Flexible OFDM/OFDMA frame structure for communication systems

• US 8,204,025 B2
• Filed: 11/07/2008
• Issued: 06/19/2012
• Est. Priority Date: 11/09/2007
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Cai, Sean, Chow, Jerry, Qu, Hongyun, Fang, Huiying
• Primary Examiner(s): Yao, Kwang B
• Assistant Examiner(s): Tran, Tung Q
• Application Number:
  US12/267,502
• Publication Number:
  US 20090185632A1
• Time in Patent Office: 1,320 Days
• Field of Search: 370/321, 370/337, 370/343, 370/344, 370/347, 370/436, 370/442, 370/458
• US Class Current: 370/337
• CPC Class Codes: H04L 27/26025 Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking allocating sub-channels of the transmission path H04L5/003
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04L 5/1469 using time-sharing

Abstract

A flexible OFDM/OFDMA frame structure technology for communication systems is disclosed. The OFDM frame structure technology comprises a configurable-length frame which contains a variable length subframe structure to effectively utilize OFDM bandwidth. Furthermore, the frame structure facilitates spectrum sharing between multiple communication systems.

Claims

1. A method of providing a frame for data communication in a communication system, comprising:

generating a frame comprising a plurality of subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration T_u-sub;

generating and transmitting a frame synchronization signal and a frame control signal for controlling the subframes in the frame, wherein the frame further comprises a plurality of pointers, wherein the plurality of pointers are configured to provide location information corresponding to a plurality of start locations of the plurality of subframes; and

generating directionality information for each subframe in the frame, wherein the frame synchronization signal and the frame control signal are located in a downlink subframe located at the beginning of the frame, wherein the frame control signal comprises the directionality information, a starting time location, and a time duration T_sub for each subframe in the frame, and wherein the directionality information, the starting time location, and the time duration T_sub for each subframe in the frame are selected from a set of predefined settings, and are not individually signaled.

2. The method of claim of 1, wherein the directionality information indicates whether the subframe is used for downlink transmission or uplink transmission.

3. The method of claim of 2, wherein the directionality information comprises a direction control bit.

4. The method of claim 1, wherein the directionality information indicates whether the subframe is used for downlink transmission, uplink transmission, or reserved.

5. The method of claim 1, wherein the directionality information indicates whether the channel bandwidth within the subframe is used for downlink transmission, uplink transmission, or reserved.

6. The method of claim 1, wherein the frame synchronization signal is easily distinguishable from other signals in the frame, and from frame synchronization signals of other transmission sources using the same transmission medium.

7. The method of claim 1, wherein the frame synchronization signal exhibits strong autocorrelation properties and weak cross-correlation properties with other signals in the frame, and with frame synchronization signals of other transmission sources using the same transmission media.

8. The method of claim of 1, wherein the starting time location of the subframe in the frame is specified by a time offset from the start of the frame.

9. The method of claim of 8, wherein the time offset of the subframe is expressed as an integer number of T_u-sub.

10. The method of claim of 9, wherein the time offset of the subframe is expressed as the sum of the time durations of all the preceding subframes in the frame.

11. The method of claim of 1, further comprising transmitting the selected set of predefined settings to a mobile station via the frame control signal.

12. The method of claim 1, further comprising:

generating one or more frame partitions in the frame, each frame partition comprising one or more subframes, and

generating a frame partition control signal for each frame partition, the frame partition control signal comprising one or more pointers that provide location information corresponding to one or more start locations of the one or more subframes within the frame partition.

13. The method of claim of 12, wherein the frame control signal comprises the number of frame partitions in the frame.

14. The method of claim of 12, wherein the frame partition control signal is located in a downlink subframe located at the beginning of the frame partition, and the frame partition signal comprises the directionality information, and a time duration T_sub for each subframe in the frame partition, and the pointer comprises a starting time location for each subframe in the frame partition.

15. The method of claim of 14, wherein the starting time location of the subframe in the frame partition is specified by a time offset from the start of the frame partition.

16. The method of claim of 15, wherein the time offset of the subframe is expressed as an integer number of T_u-sub.

17. The method of claim of 16, wherein the time offset of the subframe is expressed as the sum of the time durations of the preceding subframes in the frame partition.

18. The method of claim 15, wherein the time offset is predetermined by the predefined locations and durations of subframes within the frame and by the location and duration of the frame partition within the frame.

19. The method of claim of 14, wherein the frame partition control signal comprising a starting time location of a succeeding frame partition in the frame.

20. The method of claim of 1, wherein each subframe comprises one or more subframe partitions, each subframe partition comprises one or more unit subframes.

21. The method of claim of 20, wherein the subframe comprise a subframe partition control signal, the subframe partition control signal comprise a starting time location and a time duration T_sub for each subframe partition in the subframe.

22. The method of claim of 20, wherein the frame partition control signal comprise a starting time location and a time duration for each subframe partition in the subframe.

23. The method of claim 20, wherein units of radio resources allocable and individually or collectively identifiable for transmissions are defined within the total radio resources available for transmissions within a subframe partition.

24. The method of claim 20, wherein units of radio resources allocable and individually or collectively identifiable for transmissions are defined within the total radio resources available for transmissions within a unit subframe.

25. The method of claim of 1, wherein each unit subframe comprises one or more OFDM symbols.

26. The method of claim of 25, wherein the unit subframe comprises an idle time at the end of the unit subframe.

27. The method of claim of 25, wherein the unit subframe comprises a synchronization signal at the beginning of the unit subframe.

28. The method of claim of 1, wherein T_u-sub is equal to 0.5, 0.675, 1, 1.25, 1.5, or 2 ms.

29. The method of claim of 1, wherein the frame comprises a fixed length duration T_frame, and T_frame is equal to 5, 10, or 20 ms.

30. A method of spectrum sharing between a first communication system and a second communication system, the method comprising:

transmitting a first frame by the first communication system, the first frame comprising a plurality of subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration T_u-sub, and wherein the first frame comprises directionality information for each subframe that indicates whether the subframe is used for downlink transmission, uplink transmission, or reserved, wherein the first frame comprises a frame synchronization signal and a frame control signal in a downlink subframe located at the beginning of the first frame, wherein the frame control signal comprises the directionality information, a starting time location, and a time duration T_sub for each subframe in the frame, and wherein the directionality information, the starting time location, and the time duration T_sub for each subframe in the frame are selected from a set of predefined settings, and are not individually signaled; and

transmitting a second frame by the second communication system, the second frame comprising one or more subframes, wherein the second frame occupies the time durations of the reserved subframes in the first frame, wherein the first frame comprises a first plurality of pointers, wherein the first plurality of pointers are configured to provide location information corresponding to a plurality of start locations of the plurality of subframes in the first frame, and wherein the second frame comprises one or more pointers, wherein the one or more pointers are configured to provide location information corresponding to one or more start locations of the one or more subframes of the second frame.

31. The method of claim of 30, wherein the second communication system does not require full use of its operating spectrum at all times.

32. The method of claim 30, wherein the first communication system and the second communication system have different sub-carrier spacing.

33. The method of claim 30, wherein the first communication system and the second communication system have different symbol times.

34. The method of claim 30, wherein the first communication system and the second communication system have different OFDM/OFDMA cyclic prefix durations.

35. The method of claim 30, wherein the first communication system and the second communication system have different channel bandwidths.

36. The method of claim 30, wherein the first communication system and the second communication system have different center frequencies.

37. The method of claim 30, wherein the reserved subframes occur periodically in the first frame, and the first frame comprises a time duration equal to an integer multiple of a minimum periodicity of the reversed subframes.

38. The method of claim 37, wherein the second frame comprises a time duration equal to the minimum periodicity of the reversed subframes.

39. The method of claim 30, wherein the reserved subframes are so situated in the first frame that the second frame satisfies a timing requirement of the second communication system.

40. The method of claim 30, wherein the first communication system has a sub-carrier spacing of 12.5 kHz.

41. The method of claim 40, wherein the first carrier supports three cyclic prefix lengths:

2.5, 10, and 15 μ

s.

42. The method of claim 30, wherein the first communication system has a sub-carrier spacing of 25 kHz.

43. The method of claim 30, wherein the reserved subframes are not used by the first OFDMA communication system for data transmission.

44. The method of claim 43, wherein the first communication system complies with IEEE 802.16m, and the second communication complies with IEEE 802.16e.

45. The method of claim 30, wherein the first communication and the second communication operate on the same carrier.

46. The method of claim 30, wherein the first frame comprises a first preamble, the second frame comprises a second preamble, and the first preamble is orthogonal to the second preamble.

47. The method of claim 30, wherein the time duration of the first frame is an integer multiple of the second frame.

48. The method of claim 47, wherein the time duration of the second frame is 5 milliseconds.

49. The method of claim 30, wherein the first frame comprises one or more frame partitions, each frame partition comprises one or more subframes.

50. The method of claim of 49, wherein each frame partition comprises a frame partition control signal for controlling the subframes in the frame partition, the frame partition control signal comprises the directionality information and a time duration T_sub for each subframe in the frame partition, and a pointer configured to provide a start time location for each subframe in the frame partition.

51. The method of claim 49, wherein each subframe comprises one or more subframe partitions, each subframe partition comprises one or more unit subframes.

52. The method of claim of 51, wherein each subframe comprises a subframe partition control signal for controlling the subframe partitions in the subframe, the subframe partition control signal comprising a time duration T_sub for each subframe partition in the subframe and a pointer configured to provide a start time location for each subframe partition in the subframe.

53. The method of claim of 52, wherein the subframe partition control signal comprises directionality information for each subframe partition indicates whether the subframe partition is used for downlink transmission, uplink transmission, or reserved.

54. The method of claim 53, further comprising transmitting the second frame by the second communication system during the time durations of the reserved subframe partitions in the first frame.

55. The method of claim 30, wherein the directionality information for each reserved subframe in the first frame further indicates whether the channel bandwidth of the reserved subframes is used for downlink transmission, uplink transmission, or reserved, and the reserved channel bandwidth of reserved subframes is not used by the first communication system for transmitting the reserved subframes.

56. The method of claim 55, further comprising the first communication transmitting the reserved subframes in the first frame on the channel bandwidth that is not reserved.

57. The method of claim 56, wherein the first communication system is an OFDMA communication system.

58. The method of claim 55, wherein the channel bandwidth of the second communication system does not fully overlap with the channel bandwidth of the first communication system.

59. The method of claim 58, further comprising the second communication transmitting the second frame on the reserved channel bandwidth.

60. A method of spectrum sharing between a first communication system and a second communication system, the method comprising:

transmitting a first frame by the first communication system, the first frame comprising a plurality of subframes, each subframe comprising or more unit subframes, each unit subframe comprising a fixed length duration T_u-sub, wherein the first frame comprises directionality information for each subframe that indicates whether regions of frequency-time resources of the subframe are used for downlink transmission, uplink transmission, or reserved, wherein the first frame comprises one or more frame partitions, each frame partition comprising one or more subframes, and wherein the first frame comprises a frame partition control signal for each frame partition, the frame partition control signal comprising one or more pointers that provide location information corresponding to one or more start locations of the one or more subframes within the frame partition, wherein the frame partition control signal is located in a downlink subframe located at the beginning of the frame partition, and the frame partition signal comprises the directionality information, and a time duration T_sub for each subframe in the frame partition, and the pointer comprises a starting time location for each subframe in the frame partition, and wherein the frame partition control signal comprising a starting time location of a succeeding frame partition in the frame;

transmitting a second frame by the second communication system, the second frame comprising one or more subframes, wherein the second frame occupies the reserved regions of frequency-time resources of the subframes in the first frame, wherein the first frame comprises a first plurality of pointers, wherein the first plurality of pointers are configured to provide location information corresponding to a plurality of start locations of the plurality of subframes in the first frame, and wherein the second frame comprises one or more pointers, wherein the one or more pointers are configured to provide location information corresponding to one or more start locations of the one or more subframes of the second frame.