Sub-Band Full-Duplex Transceiver Filtering for Interference Suppression

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Solution Overview

Problem

Existing communication systems face challenges in managing cross-link interference and self-interference in sub-band full duplex (SBFD) operations, particularly in the 6 GHz frequency band, where simultaneous transmission and reception occur, due to limitations in RF filtering and interference suppression.

Innovation Solution

Implementing a transceiver arrangement with bandpass filters and circulators or duplexers to separate frequency resources by a guard band, allowing for simultaneous transmission and reception in different time slots, and using RF filtering to isolate uplink and downlink sub-bands effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simultaneous transmission and reception occur in sub-band full duplex operations, then spectrum efficiency is improved, but cross-link interference and self-interference increase

Engineering Contradiction:
Improvespectrum efficiencyVSAvoidcross-link interference
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The frequency band is segmented into multiple sub-bands, with transmission and reception occurring in different sub-bands simultaneously. This segmentation allows full duplex operation while reducing interference through frequency separation, directly addressing the contradiction between spectrum efficiency and interference levels.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If RF filtering is used to separate frequency resources, then interference suppression is improved, but device complexity increases

Engineering Contradiction:
Improveinterference suppressionVSAvoidtransceiver arrangement complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Bandpass filters are introduced as intermediary components between the antenna and the transceiver circuitry. These filters act as mediators that selectively pass desired frequency bands while blocking interfering signals, thereby improving interference suppression while managing the added complexity through standardized filter components.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If guard band is introduced to separate frequency resources, then interference between sub-bands is reduced, but frequency resource utilization decreases

Engineering Contradiction:
Improveinterference between sub-bandsVSAvoidfrequency resource utilization
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The guard band parameters (frequency position, bandwidth) are optimized to achieve the minimum necessary separation between sub-bands. By carefully adjusting these parameters, the system reduces interference between sub-bands while minimizing the spectral gap, thereby maintaining high frequency resource utilization.

Inventive Principle:
Principle #35Parameter changes

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 achieves significant interference suppression, enabling efficient simultaneous transmission and reception with up to 100 dB interference cancellation, suitable for both licensed and unlicensed technologies in the 6 GHz frequency band.

Implementation Method 1

Implementing a transceiver arrangement with bandpass filters and circulators or duplexers to separate frequency resources by a guard band

Methodology Applied
Scientific EffectRF filtering: Filter (electronic)

Implementation Method 2

Implementing a transceiver arrangement with bandpass filters and circulators or duplexers

Methodology Applied
Scientific EffectCirculator:

Implementation Method 3

Implementing a transceiver arrangement with bandpass filters and circulators or duplexers

Methodology Applied
Scientific EffectDuplexer:

Data Source

PatentEP4626098A1Method, apparatus and computer program
Publication Date: 2025.10.01 NOKIA TECHNOLOGIES OY
  • EP4626098A1 patent drawingFigure 1~2
  • EP4626098A1 patent drawingFigure 3~5
  • EP4626098A1 patent drawingFigure 4

AI summary

An apparatus comprising: means for transmitting one or more signals in one or more first time slots on a first frequency resource to one or more user equipment; and means for receiving one or more signals in one or more second time slots on the first frequency resource from one or more user equipment, and for receiving one or more signals in one or more third time slots on a second frequency resource, the first and second frequency resources being separated by a guard band, wherein the one or more first time slots are different to the one or more second time slots, one or more of the first time slots are the same as one or more of the third time slots.