Centralized NSACF Threshold Control for Slice Session Continuity

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Solution Overview

Problem

Existing network slice admission control (NSAC) systems in 3GPP Fifth Generation System (5GS) fail to guarantee session continuity during mobility events, particularly when UEs move between service areas with depleted quotas, leading to potential admission failures and loss of session continuity.

Innovation Solution

Implement a centralized Network Slice Admission Control Function (NSACF) that communicates with local NSACFs to manage UE admissions and PDU sessions, adjusting thresholds and quotas dynamically to ensure seamless session continuity and efficient resource allocation across service areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If local NSACF applies strict admission control based on maximum registered UE limits, then resource allocation efficiency is improved, but session continuity during mobility events deteriorates

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidsession continuity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces a central NSACF as an intermediary between local NSACFs and UEs. When a UE moves between service areas, the central NSACF coordinates admission control across multiple local NSACFs, ensuring session continuity even when local quotas are depleted. The central NSACF receives registration requests from local NSACFs, makes admission decisions, and provides threshold instructions to local NSACFs for future requests.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements preliminary action by having the central NSACF pre-allocate quotas and set threshold values for local NSACFs before mobility events occur. The central NSACF maintains an overview of total available resources and pre-configures local NSACFs with appropriate admission thresholds, enabling them to handle mobility events without strict local limits that would otherwise block seamless handovers.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If centralized NSACF maintains reserve quotas for mobility events, then session continuity is improved, but device complexity increases

Engineering Contradiction:

Improvesession continuityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the admission control functions of multiple local NSACFs under a single central NSACF. Instead of each local NSACF independently managing its own limited quota, the system combines resource management at the central level while local NSACFs handle local registration and threshold monitoring. This consolidation enables centralized reserve quota management without requiring each local NSACF to independently handle complex mobility scenarios.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250358765A1Support for session continuity in multiple nsacf scenarios

Publication Date: 2025.11.20 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Systems and methods for Network Slice Admission Control (NSAC) in a cellular communications system are disclosed. In one embodiment, a method performed by a local Network Slice Admission Control Function (NSACF) comprises receiving a first request to update a number of registered User Equipments (UEs) for a network slice and sending a second request to update the number of registered UEs for the network slice to a central NSACF in response to determining that a maximum number of registered UEs for the network slice is reached. The method further comprises receiving a response from the central NSACF and operating accordingly, wherein the response indicates whether admission of the particular UE to the network slice is accepted or rejected and comprises an instruction defining a threshold to be applied by the local NSACF for future requests to update the number of registered UEs for the network slice for new UE registrations.