5G NR Voice Call EPS Fallback Optimization
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Solution Overview
Problem
Current 5G NR voice call systems face challenges in establishing voice calls due to limitations in dedicated bearer resources and access barring, leading to delays and poor user experience during EPS fallback.
Innovation Solution
The proposed solution involves a wireless device (UE) that camps on a 5G NR cell, performs IMS registration or SIP invite procedures, and upon determining that voice calls cannot be established over 5G NR, performs a TAU or attachment procedure with a 4G network, omitting IMS registration or SIP invite procedures to facilitate voice call establishment over LTE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs complete IMS registration and SIP invite procedures during EPS fallback from 5G NR to 4G, then the voice call can be established over LTE, but the call establishment delay increases and user experience deteriorates
Solution Approach 1:
The UE performs IMS registration and SIP invite procedures in advance while camped on the 5G NR cell before initiating the voice call. When EPS fallback is triggered, these pre-established IMS credentials and session information can be reused, allowing the UE to skip redundant registration steps during the fallback process and rapidly establish the voice call over LTE.
Solution Approach 2:
The patent extracts and separates the essential voice call establishment elements (IMS registration and SIP invite procedures) from the complete EPS fallback process. By identifying which procedures are truly necessary for voice call setup versus which are redundant, the solution removes unnecessary steps during fallback, keeping only the critical path elements needed for rapid voice call establishment.
2Adaptability or versatility
If the UE attempts to establish voice calls over 5G NR with dedicated bearer resources, then native 5G voice service is achieved, but access barring and resource limitations prevent successful call establishment
Solution Approach 1:
The patent introduces the 4G LTE network as an intermediary system when native 5G voice call establishment fails due to access barring or resource limitations. The UE leverages the mature and reliable VoLTE infrastructure as a fallback mechanism, seamlessly transitioning from the problematic 5G voice path to the reliable 4G voice path while maintaining continuous service availability.
Solution Approach 2:
Instead of attempting to force voice call establishment through the primary 5G NR path and dealing with failures, the patent inverts the approach by preparing alternative 4G LTE credentials and procedures in advance. When 5G voice establishment is determined to be unreliable, the system immediately activates the pre-prepared 4G fallback path, reversing the traditional failover sequence for faster recovery.
Data Source
AI summary
Apparatuses, systems, and methods for a user equipment device (UE) to perform methods for EPS fallback when initiating a voice call while camped on a 5G cell. The UE may camp on a 5G network by performing an IMS registration procedure/IMS SIP invite procedure with an IMS. The UE may initiate a voice call and determine that the voice call cannot be established over the 5G NR network. In response, the UE may perform a TAU procedure or an attachment procedure with a cell of a 4G network. The IMS may be transferred to the 4G network during TAU/attachment procedure. The UE may, in response to determining that it is barred from the 4G network, transition back to the 5G network and transmit, to the 5G NR network, a SIP cancel request to allow a context associated with the UE to be cleared from the IMS.