MME Selection Synchronization for CS-to-LTE Handover
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Solution Overview
Problem
In current communication networks, there is a challenge in seamlessly switching voice services from a Circuit Switched (CS) domain of 2G/3G networks to a Packet Switched (PS) domain of LTE/HSPA networks, often resulting in handover failures due to mismatched Mobility Management Entities (MMEs) selected by the MSC server and SGSN.
Innovation Solution
The method involves the MSC server requesting context information from a source SGSN using a determined MME, ensuring that both entities interact with the same MME, thereby synchronizing PS and CS handover processes and preventing handover failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the MSC server and SGSN independently select MMEs for handover, then each entity can operate autonomously, but handover failures occur due to mismatched MME selection
Solution Approach 1:
The patent merges the MME selection process for both MSC server and SGSN by introducing a common selection criterion based on the target eNodeB ID. Both entities query the same HSS to obtain the MME identifier, ensuring they select the same MME and avoiding handover failures while maintaining operational autonomy.
Solution Approach 2:
The patent creates a universal MME selection mechanism that serves both CS domain (MSC server) and PS domain (SGSN) handovers. The HSS becomes a universal query target for both entities, and the MME selection process is made multi-functional to support both voice service handover and data service handover simultaneously.
2Adaptability or versatility
If the MSC server and SGSN select different MMEs, then system flexibility is maintained, but handover synchronization fails leading to service interruption
Solution Approach 1:
The patent applies preliminary action by having both MSC server and SGSN query the HSS for MME selection information before the actual handover execution. This advance coordination ensures that both entities have the same MME identifier ready, preventing synchronization failures and service interruptions during the handover process.
3Reliability
If context information is not synchronized between MMEs, then network security is maintained, but handover accuracy decreases causing service failures
Solution Approach 1:
The patent uses the HSS as an intermediary to transfer context information from the source MME to the target MME during handover. The HSS securely stores and retrieves user subscription data and context information, enabling accurate handover while maintaining network security through controlled information access.
Data Source
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AI summary
The present invention discloses a method and a device for handover to a serving network. The method includes: receiving a first Handover Request sent by a BSC/RNC; sending a second Handover Request to a target MME according to the first Handover Request, where the second Handover Request includes an IMSI and first information for determining a source SGSN so that the MME sends a Context Request message including the IMSI to the source SGSN and receives context information of a user equipment corresponding to the IMSI sent by the source SGSN. The device includes an MSC server, an SGSN, an MME, and a BSC/RNC. The method and apparatus according to embodiments of the present invention, by applying for context information from a source SGSN by using an MME determined by an MSC server, are capable of ensuring that, in an rSRVCC handover process, the MSC server and the SGSN interact with the same MME, thereby avoiding a handover failure because the MSC server and the SGSN select different MMEs, and further synchronizing PS and CS handover processes, improving handover accuracy and efficiency, and enhancing user experience.