Symplectic orthogonal time frequency space modulation system
View Patent ↗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.
1. A method of transmitting data over a communication channel, the method comprising:
receiving a plurality of information symbols;
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 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
transmitting the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.
2. The method of claim 1 wherein the transmitting includes using a set of M narrow-band filters to produce the M waveforms.
3. A method of transmitting data over a communication channel, the method comprising:
receiving a plurality of information symbols;
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 includes combining an inverse symplectic transform with a windowing operation; and
transmitting the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.
4. A method of transmitting data over a communication channel, the method comprising:
receiving a plurality of information symbols;
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:
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where x[l,k], k=0, . . . , N−1, l=0, . . . , M−1 represents the N×M array containing the plurality of information symbols, X[n,m], n=0, . . . , N −1, m=0, . . . , M −1 represents the two-dimensional array of modulation symbols, W tr [n,m] is a windowing function, and b k,l [n,m] represent a set of basis functions; and
transmitting the two-dimensional array of modulation symbols using M mutually orthogonal waveforms included within M frequency sub-bands.
5. An automated method of wireless communication over an impaired data channel, the method comprising:
receiving a plurality of data symbols;
encoding an N×M two-dimensional array containing the plurality of data symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of data symbols using a set of cyclically time-shifted and frequency-shifted basis functions; and
transmitting the two-dimensional array of modulation symbols using M mutually orthogonal wireless waveforms included within M frequency sub-bands.
6. The method of claim 5 , wherein the encoding 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 method of claim 5 , wherein said encoding 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 method of claim 7 , wherein the transmitting includes transmitting 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 method of claim 5 further including:
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.
10. The method of claim 8 , further including receiving 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.
11. An automated method of wirelessly communicating data over an impaired data channel, the method comprising:
encoding an N×M two-dimensional array containing a plurality 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;
transforming said at least one Information manifold according to a two-dimensional symplectic-like Fourier transform, thereby producing at least one two-dimensional Fourier transformed Information manifold; and
transmitting 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.
12. The method of claim 11 wherein said impaired data channel impairs said waveforms, said impairment being at least partially describable according to a two-dimensional channel state of said channel, thereby producing channel-convoluted waveforms, the method further including:
receiving 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; and
using said at least one receiver processor to decode and extract said data symbols from said at least one received information manifold.
13. The method of claim 12 , further including transforming said at least one N×M two-dimensional array of data according to a spreading operation either prior or after encoding said at least one N×M two-dimensional array of data symbols onto at least one symplectic analysis compatible manifold;
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.
14. The method of claim 13 , wherein said spreading operation is convolution with a two-dimensional chirp operation.
15. The method of claim 12 , wherein said non-overlapping, narrow-band frequency filters pass frequencies from said at least one two-dimensional Fourier transformed Information manifold proportional to g(t·e jkω 0 ), where j is the square root of −1, t corresponds to a given time slice of duration Tμ chosen from said at least one two-dimensional Fourier transformed Information manifold, and k corresponds to a given row position on said at least one two-dimensional Fourier transformed Information manifold, where k varies between 1 and M.
16. The method of claim 15 , wherein ω 0 is proportional to 1/T, and T=M/(allowed wireless bandwidth).
17. The method of claim 12 , wherein said receiving includes receiving said at least one two-dimensional 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.
18. The method of claim 11 , wherein said at least one two-dimensional 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 two-dimensional Fourier transformed Information manifold has overall dimensions proportional to Tμ according to a time axis and 1/T according to a frequency axis.
19. The method of claim 11 , wherein the transmitting includes transmitting the two-dimensional Fourier transformed Information 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.
20. 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; and
transmit the two-dimensional array of modulation symbols using M mutually orthogonal waveforms 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.
21. 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; and
transmit the two-dimensional array of modulation symbols using M mutually orthogonal waveforms 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.