IMS Support for Stand-Alone Non-Public Networks Using PLMN ID and NID
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Solution Overview
Problem
Existing systems fail to enable users in stand-alone non-public networks (SNPNs) to fully utilize Internet Protocol Multimedia Subsystem (IMS) services, as they lack the ability to distinguish and manage multiple SNPNs sharing the same Public Land Mobile Network (PLMN) identifier, affecting charging and statistical data collection.
Innovation Solution
Implementing methods and apparatuses that allow IMS nodes to acquire and utilize a network identifier (NID) in addition to the PLMN ID for each SNPN, enabling accurate identification and management of individual SNPNs for charging and statistical purposes, including support for handovers between SNPNs and public PLMNs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only PLMN ID is used for network identification in IMS, then system complexity is reduced, but the ability to distinguish and manage multiple SNPNs sharing the same PLMN identifier is lost
Solution Approach 1:
The network identification is segmented into two distinct parts: PLMN ID (public land mobile network identifier) and NID (network identifier). This segmentation allows the system to first identify the general network using PLMN ID, then further distinguish between multiple SNPNs within that network using NID. The segmentation resolves the contradiction by maintaining simple overall system structure while enabling precise identification of individual SNPNs.
Solution Approach 2:
The identification system transitions from a single-dimension approach (PLMN ID only) to a two-dimension approach (PLMN ID + NID). By adding the NID dimension, the system can uniquely identify multiple SNPNs that share the same PLMN ID, effectively resolving the identification precision issue without significantly increasing system complexity.
2Measurement precision
If PLMN ID and NID are implemented for individual SNPN identification, then charging and statistical data collection accuracy is improved, but device complexity increases
Solution Approach 1:
The dual-identifier system (PLMN ID + NID) is designed to serve multiple functions simultaneously: network identification, charging differentiation, statistical data collection, and handover management. This multi-functionality approach allows a single identification mechanism to address multiple requirements, improving accuracy across different operations without proportionally increasing device complexity.
Solution Approach 2:
The NID acts as an intermediary element that bridges the gap between the shared PLMN ID and the need for individual SNPN identification. It provides the additional layer of specificity required for accurate charging and statistics while maintaining compatibility with the existing PLMN ID system, thereby limiting the increase in device complexity.
3Adaptability or versatility
If IMS nodes subscribe to PLMN ID and NID notifications, then handover support between SNPNs and public PLMNs is enhanced, but information processing complexity increases
Solution Approach 1:
IMS nodes perform preliminary subscription to PLMN ID and NID notification events before handover scenarios occur. This preliminary action ensures that the necessary identification information is already available and configured when handover is needed, enabling seamless transitions between SNPNs and public PLMNs without requiring complex real-time processing during the actual handover event.
Data Source
AI summary
Apparatuses and methods for IMS support for standalone non-public networks (SNPNs) are disclosed. In one embodiment, a method implemented in a policy node includes sending a Public Land Mobile Network, PLMN, identifier, ID, and a network identifier, NID, a combination of the PLMN ID and the NID identifying a standalone non-public network, SNPN being associated with a user equipment, UE. In one embodiment, a method implemented in an application function, AF, node includes receiving an Internet Protocol, IP, Multimedia Subsystem, IMS, registration request from a user equipment, UE; and as a result of receiving the IMS registration request, subscribing to be notified of a Public Land Mobile Network, PLMN, identifier, ID, and a network identifier, NID, a combination of the PLMN ID and the NID identifying a standalone non-public network, SNPN, associated with the UE.