SMF PDB Determination for RAN CU-UP Resource Scheduling
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Solution Overview
Problem
In communication technologies, when a radio access network (RAN) device supports multiple central unit-user plane (CU-UP) entities, determining and transmitting a packet delay budget (PDB) from the CU-UP to the user plane function (UPF) network element is challenging, as the existing methods cannot accurately determine and send the core network PDB to the RAN device, affecting resource scheduling for quality of service (QoS) flows.
Innovation Solution
A communication method and device that determine a first CU-UP and UPF network element corresponding to a QoS flow, calculate the PDB for the QoS flow, and send this PDB to the RAN device, which supports multiple CU-UPs, enabling the RAN device to schedule air interface resources effectively by selecting the appropriate CU-UP based on the received PDBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the RAN device supports multiple CU-UPs, then the adaptability and resource scheduling flexibility are improved, but the difficulty of determining and transmitting the correct PDB to the RAN device increases
Solution Approach 1:
The SMF network element determines the PDB value before selecting the CU-UP, and includes this PDB information in the N2 session modification request message sent to the RAN device. This preliminary determination of PDB resolves the timing issue where previously the SMF could not determine PDB before CU-UP selection, enabling the RAN device to have the necessary scheduling information in advance.
Solution Approach 2:
The N2 session modification request message serves as an intermediary carrier that transports the PDB value from the SMF network element to the RAN device. This message includes both the CU-UP selection information and the PDB value, facilitating the transmission of critical scheduling parameters through a standardized interface.
2Measurement precision
If the PDB is determined after CU-UP selection, then the PDB can be accurately calculated based on actual transmission paths, but the RAN device cannot schedule resources in time
Solution Approach 1:
The SMF network element performs preliminary PDB determination based on available path information before final CU-UP selection is made. This allows the RAN device to receive and use the PDB value for resource scheduling without waiting for the complete CU-UP selection process to finish, thereby eliminating scheduling delays while maintaining reasonable accuracy.
3Productivity
If the SMF determines CU-UP before PDB, then the PDB can be sent to RAN device for timely resource scheduling, but the PDB value may not accurately reflect the actual transmission delay
Solution Approach 1:
The system allows for dynamic updates of PDB values. The SMF network element can revise the PDB determination after CU-UP selection based on actual measured transmission characteristics, and send updated PDB values to the RAN device through subsequent session modification procedures, ensuring both timely scheduling and accurate values.
Data Source
AI summary
A communication method includes: determining a first central unit (CU)-user plane (UP) and a user plane function (UPF) network element that correspond to a quality of service (QoS) flow, where an access network device to which the first CU-UP belongs supports at least two CU-UPs; determining a first packet delay budget (PDB) for transmitting the QoS flow between the first CU-UP and the UPF network element; and sending the first PDB to the access network device, where the first PDB is used by the access network device to schedule an air interface resource. After the CU-UP corresponding to the QoS flow is determined, the PDB of the CU-UP corresponding to the QoS flow may be sent to the radio access network (RAN) device.