Slice-Aware PLMN Selection for Faster Roaming Registration
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Solution Overview
Problem
When a user equipment (UE) roams away from its home network, it faces challenges in selecting and registering with a Public Land Mobile Network (PLMN) that supports the desired network slice due to lack of awareness about which PLMNs in a foreign country support the required slice, leading to time-consuming and power-wasting redundant registration attempts.
Innovation Solution
The UE receives a list of PLMNs that support a given network slice in a foreign country from its home PLMN or via a visited PLMN, satellite, or WiFi, and prioritizes these PLMNs for registration, using an S-NSSAI-aware mechanism to optimize PLMN selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE repeatedly attempts registration with different PLMNs without awareness of slice support, then the UE can eventually find a suitable PLMN, but the process is time-consuming and power-consuming
Solution Approach 1:
The home PLMN provides the UE with a pre-configured list of PLMNs that support the desired network slice before the UE needs to roam. This preliminary action allows the UE to immediately select a suitable PLMN upon entering a foreign country, eliminating the need for repeated trial registrations and significantly reducing time loss.
Solution Approach 2:
The patent introduces an intermediary information structure (the PLMN list with slice support indicators) that mediates between the home PLMN's knowledge of slice-capable networks and the UE's need to select an appropriate network. This intermediary enables the UE to make informed decisions without directly querying each PLMN, reducing both time and signaling overhead.
2Reliability
If the UE repeatedly attempts registration with different PLMNs without awareness of slice support, then the UE can eventually find a suitable PLMN, but power is wasted on redundant attempts
Solution Approach 1:
The UE receives and stores the PLMN list with slice support information in advance, performing the power-intensive information gathering operation beforehand when the device is likely connected to power. When roaming begins, the UE can simply query this stored list and register immediately, avoiding repeated radio activations and significant power savings.
Solution Approach 2:
The UE is empowered to autonomously select a suitable PLMN by querying its stored list of slice-supporting networks, without needing to perform energy-consuming discovery procedures or repeated registration attempts. The device serves itself by making informed decisions based on pre-provided information.
3Adaptability or versatility
If the UE uses non-preferred PLMNs to achieve ubiquitous 5GS coverage, then coverage is improved, but the desired network slice may not be supported
Solution Approach 1:
The patent applies local quality by differentiating between PLMNs based on their specific capability to support the desired network slice. The UE is provided with granular information about which PLMNs support which slices, enabling it to select a PLMN that is locally optimal for both coverage and slice support, rather than applying a generic preference rule.
Solution Approach 2:
The invention changes the selection parameter from generic PLMN preference to slice-specific PLMN capability. By incorporating slice support information into the PLMN list and using it as a selection criterion, the system transforms the selection process to prioritize both coverage and slice availability, resolving the contradiction between these two requirements.
Data Source
AI summary
A user equipment (UE) may receive a list of Public Land Mobile Networks (PLMNs) that support a given network slice in a given country, different from a home country of a home PLMN of the UE. When roaming in the given country, UE may access a PLMN of the list if the given network slice is desired. The list may be provided by the home PLMN: while the UE is in the home country; or via a visited PLMN while the UE is in the given country. The list may be received in response to a UE-initiated request, or pushed to the UE by the home PLMN. A validity timer period received with the list may indicate a duration of validity of the list. In an alternative scenario, the UE may receive the list from an entitlement server, e.g., one belonging to a visited PLMN.