UPF QoS Flow Management for Private 5G Congestion
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Solution Overview
Problem
In enterprise private 3GPP networks, such as private 5G networks, congestion and overload can lead to undesirable packet drops and Quality of Service (QoS) degradation, particularly for GBR-type QoS Flows, as the User Plane Function (UPF) may be unable to guarantee the Guaranteed Bit Rate (GBR) or Packet Delay Budget (PDB) due to network congestion.
Innovation Solution
Implementing a UPF-initiated lower-priority QoS Flow pre-emption procedure and UPF-triggered QoS Flow creation/deletion procedures, where the UPF detects packet loss or delay exceeding thresholds, triggering the Session Management Function (SMF) to either delete or downgrade lower-priority QoS Flows or create/delete dedicated QoS Flows based on traffic activity, optimizing resource usage and ensuring QoS guarantees for higher-priority flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GBR-type QoS Flows are established to guarantee minimum bit rate, then QoS reliability is improved, but network congestion and overload worsen
Solution Approach 1:
The UPF monitors traffic activity and QoS flow status in advance, detecting packet loss or delay before they critically impact service. When thresholds are exceeded, the UPF proactively triggers pre-emption of lower-priority QoS flows or deletion of inactive flows, preventing congestion before it worsens and maintaining GBR guarantees for higher-priority flows.
Solution Approach 2:
The system dynamically adjusts QoS flow allocations based on real-time network conditions. The UPF continuously monitors packet loss, delay, and traffic activity, and dynamically pre-emptes or deletes QoS flows in response to changing conditions. This dynamic management allows the network to maintain GBR guarantees when needed while releasing resources during low-activity periods to prevent congestion.
2Adaptability or versatility
If multiple QoS Flows are maintained to support diverse applications, then service versatility is improved, but resource overhead and complexity worsen
Solution Approach 1:
The UPF discards (deletes or pre-emptes) lower-priority QoS flows when network congestion is detected or when flows become inactive beyond a threshold period. These discarded flows can be recovered (re-established) when network conditions improve or when traffic activity resumes, allowing the system to support diverse applications while managing resource complexity through selective deletion and recovery.
Solution Approach 2:
The UPF autonomously monitors its own traffic conditions, detects QoS violations, and triggers pre-emption or deletion of QoS flows without requiring constant external control. This self-service capability simplifies resource management complexity by enabling the UPF to autonomously maintain service versatility while preventing congestion.
3Productivity
If QoS Flow pre-emption is implemented to alleviate congestion, then network performance is improved, but QoS flow establishment time worsens
Solution Approach 1:
The system performs preliminary actions by pre-establishing QoS flows with appropriate priorities and parameters before congestion occurs. When congestion is detected, pre-emption of lower-priority flows provides immediate relief, and pre-configured flow templates enable rapid re-establishment of necessary flows, minimizing the time loss associated with flow setup while maintaining high network performance.
Data Source
AI summary
In one illustrative example, a user plane function (UPF) may detect initial traffic for an application for a user equipment (UE) for which no current dedicated Quality of Service (QoS) flow is established. In response, the UPF may send, to a control plane function, a message which indicates a request for creating a dedicated QoS Flow for traffic for the application for the UE. The message may include flow metadata and an application identifier obtained in detecting the initial traffic. A QoS Flow may then be created for the traffic based on a selected QoS policy associated with the application identifier. Subsequently, the UPF may determine that a measured time period of traffic inactivity for the QoS Flow is outside a limit set by a threshold. Based on the determining, the UPF may send, to the control plane function, a message which indicates a request for deleting the QoS Flow.