LOW COMPLEXITY SCMA/LDS DETECTION SYSTEMS AND METHODS

• US 20160254937A1
• Filed: 02/27/2015
• Published: 09/01/2016
• Est. Priority Date: 02/27/2015
• Status: Abandoned Application

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Bayesteh, Alireza, Nikopour, Hosein, Baligh, Mohammadhadi, Taherzadehboroujeni, Mahmoud
• Application Number:
  US14/633,965
• Publication Number:
  US 20160254937A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0055 MAP-decoding

Abstract

Systems and methods of low complexity SCMA/LDS detection are disclosed by performing a detection algorithm such as a Message Passing Algorithm (MPA) in a receiver only over selective sub-graphs of a corresponding full factor graph representative of multiplexed codes for the multiple access code system.

Claims

1. In a receiver, a method of low complexity multiple access code detection comprising:

receiving a signal over an antenna, the signal containing data multiplexed over a set of subcarriers according to a multiple access code system; and

decoding, by a processor, the signal in accordance with a clustered message passing algorithm (MPA), wherein the clustered MPA corresponds to one or more sub-graphs, each of the one or more sub-graphs including fewer variable node to function node (VN-to-FN) branches for at least one function node than an underlying factor graph representative of multiplexed codes for the multiple access code system.

3. The method of claim 1 wherein the multiple access code system is a multicarrier system.

4. The method of claim 3 wherein the multicarrier system is an orthogonal frequency division multiple access (OFDMA) system.

5. The method of claim 1 wherein the multiple access code system is a sparse code multiple access (SCMA) system.

6. The method of claim 1 wherein the multiple access code system is a low density signature (LDS) system.

7. The method of claim 1 wherein the one or more sub-graphs are selected such that the least number of VN-to-FN branches connect to each function node in the one or more sub-graphs while performance loss compared to a full message passing algorithm is limited to a certain threshold.

8. The method of claim 7 wherein decoding the signal in accordance with the clustered MPA includes performing MPA detection on a given one of the one or more sub-graphs by passing information from variable nodes to function nodes over VN-to-FN branches of the given sub-graph without passing information from variable nodes to functions over VN-to-FN branches of the underlying factor graph that are excluded from the given sub-graph.

9. The method of claim 1 wherein the one or more sub-graphs are sub-graphs having maximum length of a shortest cycle.

10. The method of claim 1 wherein the sub-graphs include all variable nodes included in the underlying factor graph representative of the multiple access code system.

11. The method of claim 1 wherein the one or more sub-graphs are sub-graphs with symmetrical structures.

12. The method of claim 1 wherein a detection algorithm is run for a predetermined number of iterations on each of the one or more sub-graphs.

15. The method of claim 12 wherein the detection algorithm uses a Max-Log MAP algorithm.

49. The method of claim 1 wherein decoding the signal in accordance with the clustered MPA includes rotating between the one or more sub-graphs for a predetermined number of rotation cycles.

50. The method of claim 49 wherein rotating between the one or more sub-graphs for a predetermined number of rotation cycles comprises rotating between the one or more sub-graphs according to a predefined sequence.

51. The method of claim 49 wherein rotating between the one or more sub-graphs for a predetermined number of rotation cycles comprises rotating between the one or more sub-graphs according to a random sequence.

2. (canceled)

13-14. -14. (canceled)

16. An apparatus comprising:

a receiver configured to receive a signal over an antenna, the signal containing data multiplexed over a set of subcarriers according to a multiple access code system; and

a processor configured to decode the signal in accordance with a clustered message passing algorithm (MPA), wherein the clustered MPA corresponds to one or more sub-graphs, each of the one or more sub-graphs including fewer variable node to function node (VN-to-FN) branches for at least one function node than an underlying factor graph representative of the multiple access code system.

18. The apparatus of claim 16 wherein the multiple access code system is a multicarrier system.

19. The apparatus of claim 18 wherein the multicarrier system is an orthogonal frequency division multiple access (OFDMA) system.

20. The apparatus of claim 16 wherein the multiple access code system is a sparse code multiple access (SCMA) system.

21. The apparatus of claim 16 wherein the multiple access code system is a low density signature (LDS) system.

22. The apparatus of claim 16 wherein the one or more sub-graphs are selected such that the least number of VN-to-FN branches connect to each function node in the one or more sub-graphs while performance loss compared to a full message passing algorithm is limited to a certain threshold.

23. The apparatus of claim 16 wherein the one or more sub-graphs are sub-graphs having maximum length of a shortest cycle.

24. The apparatus of claim 16 wherein the one or more sub-graphs include all variable nodes included in the underlying factor graph representative of the multiple access code system.

25. The apparatus of claim 16 wherein the one or more sub-graphs are sub-graphs with symmetrical structures.

26. The apparatus of claim 16 wherein a detection algorithm is run for a predetermined number of iterations on each of the one or more sub-graphs.

29. The apparatus of claim 22 wherein decoding the signal in accordance with the clustered MPA includes performing MPA detection on a given one of the one or more sub-graphs by passing information from variable nodes to function nodes over VN-to-FN branches of the given sub-graph without passing information from variable nodes to functions over VN-to-FN branches of the underlying factor graph that are excluded from the given sub-graph.

30. The apparatus of claim 26 wherein the detection algorithm uses a Max-Log MAP algorithm.

46. The apparatus of claim 16, wherein decoding the signal in accordance with the clustered MPA includes rotating between the one or more sub-graphs for a predetermined number of rotation cycles.

47. The apparatus of claim 46 wherein rotating between the one or more sub-graphs for a predetermined number of rotation cycles comprises rotating between the one or more sub-graphs according to a predefined sequence.

48. The apparatus of claim 46 wherein rotating between the one or more sub-graphs for a predetermined number of rotation cycles comprises rotating between the one or more sub-graphs according to a random sequence.

17. (canceled)

27-28. -28. (canceled)

31-45. -45. (canceled)

52. A computer program product comprising a non-transitory computer readable storage medium storing programming, the programming including instructions to:

receive a signal over an antenna, the signal containing data multiplexed over a set of subcarriers according to a multiple access code system; and

decode the signal in accordance with a clustered message passing algorithm (MPA), wherein the clustered MPA corresponds to one or more sub-graphs, each of the one or more sub-graphs including fewer variable node to function node (VN-to-FN) branches for at least one function node than an underlying factor graph representative of the multiple access code system.

53. The computer program produce of claim 52, wherein the multiple access code system is a multicarrier system.

54. The computer program produce of claim 53 wherein the multicarrier system is an orthogonal frequency division multiple access (OFDMA) system.

55. The computer program produce of claim 52 wherein the multiple access code system is a sparse code multiple access (SCMA) system.

56. The computer program produce of claim 52 wherein the multiple access code system is a low density signature (LDS) system.

57. The computer program produce of claim 52 wherein the one or more sub-graphs are selected such that the least number of VN-to-FN branches connect to each function node in the one or more sub-graphs while performance loss compared to a full message passing algorithm is limited to a certain threshold.

58. The computer program produce of claim 57 wherein the instructions to decode the signal in accordance with the clustered MPA includes instructions to perform MPA detection on a given one of the one or more sub-graphs by passing information from variable nodes to function nodes over VN-to-FN branches of the given sub-graph without passing information from variable nodes to functions over VN-to-FN branches of the underlying factor graph that are excluded from the given sub-graph.

59. The computer program produce of claim 52 wherein the one or more sub-graphs are sub-graphs having maximum length of a shortest cycle.

60. The computer program produce of claim 52 wherein the sub-graphs include all variable nodes included in the underlying factor graph representative of the multiple access code system.

61. The computer program produce of claim 52 wherein the one or more sub-graphs are sub-graphs with symmetrical structures.

62. The computer program produce of claim 52 wherein a detection algorithm is run for a predetermined number of iterations on each of the one or more sub-graphs.

63. The computer program produce of claim 62 wherein the detection algorithm uses a Max-Log MAP algorithm.

64. The computer program produce of claim 52 wherein the instructions to decode the signal in accordance with the clustered MPA include instructions to rotate between the one or more sub-graphs for a predetermined number of rotation cycles.

65. The computer program produce of claim 64 wherein the instructions to rotate between the one or more sub-graphs for a predetermined number of rotation cycles include instructions to rotate between the one or more sub-graphs according to a predefined sequence.

66. The computer program produce of claim 64 wherein the instructions to rotate between the one or more sub-graphs for a predetermined number of rotation cycles include instructions to rotate between the one or more sub-graphs according to a random sequence.