PDU Session ID Uniqueness via UDM List Retrieval
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Solution Overview
Problem
The uniqueness of the PDU Session ID assigned by the SMF+PGW-C for PDN connections may not be ensured in certain scenarios, leading to duplicated IDs and potential deletion of previous PDN connections.
Innovation Solution
A method where the first network node (SMF+PGW-C) requests a list of already registered PDU Session IDs from the second network node (UDM) during PDN connection establishment and assigns a unique ID not present in the list.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SMF+PGW-C assigns PDU Session ID based on EPS Bearer ID without checking existing assignments, then the assignment process is simple and fast, but the uniqueness of PDU Session ID cannot be ensured leading to duplication
Solution Approach 1:
The SMF+PGW-C performs preliminary actions by retrieving the list of already assigned PDU Session IDs from the UDM before assigning a new ID. This preliminary check ensures that the newly assigned ID will not duplicate any existing ID, thereby resolving the technical contradiction by maintaining uniqueness while managing the assignment process systematically.
Solution Approach 2:
The system implements feedback by continuously monitoring and retrieving the list of assigned PDU Session IDs from the UDM. This feedback mechanism allows the SMF+PGW-C to adjust its ID assignment decisions based on current state information, ensuring uniqueness while managing complexity through informed decision-making.
2Reliability
If the SMF+PGW-C retrieves the list of assigned PDU Session IDs from UDM before assignment, then the uniqueness is ensured, but the assignment process becomes more complex and time-consuming
Solution Approach 1:
The UDM maintains a pre-updated list of assigned PDU Session IDs, allowing the SMF+PGW-C to quickly retrieve this information without performing complex real-time checks. This preliminary preparation of the ID list reduces the time required for assignment while ensuring uniqueness through the authoritative source maintained by the UDM.
3Productivity
If the same EPS Bearer ID is reused for different PDN connections after handover, then the resource utilization is efficient, but the same PDU Session ID may be reassigned causing deletion of previous connections
Solution Approach 1:
The system uses feedback from the UDM about previously assigned PDU Session IDs to prevent reassignment of the same ID to different PDN connections. This feedback mechanism allows efficient reuse of EPS Bearer IDs while maintaining connection stability by checking against the recorded list of active PDU Session IDs before assignment.
Solution Approach 2:
The UDM acts as an intermediary that mediates between resource reuse requirements and connection stability. It maintains the authoritative list of assigned PDU Session IDs and provides this information to the SMF+PGW-C, enabling efficient resource utilization while preventing harmful ID collisions that would delete existing connections.
Data Source
AI summary
Methods, network nodes, and computer readable storage media for ensuring uniqueness of an assigned PDU Session ID are disclosed. The method at a first network node includes: transmitting, to a second network node, during establishment of a Packet Data Network (PDN) connection, a request message for retrieving a list of PDU Session ID(s) that have been already registered for a User Equipment (UE); and receiving a response message from the second network node. The second network node is a Unified Data Management (UDM).