Shared DU RRC Message Redirection for CU Selection in Network Slicing
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Solution Overview
Problem
Current Next Generation (NG) Radio Access Network (RAN) architecture faces challenges in network sharing scenarios with multiple Cell Identity (ID) / Tracking Area Code (TAC) cell configurations, particularly with Central Unit (CU) / Distributed Unit (DU) split deployments, where geographical separation and security issues hinder easy data exchange, and existing specifications do not adequately support Initial Attach, RRC Reestablishment, and RRC Resume procedures.
Innovation Solution
The proposed solution involves implementing a method where a shared Distributed Unit (DU) receives Radio Resource Control (RRC) messages and redirects them between CUs using F1 Application Protocol (F1AP) messages, including error indications and assistance information to ensure correct CU selection, and releasing incorrect connections, thereby facilitating successful Initial Attach, RRC Reestablishment, and RRC Resume procedures in network sharing and slicing scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a shared DU is used in network sharing scenarios with multiple Cell ID/TAC configurations, then resource utilization efficiency is improved, but CU selection complexity and connection management difficulty increase
Solution Approach 1:
The patent introduces an intermediary redirection mechanism where the shared DU acts as a mediator between the UE and multiple CUs. When a UE sends an RRC message, the shared DU redirects it to the appropriate CU based on Cell ID and TAC information, eliminating the need for the UE to directly select among multiple CUs and simplifying the overall system complexity while maintaining resource sharing efficiency
Solution Approach 2:
The patent implements preliminary action by having the shared DU pre-configure redirection rules and assistance information based on Cell ID and TAC mappings before actual UE connections are established. This pre-configuration enables rapid and accurate CU selection without real-time complex decision-making, resolving the contradiction between resource sharing and selection complexity
2Adaptability or versatility
If geographical separation of CUs and DUs is implemented, then network flexibility and slicing support are improved, but data exchange reliability and security issues worsen
Solution Approach 1:
The shared DU serves as a trusted intermediary that facilitates secure data exchange between geographically separated CUs and UEs. By centralizing the F1 interface termination at the shared DU, the patent ensures reliable message routing and maintains security boundaries while allowing CUs to be geographically distributed for network flexibility and slicing support
Solution Approach 2:
The shared DU implements multi-functionality by handling multiple roles simultaneously: it serves as a common interface termination point for multiple CUs, performs redirection to appropriate CUs based on Cell ID/TAC, provides assistance information for CU selection, and manages connections for different network slices. This universal functionality enables geographical separation while maintaining data exchange reliability through a single trusted entity
3Ease of manufacture
If existing F1 interface specifications are used without redirection support, then implementation simplicity is maintained, but support for network sharing and slicing with CU-DU split deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring the shared DU with redirection rules and assistance information mappings before network operations begin. This pre-configuration approach allows the system to support network sharing and slicing scenarios without requiring complex real-time decision logic, maintaining implementation simplicity while achieving the required adaptability
Solution Approach 2:
The shared DU implements self-service by autonomously performing redirection decisions based on pre-configured rules and assistance information. It automatically determines the appropriate CU for each UE connection based on Cell ID and TAC without requiring external control or complex coordination, thereby maintaining implementation simplicity while enabling network sharing and slicing support
Data Source
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AI summary
Systems and methods for redirecting Radio Resource Control (RRC) messages in a wireless system that uses Central Unit (CU) / Distributed Unit (DU) splitting and either network sharing or network slicing are disclosed. In some embodiments, a method performed by a shared Distributed Unit (DU) comprises receiving a RRC message from a User Equipment (UE) and sending a first DU-to- Central Unit (CU) message to a first CU, where the first DU-to-CU message comprises the RRC message. The method further comprises either obtaining an indication that the first CU is a wrong CU for the RRC message or determining that the first CU is a wrong CU for the RRC message. The method further comprises sending another DU-to-CU message to a second CU, where the other DU-to-CU message comprises the RRC message or a RRC message related to the RRC message.