UE NSSP Rule Updates for Reliable PDU Session Routing

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Solution Overview

Problem

The 3GPP specifications do not describe how Network Slice Selection Policy (NSSP) rules are configured at the User Equipment (UE) or how they are updated, leading to potential inefficiencies and failures in PDU session routing due to outdated rules.

Innovation Solution

A method and system for dynamically updating NSSP rules at the UE by integrating a Policy Control Function (PCF) node and Access and Mobility Management Function (AMF) node to transmit and receive policy updates, ensuring timely configuration and updates of NSSP rules during connected or idle mode, using UE Configuration Update procedures or Network Triggered Service Requests.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If NSSP rules are only configured during registration, then the configuration process is simple, but the rules become outdated between registrations causing PDU session routing failures

Engineering Contradiction:

ImprovePDU session routing reliabilityVSAvoidUE configuration update complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The network performs preliminary actions by proactively pushing NSSP rule updates to the UE before the UE's local rules become outdated. The PCF monitors rule changes and triggers updates through the AMF using existing signaling procedures, ensuring the UE always has current routing information without waiting for registration cycles.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A feedback mechanism is established where the PCF receives notifications about policy changes from the PCO and subsequently pushes updated NSSP rules to the UE. This closed-loop feedback ensures the UE's local configuration remains synchronized with network policy decisions, preventing routing failures.

Inventive Principle:

Principle #23Feedback

2Productivity

If NSSP rules are updated dynamically between registrations, then routing reliability improves, but the system complexity increases

Engineering Contradiction:

ImproveNetwork slice utilization efficiencyVSAvoidPolicy update mechanism complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent leverages existing multi-functional signaling paths already present in the 5G architecture. The N1 interface between UE and AMF, and the N11 interface between AMF and PCF, are used for multiple purposes including mobility management, session management, and now NSSP rule updates. This avoids creating dedicated update pathways and minimizes additional complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The UE autonomously processes received NSSP rules by storing them in its local configuration and applying them to PDU session routing decisions. The UE's protocol stack automatically integrates the new rules without requiring manual intervention or complex external management, enabling efficient network slice utilization through self-service operation.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3695653B1UE configuration and update with network slice selection policy

Publication Date: 2025.09.24 NEC CORP

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AI summary

A policy control function, PCF, node, comprising: transmitting means for transmitting a message related to information for updating policies of at least one of User Equipment, UE, access and Protocol Data Unit, PDU, Session selection, to a UE via an Access and Mobility Management Function, AMF node.