5G PDU Session UP Connection Maintenance in Idle State
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Solution Overview
Problem
In 5G wireless communication systems, terminals in a CM-IDLE state release all PDU sessions and re-establish UP connections only for mobile-originated or terminated traffic, leading to inefficient signaling and resource usage during handovers, as they cannot maintain or activate UP connections independently for each PDU session.
Innovation Solution
A method is proposed where the SMF and AMF entities manage PDU sessions by transmitting messages to determine the maintenance of user plane functions based on terminal location changes, optimizing NAS signaling and allowing rapid data transmission by maintaining UP connections for established sessions, even in CM-IDLE states, through the use of indications for synchronization/asynchronization with NAS signaling connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If terminals in CM-IDLE state release all PDU sessions and re-establish UP connections only for mobile-originated or terminated traffic, then signaling overhead is reduced, but data transmission latency increases
Solution Approach 1:
The patent segments the PDU session management by introducing session-specific indication fields that allow different UP connection maintenance behaviors for different PDU sessions. The SMF can independently control whether each PDU session maintains UP connections in CM-IDLE state through the 'maintain UP connection in idle state' indication, enabling fine-grained control that balances signaling overhead reduction with latency reduction for specific sessions.
Solution Approach 2:
The patent applies preliminary action by pre-establishing and maintaining UP connections for PDU sessions that are indicated to keep connections in CM-IDLE state. When data transmission is needed, the UP connection is already available, eliminating the re-establishment delay. The SMF proactively maintains these connections based on prior indication from the AMF about which sessions should preserve connectivity.
2Loss of time
If terminals maintain UP connections for all PDU sessions in CM-IDLE state, then data transmission latency is reduced, but signaling overhead and resource usage increase
Solution Approach 1:
The patent applies local quality by allowing different UP connection maintenance characteristics for different PDU sessions based on their specific requirements. The session-specific indication field enables the SMF to assign different qualities (maintain or release connections) to different local segments (PDU sessions) rather than applying a uniform policy to all sessions, thus optimizing the balance between latency and signaling overhead on a per-session basis.
3Productivity
If terminals re-establish UP connections upon transitioning from CM-IDLE to CM-CONNECTED state, then resource efficiency is improved, but data transmission reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-maintaining UP connections for indicated PDU sessions before data transmission occurs. This ensures that when data needs to be transmitted, the connection is already established and reliable, eliminating the risk of transmission failures during connection re-establishment. The SMF proactively keeps these connections active based on prior indication, ensuring transmission reliability without compromising overall resource efficiency.
Data Source
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AI summary
The present disclosure relates to a communication method and system for converging a 5G communication system for supporting higher data rates beyond a 4G system with an IoT technology. The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The present disclosure provides a scheme for efficiently operating an UP connection of a session in case where a terminal has a plurality of sessions in a mobile communication system, such as a 5G system, having a network structure in which an AMF for mobility management and an SMF for session management are separated from each other. Through the present disclosure, a terminal (UE) can optimize a non-access stratum (NAS) signaling message, and can perform data transmission/reception with low latency.