Systems and methods for symplectic orthogonal time frequency shifting modulation and transmission of data

• US 10,158,394 B2
• Filed: 05/11/2016
• Issued: 12/18/2018
• Est. Priority Date: 05/11/2015
• Status: Active Grant

• Current Assignee: Cohere Technologies Inc
• Original Assignee: Cohere Technologies Inc
• Inventors: Hadani, Ronny, Rakib, Shlomo Selim
• Primary Examiner(s): Joseph, Jaison
• Application Number:
  US15/573,793
• Publication Number:
  US 20180109284A1
• Time in Patent Office: 951 Days
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 27/26416 Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/26532 Demodulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms
• CPC Class Codes: H04L 27/2654 Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/26546 with oversampling
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA

Abstract

An alternative method of data communications using orthogonal time frequency shifting (OTFS) wireless waveforms configured so as to transmit data in a manner that is relatively insensitive to communications channel distortions and frequency shifts. In contrast to prior methods taught by applicant, the present disclosure teaches an alternative modulation scheme that maps data symbols intended for data transmission onto a symplectic-like 2D Fourier transform which operates on a form of the original data symbols. This 2D Fourier transform in turn is passed through a filter bank of narrow band filters, and the output in turn used to modulate transmitted waveforms according to various time slices until the entire 2D Fourier transform has been transmitted. At the receiver, and inverse of this process can be used to both characterize the data channel and correct the received signals for channel distortions, thus receiving a clear form of the original data symbols.

Claims

1. An automated method of wirelessly transmitting and receiving data over an impaired data channel coupling at least one wireless transmitter and at least one wireless receiver, said data comprising a plurality of data symbols;

wherein said impaired data channel impairs said waveforms, said impairment being at least partially describable according to a 2D channel state of said impaired data channel, wherein transmitted wireless waveforms produce channel-convoluted waveforms at said at least one wireless receiver, said method comprising;

using at least one transmitter processor to package said data into at least one N×

M 2D array of data symbols, and using an encoding process to transmit said array of data symbols so that every data symbol is spread over a time and frequency range of wireless signals configured to detect a 2D channel state of said impaired data channel; and

using at least one receiver processor to receive said wireless signals, using said 2D channel state to correct said signals for said data channel impairments, and using an inverse of said encoding process to decode and extract said plurality of data symbols;

wherein said encoding process encodes said at least one N×

M 2D array 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;

using at least one transmitter processor to transform said at least one Information manifold according to a 2D symplectic-like Fourier transform, thereby producing at least one 2D Fourier transformed Information manifold;

transmitting each at least one 2D Fourier transformed Information manifold by;

over

all frequencies and times of said 2D Fourier transformed Information manifold, selecting a transmitting time slice of duration proportional to Tμ

, where μ

=1/N, and passing those frequencies in said 2D 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 2D Fourier transformed Information manifold has been transmitted.

2. The method of claim 1, wherein said at least one receiver receives each said at least one 2D Fourier transformed Information manifold by:

over at least all frequencies and times of said 2D 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 2D Fourier transformed Information manifold has been received;

performing at least one of;

a) using an inverse of said 2D symplectic-like Fourier transform to transform said approximation of said 2D Fourier transformed Information manifold into an approximation of said at least one received information manifold, and using information pertaining to said 2D channel state to correct said at least one received information manifold for said data channel impairments;

b) using information pertaining to said 2D channel state to correct said approximation of said 2D Fourier transformed Information manifold for said data channel impairments, and using the inverse of said 2D symplectic-like Fourier transform to in turn produce said at least one received information manifold.

3. An automated method of wirelessly transmitting and receiving data over an impaired data channel connecting at least one wireless transmitter and at least one wireless receiver, said data comprising a plurality of data symbols, said method comprising:

using at least one transmitter processor to package said data into at least one N×

M 2D array of data symbols, and further encoding said at least one N×

M 2D array of data symbols onto at least one symplectic 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;

using at least one transmitter processor to transform said at least one Information manifold according to a 2D symplectic-like Fourier transform, thereby producing at least one 2D Fourier transformed Information manifold;

transmitting each at least one 2D Fourier transformed Information manifold by;

over

all frequencies and times of said 2D Fourier transformed Information manifold, selecting a transmitting time slice of duration proportional to Tμ

, where μ

=1/N, and passing those frequencies in said 2D 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 2D Fourier transformed Information manifold has been transmitted;

wherein said impaired data channel impairs said waveforms, said impairment being at least partially describable according to a 2D channel state of said channel, thereby producing channel-convoluted waveforms at said at least one wireless receiver;

receiving each said at least one 2D Fourier transformed Information manifold by;

over at least all frequencies and times of said 2D 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 2D Fourier transformed Information manifold has been received;

performing at least one of;

a) using an inverse of said 2D symplectic-like Fourier transform to transform said approximation of said 2D Fourier transformed Information manifold into an approximation of said at least one received information manifold, and using information pertaining to said 2D channel state to correct said at least one received information manifold for said data channel impairments;

b) using information pertaining to said 2D channel state to correct said approximation of said 2D Fourier transformed Information manifold for said data channel impairments, and using the inverse of said 2D symplectic-like Fourier transform to in turn produce said at least one received information manifold; and

using said at least one receiver processor to decode and extract said data symbols from said at least one received information manifold.

4. The method of claim 3, wherein said processor further transforms said at least one N×

M 2D array of data according to a spreading operation either prior or after encoding said at least one N×

M 2D array of data symbols onto at least one symplectic analysis compatible manifold, and wherein said receiving processor uses an inverse of said spreading operation to decode and extract said data symbols from said at least one received information manifold.

5. The method of claim 4, wherein said spreading operation is convolution with a 2D chirp operation.

6. The method of claim 3, wherein said non-overlapping, narrow-band frequency filters pass frequencies from said at least one 2D Fourier transformed Information manifold proportional to g(t·

e<sup>jkω

0</sup>) where j is the square root of −

1, t corresponds to a given time slice of duration μ

chosen from said at least one 2D Fourier transformed Information manifold, and k corresponds to a given row position on said at least one 2D Fourier transformed Information manifold, where k varies between 1 and M.

7. The method of claim 3, wherein ω

₀ is proportional to 1/T, and T=M/(allowed wireless bandwidth).

8. The method of claim 3, wherein said at least one 2D Fourier transformed Information manifold has overall dimensions NT_μ

according to a time axis and M/T according to a frequency axis, and each cell in said at least one 2D Fourier transformed Information manifold has overall dimensions proportional to T_μ

according to a time axis and 1/T according to a frequency axis.

9. The method of claim 3, wherein said receiver receives said at least one 2D Fourier transformed Information manifold according to receiving time slices and receiving banks of different, non-overlapping, narrow-band frequency filters that oversamples the corresponding transmitting time slices and transmitting banks of different, non-overlapping, narrow-band frequency filters.

10. The method of claim 3, wherein said transmitter transmits said resulting filtered waveforms, until an entire 2D Fourier transformed Information manifold has been transmitted, as either:

1) a plurality of at least M simultaneously transmitted mutually orthogonal waveforms over either different consecutive transmitted time intervals;

or

2) a plurality OTFS data or OTFS pilot bursts comprising at least M simultaneously transmitted mutually orthogonal waveform bursts over different transmitted intervals separated by at least one spacer time interval.

11. The method of claim 10, wherein said impaired data channel is an impaired wireless data channel comprising at least one wireless reflector, each said at least one reflector comprising a reflector location, reflector velocity, reflector frequency shift comprising a reflector velocity caused Doppler shift, and at least one reflector coefficients of wireless reflection;

each said at least one wireless transmitter comprising a transmitter location, transmitter velocity, transmitter frequency and transmitter frequency shift, said transmitter frequency shift causing a change in said transmitter frequency according to a transmitter velocity caused Doppler shift;

each said at least one wireless receiver comprising a receiver location, receiver velocity, receiver frequency and receiver frequency shift, said receiver frequency shift causing a change in said receiver frequency according to a receiver velocity caused Doppler shift;

wherein said 2D channel state comprises information pertaining to relative locations, velocities, velocity induced frequency shifts caused by transmitter Doppler shifts, receiver Doppler shifts, reflector Doppler shifts, and reflector coefficients of reflection of said at least one transmitters, receivers, and reflectors;

said method comprising;

using said at least one transmitter and at least one processor to transmit direct OTFS data waveforms or waveform bursts, said direct OTFS data waveforms or waveform bursts comprising a plurality of OTFS data symbols D_pt,pf transmitted as OTFS data symbol waveform or waveform bursts D_pt,pf·

W_p(pt, pf), over a plurality of combinations of times pt and frequencies pf, where each said pt and pf are unique data time-frequency coordinates chosen from a two dimensional data OTFS time-frequency grid;

said receiver configured to receive at least said data waveforms or waveform bursts according to at least a two dimensional data OTFS time-frequency bin structure with bin sizes and bin-coordinate positions proportional to a sample or oversample of said OTFS time-frequency grid;

wherein upon propagation through said impaired data channel, said direct OTFS data waveforms or waveform bursts then travel over at least one path, said at least one path comprising at least one of;

a;

direct OTFS data waveforms or waveform bursts traveling directly from said at least one transmitter to said at least one receiver; and

b;

replica OTFS data waveforms or waveform bursts comprising direct OTFS data waveforms or waveform bursts that have reflected off of said at least one reflector before reaching said at least one receiver, thereby producing direct OTFS waveforms or waveform bursts that are further reflector time-delayed and reflector frequency-shifted at said at least one receiver;

wherein at said at least one receiver, a resulting combination of any said transmitter frequency shifted and receiver frequency shifted direct OTFS data waveforms or waveform bursts and any said replica OTFS data waveforms or waveform bursts produces channel-convoluted OTFS data waveforms or waveform bursts;

at said at least one receiver, using said bin structure to receive said channel-convoluted OTFS data waveforms or waveform bursts

using said 2D channel state and at least one processor to further perform at least one of;

a) determine said 2D channel state of said impaired data channel connecting said at least one transmitter and said at least one receiver;

b) precoding at least some of said direct data waveforms or waveform bursts at said at least one wireless transmitter to pre-compensate for said impaired data channel; and

deconvoluting at least some of said channel-convoluted data waveforms or waveform bursts at said at least one wireless receiver, thereby deriving at least an approximation of said plurality of data symbols.

12. The method of claim 11, wherein D_pt,pf corresponds to a contents of bin coordinate (pt, pf) from said at least one 2D Fourier transformed Information manifold, and Wp(pt, pf) corresponds g(t·

e<sup>jkω

0</sup>) where k=pf.

13. The method of claim 3, wherein said 2D channel state information is determined by transmitting and receiving at least one pilot symbol.

14. A wireless communication apparatus, comprising:

a memory that stores instructions;

a processor;

and a radio frequency (RF) transmitter;

wherein the processor reads instructions from the memory and implements an automated method of wirelessly transmitting data over an impaired data channel, communicatively connecting the RF transmitter and at least one wireless receiver, said data comprising a plurality of data symbols, the instructions comprising;

instructions for packaging said data into at least one N×

M 2D array of data symbols, and further encoding said at least one N×

M 2D array of data symbols onto at least one symplectic 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;

instructions for transforming said at least one Information manifold according to a 2D symplectic-like Fourier transform, thereby producing at least one 2D Fourier transformed Information manifold;

instructions for causing the RF transmitter to transmit each at least one 2D Fourier transformed Information manifold by;

over all frequencies and times of said 2D Fourier transformed Information manifold,

instructions for selecting a transmitting time slice of duration proportional to Tμ

, where μ

=1/N, and passing those frequencies in said 2D 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 2D Fourier transformed Information manifold has been transmitted;

wherein said impaired data channel impairs said waveforms, said impairment being at least partially describable according to a 2D channel state of said channel, thereby producing channel-convoluted waveforms at said at least one wireless receiver.

15. The apparatus of claim 14, wherein said processor further transforms said at least one N×

M 2D array of data according to a spreading operation either prior or after encoding said at least one N×

M 2D array of data symbols onto at least one symplectic analysis compatible manifold, and wherein said receiving processor uses an inverse of said spreading operation to decode and extract said data symbols from said at least one received information manifold.

16. The apparatus of claim 15, wherein said spreading operation is convolution with a 2D chirp operation.

17. The apparatus of claim 14, wherein said non-overlapping, narrow-band frequency filters pass frequencies from said at least one 2D Fourier transformed Information manifold proportional to g(t·

e<sup>jkω

0</sup>) where j is the square root of −

1, t corresponds to a given time slice of duration μ

chosen from said at least one 2D Fourier transformed Information manifold, and k corresponds to a given row position on said at least one 2D Fourier transformed Information manifold, where k varies between 1 and M.

18. The apparatus of claim 14, wherein ω

₀ is proportional to 1/T, and T=M/(allowed wireless bandwidth).