CS Fallback Indicator in Radio Resource Re-establishment
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Solution Overview
Problem
Current mobile communication systems face delays in performing CSFB (Circuit Switching Fallback) procedures when a terminal loses radio resource connection before receiving a response, leading to delayed voice service establishment due to the inability of new base stations to identify if a CSFB request was made.
Innovation Solution
A method where a terminal transmits a CSFB request to a mobility management entity through a first base station, detects radio resource connection failure, and sends a radio resource control re-establishment request to a second base station with a CSFB indicator, allowing the second base station to identify the request and initiate the CSFB procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal transmits CSFB request through the first base station and then experiences radio resource connection failure, then the CS service establishment is delayed because the second base station cannot identify the pending CSFB request, but if the terminal continuously retries connection to the first base station, then the connection recovery time is extended
Solution Approach 1:
The terminal performs preliminary action by storing the CSFB request information and indicator before the radio resource connection failure occurs. When connection failure is detected, the terminal can immediately transmit the stored CSFB indicator to the second base station without needing to re-establish connection to the first base station first, thus preventing service establishment delays
Solution Approach 2:
The CSFB indicator acts as an intermediary element that carries critical information between the terminal and the second base station. This indicator enables the second base station to understand that a CSFB request is pending, allowing it to appropriately handle the terminal's connection re-establishment and forward the CSFB procedure, thus bridging the information gap caused by the base station change
2Speed
If the terminal stores CSFB request information locally to enable quick re-establishment, then the service recovery speed is improved, but the terminal's memory and processing requirements increase
Solution Approach 1:
The terminal extracts only the essential CSFB indicator information needed for service recovery rather than storing complete request details. This selective extraction minimizes memory usage and processing requirements while still enabling the second base station to identify and handle the pending CSFB request appropriately
Solution Approach 2:
The CSFB indicator changes its state or value to reflect whether a CSFB request is pending. This parameter-based approach allows the terminal to store minimal information (a simple indicator flag) rather than complex request data, reducing terminal complexity while maintaining service recovery capability
Data Source
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AI summary
Disclosed are: a communication technique for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system; and a system therefor. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, and the like) on the basis of 5G communication technology and IoT related technologies. The present disclosure relates to a method by which a terminal receives a circuit switching (CS) service, and according to the present disclosure, the method by which a terminal receives a CS service, comprises the steps of: transmitting a CS fallback (CSFB) request to a mobility management entity (MME) through a first base station in order to use the CS service; detecting the failure of a radio resource connection to the first base station; and transmitting, to a second base station, a radio resource re-establishment related message including a CSFB indicator for identifying the CSFB request.