TDMA Full-Duplex Radio Using One Synthesizer and Dual VCOs

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Solution Overview

Problem

Current portable communications devices face challenges in implementing full-duplex communication in TDMA radio systems due to the added cost and complexity of using multiple synthesizers.

Innovation Solution

A portable communications device is designed with a single synthesizer and two voltage controlled oscillators, controlled by an electronic processor to switch between frequencies for each timeslot, enabling full-duplex operation without the need for multiple synthesizers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple synthesizers are used to enable full-duplex communication, then simultaneous transmission and reception on different frequencies is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvefull-duplex communication capabilityVSAvoidnumber of synthesizers
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple synthesizers into a single synthesizer by implementing a timeslot switching mechanism. The single synthesizer alternates between generating first frequency signals for transmission and second frequency signals for reception across different timeslots, effectively combining what would traditionally require separate synthesizer units into one integrated component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs periodic action through timeslot switching, where the single synthesizer periodically alternates between two operational modes: generating first frequency signals during first timeslots for transmission and generating second frequency signals during second timeslots for reception. This periodic switching enables full-duplex functionality without requiring simultaneous operation of multiple synthesizers.

Inventive Principle:
Principle #19Periodic action

2Adaptability or versatility

If multiple synthesizers are used for full-duplex operation, then simultaneous transmission and reception is enabled, but manufacturing cost increases

Engineering Contradiction:
Improvefull-duplex communication capabilityVSAvoiddevice manufacturing cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the functions of multiple synthesizers into a single synthesizer by implementing a timeslot switching mechanism. The single synthesizer alternates between generating first frequency signals for transmission and second frequency signals for reception across different timeslots, effectively combining what would traditionally require separate synthesizer units into one integrated component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single synthesizer is designed with multi-functionality to perform both transmission frequency generation and reception frequency generation roles. By making the synthesizer universal in its function and controlling it through timeslot switching, the system eliminates the need for separate dedicated synthesizers for each function, thereby reducing manufacturing costs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If a single synthesizer is used with timeslot switching, then device complexity is reduced, but frequency switching speed must be sufficient

Engineering Contradiction:
Improvenumber of synthesizersVSAvoidfrequency switching speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The patent employs periodic action through timeslot switching, where the single synthesizer periodically alternates between two operational modes: generating first frequency signals during first timeslots for transmission and generating second frequency signals during second timeslots for reception. This periodic switching enables full-duplex functionality without requiring simultaneous operation of multiple synthesizers.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary action by pre-configuring the timeslot switching schedule and preparing frequency transitions in advance. The synthesizer is controlled to switch frequencies at predetermined timeslot boundaries, allowing sufficient time for each frequency to stabilize before use, thereby managing the switching speed requirement through careful timing and scheduling.

Inventive Principle:
Principle #10Preliminary action

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 the cost and complexity of full-duplex communication by allowing simultaneous transmission and reception on different frequencies using a single synthesizer, optimizing device performance and battery life.

Implementation Method 1

a first voltage controlled oscillator, a second voltage controlled oscillator

Methodology Applied
Scientific EffectVoltage-controlled oscillation:

Implementation Method 2

a synthesizer configured to generate a first frequency when connected to the first voltage controlled oscillator and generate a second frequency when connected to the second voltage controlled oscillator

Methodology Applied
Scientific EffectFrequency synthesis:

Data Source

PatentEP4122104B1Full duplex operation of a portable communications device in a time division multiple access radio system
Publication Date: 2025.12.24 MOTOROLA SOLUTIONS INC
  • EP4122104B1 patent drawingFigure 1
  • EP4122104B1 patent drawingFigure 2A
  • EP4122104B1 patent drawingFigure 2B~3

AI summary

Portable communications device (110) and method (500) for full duplex operation in a time division multiple access radio system. The method (500) includes providing a switch (340) for connecting one of a first voltage controlled oscillator (330A) and a second voltage controlled oscillator (330B) to a synthesizer (350). The synthesizer (350) generates a first frequency when connected to the first voltage controlled oscillator (330A) and generates a second frequency when connected to the second voltage controlled oscillator (330B). The method (500) also includes controlling, using an electronic processor (310) coupled to the switch (340), the switch (340) to connect the first voltage controlled oscillator (330A) to the synthesizer (350) for a first timeslot (220A), and controlling, using the electronic processor (310), the switch (340) to disconnect the first voltage controlled oscillator (330A) from the synthesizer (350) and connect the second voltage controlled oscillator (330B) to the synthesizer (350) for a second timeslot (220B). The second timeslot (220B) is immediately adjacent to the first timeslot (220A).