5G Voice Call Handover Fallback Using Mobility Failure Indicators
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Solution Overview
Problem
Existing mobile communication systems face challenges in supporting voice call services and cell reselection processes, particularly in next-generation systems, due to failures in mobility procedures and the lack of efficient methods for handling circuit-switched fallback and closed access groups (CAGs).
Innovation Solution
A method and apparatus are provided for a UE and base station to handle mobility-related failures by identifying indicators in mobility messages, selecting appropriate cells, and performing RRC idle operations or EPS fallback procedures to support voice call services and CAG operations, thereby enhancing the reliability of handover processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mobility procedure fails in next-generation mobile communication system, then voice call service cannot be established, but conventional systems lack efficient fallback mechanisms
Solution Approach 1:
The patent applies preliminary action by pre-configuring fallback mechanisms and indicators in mobility messages before mobility failures occur. The base station includes specific indicators in mobility-related messages to guide UE behavior in advance, enabling rapid transition to alternative procedures (such as EPS fallback or CAG cell selection) when mobility fails, thus ensuring voice call service can still be established through alternative paths.
Solution Approach 2:
The patent uses indicators in mobility messages as intermediaries to communicate failure conditions and guide subsequent actions. These indicators act as mediators between the base station and UE, enabling the UE to automatically select appropriate fallback procedures (EPS fallback, CAG cell reselection) without complex human intervention or system reconfiguration, thereby improving both reliability and adaptability.
2Reliability
If UE performs conventional cell reselection after mobility failure, then it may select inappropriate cells, but efficient CAG-aware reselection mechanisms are lacking
Solution Approach 1:
The patent applies preliminary action by providing CAG configuration information and cell selection criteria to the UE in advance through mobility messages or system information. This enables the UE to perform CAG-aware cell reselection by comparing candidate cells against pre-configured CAG parameters, ensuring accurate cell selection without requiring complex real-time decision-making or additional signaling exchanges.
3Reliability
If mobility procedure includes detailed failure indicators, then UE can make informed decisions, but message overhead increases
Solution Approach 1:
The patent extracts only the essential failure indicators and CAG-related parameters from complex mobility failure scenarios and includes them in standardized fields within mobility messages. By selecting only the most critical information elements needed for UE decision-making (such as failure cause indicators and CAG cell selection criteria), the patent reduces message overhead while maintaining sufficient accuracy for reliable mobility failure handling.
Data Source
AI summary
The present disclosure relates to a communication technique for convergence between an IoT technology and a 5G communication system for supporting a higher data transmission rate than a 4G system, and a system thereof. The present disclosure may be applied to intelligence services (for example, smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security and safety related services, etc.) on the basis of a 5G communication technology and an IoT-related technology. In addition, the purpose of the present disclosure is to provide an efficient voice call method in a next-generation mobile communication system. Furthermore, the present disclosure may provide an operation method of a terminal in a wireless communication system, and an apparatus performing same, the method comprising the steps of: receiving a mobility-related message for handover from a first radio access technology (RAT) supporting new radio (NR) to a second RAT; on the basis of the mobility-related message, identifying whether a mobility procedure to the second RAT fails; in case that the failure in the mobility procedure is identified, identifying whether the mobility-related message includes an indicator; in case that the mobility-related message includes the indicator, selecting a cell of the second RAT; and performing a radio resource control (RRC) idle operation by the cell of the second RAT.