Cross-Division Duplex Sub-Bands for Uplink Coverage and Capacity

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Solution Overview

Problem

Existing wireless communication systems face inefficiencies in resource allocation and latency due to half-duplex operation, particularly in scenarios requiring simultaneous transmission and reception, which limits UL coverage, capacity, and latency in initial access procedures.

Innovation Solution

Implementing cross division duplex (XDD) operation with sub-band full duplex (SBFD) techniques, utilizing semi-static and dynamic SB directional information to configure sub-bands and guard bands, enabling efficient resource allocation and dynamic adjustment of communication directions for improved UL coverage, capacity, and reduced latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If half-duplex operation is used, then device complexity is reduced, but UL coverage and capacity deteriorate

Engineering Contradiction:
Improveoperation mode complexityVSAvoidUL coverage
Core Design Contradiction:
Device complexityVSArea of stationary object

Solution Approach 1:

The patent divides the frequency band into multiple sub-bands and assigns different directional operations to different sub-bands. Specifically, it segments the bandwidth part (BWP) into first sub-bands for downlink reception and second sub-bands for uplink transmission, allowing simultaneous full-duplex operation in different frequency segments while maintaining half-duplex simplicity where applicable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from time-division duplexing (TDD) to frequency-division duplexing (FDD) by operating in the frequency dimension. By using sub-band full-duplex (SBFD) operation, it enables simultaneous uplink and downlink transmissions in different frequency sub-bands, effectively adding a frequency dimension to the operation mode.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If half-duplex operation is used, then device complexity is reduced, but system capacity deteriorates

Engineering Contradiction:
Improveoperation mode complexityVSAvoidsystem capacity
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent segments the frequency spectrum into multiple sub-bands, allowing simultaneous uplink and downlink operations in different segments. This segmentation enables the system to achieve full-duplex capacity while maintaining the simplicity of half-duplex operation in scenarios where simultaneous transmission is not required.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic sub-band full-duplex operation where the system can flexibly switch between half-duplex and full-duplex modes based on traffic conditions and channel characteristics. The network can dynamically configure which sub-bands operate in which direction, optimizing system capacity adaptively.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If half-duplex operation is used, then device complexity is reduced, but feedback delay and latency deteriorate

Engineering Contradiction:
Improveoperation mode complexityVSAvoidfeedback delay
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

By segmenting the frequency band into multiple sub-bands with different operational directions, the patent enables simultaneous transmission and reception. This allows feedback messages to be transmitted immediately in dedicated uplink sub-bands without waiting for the next time slot, significantly reducing feedback delay and latency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent maintains continuous communication by ensuring that while some sub-bands are dedicated to downlink, other sub-bands simultaneously handle uplink transmissions. This continuity eliminates the idle periods inherent in half-duplex operation, reducing overall latency and ensuring uninterrupted data flow.

Inventive Principle:
Principle #20Continuity of useful action

4Area of stationary object

If dynamic sub-band configuration is implemented, then UL coverage and capacity are improved, but device complexity increases

Engineering Contradiction:
ImproveUL coverageVSAvoidresource management complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements preliminary configuration of sub-band full-duplex parameters through higher-layer signaling (RRC configuration). The network pre-configures the UE with sub-band information, directional operation modes, and resource allocation patterns, so that the complex dynamic operations can be executed efficiently without real-time complex decision-making at the UE side.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback mechanisms where the network monitors uplink coverage and capacity performance, and dynamically adjusts sub-band configurations based on channel conditions and traffic demands. This feedback-driven approach optimizes UL coverage while managing device complexity through adaptive rather than purely static configurations.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4145944B1Systems, methods, and apparatuses for cross division duplex operation in wireless communication
Publication Date: 2025.09.10 APPLE INC
  • EP4145944B1 patent drawingFigure 1
  • EP4145944B1 patent drawingFigure 2
  • EP4145944B1 patent drawingFigure 3

AI summary

Systems, methods, and apparatuses for cross division duplex (XDD) operation in a wireless communication system are described herein. A user equipment (UE) is configured with one or more sub-bands (SBs) within a larger overall bandwidth (BW) (e.g., represented by a component carrier (CC), a bandwidth part (BWP), etc.), and that use uplink (UL)/downlink (DL) resource allocation(s) that may be different than the larger BW. Configurations for such SB-specific (SBS) arrangements that use guard bands (GBs) between SBs are discussed. Mechanisms for slot format indications (SFIs) within such SBs using either SBS DCI or cross-SB DCI are discussed. Mechanisms for providing SBS uplink resource for initial access (e.g., random access) using at least one initial UL BWP that is configured relative to one or more SBs and that may be used by XDD-capable UEs are discussed.