Redundant PDU Session Control for Fault-Tolerant 5G Reliability
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Solution Overview
Problem
Existing wireless communication systems face challenges in ensuring end-to-end reliability and fault tolerance, particularly in ultra-reliable low latency communications (URLLC), due to the lack of effective mechanisms for managing redundant protocol data unit (PDU) sessions and user plane paths in 5G networks.
Innovation Solution
A first policy control function (PCF) in a network node receives indications of PDU session states and faults, coordinating with a second PCF to manage redundant PDU sessions, ensuring seamless transitions between active and inactive states, and facilitating packet replication and elimination functions across multiple network nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant PDU sessions are established to improve reliability, then end-to-end reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing redundant PDU sessions and configuring PCFs with fault detection capabilities before actual communication occurs. The alternative PDU session is prepared in advance with proper routing configured, so when a fault is detected in the primary session, the switch to backup session can be executed immediately without delay, thus improving reliability while managing complexity through advance preparation.
Solution Approach 2:
The patent implements feedback mechanisms where PCFs continuously monitor the operational status of PDU sessions and send notifications to SMFs when faults are detected. This feedback loop enables automatic detection and response to session failures, allowing the system to switch to redundant sessions based on real-time status information, thereby improving reliability through continuous monitoring and adaptive response.
2Reliability
If packet replication is performed to ensure fault tolerance, then fault tolerance is improved, but loss of information increases due to duplicate packets
Solution Approach 1:
The patent applies the extraction principle by implementing packet elimination functionality that selectively removes duplicate packets from the replicated data stream. The PCF and SMF work together to identify and extract redundant packet copies, keeping only the necessary packets for transmission. This extraction of duplicate information maintains fault tolerance through replication while preventing information loss through systematic removal of redundant packets.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting packet handling parameters based on session state and fault conditions. The system changes replication and elimination parameters according to the operational status of PDU sessions, enabling selective packet replication during fault conditions while maintaining normal packet processing during healthy operation, thus balancing fault tolerance with information accuracy.
3Reliability
If multiple network nodes coordinate PDU session management, then reliability is improved, but loss of time increases due to coordination overhead
Solution Approach 1:
The patent applies the merging principle by consolidating PDU session management functions across multiple network nodes (PCF, SMF, AMF) into a coordinated workflow where decisions are made through standardized interaction protocols. The PCF and SMF merge their monitoring and control capabilities to manage redundant sessions efficiently, reducing redundant coordination steps while maintaining comprehensive reliability through unified session management.
Solution Approach 2:
The patent implements preliminary action by pre-configuring PCFs with fault detection thresholds and notification protocols before faults occur. This advance setup eliminates the need for real-time complex coordination during fault events, as the response protocol is already in place. The preliminary configuration of monitoring parameters and notification mechanisms reduces coordination overhead during actual fault response while maintaining high reliability.
Data Source
AI summary
A first policy control function (PCF) in a first network node may receive an indication from a session management function (SMF) that a protocol data unit (PDU) session is an alternative PDU session, and an indication of whether the PDU session is in a drop state. The first PCF may send a message with an indication to a second PCF in a second network node to indicate that the network node is serving a PDU session that is an alternative PDU session. In an example, the message with an indication to the second PCF may also identify the PDU session. The first PCF may receive a message from the second PCF with an indication that a second PDU session has experienced a fault or degraded performance. Further, the first PCF may send a message to the SMF to change the PDU session to a no-drop state.