Adaptive Self-Interference Cancellation in Full Duplex Radio

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Solution Overview

Problem

Full duplex radio (FDR) systems face significant performance deterioration due to intra-device self-interference, which needs to be effectively cancelled to operate efficiently.

Innovation Solution

A method and apparatus for self-interference cancellation in FDR environments, where the order of self-interference components considered for cancellation is adapted based on transmit power, including linear and nonlinear digital self-interference components up to fifth-order, with variable conditions for antenna and analog self-interference cancellation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If full duplex radio is implemented to double system capacity, then transmission and reception can occur simultaneously, but intra-device self-interference is generated that significantly deteriorates system performance

Engineering Contradiction:

Improvesystem capacityVSAvoidself-interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The self-interference cancellation process is segmented into multiple stages: antenna-level cancellation, analog cancellation, and digital cancellation. Each stage handles specific components of the interference, dividing the complex cancellation task into manageable segments that address different aspects of the self-interference problem

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediate cancellation signal is generated and subtracted from the received signal to eliminate self-interference. The system creates a model of the self-interference based on the transmitted signal and uses this as an intermediary to cancel the harmful interference before the desired signal processing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If higher-order nonlinear self-interference components are cancelled to improve performance at high transmit power, then communication reliability improves, but computational complexity and processing requirements increase

Engineering Contradiction:

Improvecommunication performanceVSAvoidcancellation processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system dynamically adapts the order of nonlinear self-interference cancellation based on the current transmit power level. When transmit power is high, higher-order components (up to fifth-order) are cancelled to maintain performance. When transmit power is low, only lower-order components are cancelled, reducing computational complexity and processing requirements

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cancellation order parameter is changed according to transmit power conditions. The system adjusts which mathematical terms are included in the cancellation process based on the operating point, optimizing the balance between performance and complexity for different power levels

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10447505B2Method for performing self-interference cancellation in FDR environment and device for same

Publication Date: 2019.10.15 LG ELECTRONICS INC

AI summary

A method for performing self-interference cancellation by a device using an FDR mode comprises a step for performing nonlinear digital self-interference cancellation on the basis of a condition defined for the nonlinear digital self-interference cancellation, wherein the defined condition can comprise information about the order of a self-interference component to be considered for the nonlinear digital self-interference cancellation in correspondence with transmission power of the device.