5G PDU Session Handling at Active Session Limits
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Solution Overview
Problem
Existing wireless communication systems face challenges in establishing new PDU sessions when the maximum number of active sessions has been reached, particularly in 5G networks, leading to a need for efficient methods to manage PDU session establishment.
Innovation Solution
A method is proposed where a user equipment (UE) releases an existing 4G PDN connection to establish a new 5G PDU session by selecting and disconnecting a 4G Packet Data Network (PDN) connection, which is then used as a user-plane resource for a Multiple-Access (MA) PDU session, allowing the UE to establish a new session when the maximum number of 5G PDU sessions is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE releases an existing 5G PDU session to establish a new PDU session, then the number of active PDU sessions is reduced to allow new session establishment, but the connectivity service is interrupted for the released session
Solution Approach 1:
The patent combines 4G PDN connection and 5G PDU session into a unified MA PDU session framework. By merging the 4G EPS PDN connection as a 3GPP PDN leg with the 5G PDU session, the system allows seamless transition and session persistence across different network generations, enabling new 5G sessions without forcing release of existing connectivity.
Solution Approach 2:
The MA PDU session is designed to support multiple access types (3GPP and non-3GPP) and multiple network generations (4G and 5G) simultaneously. This multi-functionality allows the same PDU session to utilize different underlying connections, providing universal connectivity that maintains service while adapting to session establishment requirements.
2Adaptability or versatility
If the UE maintains multiple active PDU sessions, then the connectivity coverage and service availability are improved, but the system reaches the maximum number of PDU sessions limit
Solution Approach 1:
Multiple 4G PDN connections are merged into a single MA PDU session structure. Instead of counting each 4G PDN connection as a separate active session toward the maximum limit, they are consolidated under one MA PDU session identifier, effectively increasing the number of maintainable connections without increasing the session count.
Solution Approach 2:
The MA PDU session is segmented into multiple legs (3GPP PDN leg and non-3GPP 5GS leg), allowing independent management of different access networks. This segmentation enables the UE to maintain multiple physical connections while presenting them as a single logical PDU session to the network core.
3Adaptability or versatility
If the UE releases a 4G PDN connection that is established as a user-plane resource for an MA PDU session, then the maximum number of active 5G PDU sessions requirement is fulfilled, but the user-plane resource for the MA PDU session is lost
Solution Approach 1:
The MA PDU session dynamically adapts its user-plane resources based on network conditions and session requirements. When a 4G PDN connection is released, the system dynamically switches to alternative user-plane resources (such as non-3GPP access or new 5G PDU sessions) without interrupting the overall MA PDU session functionality.
Solution Approach 2:
The system establishes redundant user-plane resources and alternative paths before releasing existing connections. By preparing backup resources in advance, the system ensures that MA PDU sessions maintain continuous connectivity even when individual 4G PDN connections are released to accommodate new 5G sessions.
Data Source
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AI summary
A method is proposed for handling a 5G PDU session establishment procedure when a maximum number of active 5G PDU sessions has been reached. When the number of active 5G PDU sessions has reached the maximum number of active PDU sessions as defined for the PLMN/SNPN, a UE needs to release an existing 5G PDU session in order to add a new 5G PDU session. In one novel aspect, the UE can select a 4G PDN connection and release the selected PDN connection to fulfill the requirement for having number of 5G PDU session less than or equal to the maximum number of active 5G PDU sessions. The selected 4G PDN connection is established as a user-plane resource for an MA PDU session; by releasing the selected PDN connection, the UE is then able to establish a new PDU session, including an emergency PDU session in 5GS.