URSP Flag Mechanism for 4G to 5G Session Continuity

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Solution Overview

Problem

Existing technologies face challenges in seamlessly transitioning user equipment from a Fourth Generation (4G) network to a Fifth Generation (5G) network without interrupting ongoing sessions.

Innovation Solution

The implementation of a Policy Control Function (PCF) that creates and manages User Equipment Route Selection Policies (URSP), setting flags to indicate applicability to new or ongoing sessions, ensuring seamless transitions without disrupting existing connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If User Equipment Route Selection Policies are updated when moving from 4G to 5G network, then network generation transition capability is improved, but ongoing sessions may be interrupted

Engineering Contradiction:

Improvenetwork generation transition capabilityVSAvoidsession continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The policy update mechanism is segmented into two distinct paths: one for new sessions and one for ongoing sessions. The indication parameter enables the UE to differentiate between these two scenarios, applying policy updates only to new sessions while preserving ongoing sessions unchanged, thus resolving the contradiction between adaptability and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The network performs preliminary action by sending the indication parameter along with the URSP rules before the UE applies them. This preliminary indication allows the UE to prepare for selective application of policies, ensuring that ongoing sessions are protected before any policy changes take effect, thereby maintaining session continuity during network transition

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If traditional policy update methods are used during network transition, then implementation simplicity is maintained, but session interruption occurs

Engineering Contradiction:

Improveimplementation simplicityVSAvoidsession continuity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The indication parameter serves as an intermediary element between the network and UE that carries semantic information about policy applicability. This intermediary enables the simple yet effective differentiation between new and ongoing sessions without requiring complex protocol changes, maintaining implementation simplicity while ensuring session continuity through the straightforward interpretation of the indication value

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12335836B2Provisioning user equipment route selection policies with service assurance

Publication Date: 2025.06.17 CISCO TECHNOLOGY INC

AI summary

Provisioning User Equipment (UE) Route Selection Policies (URSP) may be provided. A policy of a user equipment (UE) may be updated by a Policy Control Function (PCF). Then, the PCF may create a UE route selection policy (URSP) based on the updated UE policy. Next, the PCF may set a flag in in the URSP that may indicate to the UE that the URSP is applicable for new sessions and inapplicable for ongoing sessions. The PCF may then send the URSP to the UE, wherein the UE applies the URSP for new sessions.