CU-DU Network Reselection Using UE Context Transfer Signaling
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Solution Overview
Problem
In a network sharing scenario with a CU-DU separation architecture, there is a challenge in retrieving UE context from a CU belonging to a previous network to a new CU during network reselection.
Innovation Solution
Implementing new signaling messages such as REROUTE RRC MESSAGE, CU NODE REALLOCATION, and RETRIEVE UE CONTEXT to facilitate the transfer of UE context between gNB-CUs in a network sharing scenario, allowing seamless network reselection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If network sharing split architecture is implemented to support multiple carrier networks, then network versatility and resource utilization are improved, but the complexity of context retrieval and network reselection procedures increases
Solution Approach 1:
The gNB is segmented into CU (Centralized Unit) and DU (Distributed Unit) with clear functional separation. The CU handles higher-layer protocols and network reselection, while the DU handles lower-layer physical layer functions. This segmentation allows the system to support multiple carrier networks through the CU while keeping the DU relatively simple, resolving the contradiction between versatility and complexity.
Solution Approach 2:
The F1 interface acts as an intermediary between the CU and DU, enabling standardized communication and context transfer. This intermediary mechanism facilitates seamless network reselection by providing a defined protocol for context retrieval between different CUs, reducing the overall system complexity despite supporting multiple networks.
2Reliability
If UE context is transferred between different CUs during network reselection, then connectivity is maintained, but the signaling overhead and reselection time increase
Solution Approach 1:
The UE context is prepared and maintained in the source CU before actual network reselection occurs. When reselection is needed, the pre-prepared context can be quickly retrieved and transferred to the target CU using the F1 interface, significantly reducing the time required for network reselection while maintaining connectivity.
Solution Approach 2:
The system implements feedback mechanisms where the UE reports measurement results and network conditions to the CU. Based on this feedback, the CU proactively prepares for potential network reselection by maintaining context information, enabling faster reselection when needed while ensuring connectivity is maintained throughout the process.
3Reliability
If new signaling messages are introduced for context retrieval and reselection, then network reselection reliability is improved, but the protocol complexity and implementation difficulty increase
Solution Approach 1:
The F1 interface is designed as a universal interface that can handle multiple functions including UE context transfer, network reselection signaling, and resource management. By making the F1 interface multi-functional, the patent reduces the need for separate dedicated signaling mechanisms, thereby improving reliability without proportionally increasing protocol complexity.
Solution Approach 2:
The patent introduces new parameters and information elements within existing message structures to enable reliable context retrieval and network reselection. Rather than creating entirely new complex protocols, the solution modifies and extends existing parameters, achieving improved reliability while minimizing implementation complexity.
Data Source
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AI summary
Methods, systems, and devices related to digital wireless communication, and more specifically, to techniques related to related to reselecting a network in a network sharing split architecture. In one exemplary aspect, a method for wireless communication includes a central node associated with a previous network receiving a rerouting message from a distributed node indicating that a network for the terminal is reselected from the previous network to a new network. The method also includes the central node associated with a previous network transmitting an allocation message to a central node associated with the new network.