US 10,693,581 B2Granted

Orthogonal time frequency space modulation over a plurality of narrow band subcarriers

AssigneeCohere Technologies, Inc.

InventorsShlomo Selim Rakib, Ronny Hadani

Life of this patent

Estimating the term…

Loading patent…

Abstract

An Orthogonal Time Frequency Space Modulation (OTFS) modulation scheme that maps data symbols, along with optional pilot symbols, using a symplectic-like transformation such as a 2D Fourier transform and optional scrambling operation, into a complex wave aggregate and be backward compatible with legacy OFDM systems, is described. This wave aggregate may be processed for transmission by selecting portions of the aggregate according to various time and frequency intervals. The output from this process can be used to modulate transmitted waveforms according to various time intervals over a plurality of narrow-band subcarriers, often by using mutually orthogonal subcarrier “tones” or carrier frequencies. The entire wave aggregate may be transmitted over various time intervals. At the receiver, an inverse of this process can be used to both characterize the data channel and to correct the received signals for channel distortions, thus receiving a clear form of the original data symbols.

Claims20

Dependent claims

A method of transmitting, on a per-frame basis, a plurality of data symbols over an impaired wireless channel comprising a plurality of narrow-band subcarriers, the method comprising:

for each frame, distributing the plurality of data symbols over a two-dimensional (2D) orthogonal time frequency space (OTFS) delay-Doppler frame by assigning each data symbol to its own unique 2D OTFS delay-Doppler frame location, wherein the 2D OTFS delay-Doppler frame comprises a 2D delay-Doppler grid, and wherein the 2D OTFS delay-Doppler frame location is a 2D delay-Doppler grid coordinate;
OTFS transforming, using an OTFS transform operation, the plurality of data symbols on the 2D OTFS delay-Doppler frame by using each data symbol and frame location to modulate a unique, location specific, 2D basis wave function selected from a set of mutually orthogonal 2D basis wave functions operating over a 2D OTFS time-frequency frame, wherein the OTFS transforming spreads each data symbol, in a lossless and invertible manner, throughout the 2D OTFS time-frequency frame, and wherein the OTFS transforming creates a 2D OTFS time-frequency frame based wave aggregate;
scrambling the 2D OTFS time-frequency frame based wave aggregate with a scrambling operation to generate a scrambled 2D OTFS time-frequency frame based wave aggregate;
and
modulating and transmitting portions of the scrambled 2D OTFS time-frequency frame based wave aggregate, over the plurality of narrow-band subcarriers, over a plurality of time intervals,
wherein a granularity and extent of the portions, the plurality of narrow-band subcarriers, and the plurality of time intervals are chosen so that the sum of the transmitted portions characterizes the scrambled 2D OTFS time-frequency frame based wave aggregate, and
wherein the impaired wireless channel distorts the transmitted portions into channel distorted portions.

4 more elements

A method of receiving, on a per-frame basis, a plurality of data symbols over an impaired wireless channel comprising a plurality of narrow-band subcarriers, wherein the plurality of data symbols corresponds to transmitted portions of a waveform, wherein the impaired wireless channel distorts the transmitted portions into channel distorted portions, the method comprising:

receiving and demodulating the channel distorted portions over the plurality of narrow-band subcarriers, over a plurality of time intervals, to recover a channel distorted replica of a scrambled two-dimensional (2D) orthogonal time frequency space (OTFS) time-frequency frame based wave aggregate;
using an inverse of a scrambling operation to descramble the channel distorted replica of the scrambled 2D OTFS time-frequency frame based wave aggregate, wherein the inverse of the scrambling operation creates a descrambled channel distorted replica of the 2D OTFS time-frequency based wave aggregate;
inverse OTFS transforming, using an inverse of an OTFS transform operation, the channel distorted replica of the 2D OTFS time-frequency frame based wave aggregate, to produce, once the channel distorted portions have been received, a channel distorted replica of a 2D OTFS delay-Doppler frame;
correcting, using a delay-Doppler 2D equalizer, the channel distorted replica of the 2D OTFS delay-Doppler frame, to produce a channel deconvoluted 2D OTFS delay-Doppler frame;
and
extracting a plurality of replica data symbols from the channel deconvoluted 2D OTFS delay-Doppler frame.

3 more elements

An apparatus for receiving, on a per-frame basis, a plurality of data symbols over an impaired wireless channel comprising a plurality of narrow-band subcarriers, the plurality of data symbols corresponding to transmitted portions of a waveform, the impaired wireless channel distorting the transmitted portions into channel distorted portions, the apparatus comprising:

a processor;
and
a memory comprising processor executable code, the processor executable code when executed by the processor causes the processor to implement:
receiving and demodulating the channel distorted portions over the plurality of narrow-band subcarriers, over a plurality of time intervals, to recover a channel distorted replica of a scrambled two-dimensional (2D) orthogonal time frequency space (OTFS) time-frequency frame based wave aggregate;
using an inverse of a scrambling operation to descramble the channel distorted replica of the scrambled 2D OTFS time-frequency frame based wave aggregate, wherein the inverse of the scrambling operation creates a descrambled channel distorted replica of the 2D OTFS time-frequency based wave aggregate;
inverse OTFS transforming, using an inverse of an OTFS transform operation, the channel distorted replica of the 2D OTFS time-frequency frame based wave aggregate, to produce, once the channel distorted portions have been received, a channel distorted replica of a 2D OTFS delay-Doppler frame;
correcting, using a delay-Doppler 2D equalizer, the channel distorted replica of the 2D OTFS delay-Doppler frame to produce a channel deconvoluted 2D OTFS delay-Doppler frame;
and
extracting a plurality of replica data symbols from the channel deconvoluted 2D OTFS delay-Doppler frame.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/743,646Filed 12 Jul 2016 · us provisional application
Priority: 12 Jul 2015
Published: US 2018/0205481 A119 Jul 2018
Granted: 23 Jun 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H04J 11/0026
Interference mitigation or co-ordination: of multi-user interference
H04J 11/00
Orthogonal multiplex systems
H04L 23/02
Apparatus or local circuits for systems other than those covered by groups H04L15/00 - H04L21/00: adapted for orthogonal signalling
H04L 27/2639
Modulators: modulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms