Superframes

• US 5,119,403 A
• Filed: 07/26/1991
• Issued: 06/02/1992
• Est. Priority Date: 04/09/1991
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Racal Data Communications Incorporated
• Inventors: Krishnan, Vedavalli G.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US07/736,370
• Time in Patent Office: 312 Days
• Field of Search: 375/25, 375/34, 375/37, 375/39, 375/58, 332/103, 370/43, 370/79, 370/82, 370/84, 370/99, 370/110.1
• US Class Current: 375/261
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/4975 Correlative coding using Tomlinson precoding, Harashima precoding, Trellis precoding or GPRS
• CPC Class Codes: H04L 27/3472 by switching between alternative constellations

Abstract

The present invention is directed toward a method and apparatus in a communications device for mapping a selected group of data bits into a predetermined number of two-dimensional symbols selected from a minimized alphabet of M two-dimensional symbols forming a symbol constellation, with one of the two-dimensional symbols being transmitter during each symbol (i.e., baud) interval. A plurality of symbol mappers in an adaptive communications device use a superframe of bits per baud. Each superframe includes at least two groups of frames, a low bit frame and a high bit frame. The superframe has A) one of these two types of frames uses whole bits per baud and the other uses fractional bits per baud or B) both of these two types of frames will use fractional bits per baud.

Claims

1. In an adaptive communications device for transmitting a plurality of data-bits over a transmission medium including a transmitter means for selecting one of a plurality of symbol-mapping means for each of a plurality of modes of operation;

each of said symbol-mapping means being operable for mapping said plurality of data-bits into a sequence of symbols with there being one of said symbols for each of a plurality of bauds;

each one of said symbol-mapping means being characterized by a plurality of frames of data-bits-per-baud rates with there being one of said data-bits-per-baud rates for each said baud of said plurality of bauds;

each of said frames being characterized by a frame-average which is an average of said data-bits-per-baud rates of said each frame, the improvement comprising;

at least a portion of said plurality of symbol-mapping means each defining one of a plurality of superframes, each of said superframes including at least one of said frames consisting of a low-bit frame and at least one of said frames consisting of a high-bit frame;

said portion of symbol-mapping means each being operable for selecting said frame average for said lowbit frame to be a low data-bits-per-baud rate and said frame average for said high bit frame to be a high data-bits-per-baud rate, said high data-bits-per-baud rate being greater in magnitude than said low data-bits-per-baud rate; and

at least one of said low and high data-bits-per-baud rates consisting of a fractional-bits-per-baud rate;

whereby use of said superframes, when changing between respective said modes of operation, allows for small changes in said data-bits-per-baud rates between said respective modes of operation.

2. In the adaptive communications device according to claim 1, wherein the numbers of said low-bit frames and said high bit frames in a given one of said superframes are X and Y, respectively, where both said X and said Y are greater than or equal to one;

and wherein for a portion of said superframes at least one of said X and said Y is greater than one;

whereby said small changes in said data-bits-per-baud rates between said respective modes of operation are dependent in part upon the ratio of said X to said Y within said superframes.

3. In the adaptive communications device according to claim 1, wherein said high data-bits-per-baud rate and said low data-bits-per-baud rate are separated by a fractional difference less than one;

whereby said small changes in said data-bits-per-baud rates between said respective modes of operation are dependent in part upon said fractional difference.

4. In the adaptive communications device according to claim 1, wherein said superframes for a first subportion of said portion of symbol-mapping means have said frame average consisting of a whole-bits-per-baud rate for one of said low-bit and high-bit frames and have said frame average consisting of two fractional-bits-per-baud rates with there being one for said low-bit frames and one for said high-bit frames;

and said superframes for a second subportion of said portion of symbol-mapping means have said frame averages consisting of two fractional-bits-per-baud rates with there being one for said low-bit frame and one for said high-bit frame.

5. In the adaptive communications device according to claim 1, wherein a portion of said superframes each further includes at least one secondary channel frame for a secondary channel.

6. In the adaptive communications device according to claim 2, wherein each of said plurality of superframes has Z said frames;

said superframes include two groups of said superframes, a first group and a second group;

each of said superframes of said first group includes Z said low-bit and high-bit frames, where Z=X+Y; and

each of said superframes of said second group includes Z-1 said low bit and high bit frames and a secondary channel frame for a secondary channel, where Z-1=X+Y.

7. In the adaptive communications device according to claim 6, wherein each of said modes of operation include a combination of a data-bits-per-second rate and a bauds-per-second rate, said combination defining said data-bit-per-baud rates, said transmitter means further including switching means for changing said modes of operation, said switching means being operable for including said secondary channel by switching to one of said symbol-mapping means using superframes of said second group, whereby an increase in said data-bits-per-second rates caused by the inclusion of said secondary channel is accommodated by an increase in said data-bits-per-baud rates instead of an increase in said bauds-per-second rates.

8. In the adaptive communications device according to claim 7, wherein said portion of said symbol-mapping means using said superframes consists of a first portion of said symbol-mapping means, said transmitter means further including at least a second portion of said symbol-mapping means with each said symbol-mapping means of said second portion including means for selecting an identical one of said frame averages for all said frames of said each symbol-mapping means;

whereby said symbol-mapping means of said second portion do not use said superframes.

9. In the adaptive communications device according to claim 8, wherein said switching means is operable for including said secondary channel by switching to one of said symbol-mapping means of said first portion using said superframes of said second group from one of said symbol-mapping means of said first portion using said superframes of said first group.

10. In the adaptive communications device according to claim 8, wherein said switching means is operable for including said secondary channel by switching to one of said symbol-mapping means of said first portion using said superframes of said second portion from one of said symbol-mapping means of said second portion.

11. In the adaptive communications device according to claim 6, wherein said superframes of said second group have more said frames than said superframes of said first group, whereby the granularity of said small changes in data-bit-per-second rates increases with the length of said superframes.

12. In the adaptive communications device according to claim 1, wherein said symbol-mapping means of said portion having said superframes each includes binary fractional-bit mapping means for using binary fractional-bit mapping for generating said fractional-bits-per-baud rate.

13. In the adaptive communications device according to claim 1, wherein said symbol-mapping means of said portion having said superframes each includes non-binary fractional-bit mapping means for using non-binary fractional-bit mapping for generating said fractional-bits-per-baud rate.

14. In the adaptive communications device according to claim 1, wherein said symbol-mapping means having said superframes each include whole-bit mapping means for using binary whole-bit mapping for generating said fractional-bits-pere-baud rate.

15. In the adaptive communications device according to claim 1, wherein each said frame has a predetermined number of said bauds, where said predetermined number of bauds is greater than one.

16. In the adaptive communications device according to claim 1, wherein each of said symbol-mapping means is operable for selecting, for said each baud, a symbol constellation providing said one of data-bit-per-baud rates and for selecting, in response to said data-bits, said symbol from said symbol constellation, said transmitter means including means for transmitting said symbol during said each baud.

17. In the adaptive communications device according to claim 1, wherein each of said symbol-mapping means is operable for selecting, for each one of said frames, at least one symbol constellation providing said frame average of data-bit-per-baud rates for said one frame and for selecting, in response to said data-bits, said symbol, for each of said bauds of said plurality of bauds, from said at least one symbol constellation, said transmitter means including means for transmitting said selected symbols.

18. In the adaptive communications device according to claim 17, wherein said at least one symbol constellation includes at least two symbol constellations.

19. In the adaptive communications device according to claim 15, wherein said predetermined number of bauds includes four said bauds.

20. In the adaptive communications device according to claim 13, wherein said data-bits-per-baud rates of each said frame comprise the same data-bits-per-baud rate.

21. In the adaptive communications device according to claim 14, wherein said data-bits-per-baud rates of each said frame comprise at least two different data-bits-per-baud rates.

22. In the adaptive communications device according to claim 15, wherein the total number of said bauds in a given said superframe is designated as T and said predetermined number of bauds of each said frame is designated as B, where T is determined by the following equation:

space="preserve" listing-type="equation">T=B(X+Y)

and wherein for a constant said T, said B may be increased if X+Y is proportionately decreased.

23. In the adaptive communications device according to claim 22, wherein said total number of bauds for said superframes with a frame for a secondary channel is in accordance with the following equation:

space="preserve" listing-type="equation">T=B(X+Y)+S

where S is equal to the number of said bauds in said frame for said secondary channel.

31. In the adaptive communications device according to claim 10, wherein said superframes including said frame for said secondary channel has more said frames than said superframes without said secondary channel, whereby the granularity of data-bit rate changes increase with the length of said superframe.

37. In the method according to claim 15, wherein said step of providing further includes providing each of said superframes with Z said frames and providing two groups of said superframes, a first group and a second group;

each of said superframes of said first group includes Z said low-bit and high-bit frames, where Z=X+Y; and

each of said superframes of said second group includes Z-1 low bit and high bit frames and a secondary channel frame for a plurality of secondary channel data-bits, where Z-1=X+Y.

38. In the method according to claim 37, wherein each of said modes of operation include a combination of a data-bits-per-second rate and a bauds-per-second rate, said combination defining said data-bits-per-baud rates, said method further including the step of switching between said modes of operation to provide said secondary channel using superframes of said second group so that an increase in said data-bits-per-second rate caused by the inclusion of said secondary channel is accommodated by increasing said frame averages of data-bits-per-baud rates instead of increasing said bauds-per-second rate.

39. In the method according to claim 38, wherein said at least a portion of said modes of operation is identified as a first portion of said modes of operation, said method further comprises, for a second portion of said modes of operation, using one of a plurality of identical frames of said data-bits-per-baud rates;

whereby said second portion of said modes of operation do not use said superframes.

40. In the method according to claim 38, wherein said step of switching includes switching to one of said superframes of said second group from one of said superframes of said first group.

41. In the method according to claim 39, wherein said step of switching includes switching to one of said superframes of said second group from one of said identical frames.

42. In the method according to claim 37, wherein said superframes of said second group have a greater number of said frames than said superframes of said first group, whereby the granularity of changes of said data-bit-per-second rate increase with the length of said superframes.

24. In an adaptive communications device for transmitting data-bits over a transmission medium, including a transmitter having a plurality of symbol-mapping means for a plurality of modes of operation;

each of said symbol-mapping means including symbol selecting means for translating, at one of a plurality of data-bits-per-baud rates, a plurality of said data-bits into one of a plurality of selected symbols for each baud of a predetermined number of bauds;

each of said symbol mapping means defining a plurality of frames of said data-bits-per-baud rates;

each of said frames having one of said data-bits-per-baud rates for each said baud of said predetermined number of bauds; and

means for transmitting one of said selected symbols during each of said bauds, wherein the improvement comprises;

at least a portion of said plurality of symbol-mapping means each having one of a plurality of superframes;

each one of said plurality of superframes including a plurality of said frames with at least one of said frames being a low-bit frame and at least another of said frames being a high-bit frame;

the numbers of said low-bit and said high bit frames being X and Y, respectively, where both said X and said Y are greater than or equal to one; and

each of said frames being characterized by a frame-average which is an average of said data-bits-per-baud rates of said each frame;

said frames-average consisting of a whole-bits-per-baud rate where said frame-average is an integer number and a fractional-bits-per-baud rate where said frame-average is a non-integer number, said frame average of said high-bit frame and said frame average of said low-bit frame being separated by a fractional difference less than one, whereby said numbers of said X low-bit frames and said Y high-bit frames in a given one of said superframes provide said given superframe with a desired average of said data-bits-per-baud rates for said bauds in said superframe.

25. In the adaptive communications device according to claim 24, wherein said superframes for a first subportion of said portion of said plurality of symbol-mapping means include one of said low-bit and high-bit frames having said frame average consisting of said whole-bits per baud rate and the other one of said low-bit and high-bit frames having said frame average consisting of said fractional bits per baud rate;

and said superframes for a second subportion of said portion of said plurality of symbol-mapping means include both said low-bit and high-bit frames having said frame averages consisting of said fractional-bits-per-baud rates.

26. In the adaptive communications device according to claim 25, wherein each of said superframes has Z said frames;

said superframes include two groups of said superframes, a first group and a second group;

each of said superframes of said first group includes Z said low-bit and high-bit frames, where Z=X+Y; and

each of said superframes of said second group includes Z-1 low bit and high bit frames and a secondary channel frame for a secondary channel, where Z-1=X+Y.

27. In the adaptive communications device according to claim 26, wherein each of said modes of operation include a combination of a data-bits rate and said baud rate, said transmitter further including switching means for changing said modes of operation, said switching means being operable for including said secondary channel by switching to one of said superframes of said second group, whereby an increase in said data-bits rate caused by the inclusion of said secondary channel is accommodated by an increase in said frame average of data-bits-per-baud rates instead of an increase in said baud rate.

28. In the adaptive communications device according to claim 26, wherein said portion of said symbol-mapping means using said superframes consists of a first portion of said symbol-mapping means, said transmitter further including at least a second portion of said symbol-mapping means with each including said frames having an identical frame-averages of said data-bits-per-baud rates;

whereby said second portion of said superframes do not use superframes.

29. In the adaptive communications device according to claim 27, wherein said switching means is operable for including said secondary channel by switching to one of said superframes of said second group from one of said superframes of said first group.

30. In the adaptive communications device according to claim 28, wherein said switching means being operable for including said secondary channel by switching to one of said superframes of said second group from one of said frames having said identical frame-average of data-bits-per-baud rates.

32. In the adaptive communications device according to claim 24, wherein said symbol-mapping means having said superframes each include binary fractional-bit mapping means for using binary fractional-bit mapping for generating said fractional-bits-per-baud rate.

33. In the adaptive communications device according to claim 24, wherein said symbol-mapping means having said superframes each include non-binary fractional-bit mapping means for using non-binary fractional-bit mapping for generating said fractional-bits-per-baud rate.

34. In the adaptive communications device according to claim 24, wherein said symbol-mapping means having said superframes each include whole-bit mapping means for using binary whole-bit mapping for generating said fractional-bits-per-baud rate.

35. In a method for transmitting a plurality of data-bits over a transmission medium, said method includes the steps of providing a plurality of modes of operation;

and, for each mode of operation, mapping, at one of a plurality of data-bits-per-baud rates, said plurality of data bits into one of a plurality of selected symbols, there being one selected symbol for each of a plurality of bauds, said method comprising;

for at least a portion of said modes of operation, using one of a plurality of superframes to specify one of said plurality of data-bits-per-baud rates for each said baud;

each of said superframes including a plurality of frames;

each of said frames including one of said data-bits-per-baud rates for each of a predetermined number of said bauds;

providing each one of said plurality of superframes with at least one of said frames consisting of a low-bit frame and at least one of said frames consisting of a high-bit frame;

the numbers of said low-bit frames and said high bit frames being X and Y, respectively, where both said X and said Y are greater than or equal to one;

each one of said frames being characterized by a frame-average which is an average of said data-bits-per-baud rates for said each frame, said frame-average including a whole-bits-per-baud rate where said frame-average is an integer number and a fractional-bits-per-baud rate where said frame-average is a non-integer number, said frame average of said high-bit frame and said frame average of said low-bit frame being separated by a fractional difference;

for each of said superframes, setting said X of said low-bit frames and said Y of said Y high-bit frames and setting said fractional difference to provide for a predetermined average of said data-bits-per-baud rates in said superframe.

36. In the method according to claim 35, wherein said step of providing further includes providing a first portion of said superframes with one of said low-bit and high-bit frames having said whole-bits-per-baud rate and the other one of said low-bit and high-bit frames having said fractional-bits-per-baud rate;

and a second portion of said superframes with both said low-bit and high-bit frames having different fractional-bits-per-baud rates.

43. In the method according to claim 35, said method further including, for said modes of operation using said superframes, the step of using binary fractional-bit mapping for generating said fractional-bits-per-baud rates specified by said superframes.

44. In the method according to claim 35, said method further including, for said modes of operation using said superframes, the step of using non-binary fractional-bit mapping for generating said fractional-bits-per-baud rates specified by said superframes.

45. In the method according to claim 35, said method further including, for said modes of operation using said superframes, the step of using binary whole-bit mapping for generating said fractional-bits-per-baud rates specified by said superframes.

46. In the method according to claim 35, said method further includes the steps of selecting, for a given said baud, a symbol constellation providing said data-bit-per-baud rate for said given baud;

selecting said selected symbol from a plurality of symbols of said symbol constellation; and

transmitting said selected symbol during said given baud.

47. In the method according to claim 35, said method further includes the steps of selecting, for each of said frames, at least one symbol constellation providing said frame average of said each frame;

selecting said selected symbol, for each of said predetermined number of bauds, from said at least one symbol constellation; and

transmitting said selected symbols.

48. In the method according to claim 47, wherein said at least one symbol constellation includes at least two symbol constellations.

49. In the method according to claim 35, wherein the total number of said bauds in a given said superframe is designated as T and said predetermined number of bauds of each said frame is designated as B, where T is determined by the following equation:

space="preserve" listing-type="equation">T=B(X+Y)

and wherein for a constant said T, said B may be increased if X+Y is proportionately decreased.