OFDM Uplink Cancellation Subcarriers for Sidelink Interference Reduction

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Solution Overview

Problem

OFDM-based wireless communication systems face interference issues due to high side lobes in the frequency domain, particularly in sidelink transmissions where UEs may not be well synchronized, leading to interference with other waveforms and inefficient use of frequency resources.

Innovation Solution

Implementing active interference cancellation (AIC) techniques by configuring UEs to use additional subcarriers with specific phase, amplitude, and time domain characteristics to suppress side lobes in uplink transmissions, reducing interference towards sidelink communications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If additional subcarriers are added for interference cancellation, then interference in sidelink transmissions is reduced, but device complexity increases

Engineering Contradiction:

Improveinterference in sidelink transmissionsVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The frequency domain resources are segmented into data subcarriers and interference cancellation subcarriers. The interference cancellation function is separated from data transmission, allowing independent optimization of each function while reducing overall interference impact on sidelink communications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Interference cancellation subcarriers act as an intermediary mechanism between uplink data transmissions and sidelink communications. These dedicated subcarriers absorb and cancel interfering signals, protecting sidelink transmissions without requiring changes to the core data transmission mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If guard bands are used to reduce interference, then interference protection is improved, but frequency resource usage efficiency deteriorates

Engineering Contradiction:

Improveinterference protectionVSAvoidfrequency resource usage efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent converts the harmful effect of spectral leakage into a beneficial cancellation mechanism. By intentionally allocating specific subcarriers to generate opposite-phase signals, the system transforms potential interference into a useful cancellation effect, eliminating the need for protective guard bands.

Inventive Principle:

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

Solution Approach 2:

The system changes the phase and amplitude parameters of specific subcarriers to create destructive interference patterns that cancel out sidelobe emissions. This parameter manipulation allows interference reduction without requiring frequency separation through guard bands.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If interference cancellation subcarriers are implemented, then spectral efficiency is enhanced, but calculation complexity increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidcalculation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The interference cancellation parameters are pre-calculated and configured before actual data transmission begins. The base station determines the appropriate cancellation subcarriers and their characteristics in advance, reducing real-time computational requirements during active communication.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the uplink transmission signal itself to generate the cancellation signal. By leveraging the existing data subcarriers and their known characteristics, the system creates cancellation subcarriers that automatically adapt to the transmitted signal, reducing the need for external interference measurement and calculation.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces interference in sidelink transmissions while optimizing frequency resource usage, avoiding the need for guard bands and enhancing spectral efficiency.

Implementation Method 1

calculating a plurality of symbols and modulating the plurality of symbols on a second plurality of subcarriers in accordance with the instruction from the network for interference cancellation

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS12396019B2Radio frequency emission reduction with interference cancellation

Publication Date: 2025.08.19 QUALCOMM INC

AI summary

Wireless communications systems and methods related to communicating information are provided. A method of wireless communication performed by a user equipment (UE). The method of wireless communication also includes receiving a configuration from a network for uplink transmission using a first plurality of subcarriers; receiving an instruction from the network for interference cancellation with respect to the first plurality of subcarriers; calculating a plurality of symbols and modulating the plurality of symbols on a second plurality of subcarriers in accordance with the instruction from the network for interference cancellation; and transmitting a waveform to the network, the waveform including the first plurality of subcarriers and the second plurality of subcarriers.