptation module (630), adapted to determine link adaptation parameters suitable for a retransmission.

55. The sending node according to claim 52 or 54, wherein the retransmission settings module (615) further comprises, or is in connection with, a channel quality measurements module (620), adapted to determine component quality indicators based on channel predictions.

56. A receiving node adapted for use in a communication system, wherein the receiving node is adapted for communication with at least a sending node, and in the communication the sending node transmits to the receiving node coded message blocks comprising a plurality of parts distributed over a plurality of components, wherein the receiving node comprising radio communication means (605) and is characterised by:

a decoding module (665) in connection with the radio communication means (655), the decoding module (665) being adapted to provide an error indication if a received coded message block could not be decoded;

a quality measurement module (675) adapted to provide quality indicators for each component;

a feedback module (670) in connection with the decoding module (665) and the quality measurement module (675), adapted to feed back to a sending node quality indicators provided from the quality measurement module (675) upon receiving an indication of a decoding error from the decoding module (665).

57. The receiving node according to claim 56, wherein the quality measurement module (675) is further adapted to identify parts of a coded message block that require retransmission, and the feedback module (670) is adapted to provide explicit repeat request information based on parts identified by the quality measurement module (675).

58. The receiving node according to claim 57, wherein the quality measurement module (675) is further adapted to identify parts of a coded message block that require retransmission by comparing quality measurements of components with a quality threshold value.