Digital Self-Interference Cancellation Model for RF Transceivers

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Solution Overview

Problem

Current self-interference cancellation techniques in wireless communication systems, especially in full duplex and multiradio scenarios, face challenges due to imperfect isolation between antennas and increased chipset integration, leading to desensitization of receivers and impaired operation, with existing analog domain methods being inaccurate and power-consuming.

Innovation Solution

A digital representation of the transmitted signal is applied to a model that includes representations of both transmitter and receiver analog circuitry to generate a self-interference compensation signal, allowing for compensation of received signals in the digital domain, thereby alleviating self-interference without the need for analog domain manipulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If analog domain signal manipulation is used for self-interference cancellation, then self-interference can be canceled, but accuracy and power consumption are not optimal

Engineering Contradiction:

Improveself-interference cancellation accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces analog domain signal manipulation with digital domain signal processing. Specifically, the transmitted signal is converted to digital form, processed through a model of the analog circuitry to generate a digital self-interference cancellation signal, which is then combined with the received signal in the digital domain. This substitution of digital processing for analog manipulation improves both accuracy and power efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a digital copy or model of the analog transmitter and receiver circuitry. This model replicates the behavior of the actual analog circuits, allowing the self-interference signal to be generated and processed digitally without requiring physical analog signal manipulation. The model includes representations of the power amplifier, antennas, and receiver circuitry to accurately predict the self-interference characteristics.

Inventive Principle:

Principle #26Copying

2Adaptability or versatility

If increased chipset integration is implemented, then device integration level increases, but self-interference problem worsens

Engineering Contradiction:

Improvechipset integration levelVSAvoidself-interference

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the transmitted signal is fed into a model of the transmitter and receiver circuitry to generate a prediction of the self-interference signal. This predicted self-interference signal is then subtracted from the received signal to cancel the interference. The feedback loop continuously adapts to changing transmission conditions, maintaining effective cancellation despite increased integration.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces a digital model as an intermediary between the transmitted signal and the received signal. This model acts as a mediator that predicts the self-interference characteristics without requiring direct physical coupling between transmitter and receiver, thereby managing the interference problem even as integration increases.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If digital domain compensation is used instead of analog domain manipulation, then power consumption is reduced, but implementation complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidimplementation complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent replaces complex analog signal manipulation circuits with digital signal processing operations. The digital model of the analog circuitry can be implemented using standard digital signal processing algorithms and hardware, which are generally more power-efficient and easier to integrate into modern chipsets despite the increased computational requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8023438B2Analog signal path modeling for self-interference cancellation

Publication Date: 2011.09.20 WSOU INVESTMENTS LLC

AI summary

Described herein is a device that includes at least one radio frequency transmitter; at least one radio frequency receiver; a copy block configurable to output a digital representation of a currently transmitted signal and a model having a representation of at least analog circuitry of the at least one radio frequency transmitter and analog circuitry of the at least one radio frequency receiver, as well as possibly one or more antennas. The model generates, in response to the digital representation of the currently transmitted signal, a self-interference compensation signal to compensate, in the digital domain, a signal that is received simultaneously with the currently transmitted signal. Also described are corresponding apparatus, methods, computer program instructions stored in a memory medium, and an integrated circuit embodiment.