User Device 5G to 4G Fallback IMS Service
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing technologies face challenges in maintaining service quality for real-time communication services like emergency calls, voice communication, and video calling during fallback from the 5G system to other systems due to time-consuming processing and congestion issues.
Innovation Solution
A user device capable of autonomously selecting and connecting to a 4G system that supports IMS-type communication service upon detecting congestion, non-IMS support, or fallback instructions in the 5G system, thereby avoiding the need for CS fallback to the 3G system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fallback from 5G system to 4G system is performed according to existing specifications, then emergency calls can be processed via 4G system, but the processing is time-consuming and service quality deteriorates
Solution Approach 1:
The user device pre-acquires system information from the target 4G cell before actual fallback occurs. This includes obtaining PLMN identities, cell identity, and other necessary configuration data in advance. When fallback is triggered, the device can immediately use this pre-acquired information to connect to the 4G system without waiting for information retrieval during the fallback process, thus reducing the time loss while ensuring reliable emergency call processing.
2Reliability
If CS fallback from 4G system to 3G system is performed, then connection can be established, but service quality deteriorates due to time-consuming conversion from IMS type to CS type communication
Solution Approach 1:
The device pre-acquires target cell information including PLMN identities and cell configuration data before fallback is needed. This allows the device to maintain IMS-type communication service continuity during fallback to 4G system, avoiding the need for time-consuming conversion to CS-type service. The pre-acquired information enables direct connection establishment while preserving service quality.
Solution Approach 2:
Instead of following the conventional fallback path from 5G to 4G to 3G with service type conversion, the invention inverts the approach by directly falling back to 4G system with pre-acquired information, maintaining IMS-type service throughout. This reverses the traditional sequence and service conversion requirement, eliminating the time-consuming CS-type conversion step while ensuring reliable connection establishment.
3Loss of time
If the user device autonomously selects target cell, then fallback time is reduced, but the device complexity increases
Solution Approach 1:
The device performs preliminary acquisition of system information from potential target 4G cells before fallback is triggered. This includes storing PLMN identities, cell identity, frequency information, and other configuration data. When fallback occurs, the device uses this pre-stored information for rapid autonomous cell selection and connection establishment, reducing fallback time while managing complexity through advance preparation.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In 5G cell (230) of 5G system (200), upon detecting that access to the 5G system (200) is barred, the 5G system (200) is congested, 5G core network (220) of the 5G system (200) does not support IMS-type communication service, or fallback to 4G system (300) is instructed, UE (100) selects 4G cell (330) of the 4G system (300) as a target cell for connection. The UE (100) transmits a connection request signal for the IMS-type communication service to the target cell for connection.