SGW Selection Logic for Inter-MME Mobility Signaling Optimization
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Solution Overview
Problem
In telecommunications, during inter-Mobility Management Entity (MME) mobility scenarios, the conventional Serving Gateway (SGW) selection process leads to sub-optimal signaling and data paths due to unwanted signaling/user-plane hopping between non-co-located control and user plane components in the Control and User Plane Separation (CUPS) EPC architecture, causing operational complexities and latency.
Innovation Solution
Implementing SGW selection logic in MMEs to determine if the SGW is co-located with the PGW during initial PDN connections, using a Co-located CUPS GW Indication (CCGWI) flag, and selecting the same SGW to host the PDN session after UE transitions, thereby avoiding conventional SGW relocation procedures and maintaining the PDN context intact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SGW selection process is used during inter-MME mobility, then mobility management is achieved, but sub-optimal signaling and data paths are created due to unwanted hopping between non-co-located control and user plane components
Solution Approach 1:
The system performs preliminary actions by determining during the initial PDN connection whether the SGW is co-located with the PGW and storing this information. This advance determination allows the second MME to quickly select the appropriate SGW during inter-MME mobility without complex real-time analysis, thereby optimizing signaling paths while managing complexity.
Solution Approach 2:
The system uses feedback from the first MME regarding SGW co-location status with the PGW. This feedback information is utilized by the second MME to make informed SGW selection decisions, ensuring optimal signaling and data paths are maintained during mobility transitions between MMEs.
2Speed
If conventional SGW relocation procedures are performed during inter-MME mobility, then mobility transition is achieved, but extra signaling hops and latency are introduced
Solution Approach 1:
The system performs preliminary determination of SGW co-location status during initial PDN connection establishment. This advance preparation enables the second MME to directly select the appropriate SGW during mobility transitions without initiating complex relocation procedures, thereby reducing signaling latency and accelerating mobility transition speed.
Solution Approach 2:
Instead of performing SGW relocation procedures during inter-MME mobility (the conventional approach), the system inverts the logic by selecting the same SGW to host the PDN session after UE transitions, thereby avoiding unnecessary relocation signaling and reducing latency.
3Ease of operation
If SGW is selected without considering co-location with PGW, then SGW selection is simplified, but operational complexities arise due to non-co-located control and user plane components
Solution Approach 1:
The system performs preliminary determination of SGW co-location status with the PGW during initial PDN connection. This advance information is stored and reused during subsequent mobility events, maintaining simple SGW selection operations while avoiding the operational complexities that would arise from non-co-located components.
Solution Approach 2:
The system utilizes feedback information from the first MME regarding SGW co-location status. This feedback mechanism enables informed SGW selection decisions that balance operational simplicity with the avoidance of complexity arising from non-co-located control and user plane components.
Data Source
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AI summary
In one example, an indication that a user equipment participating in a Packet Data Network (PDN) session hosted by a Serving Gateway (SGW) and a PDN Gateway (PGW) is transitioning from a first Mobility Management Entity (MME) to a second MME is obtained. An indication that the SGW is co-located with the PGW and an identification of the SGW are obtained. Based on the indication that the SGW is co-located with the PGW and the identification of the SGW, it is determined that the SGW is reachable from the second MME. In response to determining that the SGW is reachable from the second MME, the SGW is selected to host the PDN session after the user equipment transitions from the first MME to the second MME.