Medium access control layer that encapsulates data from a plurality of received data units into a plurality of independently transmittable blocks

• US 8,090,857 B2
• Filed: 11/24/2003
• Issued: 01/03/2012
• Est. Priority Date: 11/24/2003
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm Atheros Incorporated (Qualcomm, Inc.)
• Inventors: Yonge, Lawrence W. III, Katar, Srinivas, Kostoff, Stanley J. II, Earnshaw, William E., Blanchard, Bart W., Gargrave, Timothy R.
• Primary Examiner(s): PATEL, CHIRAG R
• Application Number:
  US10/720,742
• Publication Number:
  US 20050114489A1
• Time in Patent Office: 2,962 Days
• Field of Search: 370/469, 709/250, 709/230, 714/47, 714/48
• US Class Current: 709/230
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]

Abstract

A method of operating in a network in which a plurality of stations communicate over a shared medium, comprising providing a physical layer (e.g., PHY) for handling physical communication over the shared medium; providing a high level layer (e.g., PAL) that receives data from the station and supplies high level data units (e.g., MSDUs) for transmission over the medium; providing a MAC layer that receives the high level data units from the high level layer and supplies low level data units (e.g., MPDUs) to the physical layer; at the MAC layer, encapsulating content from a plurality of the high level data units; dividing the encapsulated content into a plurality of pieces (e.g., segments) with each piece capable of being independently retransmitted; and supplying low level data units containing one or more of the plurality of pieces.

Claims

1. A method of operating in a network in which a plurality of stations communicate over a shared medium, comprising

providing a physical layer for handling physical communication over the shared medium;

providing a high level layer that receives data from a station and supplies high level data units for transmission over the medium;

providing a MAC layer that receives the high level data units from the high level layer and supplies low level data units to the physical layer;

at the MAC layer, encapsulating content from a plurality of the high level data units into a stream of sub-frames;

dividing the encapsulated stream into a plurality of pieces with each piece capable of being independently retransmitted; and

supplying low level data units, at least some of the low level data units each containing a plurality of the pieces into which the encapsulated stream was divided, and at least some of the low level data units containing boundary demarcation information indicating boundaries between the sub-frames in the stream;

wherein at least some information common to the high level data units is not repeated for each high level data unit encapsulated in the stream;

wherein the high level data units each comprise a payload, and encapsulating comprises forming the stream comprising the payloads from a succession of high level data units;

wherein the stream comprises a succession of sub-frames, each sub-frame comprising a header and a plurality of the payloads;

wherein each sub-frame is divided into the plurality of pieces capable of being independently retransmitted; and

wherein division of a sub-frame into the plurality of pieces comprises dividing the sub-frame into a plurality of sub-blocks, and forming at least some pieces from a plurality of sub-blocks.

2. The method of claim 1 wherein the information common to the high level data units comprises destination and source addresses.

3. The method of claim 1 wherein each piece constitutes a segment that is transmitted as a physical layer block.

4. The method of claim 1 further comprising parity pieces derived from other pieces and capable of being used at a destination to recover one or more lost pieces at the destination without having to retransmit the lost pieces.

5. The method of claim 4 wherein each piece is transmitted as a physical layer block, and the parity pieces are also transmitted as parity physical layer blocks.

6. The method of claim 5 wherein the physical layer blocks are encoded using forward error correction.

7. The method of claim 1 wherein some of the pieces making up a low level data unit constitute retransmitted pieces that failed to be correctly transmitted in an earlier attempt.

8. The method of claim 7 wherein at least some retransmitted pieces are transmitted with greater forward error correction than forward error correction used in the earlier attempt.

9. The method of claim 1 wherein each sub-frame further comprises a delivery time stamp associated with at least some payloads.

10. The method of claim 1 wherein clock information characterizing the time setting of a clock in a transmitting station is transmitted to a receiving station within a header of the low level data units, and the clock information is used by the receiving station along with the delivery time stamps to establish the time at which payloads are delivered.

11. The method of claim 10 wherein the time at which a payload is delivered is substantially the time specified by the time stamp based on information derived from the clock information.

12. The method of claim 1 further comprising an integrity check value associated with each sub-frame or with a plurality of sub-frames.

13. The method of claim 1 wherein each of the plurality of payloads in a sub-frame have identical length.

14. The method of claim 1 wherein each sub-frame further comprises MAC management information.

15. The method of claim 1 wherein the MAC layer has the capability of transmitting data in a plurality of sessions within a regularly-repeated contention free interval, wherein a station to which data is transmitted is identified by a destination address and a station from which data is transmitted is identified by a source address, and wherein the stream contains a queue of payloads for the same session, same source address, and same destination address.

16. The method of claim 1 wherein the MAC layer has the capability of transmitting data in a plurality of sessions within a regularly-repeated contention free interval, wherein a station to which data is transmitted is identified by a destination address and a station from which data is transmitted is identified by a source address, and wherein the queue contains sub-frames for the same session, same source address, and same destination address.

17. The method of claim 15 wherein the MAC layer processes data transmitted in the sessions according to contention-free channel access processing.

18. The method of claim 17 wherein the sessions are transmitted within time slots of a regularly-repeated contention-free interval.

19. The method of claim 15 wherein a stream identifier is used to associate content of a queue with a particular session.

20. The method of claim 19 wherein the stream identifier is also used to associate content of a queue with a priority level for contention-based transmission over the medium.

21. The method of claim 19 wherein there are a plurality of queues of payloads in the stream, each containing payloads having a unique combination of stream identifier, source address, and destination address.

22. The method of claim 21 wherein each queue contains payloads having a unique combination of stream identifier, source address, destination address, and type of high level layer.

44. The method of claim 1, further comprising adaptively escalating the robustness of transmission of at least some of the pieces in each of at least some of the low level data units depending on the frequency of transmission errors.

45. The method of claim 44 wherein

the method further comprises incorporating forward-error correction information into the transmitted stream of low level data units, and

wherein the step of adaptively escalating comprises adaptively varying the forward-error correction information depending on the frequency of transmission errors.

46. The method of claim 45 wherein varying the forward-error correction information comprises varying one or both of the amount and type of forward-error correction information.

47. The method of claim 44 wherein decisions on adaptively escalating are made at a transmitting station.

48. The method of claim 44 wherein each of the low level data units contains a plurality of the pieces.

49. The method of claim 47 wherein the forward error correction information comprises information associated with the pieces for use at a destination for recovering a piece that is received with errors.

50. The method of claim 47 wherein the forward error correction information comprises parity pieces derived from other pieces and capable of being used at a destination to recover one or more lost pieces at the destination without having to retransmit the lost pieces.

51. The method of claim 50 wherein each piece is transmitted as a physical layer block, and the parity pieces are also transmitted as parity physical layer blocks.

60. The method of claim 1 wherein the boundary demarcation information for a given low level data unit comprises information that indicates whether a boundary between sub-frames exists within the low level data unit.

61. The method of claim 60 wherein, if such boundary does exist within the low level data unit, the boundary demarcation information further comprises information that indicates where the boundary occurs within the low level data unit.

62. The method of claim 61 wherein the information that indicates whether a boundary between high level data units exists within the low level data unit comprises a field having a value that indicates which piece in the low level data unit includes the boundary, or having a value that indicates that no boundary exists within the low level data unit.

63. The method of claim 62 wherein the information that indicates where the boundary occurs within the low level data unit comprises an offset indicating a relative position of the boundary within the piece including the boundary.

64. The method of claim 62 wherein the field is a header associated with the low-level data unit.

65. The method of claim 1 wherein at least one of the low-level data units contains a portion of at least one sub-frame, and at least one of the low-level data units contains a different portion of the at least one sub-frame.

23. A method of operating in a network in which a plurality of stations communicate over a shared medium, comprising

providing a physical layer for handling physical communication over the shared medium;

providing a high level layer that receives data from a station and supplies high level data units for transmission over the medium;

providing a MAC layer that receives the high level data units from the high level layer and supplies low level data units to the physical layer;

at the MAC layer, encapsulating content from a plurality of the high level data units into a stream of sub-frames;

dividing the encapsulated stream into a plurality of pieces with each piece capable of being independently retransmitted; and

supplying low level data units, at least some of the low level data units each containing a plurality of the pieces into which the encapsulated stream was divided, and at least some of the low level data units containing boundary demarcation information indicating boundaries between the sub-frames in the stream;

wherein at least some information common to the high level data units is not repeated for each high level data unit encapsulated in the stream;

wherein the high level data units each comprise a payload, and encapsulating comprises forming the stream comprising the payloads from a succession of high level data units;

wherein the stream comprises a succession of sub-frames, each sub-frame comprising a header and a plurality of the payloads; and

wherein the stream is divided into a plurality of sub-blocks, wherein a plurality of sub-blocks are grouped to form a segment, with a segment crossing sub-frame boundaries in the stream, wherein a segment constitutes one of the pieces.

24. The method of claim 23 wherein each sub-block is shorter than a sub-frame.

25. The method of claim 23 wherein at least some segments contain a number of sub-blocks corresponding to one or more sub-frames including at least one sub-frame whose associated sub-blocks comprise less than the whole sub-frame.

26. The method of claim 23 wherein the sub-blocks are of equal length.

27. The method of claim 23 wherein the sub-blocks have an associated sequential numbering adapted for use at the receiving station for re-establishing the correct sequential order of the sub-blocks.

28. The method of claim 27 wherein the sub-blocks have a predetermined size, which combined with the associated sequential numbering, eliminates the need for buffer reordering when out of order segments are received.

29. The method of claim 28 wherein the sub-blocks are of equal size.

30. The method of claim 23 further comprising, for at least some of the low level data units, forming the low level data unit from a plurality of segments.

31. The method of claim 30 wherein each segment in the low level data unit forms the body of a separate block transmitted by the physical layer.

32. The method of claim 30 wherein individual segments are individually encrypted.

33. The method of claim 32 wherein encryption information common to a plurality of segments is carried in a header.

34. The method of claim 33 wherein some encryption information is carried in a header and frame control of the low level data unit and in a header of the block.

35. The method of claim 32 wherein some encryption information is carried in frame control of the low level data unit and in a header of the block.

36. The method of claim 31 wherein each block separately undergoes forward error correction, and forward error correction bits for each block are transmitted in the low level data unit.

37. The method of claim 36 wherein the level of forward error correction used is different for different blocks.

38. The method of claim 37 wherein the level of forward error correction used provides greater error correction capability for selected blocks that are being retransmitted after failing to be correctly transmitted in an earlier attempt.

39. The method of claim 31 wherein most of the blocks are identical in length.

40. The method of claim 39 wherein the initial and final block of a low level data unit can be of a different length than the remaining blocks.

41. The method of claim 30 wherein information common to the plurality of segments forming the low level data unit is transmitted in a header for the low level data unit.

42. The method of claim 36 wherein the information common to the plurality of segments is transmitted only in the header.

43. The method of claim 36 wherein the low level data unit further comprises a frame control field.

52. A method of operating in a network in which a plurality of stations communicate over a shared medium, comprising

providing a physical layer for handling physical communication over the shared medium;

providing a high level layer that receives data from a station and supplies high level data units; and

providing a layer that receives the high level data units from the high level layer and supplies low level data units to the physical layer;

wherein supplying the low level data units comprises

encapsulating content from a plurality of the high level data units into a stream of sub-frames,

dividing the encapsulated stream into a plurality of sub-blocks,

forming a plurality of pieces, with each piece including one or more sub-blocks, to provide pieces capable of being independently retransmitted, and

supplying low level data units, at least some of the low level data units each containing a plurality of the pieces that include the sub-blocks into which the encapsulated content was divided, and at least some of the low level data units containing boundary demarcation information indicating boundaries between the sub-frames in the stream.

53. The method of claim 52 wherein a plurality of the plurality of pieces each include a same number of the sub-blocks.

54. The method of claim 52 wherein at least one of the plurality of pieces includes one or more sub-blocks and padding.

55. The method of claim 54 wherein an amount of padding in a piece is selected based on the number of sub-blocks in the piece and the size of the pieces.

56. The method of claim 52 wherein the high level data units each comprise a payload, and encapsulating comprises forming the stream comprising the payloads from a succession of high level data units.

57. The method of claim 56 wherein the stream comprises a succession of sub-frames, each sub-frame comprising a header and a plurality of the payloads.

58. The method of claim 57 wherein each sub-frame is divided into the plurality of pieces capable of being independently retransmitted.

59. The method of claim 58 wherein division of a sub-frame into the plurality of pieces comprises dividing the sub-frame into the plurality of sub-blocks of equal size, and forming at least some pieces from a plurality of sub-blocks.