CAG Cell Access Signaling for 5G NSA Non-Public Networks
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Solution Overview
Problem
Current 5G network standards lack a specific solution for providing non-public network services in NSA scenarios, particularly for Closed Access Group (CAG) services.
Innovation Solution
Implementing a communication method that includes broadcasting CAG IDs and PLMN IDs by base stations, allowing terminals to select and access CAG cells based on their subscription list, and ensuring legal access through verification and handover processes using CAG IDs and PLMN IDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 5G network standards support NSA non-public networks with CAG services, then network adaptability and service versatility are improved, but system complexity and implementation difficulty increase due to lack of existing solutions
Solution Approach 1:
The patent extends the existing PLMN access mechanism to support CAG services by introducing CAG IDs that can be carried in the same RRC messaging structures already used for PLMN identification. This allows the network to support both traditional public network access and new CAG-based non-public network access through unified signaling procedures, thereby improving adaptability without proportionally increasing system complexity
Solution Approach 2:
The patent segments the access control mechanism by introducing separate CAG ID identifiers that can be independently managed from PLMN IDs. This segmentation allows operators to create dedicated access groups for specific services or users while maintaining the overall PLMN structure, enabling versatile service support through modular identification
2Reliability
If terminals broadcast and verify CAG IDs through core network elements, then access security and reliability are improved, but signaling overhead and communication delay increase
Solution Approach 1:
The patent performs CAG ID verification as part of the initial RRC connection setup process rather than as a separate subsequent step. The terminal includes CAG ID information in the RRCSetupComplete message, allowing the base station to verify access authorization before allocating dedicated resources, thereby ensuring security while minimizing additional signaling delay
Solution Approach 2:
The patent combines CAG ID verification with the existing RRC connection establishment procedure. The same signaling messages used for PLMN selection and connection setup are extended to carry and verify CAG ID information, merging multiple functions into unified procedures to reduce overall signaling overhead and delay
3Productivity
If base stations broadcast CAG IDs and PLMN IDs in system information, then terminal access efficiency is improved, but information transmission overhead increases
Solution Approach 1:
The patent uses the existing system information block structures already dedicated to broadcasting PLMN identification data to also carry CAG ID information. By reusing the same broadcast messaging infrastructure for dual purposes, the network provides efficient access information to terminals without adding separate dedicated broadcast channels, thus improving access efficiency while limiting information overhead growth
Data Source
AI summary
The present disclosure relates to a communication method, system, base station, and terminal. The method includes: sending, by a first BS, a broadcast message, wherein the broadcast message comprising: one or more CAG IDs and one or more PLMN IDs supported by the first BS; receiving, by the first BS, a connection request sent from a terminal; establishing, by the first BS, a RRC connection with the terminal according to the connection request; receiving, by the first BS, a RRC connection setup complete message sent from the terminal, wherein the RRC connection setup complete message carries a CAG ID and a PLMN ID, which correspond to a CAG cell that the terminal selects to access; and allowing, by the first BS, the terminal to access the CAG cell that the terminal selects to access, according to the RRC connection setup complete message.