CU-DU Relay Mapping via Adaptation Layer
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Solution Overview
Problem
In a CU-DU architecture for base stations, implementing a UE-to-network relay communication process is challenging due to the split deployment of functions, where the CU and DU need to manage and forward RRC messages and data packets efficiently between user equipment (UE) and the network, while maintaining accurate bearer and logical channel mappings.
Innovation Solution
The method involves the CU determining the mapping relationship between the bearer identifier of the relay UE and the logical channel identifier, sending a UE context modification request to the DU to regenerate RRC configuration messages, and using adaptation layers in the protocol stack to encapsulate and transmit RRC and data packets, ensuring proper forwarding of messages and data between the relay UE and the remote UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If functions are split between CU and DU based on protocol stack, then base station deployment flexibility is improved, but UE-to-network relay communication implementation becomes complex
Solution Approach 1:
The patent introduces an adaptation layer as an intermediary component in the protocol stack between the PDCP layer and RLC layer. This adaptation layer handles the complexity of relay communication by providing standardized interfaces and mapping mechanisms, allowing the CU-DU split architecture to support UE-to-network relay without requiring complex custom implementations at each node.
Solution Approach 2:
The patent segments the relay communication functionality into distinct layers: the adaptation layer for mapping and forwarding decisions, the PDCP layer for data processing, and the RLC layer for reliable transmission. This segmentation allows each layer to be independently implemented and managed in the CU-DU architecture, reducing overall system complexity.
2Measurement precision
If bearer identifier and logical channel identifier mapping is maintained, then communication accuracy is improved, but message forwarding overhead increases
Solution Approach 1:
The patent uses copying mechanisms where the adaptation layer creates and forwards simplified copies of RRC messages between CU and DU. Instead of transmitting complete original messages with all headers and metadata, the adaptation layer extracts essential information (bearer identifier mappings) and forwards condensed representations, reducing overhead while preserving communication accuracy.
Solution Approach 2:
The patent changes the parameter representation format in forwarded messages. Instead of transmitting full bearer context information, the system transforms and transmits only the essential mapping parameters (bearer identifier to logical channel identifier mappings) that are necessary for accurate message forwarding, thereby reducing message size and overhead.
3Productivity
If RRC message regeneration is performed at DU, then communication efficiency is improved, but processing time increases
Solution Approach 1:
The patent implements preliminary action by having the CU pre-process and prepare RRC messages before forwarding them to the DU. The adaptation layer at the CU performs initial mapping of bearer identifiers to logical channel identifiers and prepares the message structure in advance. This allows the DU to perform only minimal regeneration operations, significantly reducing processing time while maintaining communication efficiency.
Data Source
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AI summary
This application provides a communication method and apparatus, and relates to the field of communication technologies, to implement a UE-to-network relay communication process based on a CU-DU architecture. The method includes: A CU generates a UE context modification request message, where the UE context modification request message is used to request a DU to modify a context of relay user equipment UE, the UE context modification request message carries an identifier of remote UE, a bearer identifier of the relay UE, and an identifier of a logical channel having a mapping relationship with the bearer identifier of the relay UE, the bearer identifier of the relay UE is an identifier of a bearer between the relay UE and the CU, and the logical channel is a logical channel between the remote UE and the relay UE; and the CU sends the UE context modification request message to the DU.