CU-DU Split Base Station Paging via F1 Interface Segmentation
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Solution Overview
Problem
There is no established procedure for performing paging in a wireless communication system with a Central Unit (CU) and Distributed Unit (DU) split, where the CU interprets paging messages from the Core Network but lacks the necessary layers to directly transmit them to User Equipment (UE).
Innovation Solution
A method and device for transmitting paging messages, where the DU receives paging information from the CU, including UE Identity Index Value, UE Paging Identity, and other relevant data, and transmits the paging message to the UE, utilizing its RLC, MAC, and PHY layers, enabling direct paging of multiple UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the base station is divided into CU and DU layers, then the system architecture becomes more flexible and scalable, but the paging procedure becomes complex and undefined
Solution Approach 1:
The base station is segmented into Central Unit (CU) and Distributed Unit (DU) with clear functional division. The CU handles upper layer protocols (RRC, PDCP) while the DU handles lower layer protocols (RLC, MAC, PHY). This segmentation enables flexible architecture and scalability while the patent defines the paging procedure to flow through these segmented units systematically.
Solution Approach 2:
The F1 interface acts as an intermediary between the CU and DU, carrying paging information from the CU to the DU. This intermediary mechanism enables the paging procedure to function smoothly across the split architecture by providing a defined communication path between the two units.
2Extent of automation
If the CU interprets paging messages from Core Network, then the control function is centralized, but the transmission function to UE is lost
Solution Approach 1:
The base station control and transmission functions are segmented between CU and DU. The CU performs centralized control by interpreting paging messages from the Core Network, while the DU retains transmission capability through its PHY layer to actually transmit paging messages to UEs. This segmentation resolves the contradiction by assigning different functions to different units.
Solution Approach 2:
The F1 interface serves as an intermediary that carries paging information from the CU to the DU, enabling the DU to perform transmission functions while maintaining CU's centralized control. This intermediary mechanism allows both control centralization and transmission capability to coexist.
3Device complexity
If no paging procedure is defined for CU-DU split, then the architecture remains simple, but the system cannot perform paging in this configuration
Solution Approach 1:
The paging procedure is segmented into distinct steps: CU receives paging message from Core Network, CU determines paging parameters, CU transmits to DU via F1 interface, and DU transmits to UE. This segmented approach enables the system to handle CU-DU split configuration while maintaining clear and manageable procedure definition.
Solution Approach 2:
The patent defines preliminary actions in advance, such as the CU determining paging parameters before transmission to the DU, and the F1 interface being pre-configured for carrying paging information. These preliminary preparations enable the system to perform paging in CU-DU split configuration smoothly.
Data Source
AI summary
A method for a wireless device in a wireless communication system includes receiving a paging from a distribution unit (DU) of a base station; and upon receiving the paging message, initiating a service request procedure. Further, the paging is based on paging information transmitted from a central unit (CU) of the base station to the DU of the base station. The paging information includes paging discontinuous reception (DRX) information and paging priority information. The DU of the base station has a radio link control (RLC) layer, a media access control (MAC) layer and a physical layer of the base station. In addition, the CU of the base station has a radio resource control (RRC) layer, a service data adaptation protocol (SDAP) layer, and a packet data convergence protocol (PDCP) layer of the base station.