5G EPS Fallback Triggering for Reduced Call Setup Time
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Solution Overview
Problem
The current 5G system call setup process is excessively long due to complex and time-consuming steps, particularly when a 5G user device lacks Voice over New Radio (VoNR) support, leading to significant delays in call setup times and a degraded customer experience.
Innovation Solution
Implementing a modified call setup method where a 5G user device automatically triggers the EPS fallback procedure to LTE without attempting multiple signaling steps to connect via 5G NR, thereby reducing call setup time by immediately reselecting to available LTE cell sites and re-establishing IMS registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the 5G system attempts to establish voice communication via NR node with multiple signaling steps, then VoNR support is attempted, but call setup time becomes excessively long
Solution Approach 1:
The UE determines in advance whether the NR node supports VoNR before attempting call setup. This preliminary check prevents unnecessary signaling steps and direct fallback attempts, allowing the system to skip directly to EPS fallback when VoNR is unavailable, thereby reducing call setup time while maintaining reliability when VoNR is supported.
2Reliability
If the 5G system performs multiple signaling steps to connect via 5G NR, then VoNR communication is attempted, but device complexity and resource consumption increase
Solution Approach 1:
The UE performs a preliminary determination of NR node VoNR support capabilities before initiating call setup procedures. This advance knowledge allows the device to select the appropriate communication path (VoNR or EPS fallback) without attempting multiple signaling sequences, thereby reducing device complexity and resource consumption while ensuring reliable VoNR communication when available.
3Loss of time
If the 5G system immediately triggers EPS fallback without attempting VoNR, then call setup time is reduced, but VoNR capability is not utilized when available
Solution Approach 1:
The UE determines in advance whether the NR node supports VoNR before initiating call setup. When VoNR is supported, the system utilizes VoNR for call setup; when not supported, it immediately triggers EPS fallback. This preliminary determination ensures both reduced call setup time and proper VoNR utilization when available.
Data Source
AI summary
Systems and methods for performing Evolved Packet System (EPS) fallback from a 5G system to an Evolved Packet Core (EPC) system are disclosed. The method, performed in a mobile device, detects a communication at the mobile device. The method then determines whether either the mobile device or a base station supports the communication over new radio. Directly in response to determining that either one of the mobile device or the base station does not support the communication over new radio, the method generates and transmits an EPS fallback message from the mobile device to the base station, wherein the EPS fallback message instructs the base station to initiate a fallback procedure from the 5G system to the EPC system.