PDN Gateway Change for SIPTO Without Real-Time Flow Disruption
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Solution Overview
Problem
Existing Selected IP Traffic Offload (SIPTO) techniques disrupt ongoing services, particularly for long-lived and real-time flows, such as conference calls, due to IP address changes in heterogeneous networks with small cells.
Innovation Solution
Implement a make-before-break scheme where a WTRU proactively establishes a new PDN connection for long-lived and real-time flows before breaking down the existing one, minimizing service disruptions during PDN gateway relocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SIPTO is performed for WTRUs in connected mode to enable local breakout of traffic from small cells, then network resource utilization is improved and routing efficiency is enhanced, but ongoing services are disrupted due to IP address changes
Solution Approach 1:
The patent applies preliminary action by establishing a new PDN connection with a new P-GW before tearing down the existing connection. The WTRU proactively sets up the new connection in advance, ensuring that long-lived flows can be seamlessly switched to the new gateway without service disruption. This is achieved through the network initiating a PDN connectivity request that includes a new P-GW address, allowing the WTRU to prepare the new connection path before the old one is terminated.
Solution Approach 2:
The patent implements dynamics by differentiating the SIPTO execution strategy based on flow characteristics. For long-lived flows, the system dynamically switches to a make-before-break approach where the new connection is established first. For short-lived flows, the system uses a break-before-make approach where the old connection is torn down first. This dynamic adaptation allows the network to optimize between resource utilization and service continuity based on the specific traffic pattern.
2Reliability
If a new PDN connection is established before tearing down the existing one for long-lived flows, then service disruption is minimized, but network complexity and signaling overhead increase
Solution Approach 1:
The patent applies segmentation by separating the SIPTO execution into distinct phases based on flow type. The system segments long-lived flows requiring make-before-break execution from short-lived flows suitable for break-before-make execution. This segmentation allows the complex make-before-break procedure to be applied only where necessary, reducing overall signaling overhead while maintaining service continuity for critical flows.
Solution Approach 2:
The patent utilizes parameter changes by modifying the SIPTO execution parameters based on flow characteristics. The system changes the execution mode (make-before-break vs. break-before-make) as a controllable parameter depending on whether the flow is long-lived or short-lived. This parameter-based control allows flexible management of connection complexity versus service continuity trade-offs.
3Reliability
If SIPTO is avoided for WTRUs in connected mode to prevent service disruption, then service continuity is maintained, but network resource utilization and routing efficiency deteriorate
Solution Approach 1:
The patent implements self-service by enabling the WTRU to autonomously detect and report its capability to support make-before-break SIPTO execution. The WTRU includes this capability indication in its attach or tracking area update messages to the network. This self-service mechanism allows the network to identify capable WTRUs and apply optimized SIPTO procedures automatically, improving routing efficiency while maintaining service continuity without requiring manual configuration.
Data Source
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AI summary
Coordinated P-GW change for SIPTO may be provided. A WTRU may send and/or receive one or more flows via a first PDN connection and via a first P-GW. The WTRU may send an indication to the network that at least one flow of the first PDN connection is available for SIPTO. The indication may include one or more SIPTO preferences. The WTRU may receive a message from a MME. The message may trigger establishment of a second PDN connection via a second P-GW. The WTRU may move, while maintaining the first PDN connection, the at least one flow from the first PDN connection to the second PDN connection. The WTRU may deactivate the first PDN connection when the one or more flows have been moved to the second PDN connection and/or when no information has been received via the first PDN connection after a predetermined duration.