PDCP-Terminating Network Node for SBI RAN-Core Integration

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Solution Overview

Problem

The integration of the Service Based Interface (SBI) to the center-edge boundary link between the Radio Access Network (RAN) and the core network is hindered by the configuration where a part of the gNB-CU is arranged on the core network side, necessitating a configuration that includes gNB-CU and core network functions.

Innovation Solution

A network node is provided with a control unit to terminate PDCP and a communication unit to perform communications on the C plane via SBI, U plane via N3 interface, and with a DU via F1 interface, integrating the boundary interface between RAN and core network into the core network side interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a part of the gNB-CU is arranged on the core network side, then the network architecture flexibility is improved, but the SBI cannot be applied to the center-edge boundary link

Engineering Contradiction:
Improvenetwork architecture flexibilityVSAvoidSBI applicability to center-edge boundary link
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The gNB-CU is divided into separate functional units (control plane and user plane) that can be independently deployed. The control plane function terminates PDCP and communicates with the core network via SBI, while the user plane function handles data traffic. This segmentation allows SBI to be applied to the center-edge boundary link for control plane communications while maintaining flexible deployment options.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A control plane function is introduced as an intermediary between the gNB-CU and the core network. This intermediary terminates the PDCP protocol and establishes SBI communications with the core network, enabling SBI applicability to the center-edge boundary link while allowing the gNB-CU to maintain its flexible architectural positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the boundary interface between RAN and core network is integrated into the core network side interface, then the network architecture is optimized for cloud infrastructure, but the device complexity increases

Engineering Contradiction:
Improvenetwork architecture optimizationVSAvoidnetwork node configuration
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The control plane function and the gNB-CU are merged into a single network node that performs both PDCP termination and SBI communications. This merging optimizes the network architecture by consolidating functions that can operate together, reducing the number of separate components while maintaining the ability to interface with both the core network via SBI and the user plane functions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The network node is designed with multi-functionality, serving as both a PDCP termination point and an SBI communication endpoint. This universal design allows a single node to fulfill multiple roles in the network architecture, optimizing cloud infrastructure utilization while managing device complexity through functional integration rather than proliferation of separate components.

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

Data Source

PatentEP4642078A1Network node and communication method
Publication Date: 2025.10.29 NTT DOCOMO INC
  • EP4642078A1 patent drawingFigure 1
  • EP4642078A1 patent drawingFigure 2
  • EP4642078A1 patent drawingFigure 3

AI summary

A network node includes: a control unit configured to terminate a PDCP (Packet Data Convergence Protocol); and a communication unit configured to perform communications on a C plane (Control Plane) with a network node that terminates an RRC (Radio Resource Control) via an SBI (Service Based Interface), perform communications on a U plane (User Plane) with a network node that terminates a U plane protocol of an N3 interface, and perform communications with a DU (Distributed Unit) via an F1 interface.