Target AF Notification for 5G Session Continuity During DNAI Changes
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Solution Overview
Problem
The challenge of maintaining session continuity for user equipment (UE) in a wireless communication system when the local data network (DN) changes due to mobility, particularly in the context of 5G communication systems, has not been adequately addressed.
Innovation Solution
A method and apparatus that involve an application function (AF) receiving a late notification message from a session management function (SMF) about a data network access identifier (DNAI) change, identifying the need for AF change, and transmitting a response message to the SMF with information for a target AF, including an indication of AF change, target AF ID, or notification target address, to ensure seamless session continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the local data network changes due to UE mobility, then the UE can access new data networks, but session continuity is disrupted and service interruption occurs
Solution Approach 1:
The source AF sends an early notification to the target AF before the UE actually moves to the new data network. This advance notification allows the target AF to prepare for the session transfer, ensuring that when the UE arrives at the new DN, the session can be seamlessly continued without interruption. The early notification includes necessary session information that enables the target AF to establish the session in advance.
Solution Approach 2:
The SMF acts as an intermediary between the AFs and the UE. It receives notifications from the source AF, manages the session information, and coordinates the transfer to the target AF. The SMF also sends late notifications to ensure the target AF is fully prepared before the actual handover, mediating the complex interaction between multiple network functions to maintain session continuity.
2Reliability
If application function information is not timely updated during mobility, then network complexity is reduced, but service delivery is interrupted and reliability decreases
Solution Approach 1:
The notification mechanism ensures continuous updating of AF information throughout the mobility process. The source AF notifies the target AF in advance, and the SMF sends late notifications to confirm session transfer status. This continuous information flow ensures that the AF information is always current, maintaining service delivery continuity without gaps or interruptions during the mobility event.
Solution Approach 2:
The system implements feedback mechanisms where the SMF sends late notifications to the target AF after the UE has moved, confirming the session transfer status. This feedback loop ensures that all network functions have the correct, up-to-date information about the current session location, allowing for reliable service delivery while managing complexity through structured feedback rather than constant active monitoring.
3Reliability
If early notification is sent to target AF before DNAI change, then session continuity is improved, but timing coordination becomes complex and may cause premature or delayed AF relocation
Solution Approach 1:
The source AF sends an early notification to the target AF before the DNAI change occurs, allowing the target AF to prepare for the session transfer in advance. This preliminary action ensures that when the time comes for the actual handover, the target AF is already ready to receive and continue the session, minimizing any potential delays and ensuring smooth continuity.
Solution Approach 2:
The SMF acts as a mediator that manages the timing and coordination between early and late notifications. It receives the early notification, stores the session information, and then sends a late notification at the appropriate time after the DNAI change. This intermediary role simplifies the timing coordination by centralizing the management of notification sequences, preventing premature or delayed AF relocation.
4Measurement precision
If late notification is sent after DNAI change, then AF information accuracy is improved, but session establishment time increases
Solution Approach 1:
The system sends an early notification to the target AF before the DNAI change occurs, allowing the target AF to prepare for the session transfer in advance. This preliminary action ensures that when the late notification is sent after the DNAI change with accurate AF information, the session establishment can proceed quickly because the target AF is already prepared and configured to receive the session.
Solution Approach 2:
The combination of early and late notifications creates a continuous information flow that maintains both accuracy and efficiency. The early notification initiates preparation actions, and the late notification confirms the actual session transfer with accurate AF information. This continuous process ensures that the session establishment is both accurate and timely, avoiding delays that would result from waiting for all information to be gathered after the DNAI change.
Data Source
AI summary
A method performed by an application function (AF) in a wireless communication system is provided. The method includes receiving, from a session management function (SMF), a late notification message indicating a change of a data network access identifier (DNAI), identifying whether an AF change is needed based on the late notification message, and transmitting, to the SMF, a response message including information for change to a target AF for a target DNAI based on a result of identifying that the AF change is needed.