Method and radio system for digital signal transmission using complex space-time codes

• US RE43,746 E1
• Filed: 06/22/2011
• Issued: 10/16/2012
• Est. Priority Date: 02/22/2000
• Status: Expired due to Fees

• Current Assignee: CommWorks Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Amosmet Investments LLC (Intellectual Ventures LLC)
• Inventors: Hottinen, Ari, Tirkkonen, Olav
• Primary Examiner(s): Tran, Khai
• Application Number:
  US13/166,702
• Time in Patent Office: 482 Days
• Field of Search: 275/299, 275/222, 275/267, 275/347, 275/223, 341/106, 341/174, 370/203, 370/208
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/0618 Space-time coding

Abstract

The invention relates to a method and an arrangement for transmitting a digital signal consisting of symbols, which arrangement comprises a coder (308) for coding complex symbols to channel symbols in blocks having the length of a given K, means (312) for transmitting the channel symbols via several different channels and two or more antennas (314 to 318). The coder (308) is arranged to code the symbols using a code matrix, which can be expressed as a sum of 2K elements, in which each element is a product of a symbol or symbol complex conjugate to be transmitted and a N×N representation matrix of a complexified anti-commutator algebra, extended by a unit element, and in which each matrix is used at most once in the formation of the code matrix. A code matrix is also provided which is formed by matrices of a portion of the symbols placed on the diagonal of the code matrix and by matrices of a second portion of symbols along the anti-diagonal of the code matrix.

Claims

1. A method of transmitting a signal consisting of symbols comprising the steps of:

coding complex symbols to channel symbols in blocks having the length of a given K, wherein the coding is defined by a code matrix, which can be expressed as a sum of 2K elements, in which each element is a product of a symbol or symbol complex conjugate to be transmitted and a N×

N representation matrix of a complexified anti-commutator algebra, extended by a unit element, and in which each matrix is used at most once in the formation of the code matrix; and

transmitting the symbols via several different channels and a plurality of antennas.

2. The method of claim 1, wherein the step of signal coding further comprises negation and repetition of at least some symbols.

3. The method of claim 1, wherein the step of transmitting the channel symbols comprises the steps of:

dividing the channel symbols into several time slots; and

transmitting the divided channel symbols via a plurality of antennas.

4. The method of claim 1, wherein the step of transmitting the channel symbols comprises the steps of:

dividing the channel symbols into several frequencies; and

transmitting the divided channel symbols via a plurality of antennas.

5. The method of claim 1, wherein the step of transmitting the channel symbols comprises the steps of:

multiplying the channel symbols by several spreading codes; and

transmitting the channel symbols via two or more antennas.

6. The method of claim 1, further comprising the step of multiplying the code matrix by unitary matrices.

7. The method of claim 6, wherein the unitary matrices are selected such that power levels of the antennas used in the signal transmission are equally high on the average.

8. The method of claim 6, wherein the unitary matrices are selected such that the difference between the highest and the lowest power level of the antennas used in the signal transmission is as small as possible.

9. The method of claim 6, wherein the unitary matrices are selected such that the difference between a power level peak value and a power level average value of the antennas used in the signal transmission is as small as possible.

10. The method of claim 3, wherein the number of antennas being N at the most and the number of time slots being N.

11. The method of claim 4, wherein the number of antennas being N at the most and the number of frequencies being N.

12. The method of claim 5, wherein the number of antennas being N at the most and the number of spreading codes being N.

13. The method of claim 1, wherein the number of transmit antennas being the same as the number of columns in the code matrix.

14. The method of claim 1, further comprising step of deleting one or more columns from the code matrix before the step of transmitting.

15. The method of claim 1, wherein the code matrix includes zero elements.

16. The method of claim 1, wherein the step of transmitting comprises the steps of transmitting at least two parallel channels simultaneously and by implementing a power uniformization between the channels by permutating the antennas in the code matrix.

17. The method of claim 1, wherein the step of transmitting comprises the steps of transmitting at least two parallel channels simultaneously and by implementing a power uniformization between the channels such that instead of transmitting zeros of the code matrix, orthogonalized information is transmitted.

18. A method of transmitting a signal consisting of symbols comprising the steps of:

coding complex symbols to channel symbols in blocks having the length of a given K, comprising the steps of;

forming a code matrix freely selecting 2K−

1 unitary, antihermitean N×

N matrices anticommuting with each other;

forming K−

1 pairs of the matrices, wherein the remaining matrix forms a pair with an N-dimensional unit matrix;

forming two matrices of each the pair wherein a second matrix of the pair, multiplied by an imaginary unit, is added to and subtracted from a first matrix of the pair, and in which each matrix formed in the above manner defines the dependence of the code matrix on one symbol or symbol complex conjugate to be coded; and

transmitting the channel symbols via several different channels and a plurality of antennas.

19. The method of claim 18, wherein the step of signal coding further comprises negation and repetition of at least some symbols.

20. The method of claim 18, wherein the step of transmitting the channel symbols comprises the steps of:

dividing the channel symbols into several time slots; and

transmitting the divided channel symbols via a plurality of antennas.

21. The method of claim 18, wherein the step of transmitting the channel symbols comprises the steps of:

dividing the channel symbols into several frequencies; and

transmitting the divided channel symbols via a plurality of antennas.

22. The method of claim 18, wherein the step of transmitting the channel symbols comprises the steps of:

multiplying the channel symbols by several spreading codes; and

transmitting the channel symbols via two or more antennas.

23. The method of claim 18, further comprising the step of multiplying the code matrix by unitary matrices.

24. The method of claim 23, wherein the unitary matrices are selected such that power levels of the antennas used in the signal transmission are equally high on average.

25. The method of claim 23, wherein the unitary matrices are selected such that the difference between a highest and a lowest power level of the antennas used in the signal transmission is as small as possible.

26. The method of claim 23, wherein the unitary matrices are selected such that the difference between a power level peak value and a power level average value of the antennas used in the signal transmission is as small as possible.

27. The method of claim 20, wherein the number of antennas being N at the most and the number of time slots being N.

28. The method of claim 21, wherein the number of antennas being N at the most and the number of frequencies being N.

29. The method of claim 22, wherein the number of antennas being N at the most and the number of spreading codes being N.

30. The method of claim 18, wherein the number of transmit antennas being the same as the number of columns in the code matrix.

31. The method of claim 18, further comprising step of deleting one or more columns from the code matrix before the step of transmitting.

32. The method of claim 18, wherein the code matrix includes zero elements.

33. The method of claim 18, wherein the step of transmitting comprises the steps of transmitting at least two parallel channels simultaneously and by implementing a power uniformization between the channels by permutating the antennas in the code matrix.

34. The method of claim 18, wherein the step of transmitting comprises the steps of transmitting at least two parallel channels simultaneously and by implementing a power uniformization between the channels such that instead of transmitting zeros of the code matrix, orthogonalized information is transmitted.

35. An arrangement for transmitting a signal consisting of symbols comprising:

a coder for coding complex symbols to channel symbols in blocks having the length of a given K; and

means for transmitting the channel symbols via several different channels and a plurality of antennas;

wherein the coder is arranged to code the symbols using a code matrix, which can be expressed as a sum of 2K elements, in which each element is a product of a symbol or symbol complex conjugate to be transmitted and a N×

N representation matrix of a complexified anti-commutator algebra, extended by a unit element, and in which each matrix is used at most once in the formation of the code matrix.

36. The arrangement of claim 35, further comprising a means for transmitting the channel symbols, divided into several time slots, via a plurality of antennas.

37. The arrangement of claim 35, further comprising a means for transmitting the channel symbols, divided into several frequencies, via a plurality of antennas.

38. The arrangement of claim 35, further comprising a means for transmitting the channel symbols multiplied by several spreading codes, via a plurality of antennas.

39. The arrangement of claim 36, wherein the number of antennas is N at the most and the number of time slots is N.

40. The arrangement of claim 37, wherein the number of antennas is N at the most and the number of frequencies is N.

41. The arrangement of claim 38, wherein the number of antenna is N at the most and the number of spreading codes is N.

42. The arrangement of claim 35, wherein the number of transmit antennas is the same as the number of columns in the code matrix.

43. The arrangement of claim 35, wherein the coder is arranged to code the symbols by using the code matrix from which one or more columns are deleted.

44. An arrangement for transmitting a signal consisting of symbols comprising:

a coder for coding complex symbols to channel symbols in blocks having the length of a given K; and

means for transmitting the channel symbols via several different channels and plurality of antennas;

wherein the coder is arranged to code the symbols using a code matrix which is formed by freely selecting 2K−

1 unitary, anti-hermitean N×

N matrices anti-commuting with each other, forming K−

1 pairs of the matrices, whereby the remaining matrix forms a pair with an N-dimensional unit matrix, forming two matrices of each pair such that a second matrix of the pair, multiplied by an imaginary unit, is added to and subtracted from the first matrix of the pair, and in which each matrix formed in the above manner defines the dependence of the code matrix on one symbol or symbol complex conjugate to be coded.

45. The arrangement of claim 44, further comprising a means for transmitting the channel symbols, divided into several time slots, via a plurality of antennas.

46. The arrangement of claim 44, further comprising a means for transmitting the channel symbols, divided into several frequencies, via a plurality of antennas.

47. The arrangement of claim 44, further comprising a means for transmitting the channel symbols multiplied by several spreading codes, via a plurality of antennas.

48. The arrangement of claim 45, wherein the number of antennas is N at the most and the number of time slots is N.

49. The arrangement of claim 46, wherein the number of antennas is N at the most and the number of frequencies is N.

50. The arrangement of claim 47, wherein the number of antenna is N at the most and the number of spreading codes is N.

51. The arrangement of claim 44, wherein the number of transmit antennas is the same as the number of columns in the code matrix.

52. The arrangement of claim 44, wherein the coder is arranged to code the symbols by using the code matrix from which one or more columns are deleted.