Local Gateway PDN Connection Management for LTE Mobility
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Solution Overview
Problem
In mobile communications networks, particularly those following LTE standards, there is a challenge in efficiently deactivating a Packet Data Network (PDN) connection when a user equipment (UE) moves out of the coverage area of a femtocell or macrocell, leading to potential disruptions in mobile terminating traffic and increased signaling due to repeated connection activations and deactivations.
Innovation Solution
Implementing a Local Gateway (L-GW) that determines direct connectivity with network nodes and initiates PDN connection deactivation procedures based on user location information and mobility events, using mechanisms like the 'reactivation requested' cause value in messages to manage SIPTO PDN connections effectively, and employing timers to mitigate the 'ping-pong' effect of frequent reconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the PDN connection is deactivated when UE moves out of femtocell coverage, then signaling overhead is reduced, but mobile terminating traffic continuity is disrupted
Solution Approach 1:
The patent introduces a Local Gateway (L-GW) as an intermediary component that maintains the PDN connection even when the UE moves out of femtocell coverage. The L-GW acts as a mediator between the core network and the UE, allowing mobile terminating traffic to continue flowing through the L-GW to the UE's current location, thus preventing traffic disruption while avoiding unnecessary connection reactivations that would generate signaling overhead.
Solution Approach 2:
The patent implements a timer mechanism that initiates a waiting period before deactivating the PDN connection after the UE moves out of coverage. This preliminary action allows the system to wait and see if the UE returns to coverage area, preventing premature connection deactivation and ensuring traffic continuity without requiring immediate reactivation signaling.
2Reliability
If the PDN connection is maintained during UE mobility, then mobile terminating traffic continuity is ensured, but signaling overhead increases due to repeated activations and deactivations
Solution Approach 1:
The Local Gateway (L-GW) serves as a stable intermediary that anchors the PDN connection during UE mobility. By maintaining the connection through the L-GW rather than requiring direct UE-to-core-network connectivity, the system ensures traffic continuity while the L-GW manages connection state, preventing unnecessary activation/deactivation cycles and reducing associated signaling overhead.
Solution Approach 2:
The patent implements a timer-based feedback mechanism that monitors UE presence in coverage area. The timer provides feedback about whether to maintain or deactivate the connection, creating a controlled decision-making process that prevents oscillating connection states and reduces signaling overhead from repeated activations and deactivations.
3Productivity
If the PDN connection is quickly deactivated upon UE movement, then network resources are freed, but traffic disruption occurs
Solution Approach 1:
The patent implements a timer mechanism that delays PDN connection deactivation for a predetermined period after UE moves out of coverage. This preliminary waiting period allows the system to check if the UE returns to coverage, ensuring traffic continuity while still ultimately freeing network resources if the UE remains absent, thus balancing resource efficiency with service reliability.
Solution Approach 2:
The timer mechanism provides a cushioning period before connection deactivation, creating a buffer that prevents immediate resource release and potential traffic disruption. This beforehand cushioning allows the system to handle edge cases where UE may temporarily move out of coverage but return soon, maintaining service continuity while still managing network resources efficiently.
Data Source
AI summary
A packet data network (PDN) gateway receives a message associated with a user equipment (UE) having a PDN connection. The PDN gateway determines whether the UE is accessing a network node that has a predetermined association with the PDN gateway based on the message. In response to the determination, the PDN connection is maintained or deactivated.