Signal Routing Assembly for Full Duplex Isolation

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Solution Overview

Problem

Full duplex wireless communication systems face challenges in isolating transmitted signals from received signals, leading to corruption, distortion, and desensitization in the receiver due to inadequate isolation provided by circulators and directional couplers, especially when operating at the same or closely spaced RF carrier frequencies.

Innovation Solution

A signal routing assembly that uses a combination of signal dividers, routing devices, and combiners to achieve high isolation between transmission and reception paths, allowing operation at the same or close RF carrier frequencies by dividing and phase-shifting signals to cancel leakage, thereby preventing undesired signal interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a circulator or directional coupler is used to isolate transmitted signals from received signals, then signal routing is achieved, but isolation performance is insufficient (only 20-25 dB) causing receiver desensitization

Engineering Contradiction:

Improveisolation performanceVSAvoidtransmitter energy leakage into receiver

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the signal routing function into multiple separate components: a first circulator for transmit signal routing, a second circulator for receive signal routing, and a directional coupler for isolation. This segmentation allows each component to be optimized independently, achieving better overall isolation performance than a single integrated device could provide.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary signal combining assembly that combines signals from both circulators. This intermediary structure enables the system to achieve high isolation by carefully managing and canceling leakage signals through the combining mechanism, rather than relying on a single device's inherent isolation properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a duplexing filter is used to isolate transmitted energy from the receiver, then frequency separation is achieved, but the system cannot operate at the same or closely spaced RF carrier frequencies

Engineering Contradiction:

Improvefrequency operation flexibilityVSAvoidisolation between transmitter and receiver

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the fundamental parameters of signal routing by using circulators with specific directional properties and phase characteristics. This allows the system to achieve isolation through parameter-based signal manipulation rather than frequency-based filtering, enabling operation at the same or closely spaced RF carrier frequencies.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If conventional circulators with minimum isolation of 20-25 dB are used, then basic signal routing is achieved, but receiver performance degrades due to insufficient isolation

Engineering Contradiction:

Improvesignal routing capabilityVSAvoidreceiver performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent merges the functions of multiple circulators and a directional coupler into a unified signal routing assembly. This combination allows the system to achieve isolation levels exceeding 30 dB by leveraging the complementary properties of each component working together, thereby maintaining receiver performance while preserving ease of operation.

Inventive Principle:

Principle #5Merging (Combining)

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

The solution effectively cancels transmission leakage signals, achieving isolation of at least 22 dB, and up to 37 dB or more, significantly improving the performance of full duplex wireless communication systems by reducing receiver desensitization and maintaining signal integrity.

Implementation Method 1

Methodology Applied

Scientific EffectSignal phase shifting and cancellation: Interference

Data Source

PatentUS8750173B2High isolation signal routing assembly for full duplex communication

Publication Date: 2014.06.10 KNOX MICHAEL E DR

AI summary

A signal routing assembly accepts a first transmission signal at an input and outputs a substantial portion of the signal at a common port of the signal routing assembly. A second transmission signal is received at the common port and is routed through the signal routing assembly delivered to output of the signal routing assembly. Leakage signals from routing devices leaking the first transmission signal are terminated inside the signal routing assembly. Leakage signal from a divider/combiner are cancelled by reflect signal from at least one reflector device. A transmitter produces the first transmission signal and the signal routing assembly delivers this signal to the common port of the signal routing assembly. In full duplex operation, second transmission signals received at the common port are routed to the output to be applied to a receiver.