UE Network Slice Registration Updates for Rejected S-NSSAI Access

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Solution Overview

Problem

User Equipment (UE) faces challenges in accessing desired network slices that are not part of the allowed Single-Network Slice Selection Assistance Information (S-NSSAI) list, leading to prolonged access delays and inefficient management of rejected and configured S-NSSAIs, resulting in unpredictable behavior and poor user experience due to misaligned S-NSSAI interpretations across different Public Land Mobile Networks (PLMNs).

Innovation Solution

The UE is equipped with engines to manage and modify the allowed NSSAI list, perform S-NSSAI mapping, and handle rejected NSSAIs, ensuring timely access to desired network slices by initiating mobility registration updates based on trigger conditions and S-NSSAI mapping across PLMNs, particularly in idle mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE stores rejected S-NSSAIs locally and waits for network reconfiguration, then the UE avoids attempting to access rejected slices, but the UE experiences prolonged access delays and cannot quickly access desired network slices when network conditions change

Engineering Contradiction:

Improvenetwork slice access reliabilityVSAvoidaccess delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The UE proactively monitors trigger conditions (timer expiry, TAU update, RRC reconfiguration, network slice availability changes) and initiates mobility registration updates before being explicitly reconfigured by the network. This preliminary action allows the UE to refresh its allowed NSSAI list and access desired slices faster, reducing access delays while maintaining reliable slice selection through the trigger condition framework

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE implements a feedback mechanism by monitoring network responses, timer expirations, and configuration updates to determine when to initiate registration updates. This feedback loop allows the UE to adapt its slice access behavior dynamically, refreshing the allowed NSSAI list when network conditions change, thereby reducing access delays while maintaining reliable slice selection

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If the UE maintains separate rejected NSSAI lists for each PLMN, then the UE can manage slice selections per network, but the UE experiences unpredictable behavior and management complexity when moving between different PLMNs with different S-NSSAI interpretations

Engineering Contradiction:

ImprovePLMN-specific slice management adaptabilityVSAvoidrejected NSSAI list management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The UE segments the rejected NSSAI management by maintaining separate rejected NSSAI lists for each PLMN and each 5GMM mode (idle and connected). This segmentation allows the UE to manage slice rejections independently per network and operational mode, adapting to PLMN-specific slice interpretations while keeping management complexity organized through clear separation rather than mixing all rejections into a single list

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The UE applies local quality by allowing different rejected NSSAI configurations for different PLMNs and 5GMM modes. Each PLMN-specific list contains only the S-NSSAIs rejected by that particular network, enabling the UE to adapt slice management behavior locally to each network's requirements while moving between PLMNs, thereby reducing unpredictable behavior through PLMN-specific adaptation

Inventive Principle:

Principle #3Local quality

3Speed

If the UE initiates mobility registration updates frequently to check for allowed NSSAI changes, then the UE can quickly access desired network slices, but the UE consumes excessive signaling resources and increases network load

Engineering Contradiction:

Improveslice access speedVSAvoidsignaling resource consumption

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The UE implements periodic action through timer-based mechanisms (e.g., T3540 timer) that trigger mobility registration updates at appropriate intervals rather than continuously. The timer is started or restarted upon specific events (configuration updates, TAU updates), ensuring the UE checks for allowed NSSAI changes periodically and event-driven, which balances quick slice access with reduced signaling resource consumption compared to continuous monitoring

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The UE applies dynamics by making the registration update initiation adaptive based on monitored trigger conditions. The UE dynamically decides when to initiate updates based on timer expiry, TAU updates, RRC reconfigurations, and network slice availability changes, rather than using a fixed periodic schedule. This dynamic approach optimizes the balance between slice access speed and signaling resource consumption by updating only when necessary

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12568429B2Enhancements for user equipment network slice management

Publication Date: 2026.03.03 APPLE INC

AI summary

A user equipment (UE) configured to transmit a registration request message to a network, the registration request message comprising a request to register to a set of one or more single-network slice selection assistance information (S-NSSAIs), receive a response to the registration request message, the response indicating that the request to register to the set of one or more S-NSSAIs is rejected and store the set of one or more S-NSSAIs in a rejected NSSAI list locally at the UE.