Full-Duplex RACH Configuration for Self-Interference Mitigation

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Solution Overview

Problem

Existing wireless communication systems, particularly in 5G NR, face challenges in optimizing random access channel (RACH) procedures in full-duplex (FD) operations due to self-interference issues, limiting the efficient utilization of both uplink and downlink resources in overlapping frequency bands.

Innovation Solution

A framework is introduced that allows for the configuration of both in-band full-duplex (IBFD) and sub-band full-duplex (SBFD) RACH resources, enabling flexible RACH procedures by incorporating FD RACH occasions with guard bands and separate HD RACH occasions to manage self-interference, allowing both FD-capable and non-FD-capable UEs to perform RACH operations effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If full-duplex RACH resources are configured in overlapping frequency bands, then resource utilization efficiency is improved, but self-interference between uplink and downlink transmissions increases

Engineering Contradiction:
Improveresource utilization efficiencyVSAvoidself-interference
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent segments RACH resources into separate HD RACH occasions and IBFD/SBFD RACH occasions. HD RACH occasions use traditional half-duplex resources without self-interference, while IBFD/SBFD RACH occasions utilize full-duplex capabilities with guard bands to mitigate interference. This segmentation allows the system to serve both FD-capable and non-FD-capable UEs simultaneously, improving overall resource utilization while managing self-interference through controlled separation of transmission types.

Inventive Principle:
Principle #1Segmentation

2Object-generated harmful factors

If guard bands are introduced in IBFD/SBFD RACH occasions to mitigate self-interference, then self-interference is reduced, but available frequency resources are consumed

Engineering Contradiction:
Improveself-interferenceVSAvoidavailable frequency resources
Core Design Contradiction:
Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

The patent applies local quality by introducing guard bands specifically at the boundaries between uplink and downlink frequency bands within IBFD/SBFD RACH occasions, rather than reducing the overall bandwidth. The guard bands are localized to where self-interference occurs most severely (at the interface between opposing transmission directions), allowing maximum frequency resource utilization elsewhere while providing targeted interference mitigation where needed.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If separate HD RACH occasions are configured alongside IBFD/SBFD RACH occasions, then compatibility with non-FD-capable UEs is improved, but system complexity increases

Engineering Contradiction:
ImproveUE capability compatibilityVSAvoidRACH configuration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements universality by designing a unified RACH configuration framework that simultaneously supports multiple UE capabilities. The base station configures both HD RACH occasions (for non-FD-capable UEs) and IBFD/SBFD RACH occasions (for FD-capable UEs) within the same system, allowing a single RACH configuration to serve diverse UE types. UEs autonomously select appropriate RACH occasions based on their capabilities, eliminating the need for separate configuration procedures and reducing operational complexity.

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

Data Source

PatentEP4412141B1Random access configuration and procedure in full-duplex operation
Publication Date: 2026.02.18 QUALCOMM INC
  • EP4412141B1 patent drawingFigure 1
  • EP4412141B1 patent drawingFigure 2A~2D
  • EP4412141B1 patent drawingFigure 3

AI summary

The present disclosure relates to methods and devices for wireless communication at an apparatus, e.g., a UE or a base station. The base station may be configured to configure one or more RACH resources for a FD RACH configuration and transmit, to at least one UE, an indication of the one or more RACH resources configured for the FD RACH configuration. The UE may be configured to receive the indication of the FD RACH configuration for the one or more RACH resources. The UE may further be configured to select, based on the received indication, at least one RACH resource of the one or more RACH resources for the FD RACH configuration and transmit, to the first base station via the selected at least one RACH resource, at least one message of a RACH procedure based on the FD RACH configuration.