Orthonormal time-frequency shifting and spectral shaping communications method

• US 9,083,483 B1
• Filed: 07/27/2014
• Issued: 07/14/2015
• Est. Priority Date: 05/28/2010
• Status: Active Grant

• Current Assignee: Cohere Technologies Inc
• Original Assignee: Cohere Technologies Inc
• Inventors: Rakib, Shlomo Selim, Hadani, Ronny
• Primary Examiner(s): ADHAMI, MOHAMMAD SAJID
• Application Number:
  US14/341,820
• Time in Patent Office: 352 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04J 11/0063 of multipath interference, e.g. Rake receivers
• CPC Class Codes: H04L 23/02 adapted for orthogonal signalling
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2697 in combination with other modulation techniques
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04W 28/065 using assembly or disassembly of packets
• CPC Class Codes: H04W 72/00 Local resource management

Abstract

A wireless combination time, frequency and spectral shaping communications method that transmits data in convolution unit matrices (data frames) of N×N (N²), where generally either all N² data symbols are received over N spreading time intervals (each composed of N time slices), or none are. To transmit, the N² sized data frame matrix is multiplied by a first N×N time-frequency shifting matrix, permuted, and then multiplied by a second N×N spectral shaping matrix, thereby mixing each data symbol across the entire resulting N×N matrix (TFSSS data matrix). Columns from this N² TFSSS data matrix are selected, modulated, and transmitted, on a one element per time slice basis. At the receiver, the replica TFSSS matrix is reconstructed and deconvoluted, revealing the data. The method can accommodate multiple users at once, can adapt to changing channel conditions, and is particularly useful for coping with channel impairments such as Doppler shifts.

Claims

1. A method of transmitting and receiving at least one frame of data ([D]) over a communications link, said frame of data comprising a matrix of up to N² data elements, N being greater than 1, said method comprising:

obtaining an orthonormal matrix set,

said orthonormal matrix set comprising a first N×

N matrix ([U₁]) and a second N×

N matrix ([U₂]);

wherein said communications link and said orthonormal matrix set are chosen to be capable of transmitting at least N elements from a matrix product of said first N×

N matrix ([U₁]), a frame of data ([D]), and said second N×

N matrix ([U₂]) over one time spreading interval;

said time spreading interval consisting of at least N time slices;

forming a first matrix product of said first N×

N matrix (pa and said frame of data ([D]);

permuting said first matrix product by an invertible permutation operation P forming a permuted first matrix product P([U₁][D]);

forming a second matrix product of said permuted first matrix product P([U₁][D]) and said second matrix ([U₂]) forming a convoluted data matrix;

transmitting, using a hybrid analog and digital transmitter, and receiving, using a hybrid analog and digital wireless receiver, said convoluted data matrix over said communications link by the steps of;

1;

for each single time-spreading interval, selecting N different elements of said convoluted data matrix;

2;

over different said time slices in said time spreading interval, using said transmitter to perform the process of selecting said N different elements of said convoluted data matrix, modulating said N different elements, and transmitting said N different elements so that each said N different elements are transmitted over said time spreading interval;

3;

using said receiver to perform the process of receiving said N different elements of said convoluted data matrix over different said time slices in said time spreading interval;

4;

demodulating said N different elements of said convoluted data matrix;

repeating steps 1, 2, 3, and 4 up to total of N times, thereby reassembling a replica of said convoluted data matrix at said receiver;

using said receiver, said first N×

N matrix ([U₁]) and said second N×

N matrix ([U₂]) to reconstruct said frame of data ([D]) from said convoluted data matrix; and

wherein an arbitrary data element of an arbitrary frame of data ([D]) cannot be guaranteed to be reconstructed with full accuracy until a substantially complete replica of said convoluted data matrix has been recovered.

2. The method of claim 1, wherein said first matrix ([U₁]) and said second matrix ([U₂]) are selected from the group consisting of 1:

said first matrix ([U₁]) is a DFT matrix and said second matrix ([U₂]) is a Hadamard matrix, 2;

said first matrix ([U₁]) is a DFT matrix and said second matrix ([U₂]) is a chirp matrix, 3;

said first matrix ([U₁]) is a DFT matrix and said second matrix ([U₂]) is a DFT matrix.

3. The method of claim 1, wherein said first N×

N matrix ([U_i]) is a time-frequency shifting matrix ([U₁]), and said second N×

N matrix ([U₂]) is a spectral-shaping matrix ([U₂]).

4. The method of claim 1, wherein after forming a first matrix product of said first N×

N matrix ([U₁]), and said frame of data ([D]), and permuting said first matrix product by an invertible permutation operation P thereby, forming a permuted first matrix product P([U₁][D]) further following the steps comprising;

at said transmitter, using a third unitary N×

N matrix ([U₃]), which is a DFT matrix or an IDFT matrix, to matrix multiply said permuted first matrix product P([U₁][D]); and

at said receiver using said third unitary matrix ([U₃]) to reconstruct said frame of data ([D]).

20. The method of claim 1, wherein said N different elements are transmitted over said time spreading interval as complex sinusoidal shaped waveforms described by a Fourier vector;

wherein said first N×

N matrix ([U₁]) comprise rows corresponding to at least one of Legendre symbols or spreading sequences, and wherein each successive row is a cyclically shifted version of said at least one of Legendre symbols or spreading sequences in the row above it;

wherein for said transmission, said second N×

N matrix ([U₂]) comprise either a Discrete Fourier Transform Matrix (DFT) or Inverse Discrete Fourier Transform (IDFT);

further using said N×

N matrix ([U₂]) and said hybrid analog and digital wireless transmitter to modulate said permuted first matrix product P([U₁][D]) into a series of complex sinusoidal waveforms of the type

24. The method of claim 1, wherein between each repeating step of transmitting said N different elements over said time spreading interval, further allocating extra time slices before repeating.

5. A method of transmitting and receiving at least one frame of data ([D]) over a communications link, said frame of data comprising a matrix of up to N² data elements, N being greater than 1, said method comprising:

obtaining an orthonormal time-frequency shifting and spectral shaping matrix set,

said orthonormal time-frequency shifting and spectral shaping matrix set comprising a first N×

N time-frequency shifting matrix ([U₁]) and a second N×

N spectral-shaping matrix ([U₂]);

wherein said communications link and said orthonormal time-frequency shifting and spectral-shaping matrix set are chosen to be capable of transmitting at least N elements from a matrix product of said first N×

N time-frequency shifting matrix ([U₁]), a frame of data ([D]), and said second N×

N spectral shaping matrix ([U₂]) over one time spreading interval;

said time spreading interval consisting of at least N time slices;

forming a first matrix product of said first N×

N time-frequency shifting matrix ([U₁]), and said frame of data ([D]);

permuting said first matrix product by an invertible permutation operation P forming a permuted first matrix product P([U₁][D]);

forming a second matrix product of said permuted first matrix product P([U₁][D]) and said spectral-shaping matrix ([U₂]) forming a time-frequency-shifted spectral-shaping data matrix (TFSSS data matrix);

transmitting, using a hybrid analog and digital transmitter, and receiving, using a hybrid analog and digital wireless receiver, said TFSSS data matrix over said communications link by the steps of;

1;

for each single time-spreading interval, selecting N different elements of said TFSSS data matrix;

2;

over different said time slices in said time spreading interval, using said transmitter to perform the process of selecting said N different elements of said TFSSS data matrix, modulating said N different elements, and transmitting said N different elements so that each said N different elements are transmitted over said time spreading interval;

3;

using said receiver to perform the process of receiving said N different elements of said TFSSS data matrix over different said time slices in said time spreading interval;

4;

demodulating said N different elements of said TFSSS data matrix;

repeating steps 1, 2, 3, and 4 up to total of N times, thereby reassembling a replica of said TFSSS data matrix at said receiver;

using said receiver, said first N×

N time-frequency shifting matrix ([U₁]) and said second N×

N spectral shaping matrix ([U₂]) to reconstruct said frame of data ([D]) from said TFSSS data matrix; and

wherein an arbitrary data element of an arbitrary frame of data ([D]) cannot be guaranteed to be reconstructed with full accuracy until a substantially complete replica of said TFSSS data matrix has been recovered.

6. The method of claim 5, in which said first N×

N time-frequency shifting matrix ([U₁]) is a Discrete Fourier Transform (DFT) matrix, and the second N×

N spectral-shaping matrix ([U₂]) is composed of cyclically shifted Legendre symbols.

7. The method of claim 5, in which said first N×

N time-frequency shifting matrix ([U₁]) is composed of cyclically shifted Legendre symbols, and the second N×

N spectral-shaping matrix ([U₂]) is a Discrete Fourier Transform (DFT) matrix.

8. The method of claim 5, wherein said time-frequency shifting matrix ([U₁]) and said spectral-shaping matrix ([U₂]) are selected from the group consisting of 1:

said time frequency shifting matrix ([U₁]) is a DFT matrix and said spectral-shaping matrix ([U₂]) is a Hadamard matrix, 2;

said time-frequency shifting matrix ([U₁]) is a DFT matrix and said spectral-shaping matrix ([U₂]) is a chirp matrix, 3;

said time-frequency-shifting matrix ([U₁]) is a DFT matrix and said spectral-shaping matrix ([U₂]) is a DFT matrix.

9. The method of claim 5, wherein said orthonormal time-frequency shifting and spectral shaping matrix set are chosen based upon communications link conditions.

10. The method of claim 5, in which a plurality of different transmitters may communicate over said communications link by each selecting different or non-overlapping data elements of said frame of data to use to transmit or receive their respective data.

11. The method of claim 10, wherein said first N×

N time-frequency shifting matrix ([U₁]) and said second N×

N spectral-shaping matrix ([U₂]) are selected to minimize the impact of an aberrant transmitter suffering from Doppler shift or frequency shift on adjacent elements to the elements of said TFSSS data matrix occupied by said aberrant transmitter.

12. The method of claim 10, in which a transmitter suffering from Doppler shift or frequency shift is detected by at least one receiver and instructed to correct for said Doppler shift or said frequency shift.

13. The method of claim 5, in which said first N×

N time-frequency shifting matrix ([U₁]), is a matrix of Orthogonal Frequency Division Multiplexing (OFDM) spreading codes, and said second N×

N spectral-shaping-matrix ([U₂]) is a matrix of Code Division Multiple Access (CDMA) spreading codes.

14. The method of claim 5, in which said permutation operation P is an identity operation.

15. The method of claim 5, in which selecting N different elements of said TFSSS data matrix is done by selecting said N different elements from the columns of said TFSSS data matrix.

21. The method of claim 5, wherein said N different elements are transmitted over said time spreading interval as complex sinusoidal shaped waveforms described by a Fourier vector;

wherein said first N×

N matrix ([U₁]) comprise rows corresponding to at least one of Legendre symbols or spreading sequences, and wherein each successive row is a cyclically shifted version of said at least one of Legendre symbols or spreading sequences in the row above it;

wherein for said transmission, said second N×

N matrix ([U₂]) comprise either a Discrete Fourier Transform Matrix (DFT) or Inverse Discrete Fourier Transform (IDFT);

further using said N×

N matrix ([U₂]) and said hybrid analog and digital wireless transmitter to modulate said permuted first matrix product P([U₁][D]) into a series of complex sinusoidal waveforms of the type

25. The method of claim 5, wherein between each repeating step of transmitting said N different elements over said time spreading interval, further allocating extra time slices before repeating.

16. A method of transmitting at least one frame of data ([D]) over a communications link, said frame of data comprising a matrix of up to N² data elements, N being greater than 1, said method comprising:

obtaining an orthonormal matrix set,

said orthonormal matrix set comprising a first N×

N matrix ([U₁]) and a second N×

N matrix ([U₂]);

wherein said communications link and said orthonormal matrix set are chosen to be capable of transmitting at least N elements from a matrix product of said first N×

N matrix ([U₁]) a frame of data ([D]), and said second N×

N matrix ([U₂]) over one time spreading interval;

said time spreading interval consisting of at least N time slices;

forming a first matrix product of said first N×

N matrix (pa and said frame of data ([D]);

permuting said first matrix product by an invertible permutation operation P forming a permuted first matrix product P([U₁][D]);

forming a second matrix product of said permuted first matrix product P([U₁][D]) and said second matrix ([U₂]), thus forming a convoluted data matrix;

transmitting, using a hybrid analog and digital transmitter, and receiving, using a hybrid analog and digital wireless receiver, said convoluted data matrix over said communications link by the steps of;

1;

for each single time-spreading interval, selecting N different elements of said convoluted data matrix;

2;

over different said time slices in said time spreading interval, selecting said N different elements of said convoluted data matrix, modulating said N different elements, and transmitting said N different elements so that each said N different elements are transmitted over said time spreading interval;

repeating steps 1, and 2, up to total of N times, until a substantially complete replica of said convoluted data matrix has been transmitted.

17. The method of claim 16, wherein said hybrid analog and digital wireless transmitter comprises a microprocessor or a digital signal processor.

22. The method of claim 16, wherein said N different elements are transmitted over said time spreading interval as complex sinusoidal shaped waveforms described by a Fourier vector;

wherein said first N×

N matrix ([U₁]) comprise rows corresponding to at least one of Legendre symbols or spreading sequences, and wherein each successive row is a cyclically shifted version of said at least one of Legendre symbols or spreading sequences in the row above it;

wherein for said transmission, said second N×

N matrix ([U₂]) comprise either a Discrete Fourier Transform Matrix (DFT) or Inverse Discrete Fourier Transform (IDFT);

further using said N×

N matrix ([U₂]) and said hybrid analog and digital wireless transmitter to modulate said permuted first matrix product P([U₁][D]) into a series of complex sinusoidal waveforms of the type

26. The method of claim 16, wherein between each repeating step of transmitting said N different elements over said time spreading interval, further allocating extra time slices before repeating.

18. A method of receiving at least one frame of data ([D]) over a communications link, said frame of data comprising a matrix of up to N² data elements, N being greater than 1, said method comprising:

obtaining an orthonormal matrix set and a permutation operation P used by at least one transmitter to transmit said at least one frame of data [D],

said orthonormal matrix set comprising a first N×

N matrix ([U₁]) and a second N×

N matrix ([U₂]);

said orthonormal matrix set is chosen to be capable of receiving at least N elements from a matrix product of said first N×

N matrix ([U₁]), a frame of data ([D]), and said second N×

N matrix ([U₂]) over one time spreading interval;

said time spreading interval consisting of at least N time slices;

receiving, using a hybrid analog and digital wireless receiver, using said receiver, a replica of a convoluted [P([U₁][D])][U₂] data matrix over said communications link by the steps of;

1;

for each single time-spreading interval, receiving transmitted signals corresponding to substantially all of said N elements;

2;

demodulating substantially all of said N different elements;

repeating steps 1, and 2 up to total of N times, thereby reassembling a replica of said convoluted [P([U₁][D])][U₂] data matrix at said receiver;

using said permutation operation P, said first N×

N matrix ([U₁]) and said second N×

N matrix ([U₂]) to reconstruct said frame of data ([D]) from said replica of a convoluted [P([U₁][D])][U₂] data matrix; and

wherein an arbitrary data element of an arbitrary frame of data ([D]) cannot be guaranteed to be reconstructed with full accuracy until a substantially complete replica of a convoluted [P([U₁][D])][U₂] data matrix has been recovered.

19. The method of claim 18, wherein said hybrid analog and digital wireless receiver comprises a microprocessor or a digital signal processor.

23. The method of claim 18, wherein said N different elements were previously transmitted by a hybrid analog and digital wireless transmitter over said time spreading interval as complex sinusoidal shaped waveforms described by a Fourier vector;

wherein said first N×

N matrix ([U₁]) comprised rows corresponding to at least one of Legendre symbols or spreading sequences, and wherein each successive row was a cyclically shifted version of said at least one of Legendre symbols or spreading sequences in the row above it;

wherein for said previous transmission, said second N×

N matrix ([U₂]) comprised either a Discrete Fourier Transform Matrix (DFT) or Inverse Discrete Fourier Transform (IDFT);

wherein said previous transmission further used said N×

N matrix ([U₂]) and said hybrid analog and digital wireless transmitter to modulate said permuted first matrix product P([U₁][D]) into a series of complex sinusoidal waveforms of the type

27. The method of claim 18, wherein between each repeating step of transmitting said N different elements over said time spreading interval, further allocating extra time slices before repeating.