Technique for designing a multidimensional signaling scheme

• US 5,115,453 A
• Filed: 10/01/1990
• Issued: 05/19/1992
• Est. Priority Date: 10/01/1990
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Ozarow, Lawrence H., Calderbank, Arthur R.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): TSE, YOUNG TOI
• Application Number:
  US07/590,849
• Time in Patent Office: 596 Days
• Field of Search: 375/37, 375/38, 375/39, 371/37.8, 371/43, 332/103
• US Class Current: 375/265
• CPC Class Codes: H03M 13/25 Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] modulation codes H03M13/31
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• CPC Class Codes: H04L 27/3438 using an underlying generalised cross constellation

Abstract

In a system where a signal constellation is used for data communications, signal points in the signal constellation are selected to represent incoming data. The signal points, thus selected, are transmitted through a channel. The signal constellation is divided into a plurality of regions each including an equal number of signal points. A coding scheme is employed to ensure that signal points within any one region are selected equiprobably, and the probability of selecting any signal point in one region is different from that in another region.

Claims

1. Data transmission apparatus comprising

means for selecting signal points in a signal constellation in response to incoming data, said signal constellation including a plurality of regions with each region having an identical number of signal points, said selecting means carrying out said selecting in accordance with a predetermined signal point probability distribution in which the selection of signal points within any one region is equally probable and the probability of selecting any signal point in one region is different from that in another region, and

means for transmitting a signal representative of the selected signal points.

2. The apparatus of claim 1 wherein said selecting means further includes means for mapping a first number of bits in said incoming data into a second number of bits, said second number being greater than said first number.

3. The apparatus of claim 2 wherein a predetermined subset of said second number of bits determines said predetermined probability distribution.

4. The apparatus of claim 1 wherein said signal constellation is multidimensional.

5. The apparatus of claim 1 wherein said incoming data is encoded with a trellis code.

6. The apparatus of claim 1 wherein said predetermined probability distribution is designed so as to decrease a peak-to-average-power ratio (PAR) and increase a shape gain associated with said signal constellation.

7. Apparatus for transmitting a plurality of signal points in a signal constellation, each of said plurality of signal points representing incoming data, said apparatus comprising

means for defining a plurality of regions within said constellation, each one of said regions including an identical number of signal points, and

means for assigning a plurality of probabilistic values to said regions so that each one of said regions is assigned a different one of said probabilistic values, and for selecting signal points in any particular one of said regions with a probability equal to the probabilistic value assigned to that particular region.

8. The apparatus of claim 7 wherein said apparatus further includes means for mapping a first number of bits in said incoming data into a second number of bits, said second number being greater than said first number.

9. The apparatus of claim 7 wherein said signal constellation is multidimensional.

10. The apparatus of claim 7 wherein said incoming data is encoded with a trellis code.

11. The apparatus of claim 7 wherein said plurality of probabilistic values are so determined as to decrease a PAR and increase a shape gain associated with said signal constellation.

12. A communications system using a signal constellation, which includes a plurality of signal points, to communicate data, said communications system comprising

means for selecting ones of said signal points in said signal constellation for transmission, said signal constellation including a plurality of regions with each region having an identical number of signal points, said selecting means carrying out said selecting in accordance with a predetermined signal point probability distribution in which the selection of signal points within any one region is equally probable and the probability of selecting any signal point in one region is different from that in another region,

means for transmitting a signal representing the selected signal points, and

means responsive to said signal for recovering said selected signal points.

13. The system of claim 12 wherein said selecting means further includes means for mapping a first number of bits in said data into a second number of bits, said second number being greater than said first number.

14. The system of claim 13 wherein a predetermined subset of said second number of bits determines said predetermined probability distribution.

15. The system of claim 12 wherein said signal constellation is multidimensional.

16. The system of claim 12 wherein said data is encoded with a trellis code.

17. The system of claim 12 wherein said predetermined probability distribution is designed so as to decrease a PAR and increase a shape gain associated with said signal constellation.

18. A method for transmitting data, said method comprising the steps of

selecting signal points in a signal constellation in response to incoming data, said signal constellation including a plurality of regions with each region having an identical number of signal points, said selecting means carrying out said selecting in accordance with a predetermined signal point probability distribution in which the selection of signal points within any one region is equally probable and the probability of selecting any signal point in one region is different from that in another region, and

transmitting a signal representative of the selected signal points.

19. The method of claim 18 wherein said selecting step further includes the step of mapping a first number of bits in said incoming data into a second number of bits, said second number being greater than said first number.

20. The method of claim 19 wherein a predetermined subset of said second number of bits determines said predetermined probability distribution.

21. The method of claim 18 wherein said signal constellation is multidimensional.

22. The method of claim 18 wherein said incoming data is encoded with a trellis code.

23. The method of claim 18 wherein said predetermined probability distribution is designed so as to decrease a PAR and a shape gain associated with said signal constellation.

24. A method for transmitting a plurality of signal points in a signal constellation, each of said plurality of signal points representing incoming data, said method comprising the steps of

defining a plurality of regions within said constellation, each one of said regions including an identical number of signal points,

assigning a plurality of probabilistic values to said regions so that each one of said regions is assigned a different one of said probabilistic values, and

selecting signal points from any particular one of said regions with a probability equal to the probabilistic value assigned to that particular region.

25. The method of claim 24 wherein said method further includes the step of mapping a first number of bits in said incoming data into a second number of bits, said second number being greater than said first number.

26. The method of claim 24 wherein said signal constellation is multidimensional.

27. The method of claim 24 wherein said incoming data is encoded with a trellis code.

28. The method of claim 27 wherein said plurality of probabilistic values are so determined as to decrease a PAR and a shape gain associated with said signal constellation.

29. A method for use in a communications system employing a signal constellation to communicate data, said signal constellation includes a plurality of signal points, said method comprising the steps of

selecting ones of said signal points in said signal constellation for transmission, said signal constellation including a plurality of regions with each region having an identical number of signal points, said selecting step carrying out said selecting in accordance with a predetermined signal point probability distribution in which the selection of signal points within any one region is equally probable and the probability of selecting any signal point in one region is different from that in another region,

transmitting a signal representing the selected signal points, and

recovering said selected signal points in response to said signal.

30. The method of claim 29 wherein said selecting step further includes the step of mapping a first number of bits in said data into a second number of bits, said second number being greater than said first number.

31. The method of claim 30 wherein a predetermined subset of said second number of bits determines said predetermined probability distribution.

32. The method of claim 29 wherein said signal constellation is multidimensional.

33. The method of claim 29 wherein said data is encoded with a trellis code.

34. The method of claim 29 wherein said predetermined probability distribution is designed so as to decrease a PAR and increase a shape gain associated with said signal constellation.