MME Context Transfer Indicator for S1 Handover Security
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Solution Overview
Problem
During S1 handover in LTE-A networks, security information of UE is lost due to the lack of context transfer between the source and target MMEs, resulting in inadequate security protection for NAS messages between the UE and the target MME.
Innovation Solution
A method and system for transferring the context of a UE from a source MME to a target MME using an indicator, ensuring the target MME acquires necessary security information of the UE during S1 handover on a relay node, thereby maintaining communication continuity and implementing security protection for NAS messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If S1 handover occurs on the relay node RN without UE context transfer, then the handover process is simple and fast, but the security information of the UE is lost and security protection cannot be implemented
Solution Approach 1:
The source MME proactively determines whether UE context transfer is needed before the handover completes, and initiates the context transfer process in advance. This preliminary action ensures security information is transferred before the target MME needs it, resolving the contradiction between fast handover and secure communication.
Solution Approach 2:
The source MME acts as an intermediary that receives notification from the target MME about UEs served by the RN, determines which UEs need context transfer, and facilitates the context transfer process. This intermediary role enables coordinated context transfer without disrupting the overall handover speed.
2Reliability
If the source MME transfers context of all UEs during S1 handover on RN, then security protection is ensured, but the signaling overhead and processing complexity increase
Solution Approach 1:
Instead of uniformly transferring context for all UEs, the source MME applies local quality by selectively determining which specific UEs need context transfer based on whether they are served by the RN. This selective approach maintains security protection where needed while reducing unnecessary processing complexity.
Solution Approach 2:
The system performs partial action by transferring context only for UEs that are actually served by the RN, rather than all UEs. This partial approach avoids excessive processing while ensuring adequate security protection for the relevant UEs.
3Productivity
If the source MME does not transfer UE context during S1 handover on RN, then the processing load is reduced, but the target MME cannot acquire security information for NAS message protection
Solution Approach 1:
The target MME sends a notification message back to the source MME indicating which UEs are served by the RN. This feedback mechanism enables the source MME to identify which UEs need context transfer, balancing processing efficiency with preventing security information loss.
Solution Approach 2:
The source MME serves as an intermediary that receives feedback from the target MME, processes the information to determine which UEs need context transfer, and executes the selective context transfer. This intermediary function optimizes the balance between processing efficiency and information preservation.
Data Source
AI summary
The present invention discloses a method for transferring a context and a mobility management entity. When S1 handover occurs on an RN, the method includes: acquiring, by a source MME to which a UE is attached, an indicator for transferring a context of the UE, where the UE is a UE served by the RN when the S1 handover occurs; and transferring, by the source MME to which the UE is attached, the context of the UE to a target MME according to the indicator for transferring the context of the UE, so that the target MME acquires security information of the UE according to the context of the UE, where the target MME is an MME to which the UE needs to be attached in the handover process.