Modulation and equalization in an orthonormal time-shifting communications system
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.
1. A method of processing signals at a receiver, comprising:
receiving, from a first transmitter, a first orthogonal time frequency space (OTFS) signal transmission comprising a first data stream, wherein the first OTFS signal is generated using a first basis matrix;
receiving, from a second transmitter, a second orthogonal time frequency space (OTFS) signal transmission comprising a second data stream, wherein the second OTFS signal is generated using a second basis matrix;
generating a first one dimensional data stream by OTFS decoding the first OTFS signal transmission;
generating a second one dimensional data stream by OTFS decoding the second OTFS signal transmission;
recovering the first data stream by operating a first feed forward equalizer and a first feedback equalizer and a first slicer, wherein a first residual error signal at an output of the first slicer is used as an input to the first feed forward equalizer and the first feedback equalizer and wherein an input to the first slicer is obtained by differencing an output of the first feed forward equalizer and the first feedback equalizer; and
recovering the second data stream by operating a second feed forward equalizer and a second feedback equalizer and a second slicer; wherein a second residual error signal at an output of the second slicer is used as an input to the second feed forward equalizer and the second feedback equalizer and wherein an input to the second slicer is obtained by differencing an output of the second feed forward equalizer and the second feedback equalizer.
2. The method of claim 1 , wherein the input to the first feed forward equalizer is adjusted based on an output of a first cross talk canceller that operates on the second residual error signal and
the input to the second feed forward equalizer is adjusted based on an output of a second cross talk canceller that operates on the first residual error signal.
3. The method of claim 1 , further including:
modeling a channel over which the first OTFS transmission and the second OTFS transmissions are received as a two-dimensional time/frequency channel.
4. The method of claim 1 , wherein the first OTFS transmission and the second OTFS transmission are received in a same frequency band.
5. The method of claim 1 , wherein the first OTFS transmission and the second OTFS transmission carry each data element over a cyclically varying range of frequencies and over a series of spreading time intervals.
6. The method of claim 1 , wherein the first transmitter and the second transmitter are co-located.
7. The method of claim 1 , wherein the first transmitter and the second transmitter are non-co-located.
8. The method of claim 1 , wherein the receiver is configured to perform a full duplex communication with the first transmitter and the second transmitter.
9. A receiver apparatus, comprising electronic circuitry, wherein the electronic circuitry is configured to:
receive, from a first transmitter, a first orthogonal time frequency space (OTFS) signal transmission comprising a first data stream, wherein the first OTFS signal is generated using a first basis matrix;
receive, from a second transmitter, a second orthogonal time frequency space (OTFS) signal transmission comprising a second data stream, wherein the second OTFS signal is generated using a second basis matrix;
generate a first one dimensional data stream by OTFS decoding the first OTFS signal transmission;
generate a second one dimensional data stream by OTFS decoding the second OTFS signal transmission;
recover the first data stream by operating a first feed forward equalizer and a first feedback equalizer and a first slicer, wherein a first residual error signal at an output of the first slicer is used as an input to the first feed forward equalizer and the first feedback equalizer and wherein an input to the first slicer is obtained by differencing an output of the first feed forward equalizer and the first feedback equalizer; and
recover the second data stream by operating a second feed forward equalizer and a second feedback equalizer and a second slicer; wherein a second residual error signal at an output of the second slicer is used as an input to the second feed forward equalizer and the second feedback equalizer and wherein an input to the second slicer is obtained by differencing an output of the second feed forward equalizer and the second feedback equalizer.
10. The receiver apparatus of claim 9 , wherein the input to the first feed forward equalizer is adjusted based on an output of a first cross talk canceller that operates on the second residual error signal and
the input to the second feed forward equalizer is adjusted based on an output of a second cross talk canceller that operates on the first residual error signal.
11. The receiver apparatus of claim 9 , wherein the electronic circuitry is further configured to:
model a channel over which the first OTFS transmission and the second OTFS transmissions are received as a two-dimensional time/frequency channel.
12. The receiver apparatus of claim 9 , wherein the first OTFS transmission and the second OTFS transmission are received in a same frequency band.
13. The receiver apparatus of claim 9 , wherein the first OTFS transmission and the second OTFS transmission carry each data element over a cyclically varying range of frequencies and over a series of spreading time intervals.
14. The receiver apparatus of claim 9 , wherein the first transmitter and the second transmitter are co-located.
15. The receiver apparatus of claim 9 , wherein the first transmitter and the second transmitter are non-co-located.
16. The receiver apparatus of claim 9 , wherein the receiver is configured to perform a full duplex communication with the first transmitter and the second transmitter.