Orthogonal time frequency space communication system compatible with OFDM

• US 9,912,507 B2
• Filed: 06/27/2016
• Issued: 03/06/2018
• Est. Priority Date: 06/25/2012
• Status: Active Grant

• Current Assignee: Cohere Technologies Inc
• Original Assignee: Cohere Technologies Inc
• Inventors: Rakib, Selim Shlomo, Hadani, Ronny
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US15/194,494
• Publication Number:
  US 20170149595A1
• Time in Patent Office: 617 Days
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04L 23/02 adapted for orthogonal signalling
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 27/2639 Modulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2697 in combination with other modulation techniques
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks

Abstract

A system and method for orthogonal time frequency space communication and waveform generation. The method includes receiving a plurality of information symbols and encoding an N×M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency. The two-dimensional array of modulation symbols is then transmitted using M mutually orthogonal waveforms included within M frequency sub-bands.

Claims

1. A wireless device, comprising:

a data modulator including an input for receiving a plurality of information symbols, the data modulator encoding an N×

M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency wherein the encoding performed by the data modulator includes;

transforming the N×

M array into an array of filtered OFDM symbols using at least one Fourier transform and a filtering process;

transforming the array of filtered OFDM symbols into an array of orthonormal time-frequency shifting (OTFS) symbols using at least one two-dimensional Fourier transform wherein the array of OTFS symbols corresponds to the two-dimensional array of modulation symbols; and

a transmitter configured to transmit the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.

2. The wireless device of claim 1 wherein the transmitter is further configured to use a set of M narrow-band filters to produce the M waveforms.

3. A wireless device, comprising:

a data modulator including an input for receiving a plurality of information symbols, the data modulator encoding an N×

M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency wherein the encoding performed by the data modulator includes combining an inverse symplectic transform with a windowing operation; and

a transmitter configured to transmit the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.

4. A wireless device, comprising:

a data modulator including an input for receiving a plurality of information symbols, the data modulator encoding an N×

M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency wherein the encoding is performed in accordance with the following relationship;

5. A wireless device, comprising:

a data modulator including an input for receiving a plurality of information symbols, the data modulator encoding an N×

M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency wherein the encoding performed by the data modulator includes-spreading each of the plurality of data symbols using a set of cyclically time-shifted and frequency-shifted basis functions; and

a transmitter configured to transmit the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.

6. The wireless device of claim 5, wherein the encoding performed by the data modulator includes:

transforming the N×

M two-dimensional array of data symbols into an array of filtered OFDM symbols using at least one Fourier transform and a filtering process; and

transforming the array of filtered OFDM symbols into an array of orthonormal time-frequency shifting (OTFS) symbols using at least one two-dimensional Fourier transform wherein the array of OTFS symbols corresponds to the two-dimensional array of modulation symbols.

7. The wireless device of claim 5, wherein said encoding performed by the data modulator includes:

encoding the N×

M two-dimensional array containing the plurality of data symbols onto at least one symplectic-like analysis compatible manifold distributed over a column time axis of length T and row frequency axis of length F, thereby producing at least one Information manifold;

transforming the at least one Information manifold in accordance with a two-dimensional symplectic-like Fourier transform, thereby producing at least one two-dimensional Fourier transformed Information manifold.

8. The wireless device of claim 7, wherein the transmitter is further configured to transmit each at least one two-dimensional Fourier transformed Information manifold by:

over all frequencies and times of said two-dimensional Fourier transformed Information manifold, selecting a transmitting time slice of duration proportional to Tμ

, where μ

=1/N, and passing those frequencies in said two-dimensional Fourier transformed Information manifold corresponding to said transmitting time slice through a bank of at least M different, non-overlapping, narrow-band frequency filters, and transmitting resulting filtered waveforms as a plurality of at least M simultaneously transmitted mutually orthogonal waveforms, over different transmitted time intervals, until an entire two-dimensional Fourier transformed Information manifold has been transmitted.

9. The wireless device of claim 8 further including a receiver configured to receive each said at least one two-dimensional Fourier transformed Information manifold by:

over at least all frequencies and times of said two-dimensional Fourier transformed Information manifold, using at least one receiver processor to select a receiving time slice that is less than or equal to the duration of the transmitted time intervals, and receiving these channel convoluted waveforms on each said receiving time slice through a receiving bank of at least M different, non-overlapping, narrow-band frequency filters, and receiving said channel-convoluted waveforms over every receiving time slice until an approximation of said two-dimensional Fourier transformed Information manifold has been received;

performing at least one of;

a) using an inverse of said two-dimensional symplectic-like Fourier transform to transform said approximation of said two-dimensional Fourier transformed Information manifold into an approximation of said at least one received information manifold, and using information pertaining to said two-dimensional channel state to correct said at least one received information manifold for said data channel impairments;

b) using information pertaining to said two-dimensional channel state to correct said approximation of said two-dimensional Fourier transformed Information manifold for said data channel impairments, and using the inverse of said two-dimensional symplectic-like Fourier transform to in turn produce said at least one received information manifold.

10. The wireless device of claim 5 further including a receiver, the receiver including a processor configured for:

receiving the M mutually orthogonal wireless waveforms;

determining a two-dimensional channel state;

using an inverse of the encoding and the two-dimensional channel state to extract the plurality of data symbols from the M mutually orthogonal wireless waveforms.

11. A communication device, comprising:

a wireless transmitter;

a processor; and

a memory including program code executable by the processor, the program code including code for causing the processor to;

receive a plurality of information symbols;

encode the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency;

generate M mutually orthogonal waveforms based upon the two-dimensional array of modulation symbols; and

transmit the M mutually orthogonal waveforms wherein the M mutually orthogonal waveforms are included within M frequency sub-bands;

wherein the code for causing the processor to encode includes code for causing the processor to;

transform the N×

M array into an array of filtered OFDM symbols using at least one Fourier transform and a filtering process;

transform the array of filtered OFDM symbols into an array of orthonormal time-frequency shifting (OTFS) symbols using at least one two-dimensional Fourier transform.

12. A communication device, comprising:

a wireless transmitter;

a processor; and

a memory including program code executable by the processor, the program code including code for causing the processor to;

receive a plurality of information symbols;

encode an N×

M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency;

generate M mutually orthogonal waveforms based upon the two-dimensional array of modulation symbols; and

transmit the M mutually orthogonal waveforms wherein the M mutually orthogonal waveforms are included within M frequency sub-bands;

wherein the code for causing the processor to encode includes code for causing the processor to combine an inverse symplectic transform with a windowing operation.

13. A method of receiving data transmitted over a communication channel, the method comprising:

receiving M mutually orthogonal waveforms included within M frequency sub-bands;

demodulating the M mutually orthogonal waveforms to recover an estimate of a two-dimensional array of orthonormal time-frequency shifting (OTFS) symbols; and

decoding the two-dimensional array of OTFS symbols in order to generate an estimate of an N×

M array containing a plurality of information symbols, the N×

M array having been encoded prior to transmission of the data by spreading each of the plurality of information symbols with respect to both time and frequency.

14. The method of claim 13 wherein the decoding includes transforming the two-dimensional array of OTFS symbols into an array of OFDM symbols using at least one two-dimensional Fourier transform and transforming the array of OFDM symbols into the estimate of the N×

M array using at least one inverse Fourier transform.