URLLC Handover Flow Prioritization via Control Plane Redundancy
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Solution Overview
Problem
During handover procedures in 3GPP 5G networks, the relocation of redundant PDU connections due to user equipment mobility often results in resource crunches at target radios, leading to dropped traffic flows, which compromises the reliability and latency requirements of Ultra Reliability and Low Latency Communication (URLLC).
Innovation Solution
The control plane establishes first and second PDU connections, relocates these connections to target radios, and uses a correlation identifier to prioritize rejected flows on the second PDU connection, ensuring that all flows are activated on at least one target radio by initially activating high-priority flows on the second target radio and then activating lower-priority flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If redundant PDU connections are relocated to target radios during handover, then user equipment mobility is supported, but resource crunches occur at target radios causing flow drops
Solution Approach 1:
The control plane performs preliminary actions by establishing both first and second PDU connections through different source radios before handover occurs. This redundant connection setup in advance ensures that when handover happens, there are alternative paths available, preventing flow drops even if resource crunches occur at target radios.
Solution Approach 2:
The system changes the parameter of connection redundancy by maintaining multiple PDU connections simultaneously with different redundancy ratios. During handover, the control plane manages the transition of these connections with different redundancy levels to target radios, allowing flexible adaptation to resource availability while maintaining reliability.
2Productivity
If all traffic flows are activated on the first target radio, then resource utilization is maximized, but reliability is compromised when the target radio lacks sufficient resources
Solution Approach 1:
The control plane segments the traffic flows by dividing them into different PDU connections (first and second PDU connections). This segmentation allows selective activation of flows on different target radios based on resource availability, ensuring that critical URLLC flows are protected while optimizing overall resource utilization.
Solution Approach 2:
The system applies local quality by assigning different redundancy ratios to different PDU connections. The control plane can prioritize certain flows with higher redundancy on specific target radios based on local resource conditions, ensuring that URLLC requirements are met at critical points while optimizing resource usage elsewhere.
3Reliability
If redundant PDU connections are maintained through handover, then flow delivery reliability is improved, but network complexity increases
Solution Approach 1:
The control plane implements a universal management mechanism that handles multiple PDU connections and their handovers through a single centralized entity. This multi-functional approach consolidates the complexity of managing redundant connections, flow prioritization, and target radio selection into one coordinated system, reducing overall network complexity while maintaining reliability.
Data Source
AI summary
A control plane of a network, including radios of a radio access network controlled by the control plane and user plane functions controlled by the control plane, establishes first and second protocol data unit (PDU) connections each to handle the same flows of traffic for ultra-reliable low latency communications (URLLC) from user equipment to a data network through first and second source radios, respectively. Due to mobility of the user equipment, the control plane relocates the flows from the first and second source radios to first and second target radios, respectively. To relocate the flows, the control plane receives from the first target radio a notification that identifies flows that cannot be activated on the first target radio. In response to the notification, the control plane commands the first target radio to prioritize the flows that cannot be activated above remaining ones of the flows.