SGSN Identification via TLLI Derivation for SRVCC Handover
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Solution Overview
Problem
In wireless communication systems, there is no reliable method for the Mobile Switching Centre (MSC) to identify the Serving GPRS Support Node (SGSN) of a mobile station during handovers from UTRAN/GERAN to E-UTRAN/HSPA networks, hindering seamless voice call continuity and reverse SRVCC handback.
Innovation Solution
A method and network node that acquire a Temporary Link Layer Identifier (TLLI) from the mobile station, derive the SGSN identity from it, and provide this identity to the MSC, enabling reliable SGSN selection and handover processes without modifying existing network architecture or protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MSC uses traditional identification methods, then the existing network architecture and protocols are maintained, but the SGSN identification during handovers from UTRAN/GERAN to E-UTRAN/HSPA networks is unreliable
Solution Approach 1:
The patent uses the TLLI as a copy or alternative identifier that can be derived to obtain the SGSN identity. Instead of requiring direct SGSN identification mechanisms, the system copies the identification function through TLLI derivation, allowing the MSC to reliably identify the SGSN using existing identifier structures without adding new identification protocols.
Solution Approach 2:
The TLLI acts as an intermediary element between the mobile station and the SGSN identification process. By acquiring the TLLI from the mobile station and deriving the SGSN identity from it, the system introduces an intermediate identifier that bridges the gap between existing network elements and the required SGSN identification function.
2Reliability
If the MSC acquires TLLI and derives SGSN identity, then reliable SGSN identification is achieved, but additional information processing steps are required
Solution Approach 1:
The mobile station itself provides the TLLI information needed for SGSN identification. By enabling the mobile station to supply its own TLLI during the handover process, the system eliminates the need for complex inter-node signaling arrangements, as the required identification data is self-provided by the mobile station.
Solution Approach 2:
The TLLI is acquired and the SGSN identity is derived in advance during the handover preparation phase, before the actual handover execution. This preliminary identification action ensures that the MSC has the correct SGSN information ready when needed, avoiding last-minute complexity during the critical handover moment.
3Productivity
If seamless SRVCC handback is enabled through TLLI-based SGSN identification, then voice call continuity is improved, but the handover process requires additional derivation steps
Solution Approach 1:
The system changes the parameter used for SGSN identification from traditional direct identification methods to TLLI-based derivation. By changing the identification parameter approach, the system enables seamless handback while using a different (but compatible) identification mechanism that works within existing protocol frameworks.
Data Source
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Figure 2A~2B
Figure 3
AI summary
Method in a network node (110, 120) for identifying an SGSN (130) of a mobile station (140). The method comprises acquiring (301 ) a TLLI, and identifying (302) the SGSN (130) of the mobile station (140) by deriving the identity of the SGSN (130) from the acquired (301 ) TLLI. Also, a corresponding network node (110, 120) is described.