Bearer Mapping for RRC Relay Reestablishment in CU-DU Split
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Solution Overview
Problem
The challenge in sidelink UE-to-network relay (SL U2N Relay) systems is how the distributed unit (DU) correctly forwards radio resource control (RRC) connection reestablishment or resume messages to the relay UE and remote UE, especially in CU-DU split architectures, where the DU's forwarding mechanism is unclear.
Innovation Solution
The proposed solution involves the DU receiving indication information to determine a mapping relationship between bearers, using identifiers and context information to correctly forward RRC messages, allowing the remote UE to access the network through the relay UE by configuring or updating the appropriate bearer mappings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DU forwards RRC messages in a CU-DU split architecture, then the remote UE can access the network through relay UE, but the forwarding mechanism is unclear and message routing may be incorrect
Solution Approach 1:
The patent introduces indication information as an intermediary that carries mapping relationships between first bearers (between remote UE and relay UE) and second bearers (between relay UE and DU). This intermediary enables the DU to correctly identify which second bearer to use for forwarding RRC messages by referencing the mapping relationship provided in the indication information, thus resolving the forwarding mechanism complexity while ensuring message routing accuracy.
Solution Approach 2:
The patent applies preliminary action by pre-establishing the mapping relationship between first bearers and second bearers through indication information before actual message forwarding occurs. The DU receives and processes this indication information in advance, so when RRC messages need to be forwarded, the correct bearer mapping is already available, eliminating the need for complex real-time routing decisions and ensuring reliable message delivery.
2Adaptability or versatility
If the DU determines bearer mapping relationships dynamically, then message routing flexibility improves, but processing time and complexity increase
Solution Approach 1:
The patent resolves this contradiction by performing the bearer mapping determination in advance through the indication information mechanism. The mapping relationship between first bearers and second bearers is established beforehand and communicated to the DU through indication information, allowing the DU to simply reference pre-determined mappings during message forwarding rather than performing complex dynamic determination, thus reducing processing time while maintaining flexibility.
Solution Approach 2:
The patent uses copying by transmitting the bearer mapping relationship from the CU to the DU through indication information. Instead of the DU independently determining complex mapping relationships in real-time, the CU prepares and sends the mapping information in advance, and the DU copies this information for use during message forwarding, significantly reducing processing time while preserving the adaptability of bearer mapping.
Data Source
AI summary
This application provides a communication method and a communication apparatus. In the method, before sending a first message or when sending a first message, a second network device sends indication information to a first network device, so that the first network device can determine, based on the indication information, a configuration of a first mapping relationship used to transmit the first message. In this way, the first message is correctly transmitted, so that a first terminal device reestablishes or resumes a first connection by using a second terminal device, and correctly accesses a corresponding access network device.