PGW Session Synchronization Using IP Anycast for Low-Latency Roaming

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Solution Overview

Problem

Existing communication systems experience delays in international roaming due to sessions being created between geographically distant networks, leading to inefficient packet transmission.

Innovation Solution

Implementing a system where PGWs and UPFs in different networks share identical IP addresses and session information using IP Anycast, allowing routers to select the shortest route for packet transmission based on BGP best path selection algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sessions are created between geographically distant networks for international roaming, then global connectivity is achieved, but transmission delay increases

Engineering Contradiction:
Improveglobal connectivityVSAvoidtransmission delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by allowing different PGWs in different geographic locations to have identical IP addresses, enabling local session creation. When a terminal roams internationally, the SGW creates a session with the local PGW in the same geographic region, achieving both global connectivity through IP Anycast and low transmission delay through local packet forwarding.

Inventive Principle:
Principle #3Local quality

2Speed

If identical IP addresses are allocated to PGWs in different networks, then routing optimization is enabled, but network complexity increases

Engineering Contradiction:
Improvepacket transmission speedVSAvoidnetwork configuration complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent uses IP Anycast as an intermediary mechanism that allows multiple PGWs to share the same IP address without requiring complex manual configuration. The BGP routing protocol automatically handles the selection of the nearest PGW based on the shortest path, simplifying the network configuration while enabling optimized packet transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the network parameter of IP address allocation by allowing identical IP addresses to be assigned to multiple PGWs in different networks. This parameter change, combined with IP Anycast and BGP routing, enables automatic route selection based on geographic proximity, optimizing packet transmission speed while managing network complexity through standardized protocols.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If session information is synchronized between multiple PGWs, then session continuity is improved, but information synchronization overhead increases

Engineering Contradiction:
Improvesession continuityVSAvoidsynchronization overhead
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent uses copying by creating identical session information copies in multiple PGWs through IP Anycast. When a terminal attaches to the network, the session information is copied to the local PGW, ensuring session continuity without requiring complex real-time synchronization. This copying approach maintains session stability while minimizing synchronization overhead.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP4716357A1System, PGW, information processing device, SMF, and method
Publication Date: 2026.03.25 SOFTBANK CORPORATION
  • EP4716357A1 patent drawingFigure 1
  • EP4716357A1 patent drawingFigure 2
  • EP4716357A1 patent drawingFigure 3

AI summary

Provided is a system including: a first PGW; a second PGW which is located in a network having an ASN different from an ASN of a network in which the first PGW is located and to which an IP address identical to an IP address allocated to the first PGW is allocated; a first storage unit corresponding to the first PGW; and a second storage unit corresponding to the second PGW, wherein the first PGW includes: a request reception unit which receives, from an SGW, a session creation request by a communication terminal; a session information creation unit which, in response to the request reception unit receiving the session creation request, creates session information on the communication terminal; and a registration unit which registers, in the first storage unit, the session information, and wherein the system further includes a session information synchronization unit which synchronizes the session information between the first storage unit and the second storage unit.