Distributed Unit Bearer Establishment for 5G RRC Reliability
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Solution Overview
Problem
In wireless communication systems, particularly in 5G networks, there is a need for a method to transmit Radio Resource Control (RRC) messages and data between a Central Unit (CU) and a Distributed Unit (DU) of a base station, as well as between the DU and a User Equipment (UE, since RRC messages cannot be transmitted directly from the CU to the UE, and data must be routed through the DU.
Innovation Solution
The method involves establishing a bearer by the DU of a base station, which includes receiving an RRC message or data from the CU, and transmitting it to the UE through the control plane interface (F1-C) and user plane interface (Uu), using a processor to control the transceiver for message and data transmission, and including a memory to store necessary information for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RRC messages are transmitted through the DU via the F1-C interface between CU and DU, then the message transmission path is established according to the CU-DU split architecture, but the transmission complexity increases due to the indirect routing requirement
Solution Approach 1:
The DU acts as an intermediary node between the CU and UE. The F1-C interface serves as the mediator for control plane message transmission, allowing the CU to communicate with the UE indirectly through the DU without requiring direct CU-UE connection, thus maintaining the CU-DU split architecture while enabling reliable message delivery
2Reliability
If data is routed through the DU between CU and UE, then the data transmission follows the distributed architecture requirements, but the transmission delay increases due to the additional routing hop
Solution Approach 1:
The bearer establishment procedure is performed in advance before actual data transmission. By pre-configuring the data radio bearers and establishing the transmission paths through the DU beforehand, the system prepares the routing infrastructure in advance, so that when data needs to be transmitted, the path is already ready and no additional setup delay occurs
3Adaptability or versatility
If multiple bearers (SRB0, SRB1, SRB2, SRB3) are established for different RRC messages, then the communication functionality is enhanced, but the bearer management complexity increases
Solution Approach 1:
The communication bearers are segmented into different types (SRB0 for initial access, SRB1 for RRC messages during connection establishment, SRB2 for data transmission, SRB3 for specific scenarios) with distinct functions. Each bearer type is configured and managed independently with specific protocols and procedures, allowing the system to handle different communication requirements through specialized bearers rather than a single general-purpose bearer
Solution Approach 2:
The bearer configuration is dynamic and adaptive to different communication scenarios. The system can establish, modify, or release specific bearers based on the current RRC state and communication needs. For example, SRB0 is used only during initial access, while SRB1-SRB3 are used after connection establishment, allowing the bearer set to dynamically adapt to the operational phase
Data Source
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AI summary
Provided are method for a distributed unit (DU) of a base station establishing a bearer in a wireless communication system, and an apparatus for supporting the same. The method may comprise the steps of: receiving a first message including a signaling radio bearer (SRB) identity (ID) from a central unit (CU) of the base station; and establishing a SRB corresponding to the received SRB ID.