Orthogonal Time-Frequency Shifting Modulation for Wireless Signal Integrity

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Solution Overview

Problem

Existing communication systems face challenges in maintaining data integrity and efficiency due to issues like Doppler shifts, multi-path effects, and background noise, particularly in wireless networks, where low-power signals from moving devices are prone to distortions and interference.

Innovation Solution

The Orthonormal Time-Frequency Shifting and Spectral Shaping (OTFS) method spreads data symbols over a large range of times, frequencies, and spectral shapes, using time-frequency shifting and spectral shaping codes to generate modulated signals that are resistant to Doppler shifts, multi-path effects, and background noise, allowing for high data rate transmission despite impairments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If low-power wireless signals are transmitted from moving devices, then energy consumption is reduced, but signal reliability deteriorates due to Doppler shifts and multi-path effects

Engineering Contradiction:

Improvepower consumptionVSAvoidsignal integrity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent transforms the traditional one-dimensional frequency modulation approach into a two-dimensional time-frequency modulation scheme. By mapping data symbols onto a time-frequency grid and applying orthogonal time-frequency shifting, the system creates signal representations that are inherently more robust to Doppler shifts and multi-path effects, thereby improving signal reliability without increasing power consumption

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the modulation parameters by introducing time-shifting and frequency-shifting operations in the orthogonal domain. The use of orthogonal time-frequency shifting codes with different time shifts and frequency shifts allows the system to adapt to channel conditions and maintain signal integrity under varying Doppler and multi-path conditions while keeping power consumption low

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional modulation schemes are used, then device complexity is low, but data transmission reliability deteriorates in noisy environments with Doppler shifts and multi-path effects

Engineering Contradiction:

Improvemodulation scheme complexityVSAvoiddata transmission reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the modulation process into distinct orthogonal time-shifting and frequency-shifting components. By dividing the data stream into blocks and applying orthogonal time-frequency shifting codes to each block, the system achieves robustness against channel impairments while maintaining manageable complexity through modular processing stages

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces orthogonal time-frequency shifting codes as intermediary elements between the data symbols and the transmitted signal. These codes act as mediators that embed the data in a time-frequency domain representation, providing protection against Doppler shifts and multi-path effects while allowing for straightforward decoding through inverse orthogonal time-frequency shifting operations

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If data is transmitted over wireless channels, then communication coverage is extended, but data integrity deteriorates due to background noise and channel impairments

Engineering Contradiction:

Improvecommunication coverageVSAvoiddata integrity

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies preliminary orthogonal time-frequency shifting encoding to data symbols before transmission. This pre-processing step embeds the data in a time-frequency domain representation that is inherently more resistant to channel impairments, effectively preparing the signal to withstand background noise, Doppler shifts, and multi-path effects during wireless transmission

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent transforms the harmful effects of Doppler shifts and multi-path interference into beneficial features by exploiting the orthogonality properties of time-frequency shifting codes. The channel impairments that would normally cause interference are converted into orthogonal components that can be easily separated and eliminated during the decoding process, thereby preserving data integrity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11665041B2Modulation and equalization in an orthonormal time-frequency shifting communications system

Publication Date: 2023.05.30 COHERE TECHNOLOGIES INC

AI summary

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.