PSCell Switching in Split 5G Architecture
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Solution Overview
Problem
There is no existing solution for handling primary secondary cell (PSCell) changes of user equipment when the LTE system interworks tightly with the 5G system, especially when secondary nodes are split between central units and distribute units in the 5G network.
Innovation Solution
A method and device for PSCell change that involves receiving a Measurement Report message from user equipment, determining the feasibility of PSCell change, and transmitting a message with a tunnel endpoint identifier (TEID) to enable data exchange between the master node and the target distribute unit, which provides NR user plane and control plane protocol termination, connected to the 5G core network via the NG interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If secondary nodes are split between central units and distribute units in the 5G network, then network functionality and flexibility are improved, but the complexity of handling PSCell changes increases
Solution Approach 1:
The secondary node is segmented into two independent functional units: the central unit (CU) that handles control plane functions and the distribute unit (DU) that handles user plane functions. This segmentation allows the PSCell change process to be divided into separate control signaling (handled by CU) and data forwarding (handled by DU), reducing the overall complexity of managing PSCell changes in split architecture networks.
Solution Approach 2:
The patent introduces an intermediary message exchange mechanism between the source DU, target DU, and master node that coordinates the PSCell change process. The master node acts as an intermediary that receives measurement reports, determines the need for PSCell change, and coordinates the switching between source and target DUs, thereby simplifying the complexity of direct DU-to-DU coordination.
2Adaptability or versatility
If PSCell change is implemented in LTE-5GC tight interworking scenario, then mobility support is improved, but data transmission continuity may be affected
Solution Approach 1:
The patent establishes data forwarding paths and tunnel configurations in advance before the PSCell change is executed. The source DU prepares the data forwarding address information and tunnel endpoint identifiers (TEIDs) beforehand, so that when the PSCell change occurs, data transmission can continue seamlessly through the pre-configured forwarding paths, maintaining transmission continuity during mobility.
Solution Approach 2:
The patent implements continuous data transmission during PSCell change by maintaining active data forwarding paths. The source DU continues to forward data to the target DU through established tunnels even as the UE switches cells, ensuring that the useful action of data transmission continues uninterrupted throughout the mobility process.
3Extent of automation
If measurement report processing is centralized in gNB-CU, then control efficiency is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts the critical PSCell change decision logic and data forwarding configuration functions from the centralized gNB-CU and places them in the distribute units (DUs). The gNB-CU retains only the essential measurement report reception and high-level coordination functions, while the DUs handle the detailed processing of measurement results and direct configuration of data forwarding paths, thereby reducing the signaling overhead between CU and DUs during PSCell changes.
Data Source
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AI summary
Disclosed by the present application are a method and device for primary secondary cell (pscell)-switching, the method comprising: a slave node (SN) determines that a switched target Pscell of a user equipment (UE) is located in a target gNodeB distributed unit (gNB-DU); and the SN sends a message carrying a tunnel endpoint identifier (TEID) to a master node (MN) such that the MN carries out data exchange with the UE by means of the target gNB-DU, the TEID being used to identify a data link between the target gNB-DU and the MN