Tomlinson-Harashima precoding in an OTFS communication system

Patent metadata

Field	Value
Publication number	US-10063295-B2
Application number	US-201715478174-A
Country	US
Kind code	B2
Filing date	Apr 3, 2017
Priority date	Apr 1, 2016
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A method for signal transmission using precoded symbol information involves estimating a two-dimensional model of a communication channel in a delay-Doppler domain. A perturbation vector is determined in a delay-time domain wherein the delay-time domain is related to the delay-Doppler domain by an FFT operation. User symbols are modified based upon the perturbation vector so as to produce perturbed user symbols. A set of Tomlinson-Harashima precoders corresponding to a set of fixed times in the delay-time domain may then be determined using a delay-time model of the communication channel. Precoded user symbols are generated by applying the Tomlinson-Harashima precoders to the perturbed user symbols. A modulated signal is then generated based upon the precoded user symbols and provided for transmission over the communication channel.

First claim

What is claimed is:

1. A method for signal transmission using precoded symbol information, the method comprising:
estimating a two-dimensional model of a communication channel in a delay-Doppler domain wherein the two-dimensional model of the communication channel is a function of time delay and frequency shift;
determining a perturbation vector in a delay-time domain wherein the delay-time domain is related to the delay-Doppler domain by an FFT operation;
modifying user symbols based upon the perturbation vector so as to produce perturbed user symbols;
determining, using a delay-time model of the communication channel, a set of Tomlinson-Harashima precoders corresponding to a set of fixed times in the delay-time domain;
generating precoded user symbols by applying the Tomlinson-Harashima precoders to the perturbed user symbols; and
providing, based upon the precoded user symbols, a modulated signal for transmission over the communication channel.

2. The method of claim 1 wherein the applying includes using FFT operations to apply the Tomlinson-Harashima precoders to the perturbed user symbols.

3. The method of claim 1 wherein the determining a set of Tomlinson-Harashima precoders includes performing a decomposition of the delay-time model of the communication channel.

4. The method of claim 3 in which the decomposition comprises an LQD decomposition where L is a lower triangular matrix, D is a diagonal matrix, and Q is a unitary matrix.

5. The method of claim 1 wherein the estimating the two-dimensional model of the communication channel includes:
receiving at least a first pilot signal wherein the first pilot signal occupies a first predetermined coordinate position in a time-frequency plane,
determining a first time shift of the first pilot signal and a first frequency shift of the first pilot signal.

6. A communication apparatus, comprising:
a plurality of antennas;
a processor configured to:
estimate a two-dimensional model of a communication channel in a delay-Doppler domain wherein the two-dimensional model of the communication channel is a function of time delay and frequency shift;
determine a perturbation vector in a delay-time domain wherein the delay-time domain is related to the delay-Doppler domain by an FFT operation;
modify user symbols based upon the perturbation vector so as to produce perturbed user symbols;
determine, using a delay-time model of the communication channel, a set of Tomlinson-Harashima precoders corresponding to a set of fixed times in the delay-time domain;
generate precoded user symbols by applying the Tomlinson-Harashima precoders to the perturbed user symbols; and

a transmitter configured to provide, based upon the precoded user symbols, a modulated signal to the plurality of antennas for transmission over the communication channel.

7. The communication apparatus of claim 6 wherein the processor is further configured to use FFT operations to apply the Tomlinson-Harashima precoders to the perturbed user symbols.

8. The communication apparatus of claim 6 wherein the processor is further configured to determine the set of Tomlinson-Harashima precoders by performing a decomposition of the delay-time model of the communication channel.

9. The communication apparatus of claim 8 where the decomposition comprises an LQD decomposition where L is a lower triangular matrix, D is a diagonal matrix, and Q is a unitary matrix.

10. The communication apparatus of claim 6 wherein the processor, as part of estimating the two-dimensional model of the communication channel, is further configured to:
receive at least a first pilot signal wherein the first pilot signal occupies a first predetermined coordinate position in a time-frequency plane, and
determine a first time shift of the first pilot signal and a first frequency shift of the first pilot signal.

Assignees

• Cohere Tech Inc

Inventors

• Delfeld Jim
• Rakib Shlomo Selim

Classifications

• H04B7/0413

  MIMO systems · CPC title

• H04L25/0222

  Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency · CPC title

• H04L25/4975

  Correlative coding using Tomlinson precoding, Harashima precoding, Trellis precoding or GPRS · CPC title

• H04L25/03343

  Arrangements at the transmitter end · CPC title

• H04B7/0456 Primary

  Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting · CPC title