Circuit Switched Fallback Conflict Resolution in LTE Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current circuit switched fallback (CSFB) methods in LTE networks often fail to successfully establish CS services when they conflict with serving cell handover processes, leading to incomplete voice services.
Innovation Solution
A method and system that determine when a serving cell handover process is complete and necessitates a move to a second network supporting CS services, allowing the network device to move the UE to this network, thereby ensuring CS service continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network device implements the serving cell handover process when CSFB is triggered during handover, then the handover process is completed, but the voice service cannot be successfully established
Solution Approach 1:
The network device performs preliminary judgment to determine whether CSFB is triggered during the serving cell handover process. Based on this preliminary action, the device decides whether to suspend the handover process and wait for CSFB completion first, thereby preventing the conflict between handover and CS service establishment before it occurs
Solution Approach 2:
The network device dynamically adjusts the handover process based on the triggering condition of CSFB. When CSFB is triggered, the handover process is suspended and adapted to wait for CSFB completion; when CSFB is not triggered, the handover process proceeds normally. This dynamic adjustment resolves the contradiction between maintaining handover productivity and ensuring CS service reliability
2Reliability
If the network device waits for CSFB completion before handover, then CS service can be established, but handover process is delayed
Solution Approach 1:
The network device performs preliminary judgment to determine whether CSFB is triggered during the serving cell handover process. Only when CSFB is actually triggered does the device suspend the handover process to wait for CSFB completion. This preliminary action avoids unnecessary delays when CSFB is not triggered, thereby reducing time loss while ensuring CS service reliability when needed
3Ease of operation
If multiple signaling exchanges are required during handover, then handover can be completed, but CS service establishment fails when CSFB is triggered
Solution Approach 1:
The network device performs preliminary judgment to detect whether CSFB is triggered during the handover signaling exchange process. When CSFB is detected, the device suspends the handover process and waits for CSFB completion before proceeding with handover signaling exchanges, thereby ensuring that CS service establishment prerequisites are met before attempting handover operations
Solution Approach 2:
The network device introduces a judgment mechanism as an intermediary between the CSFB triggering condition and the handover process. This intermediary judgment determines whether to proceed with handover signaling exchanges or suspend for CSFB completion, thereby coordinating the conflicting requirements of handover completion and CS service establishment success
Data Source
AI summary
Embodiments of the present disclosure disclose a circuit switched fallback method, a network device, and a system. The method includes: determining, by the network device, that a serving cell handover process of UE is ended; determining, by the network device, that before the serving cell handover process of the UE is ended, it has been determined that the UE needs to be moved to a second network supporting a circuit switched service; and moving, by the network device, the UE to the second network. According to the foregoing method, when CSFB triggered by a CS service initiated by UE conflicts with a serving cell handover process of the UE, the CS service of the UE can continue to be performed after completing the serving cell handover process of the UE. In this way, a success rate of establishing the CS service is increased.