LTE to CS Domain Handover via MME Coordination
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Solution Overview
Problem
In current communication networks, the handover process from LTE to 2G or 3G networks for voice calls often results in interruptions due to differences in bearing mechanisms, leading to poor user experience and increased voice call duration.
Innovation Solution
A network handover method that triggers UE to directly hand over from the LTE network to the CS domain of 2G or 3G networks, reducing access delay by allocating resources on the network side for CS domain access, thereby avoiding the need for handover through the PS domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE hands over from LTE network to PS domain of 2G or 3G network before initiating voice call, then voice service can be provided in legacy networks, but access delay increases and user experience deteriorates
Solution Approach 1:
The network side (MME) proactively initiates handover preparation to CS domain before the UE actually needs to make or receive a voice call. By sending handover request messages to MSC and allocating CS domain resources in advance, the system eliminates the delay that would otherwise occur when UE transitions from PS to CS domain at call initiation time.
Solution Approach 2:
The MME acts as an intermediary that coordinates the handover process between LTE network and legacy 2G/3G networks. It sends notification messages to eNodeB, initiates handover to CS domain via MSC, and manages the transition without requiring UE to manually switch domains, thereby streamlining the process and reducing access delay.
2Loss of time
If UE hands over from LTE network to CS domain directly, then access delay is reduced and user experience improves, but network coordination complexity increases
Solution Approach 1:
The MME performs multiple functions: it acts as the LTE core network element, initiates handover to CS domain, allocates resources, and coordinates with both eNodeB and MSC. This multi-functionality consolidates complex coordination tasks into a single network element, managing complexity rather than increasing it.
Solution Approach 2:
The network side automatically initiates and manages the handover process without requiring UE intervention. The MME autonomously sends handover requests, allocates CS domain resources, and coordinates the transition, making the system self-organizing and reducing the perceived complexity for end users.
3Adaptability or versatility
If UE moves to PS domain before initiating voice call in 2G or 3G network, then network compatibility is maintained, but voice call duration increases
Solution Approach 1:
By pre-establishing CS domain connectivity and allocating resources before the voice call begins, the system eliminates the time required for domain switching during the call setup phase. This preliminary action reduces the overall voice call duration while maintaining compatibility with legacy 2G/3G networks.
Data Source
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AI summary
The present invention discloses a network handover method, where after UE in an LTE network initiates a request message for requesting circuit switched fallback CSFB, an MME instructs an eNB to move the UE from the LTE network to a 2G or 3G network, and requests an MSC to hand over the UE from the LTE network to a CS domain of the 2G or 3G network for the CSFB, so that the 2G or 3G network allocates a CS domain resource to the UE, where the CS domain resource is used for the UE to hand over from the LTE network to the CS domain of the 2G or 3G network, so that the UE can hand over to a PS domain of the 2G or 3G network in a manner of handing over from the LTE network to the CS domain of the 2G or 3G network. After handing over to the PS domain, the UE may perform a CS domain call. By using embodiments of the present invention, an access delay is reduced when the UE accesses the CS domain of the 2G or 3G network, duration of an entire voice call is shortened, and user experience is improved.