MODULATION AND EQUALIZATION IN AN ORTHONORMAL TIME-FREQUENCY SHIFTING COMMUNICATIONS SYSTEM

• US 20140161154A1
• Filed: 06/25/2013
• Published: 06/12/2014
• Est. Priority Date: 05/26/2011
• Status: Active Grant

• Current Assignee: Cohere Technologies Inc
• Original Assignee: Cohere Technologies Inc
• Inventors: Hadani, Ronny, Rakib, Salim Shlomo
• Granted Patent: US 9,031,141 B2
• Time in Patent Office: Days
• US Class Current: 375/138
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04L 23/02 adapted for orthogonal signalling
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2697 in combination with other modulation techniques
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/065 using assembly or disassembly of packets
• CPC Class Codes: H04W 72/00 Local resource management

Abstract

A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

Claims

1. A method of data modulation, comprising:

arranging a set of data elements into an original data frame having a first dimension of N elements and a second dimension of N elements, where N is greater than one;

transforming the original data frame in accordance with a time-frequency shifting matrix so as to form an intermediate data matrix having at least N² elements;

providing a transformed data matrix by permuting at least a portion of the elements of the intermediate data matrix; and

generating a modulated signal based upon elements of the transformed data matrix.

2. The method of claim 1 wherein the generating includes selecting the elements of the transformed data matrix on a column by column basis at different times, wherein the transformed data matrix includes at least N columns and at least N rows.

3. The method of claim 1 wherein the permuting at least a portion of the elements shifts the at least a portion of the elements along a time shift axis of the intermediate data matrix.

4. The method of claim 1 wherein the time-frequency shifting matrix is one of a DFT matrix and an IDFT matrix.

5. The method of claim 1 wherein the original data frame includes a first set of elements associated with a first user device and a second set of elements associated with a second user device.

6. The method of claim 5, wherein the first set of elements is smaller than the second set of elements and wherein first user is associated with a first transmission distance longer than a second transmission distance with which the second user is associated.

7. The method of claim 1 wherein the providing further includes transforming a result of the permuting with a spectral shaping matrix.

8. The method of claim 1 wherein the transformed data matrix includes N columns and N rows and wherein the generating the modulation signal further includes selecting a first set of N modulation elements comprising a first of the N columns and subsequently selecting a second set of N modulation elements comprising a second of the N columns.

9. The method of claim 8 further including timing the selecting the first set of N modulation elements and the selecting of the second set of N modulation elements so as to provide a guard time between transmission of data signals corresponding to the first set of N modulation elements and the second set of N modulation elements.

10. A method of receiving data comprising:

receiving data signals corresponding to a transmitted data frame comprised of a set of data elements;

constructing, based upon the data signals, a received data frame having a first dimension of at least N elements and a second dimension of at least N elements, where N is greater than one;

inverse permuting at least a portion of the elements of the received data frame so as to form an non-permuted data frame; and

inverse transforming the non-permuted data frame in accordance with a first inverse-transformation matrix so as to form a recovered data frame corresponding to a reconstructed version of the transmitted data frame.

11. The method of claim 10 further comprising determining an existence of signal distortion within the received data signals, the signal distortion being indicative of a channel distortion relating to at least one of a frequency shift and a time shift.

12. The method of claim 11 further including transmitting an indication of the signal distortion.

13. The method of claim 11 further including compensating for the channel distortion using a pattern matching technique.

14. The method of claim 11 further including compensating for the channel distortion using an adaptive linear equalization technique.

15. The method of claim 11 further including compensating for the channel distortion using an adaptive decision feedback equalization technique.

16. A data modulator, comprising:

an input port;

an output port;

a processor;

a memory including program code executable by the processor, the program code including;

code for receiving, at the input port, a set of data elements;

code for arranging the set of data elements into an original data frame having a first dimension of N elements and a second dimension of N elements, where N is greater than one;

code for transforming the original data frame in accordance with a time-frequency shifting matrix so as to form an intermediate data matrix having at least N² elements;

code for providing a transformed data matrix by permuting at least a portion of the elements of the intermediate data matrix; and

code for generating a modulated signal based upon elements of the transformed data matrix.

17. The data modulator of claim 16 wherein the code for generating includes code for selecting the elements of the transformed data matrix on a column by column basis at different times, wherein the transformed data matrix includes at least N columns and at least N rows.

18. The data modulator of claim 16 wherein the code for permuting at least a portion of the elements includes code for shifting the at least a portion of the elements along a time shift axis of the intermediate data matrix.

19. The data modulator of claim 16 wherein the time-frequency shifting matrix is one of a DFT matrix and an IDFT matrix.

20. The data modulator of claim 16 wherein the original data frame includes a first set of elements associated with a first user device and a second set of elements associated with a second user device.

21. The data modulator of claim 20 wherein the first set of elements is smaller than the second set of elements and wherein first user is associated with a first transmission distance longer than a second transmission distance with which the second user is associated.

22. The data modulator of claim 16 wherein the code for providing further includes code for transforming a result of the permuting with a spectral shaping matrix.

23. The data modulator of claim 16 wherein the transformed data matrix includes N columns and N rows and wherein the code for generating the modulation signal further includes code for selecting a first set of N modulation elements comprising a first of the N columns and for subsequently selecting a second set of N modulation elements comprising a second of the N columns.

24. The data modulator of claim 23 further including timing the selecting the first set of N modulation elements and the selecting of the second set of N modulation elements so as to provide a guard time between transmission of data signals corresponding to the first set of N modulation elements and the second set of N modulation elements.

25. A data receiver, comprising:

an input port;

an output port;

a processor;

a memory including program code executable by the processor, the program code including;

code for receiving, at the input port, data signals corresponding to a transmitted data frame comprised of a set of data elements;

code for constructing, based upon the data signals, a received data frame having a first dimension of at least N elements and a second dimension of at least N elements, where N is greater than one;

code for inverse permuting at least a portion of the elements of the received data frame so as to form an non-permuted data frame; and

code for inverse transforming the non-permuted data frame in accordance with a first inverse-transformation matrix so as to form a recovered data frame corresponding to a reconstructed version of the transmitted data frame.

26. The data receiver of claim 25 wherein the program code further includes code for determining an existence of signal distortion within the received data signals, the signal distortion being indicative of a channel distortion relating to at least one of a frequency shift and a time shift.

27. The data receiver of claim 26 wherein the data receiver further includes a transmitter, the program code further including code for causing the transmitter to transmit an indication of the signal distortion.

28. The data receiver of claim 26 wherein the program code further includes code for compensating for the channel distortion using a pattern matching technique.

29. The data receiver of claim 26 wherein the program code further includes code for compensating for the channel distortion using an adaptive linear equalization technique.

30. The data receiver of claim 26 wherein the program code further includes code for compensating for the channel distortion using an adaptive decision feedback equalization technique.

31. A non-transitory computer readable medium including program instructions for execution by a processor in a data modulator, the program instructions comprising instructions for causing the processor to:

receive, at an input port of the data modulator, a set of data elements;

arrange a set of data elements into an original data frame having a first dimension of N elements and a second dimension of N elements, where N is greater than one;

transform the original data frame in accordance with a time-frequency shifting matrix so as to form an intermediate data matrix having at least N² elements;

provide a transformed data matrix by permuting at least a portion of the elements of the intermediate data matrix; and

generate a modulated signal based upon elements of the transformed data matrix.

32. The non-transitory computer readable medium of claim 31 wherein the instructions for causing the processor to generate include instructions for causing the processor to select the elements of the transformed data matrix on a column by column basis at different times, wherein the transformed data matrix includes at least N columns and at least N rows.

33. The non-transitory computer readable medium of claim 31 wherein the instructions for causing the processor to permute at least a portion of the elements include instructions for causing the processor to shift the at least a portion of the elements along a time shift axis of the intermediate data matrix.

34. The non-transitory computer readable medium of claim 31 wherein the time-frequency shifting matrix is one of a DFT matrix and an IDFT matrix.

35. The non-transitory computer readable medium of claim 31 wherein the original data frame includes a first set of elements associated with a first user device and a second set of elements associated with a second user device.

36. The non-transitory computer readable medium of claim 31, wherein the first set of elements is smaller than the second set of elements and wherein first user is associated with a first transmission distance longer than a second transmission distance with which the second user is associated.

37. The non-transitory computer readable medium of claim 31 wherein the instructions for causing the processor to provide further include instructions for transforming a result of the permuting with a spectral shaping matrix.

38. The non-transitory computer readable medium of claim 31 wherein the transformed data matrix includes N columns and N rows and wherein the instructions for causing the processor to generate the modulation signal further include includes instructions for causing the processor to select a first set of N modulation elements comprising a first of the N columns and to subsequently select a second set of N modulation elements comprising a second of the N columns.

39. The non-transitory computer readable medium of claim 38 wherein the program instructions further include instructions for causing the processor to time selection of the first set of N modulation elements and selection of the second set of N modulation elements so as to provide a guard time between transmission of data signals corresponding to the first set of N modulation elements and the second set of N modulation elements.

40. A non-transitory computer readable medium including program instructions for execution by a processor in a data receiver, the program instructions comprising instructions for causing the processor to:

receive, at an input port of the data receiver, data signals corresponding to a transmitted data frame comprised of a set of data elements;

construct, based upon the data signals, a received data frame having a first dimension of at least N elements and a second dimension of at least N elements, where N is greater than one;

inverse permute at least a portion of the elements of the received data frame so as to form an non-permuted data frame; and

inverse transform the non-permuted data frame in accordance with a first inverse-transformation matrix so as to form a recovered data frame corresponding to a reconstructed version of the transmitted data frame.

41. The non-transitory computer readable medium of claim 40 wherein the program instructions further include instructions for causing the processor to determine an existence of signal distortion within the received data signals, the signal distortion being indicative of a channel distortion relating to at least one of a frequency shift and a time shift.

42. The non-transitory computer readable medium of claim 41 wherein the program instructions further include instructions for causing the processor to transmit an indication of the signal distortion.

43. The non-transitory computer readable medium of claim 41 wherein the program instructions further include instructions for causing the processor to compensate for the channel distortion using a pattern matching technique.

44. The non-transitory computer readable medium of claim 41 wherein the program instructions further include instructions for causing the processor to compensate for the channel distortion using an adaptive linear equalization technique.

45. The non-transitory computer readable medium of claim 41 wherein the program instructions further include instructions for causing the processor to compensate for the channel distortion using an adaptive decision feedback equalization technique.