RAN Node Signaling for S-NSSAI-Specific Congestion Control
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Solution Overview
Problem
Current congestion control mechanisms in 5G networks fail to distinguish between general NAS level and network slice congestion, leading to non-deterministic UE behavior and potential network failures due to insufficient information being sent to the UE about wait timers and network slice identifiers, resulting in unnecessary signaling and network overload.
Innovation Solution
The proposed solution involves the RAN node sending a list of congested S-NSSAIs and wait timers to the UE, allowing the UE to determine the type of congestion and refrain from initiating signaling procedures during the indicated time periods, thereby reducing network load and preventing further congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the AMF sends only general NAS level congestion control messages without S-NSSAI information, then the congestion control mechanism is simple to implement, but the UE cannot distinguish between general NAS level congestion and network slice congestion, leading to non-deterministic UE behavior
Solution Approach 1:
The patent segments congestion control information by introducing S-NSSAI-specific congestion indicators alongside general NAS level indicators. This allows the system to provide differentiated congestion control messages for different network slices while maintaining the existing general congestion control framework, enabling UE to distinguish between general and slice-specific congestion conditions.
Solution Approach 2:
The patent introduces an intermediary information element that carries S-NSSAI identifiers in congestion control messages. This intermediary element acts as a bridge between the AMF and UE, providing additional context about which specific network slice is experiencing congestion without requiring fundamental changes to the congestion control protocol.
2Reliability
If the AMF includes S-NSSAI information in congestion control messages, then the UE can determine the type of congestion and behave appropriately, but the message complexity and information overhead increase
Solution Approach 1:
The patent applies local quality by making S-NSSAI information optional and context-specific in congestion control messages. Rather than always including full S-NSSAI details, the system includes this information only when slice-specific congestion control is needed, keeping messages simple for general congestion cases while providing detailed information when required.
Solution Approach 2:
The patent implements partial action by including only the necessary S-NSSAI information in congestion control messages based on the specific congestion scenario. When general NAS level congestion occurs, no S-NSSAI information is included; when slice-specific congestion occurs, only the relevant S-NSSAI identifiers are included, avoiding unnecessary information overhead.
3Reliability
If the UE continues to initiate signaling procedures during network slice congestion without proper identification, then the UE maintains service availability attempts, but the network overload increases and congestion worsens
Solution Approach 1:
The patent implements feedback by providing the UE with specific congestion information including S-NSSAI identifiers and wait timer values. The UE uses this feedback to adjust its signaling behavior, refraining from initiating new signaling procedures for the indicated network slice during the wait period, thereby reducing network overload while maintaining service availability for non-congested slices.
Solution Approach 2:
The patent applies preliminary anti-action by having the UE proactively suppress signaling attempts for congested network slices based on the congestion indication received from the AMF. Rather than allowing continued signaling that would worsen congestion, the UE preemptively reduces signaling activity for the affected slice during the indicated wait period.
Data Source
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AI summary
A RAN node includes means for receiving a N2 message containing a list of S-NSSAI of the congested network slice from an AMF and means for sending the list of S-NSSAI and a wait timer for each S-NSSAI in the list in first AN signaling message to an UE when receiving, from the UE, second signaling message containing the list of S-NSSAI to establish an AN signaling connection, the S-NSSAI being indicated in the N2 message as congested by the AMF.