UE PDU Session Management for 5G Congestion Control
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Solution Overview
Problem
In 5G mobile communications systems, the processing of system changes during congestion management is unclear, particularly in managing control signals based on reasons other than congestion.
Innovation Solution
A mechanism is implemented in user equipment (UE) to initiate an Evolved Packet System (EPS) Session Management procedure using a given Access Point Name (APN) when a timer for Single Network Slice Selection Assistance Information (S-NSSAI) and Data Network Name (DNN) is operating, allowing for congestion management and other management processing in the 5G System.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a timer for S-NSSAI and DNN is operating during congestion management, then congestion control is implemented, but the processing of system changes and control signal management becomes unclear
Solution Approach 1:
The patent segments the congestion management process into distinct phases: timer activation phase, system change prohibition phase, and timer expiration phase. This segmentation clarifies that during timer operation, the UE shall not initiate new PDU sessions or perform system changes, while allowing existing sessions to continue. The clear phase separation resolves the ambiguity in control signal management during congestion.
Solution Approach 2:
The network sends a PDU session establishment reject message with a timer value BEFORE allowing new sessions. This preliminary action prevents the UE from initiating system changes or new PDU sessions during the timer period, avoiding the need for complex real-time control signal management during congestion. The UE proactively restricts its own actions based on the received timer value.
2Reliability
If system changes are restricted during timer operation, then congestion management is effective, but system adaptability decreases
Solution Approach 1:
The system dynamically adjusts its behavior based on the timer state. When the timer is operating, system changes are restricted to manage congestion. When the timer expires, the UE automatically regains the ability to initiate PDU sessions and perform system changes. This dynamic adjustment allows the system to adapt between congestion control mode and normal operation mode, resolving the contradiction between effective congestion management and system adaptability.
Solution Approach 2:
The congestion management mechanism operates periodically through the timer. The UE enters a restricted state when the timer is active, then automatically transitions to an unrestricted state when the timer expires. This periodic alternation between restricted and unrestricted modes allows the system to enforce congestion control only when necessary, maintaining adaptability during normal operation while ensuring reliability during congestion events.
Data Source
AI summary
A user equipment (UE) with a transmission/reception unit is provided. The UE comprises: when a timer for a Single Network Slice Selection Assistance Information (S-NSSAI) and a Data Network Name (DNN) is operating, the transmission/reception unit initiates an Evolved Packet System (EPS) Session Management (ESM) procedure in the EPS by using a Access Point Name (APN); the APN is same as the DNN; and the transmission/reception unit receives a value of the timer in a Protocol Data Unit (PDU) session establishment reject message.