Precoding in wireless systems using orthogonal time frequency space multiplexing
AssigneeCohere Technologies, Inc.
InventorJames Delfeld
Life of this patent
Estimating the term…
Abstract
Device, methods and systems for recoding in wireless systems using orthogonal time frequency space multiplexing are described. An exemplary method for transmitting wireless signals includes mapping data to generate a quadrature amplitude modulation (QAM) signal in a delay Doppler domain, determining a perturbation signal to minimize expected interference and noise, perturbing the QAM signal with the perturbation signal, thereby producing a perturbed signal, generating a pre-coded signal by pre-coding, using a linear pre-coder, the perturbed signal, and transmitting the pre-coded signal using an orthogonal time frequency space modulation signal scheme.
Claims20
A method for transmitting a wireless signal, comprising:
- mapping a plurality of data bits to generate a quadrature amplitude modulation (QAM) signal in a delay-Doppler domain;
- determining a perturbation signal to minimize expected interference and noise;
- perturbing the QAM signal with the perturbation signal to produce a first perturbed signal;
- transforming, using a two-dimensional (2D) Fourier transform, the first perturbed signal into a second perturbed signal from the delay-Doppler domain to a time-frequency domain;
- generating a pre-coded signal by pre-coding, using a linear pre-coder, the second perturbed signal;
- and
- transmitting the pre-coded signal using an orthogonal time frequency space (OTFS) modulation signal scheme.
A method for receiving a wireless communication, including:
- receiving a quadrature amplitude modulation (QAM) signal in a time-frequency domain;
- applying an orthogonal transformation to convert the received QAM signal from the time-frequency domain to a delay-Doppler domain;
- determining a closest lattice point corresponding to a QAM constellation point of the QAM signal in the delay-Doppler domain;
- removing a perturbation in the received QAM signal by subtracting the closest lattice point from the QAM constellation point to generate an un-perturbed QAM signal;
- and
- demodulating the un-perturbed QAM signal to obtain a plurality of data bits.
The method of 9, wherein the determining the closest lattice point comprises minimizing the quadratic form
- argmin
- p
- ∈
- (
- 2
-
- ℤ
- +
- 2
-
- j
-
-
- ℤ
- )
- L
- u
-
- (
- r
-
- (
- τ
- )
- +
- p
- )
- *
-
- D
-
- (
- τ
- )
-
- (
- r
-
- (
- τ
- )
- +
- p
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- wherein p is the perturbation, r(τ) is the received QAM signal in the delay-Doppler domain, Lu is a length of a transmitted QAM signal corresponding to the plurality of data bits, 2+2j is a coarse lattice structure, and D(τ) is a τ-th block diagonal entry of a positive definite block diagonal matrix corresponding to a Cholesky decomposition of the perturbation.
An apparatus for wireless communication, comprising:
- a processor;
- and
- a transceiver circuitry coupled to the processor,
- wherein the transceiver circuitry is configured to:
- receive a quadrature amplitude modulation (QAM) signal in a time-frequency domain, and
- wherein the processor is configured to:
- apply an orthogonal transformation to convert the received QAM signal from the time-frequency domain to a delay-Doppler domain,
- determine a closest lattice point corresponding to a QAM constellation point of the QAM signal in the delay-Doppler domain,
- remove a perturbation in the received QAM signal by subtracting the closest lattice point from the QAM constellation point to generate an un-perturbed QAM signal, and
- demodulate the un-perturbed QAM signal to obtain a plurality of data bits.
The apparatus of 15, wherein the determining the closest lattice point comprises minimizing the quadratic form
- argmin
- p
- ∈
- (
- 2
-
- ℤ
- +
- 2
-
- j
-
-
- ℤ
- )
- L
- u
-
- (
- r
-
- (
- τ
- )
- +
- p
- )
- *
-
- D
-
- (
- τ
- )
-
- (
- r
-
- (
- τ
- )
- +
- p
- )
- wherein p is the perturbation, r(τ) is the received QAM signal in the delay-Doppler domain, Lu is a length of a transmitted QAM signal corresponding to the plurality of data bits, 2+2j is a coarse lattice structure, and D(τ) is a τ-th block diagonal entry of a positive definite block diagonal matrix corresponding to a Cholesky decomposition of the perturbation.
Dependencies are inferred from the claim text.