Cell Reservation Logic for 5G NPN Access Control

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Solution Overview

Problem

Current wireless communication systems, particularly in 5G NR, face challenges in efficiently managing cell reservations and access restrictions across various network types, including public and non-public networks (NPNs), which affects network flexibility and user equipment (UE) compatibility.

Innovation Solution

The proposed method involves a UE that can ignore specific broadcasted information, such as cellReservedForOtherUse, and use PLMN-specific or CAG-specific indicators to determine whether a cell is barred or should be treated as a candidate for cell selection and reselection, thereby enhancing compatibility with NPNs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cellReservedForOtherUse is set to true to prevent access by legacy UEs, then network security and access control are improved, but compatibility with legacy UEs deteriorates

Engineering Contradiction:
Improveaccess controlVSAvoidUE compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the cell reserved status indicator into two separate fields: cellReservedForOtherUse (for legacy UEs) and cellReservedForOperatorUse (for 5G UEs). This segmentation allows each field to serve its specific UE type independently, resolving the contradiction by enabling legacy UEs to respect the first field while 5G UEs can ignore it and check the second field instead.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by making the cellReservedForOperatorUse field PLMN-specific, allowing different reserved status configurations for different public land mobile networks. This enables targeted access control policies for specific operators while maintaining general compatibility, addressing both security requirements and UE diversity.

Inventive Principle:
Principle #3Local quality

2Device complexity

If a single cellReservedForOtherUse field is used for all UEs, then system simplicity is maintained, but flexibility in supporting multiple network types deteriorates

Engineering Contradiction:
Improvesystem complexityVSAvoidnetwork type flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent divides the single cellReservedForOtherUse field into two distinct fields: cellReservedForOtherUse and cellReservedForOperatorUse. This segmentation enables the system to support multiple network types (public and non-public networks) simultaneously while maintaining clear, separate control mechanisms for each type.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent adds a new dimension to cell reservation by introducing the PLMN-specific cellReservedForOperatorUse field. This creates a hierarchical structure where the general cellReservedForOtherUse applies to all UEs, while the PLMN-specific field provides additional granularity for operator-controlled access, enabling support for NPNs without compromising public network operations.

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

3Reliability

If legacy UE access control mechanisms are applied to NPNs, then access security is improved, but network functionality and service availability deteriorate

Engineering Contradiction:
Improveaccess securityVSAvoidservice availability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements local quality by allowing 5G UEs to apply different access control logic depending on the network type. For NPNs, 5G UEs can ignore cellReservedForOtherUse and evaluate cellReservedForOperatorUse instead, enabling seamless access to NPN services while maintaining security through operator-defined policies specific to each PLMN.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4035431B1Method and apparatus for cell reservation and access restriction
Publication Date: 2025.05.28 SHARP KK
  • EP4035431B1 patent drawingFigure 1
  • EP4035431B1 patent drawingFigure 2
  • EP4035431B1 patent drawingFigure 3

AI summary

A method for wireless communication performed by a user equipment (UE) is provided. The method includes: receiving a master information block (MIB) from a cell, the MIB including a cell barred information element (IE); receiving a system information block type 1 (SIB1) from the cell, the SIB1 including a first non-public network (NPN) identity (ID), a first cell reserved for operator use IE associated with the first NPN ID, and a cell reserved for other use IE; and determining to treat the cell as a candidate cell for cell selection or cell reselection procedures when the cell barred IE is "not barred", the cell reserved for other use IE is not "true", the first cell reserved for operator use IE is "reserved", the first NPN ID matches a registered stand-alone NPN (SNPN) ID of the UE, and an access ID of the UE is 11 or 15.