Modulation and equalization in an orthonormal time-frequency 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 device for wireless communication, comprising:
a processor; and
a transceiver, coupled to the processor, configured to:
receive each of N orthonormal time frequency space (OTFS) signals, and wherein the processor is configured to:
construct, based on the N OTFS signals, a received data matrix,
generate an equalized data matrix with N 2 elements by performing an equalization operation on the received data matrix, and
transform the equalized data matrix into a data frame with N 2 data symbols, wherein each of the N 2 elements carries information corresponding to all N 2 data symbols.
2. The device of claim 1 , wherein the equalization operation comprises a linear equalization operation.
3. The device of claim 1 , wherein the equalization operation comprises a decision feedback least means square (DF-LMS) equalization operation.
4. The device of claim 1 , wherein the transceiver is further configured to:
transmit, based on the equalization operation, a feedback signal that corresponds to a wireless channel.
5. The device of claim 4 , wherein at least one of the N OTFS signals experiences an echo reflection in the wireless channel, and wherein the feedback signal comprises an indication of an anti-echo cancellation waveform.
6. The device of claim 4 , wherein at least one of the N OTFS signals experiences a frequency shift in the wireless channel, and wherein the feedback signal comprises an indication of a compensatory reverse frequency shift.
7. A method for wireless communication from a transmitter to a receiver over a wireless channel, comprising:
receiving, by the transmitter from the receiver, a feedback signal comprising information regarding echo reflections or frequency shifts associated with the wireless channel;
transforming, based on the feedback signal, a first data matrix into a second data matrix, wherein the first data matrix is processed based on at least one of an anti-echo cancellation waveform or a compensatory reverse frequency shift;
generating a waveform based on modulating the second data matrix; and
transmitting the waveform as an orthonormal time frequency space (OTFS) signal.
8. The method of claim 7 , wherein transforming the first data matrix comprises:
generating, based on the feedback signal, a time-frequency shifting (TFS) matrix; and
multiplying the TFS matrix and the first data matrix to generate the second data matrix.
9. The method of claim 8 , wherein the TFS matrix comprises Legendre symbols, and wherein each successive row of the TFS matrix is a cyclically shifted version of the Legendre symbols in a preceding row of the TFS matrix.
10. The method of claim 8 , wherein the TFS matrix is a Hadamard matrix.
11. The method of claim 7 , further comprising:
multiplying, prior to generating the waveform, the second data matrix with a spectral shaping matrix.
12. The method of claim 11 , wherein the spectral shaping matrix is a Discrete Fourier Transform (DFT) matrix or an Inverse Discrete Fourier Transform (IDFT) matrix.
13. A device for wireless communication, comprising:
a processor; and
a transceiver, coupled to the processor, configured to:
receive, by the transmitter from the receiver, a feedback signal comprising information regarding echo reflections or frequency shifts associated with the wireless channel,
wherein the processor is configured to:
transform, based on the feedback signal, a first data matrix into a second data matrix, wherein the first data matrix is processed based on at least one of an anti-echo cancellation waveform or a compensatory reverse frequency shift, and
generate a waveform based on modulating the second data matrix, and wherein the transceiver is further configured to:
transmit the waveform as an orthonormal time frequency space (OTFS) signal.
14. The device of claim 13 , wherein the processor is further configured, as part of transforming the first data matrix, to:
generate, based on the feedback signal, a time-frequency shifting (TFS) matrix; and
multiply the TFS matrix and the first data matrix to generate the second data matrix.
15. The device of claim 14 , wherein the TFS matrix comprises Legendre symbols, and wherein each successive row of the TFS matrix is a cyclically shifted version of the Legendre symbols in a preceding row of the TFS matrix.
16. The device of claim 14 , wherein the TFS matrix is a Hadamard matrix.
17. The device of claim 13 , wherein the processor is further configured to:
multiplying, prior to generating the waveform, the second data matrix with a spectral shaping matrix.
18. The device of claim 17 , wherein the spectral shaping matrix is a Discrete Fourier Transform (DFT) matrix or an Inverse Discrete Fourier Transform (IDFT) matrix.