Wireless Redirection Handling via Segmented RAT and CN Information
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Solution Overview
Problem
In wireless communication systems, there is a lack of clear guidance on how user equipment (UE) selects and connects to either an Evolved Packet Core (EPC) network or a 5G Core (5GC) network in response to a redirection message, as the base station cannot control the UE's selection between these networks.
Innovation Solution
A communication device and base station handle system redirection by processing a redirection message that includes radio access technology (RAT) and core network (CN) information, allowing the UE to enter an idle state, select a second cell of a different RAT, establish a radio resource control (RRC) connection, and generate a non-access-stratum (NAS) message to the indicated CN, ensuring seamless network redirection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station provides redirection message with RAT and CN information, then the UE can correctly select and connect to the target network, but the device complexity increases due to additional processing requirements
Solution Approach 1:
The redirection message is segmented into distinct components: RAT information (indicating the target radio access technology) and CN information (indicating the target core network). This segmentation allows the UE to process and interpret each component separately, reducing the complexity of handling the overall redirection procedure while ensuring accurate network selection.
Solution Approach 2:
The base station performs preliminary action by pre-configuring and including both RAT and CN information in the redirection message before the UE needs to execute the redirection. This advance preparation eliminates the need for the UE to perform complex real-time analysis, simplifying the UE's processing requirements while ensuring reliable network selection.
2Ease of operation
If the UE autonomously selects between EPC and 5GC networks, then the ease of operation improves, but the reliability of network selection deteriorates due to lack of clear guidance
Solution Approach 1:
The redirection message serves as feedback from the base station to the UE, providing clear guidance on the intended target network (EPC or 5GC) along with associated RAT and CN information. This feedback mechanism enables the UE to autonomously make informed selection decisions while maintaining high reliability, as the base station's guidance ensures the selection aligns with network requirements and UE capabilities.
3Reliability
If the base station controls the UE's network selection, then the reliability of redirection improves, but the ease of operation deteriorates due to reduced UE flexibility
Solution Approach 1:
The redirection message acts as an intermediary carrier that conveys the base station's redirection intent to the UE in a structured and interpretable format. By using this intermediary mechanism, the base station maintains control over redirection reliability through careful message construction, while the UE retains operational flexibility by autonomously processing the message according to its capabilities and current state.
Data Source
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AI summary
A communication device for handling a redirection comprises at least one storage device storing instructions of receiving a redirection message from a first base station (BS) of the first radio access technology (RAT) via a first cell, wherein the redirection message comprises RAT information indicating a second RAT and indicates a first core network (CN); entering an idle state in response to the redirection message; selecting a second cell of the second RAT according to the RAT information; establishing a radio resource control (RRC) connection via the second cell to a second BS in the idle state; generating a non-access-stratum (NAS) message for the first CN according to the redirection message; and transmitting the NAS message on the RRC connection via the second cell to the second BS.