Early EPS Fallback for IMS Voice in 5G Terminals
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Solution Overview
Problem
Current 5G mobile communication systems face delays in EPS fallback operations due to measurement configuration and reporting requirements, which hinder the efficient provision of IMS voice services during inter-RAT handovers.
Innovation Solution
A method and apparatus that enable early EPS fallback by allowing terminals to collect and report relevant information, utilizing early measurement reporting (EMR) to quickly identify suitable cells for inter-RAT handovers, and logging access times to optimize the fallback process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measurement configuration and reporting are performed for EPS fallback, then cell selection reliability is improved, but fallback time is increased
Solution Approach 1:
The terminal performs measurements on target cells of another RAT system in advance while connected to the source cell, and stores measurement results for later use during EPS fallback. This preliminary measurement action eliminates the need for new measurements during handover, thus reducing fallback time while maintaining reliable cell selection based on pre-collected measurement data.
2Speed
If early measurement reporting is implemented, then fallback speed is improved, but measurement precision may be compromised
Solution Approach 1:
The terminal is configured with measurement parameters in advance and performs measurements on target cells before actual handover occurs. By completing measurements preliminarily and storing results, the system achieves fast fallback execution without sacrificing measurement quality, as measurements are performed with full configuration rather than rushed approximations.
Data Source
AI summary
The disclosure relates to a 5G or 6G communication system for supporting higher data rates. The disclosure discloses a method and an apparatus capable of optimizing early EPS fallback. A method performed by a terminal in a wireless communication system includes receiving, from a base station of a first RAT, a message to command an inter-RAT HO, the message including information indicating that the inter-RAT HO is triggered by EPS fallback for IMS voice; performing the inter-RAT HO based on the message; based on a failure of the inter-RAT HO, identifying whether there is a suitable cell of a second RAT for selection; in case that there is no suitable cell of the second RAT, selecting an acceptable cell of the second RAT based on the IMS voice being for an emergency service; and logging a time until the terminal accesses the acceptable cell of the second RAT.