Simultaneous Transmit Receive Self-Interference Cancellation

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Solution Overview

Problem

Current wireless communications face challenges in spectral efficiency due to limited spectrum availability and self-interference issues when devices operate on the same frequency band for simultaneous transmission and reception.

Innovation Solution

A communications device with a transmit path and a receive path operating simultaneously at the same frequency, utilizing processing circuitry to generate a feedforward signal based on the baseband signal to reduce self-interference, and incorporating predistortion and adaptive filtering to align and scale the feedforward signal for effective interference cancellation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simultaneous transmit and receive at the same frequency is implemented, then spectral efficiency is improved, but self-interference from transmit path to receive path increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidself-interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful self-interference signal into a beneficial cancellation signal by capturing the transmit path output and using it to generate an inverted replica that cancels the interference in the receive path, thereby enabling simultaneous transmit and receive operations at the same frequency

Inventive Principle:

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

Solution Approach 2:

The patent implements feedback by continuously monitoring the transmit path output and using it to adjust the interference cancellation signal, creating a closed-loop system that adapts to changing conditions and maintains effective self-interference reduction

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If Class C or E power amplifiers are used, then energy efficiency is improved, but signal distortion increases

Engineering Contradiction:

Improvepower amplifier efficiencyVSAvoidsignal linearity

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-distorting the input signal to the power amplifier in anticipation of the amplifier's nonlinear effects, so that when the signal passes through the Class C or E amplifier, the distortion is canceled and linear output is achieved

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the signal parameters by applying predistortion that compensates for the amplifier's nonlinear characteristics, effectively transforming the signal to maintain linearity despite using inefficient but compact power amplifier classes

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9461698B2Communications device with simultaneous transmit and receive and related methods

Publication Date: 2016.10.04 SMARTSKY NETWORKS LLC

AI summary

A communications device may include a transmit path, a receive path operable simultaneously with the transmit path and at a same frequency as the transmit path, and processing circuitry. The processing circuitry may be configured to generate a baseband signal for the transmit path, generate a feedforward signal based upon the baseband signal, and use the feedforward signal to reduce self-interference in the receive path from the transmit path.