RRC Establishment Cause for Early EPS Fallback Triggering
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Solution Overview
Problem
The existing EPS fallback scheme for voice calls in 5G SA systems experiences longer setup times due to the EPS fallback trigger procedure, RAT and core change, and TAU procedures, leading to quality deterioration and negative user experience when NR coverage is insufficient.
Innovation Solution
A method and apparatus that utilize an RRC establishment cause to detect voice or video call service requests, allowing for early triggering of EPS fallback by a base station, thereby reducing the initial setup time by directly determining the need for fallback based on the RRC connection request message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EPS fallback scheme is used to provide voice call service in 5G SA system, then voice call quality is maintained equivalent to VoLTE, but voice call setup time is longer due to additional procedures
Solution Approach 1:
The base station performs preliminary detection of call service requests by examining the RRC establishment cause before initiating the fallback procedure. This early detection allows the system to prepare for and trigger EPS fallback proactively, reducing the overall setup time while maintaining the necessary quality standards through the established fallback mechanism
2Loss of time
If VoNR scheme is used for voice call service, then voice call setup time is shorter, but voice service quality deteriorates when NR coverage is insufficient due to connection changes during call
Solution Approach 1:
The system uses feedback from the RRC establishment cause to determine whether to initiate EPS fallback. By monitoring this indicator, the base station can make informed decisions about triggering fallback procedures, ensuring that voice service quality is maintained by switching to LTE when appropriate, while minimizing unnecessary fallback operations to preserve the faster VoNR setup time
Data Source
AI summary
A method and apparatus for triggering fallback using RRC establishment cause in a communications system is disclosed herein. An aspect of the present disclosure provides a base station of a first wireless communication system for triggering fallback from the first wireless communication system to a second wireless communication system, the base station including: a receiving unit configured to receive an RRC connection request message from user equipment and check whether or not the user equipment requests a call service using the RRC connection request message; and a fallback trigger unit configured to trigger the fallback to the second wireless communication system when the user equipment requests the call service.