CU-DU Mobility Control Using CU-Guided Target Cell Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the context of CU-DU split in wireless networks, gNB-DUs may determine incorrect target cells during L1/L2-based inter-cell mobility due to lack of information about neighboring gNB-DUs, leading to mobility failures.
Innovation Solution
A method where the gNB-DU receives an RRC reconfiguration from the CU, forwards it to the UE, and upon receiving an L1 measurement report, transmits candidate target cell information to the CU, which determines the final target cell considering the candidate gNB-DUs' status and informs the gNB-DU, which then provides the target cell information to the UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If gNB-DU autonomously determines target cell based on L1 measurement report, then mobility latency is reduced, but target cell selection accuracy deteriorates due to lack of neighboring gNB-DU status information
Solution Approach 1:
The gNB-CU acts as an intermediary between the gNB-DU and neighboring gNB-DUs. It collects status information from neighboring gNB-DUs, evaluates candidate target cells, and provides guidance to the source gNB-DU for accurate target cell selection, thereby resolving the information asymmetry problem while maintaining fast mobility
Solution Approach 2:
The system implements feedback mechanisms where the gNB-CU receives L1 measurement reports from the gNB-DU, evaluates candidate cells based on neighboring gNB-DU status, and provides feedback information to guide the gNB-DU's target cell selection, improving selection accuracy while maintaining low latency
2Device complexity
If gNB-DU determines target cell without neighboring gNB-DU status information, then device complexity is reduced, but mobility failure rate increases
Solution Approach 1:
The system segments the mobility management functions between gNB-DU (local measurement and candidate identification) and gNB-CU (centralized evaluation and decision support). This segmentation allows the gNB-DU to remain simple while the gNB-CU handles the complexity of evaluating multiple candidate cells based on neighboring gNB-DU status
Solution Approach 2:
The gNB-CU serves as an intermediary that provides the gNB-DU with evaluated target cell information without requiring the gNB-DU to directly interact with neighboring gNB-DUs, thus maintaining low gNB-DU complexity while improving mobility success rate through centralized information gathering and evaluation
Data Source
AI summary
A method and apparatus for supporting L1/L2-based mobility in CU-DU split in a wireless network system is provided. A DU of a gNB receives, from a UE, a Layer 1 (L1) measurement report. A DU of a gNB transmits, to a CU of the gNB, a UE Context Modification Required message including information on at least one candidate target cell. A DU of a gNB receives, from the CU of the gNB, a UE Context Modification Confirm message include information on a target cell among the at least one candidate target cell. A DU of a gNB transmits, to the UE, a cell switching command including information on the target cell.