Dynamic PGW Selection for 4G Network Redundancy

Solution Overview

Problem

Current 4G cellular networks lack sufficient redundancy to prevent total network outages due to catastrophic failures, as the Mobility Management Entity (MME) only supports a single Virtual IP (VIP) address for PGW selection, which becomes unreachable in such scenarios, leading to service unavailability.

Innovation Solution

Implementing a system that allows the MME to dynamically select multiple PGW IP addresses during UE attachment, determining primary and backup PGWs based on proximity to the Serving Gateway (SGW), ensuring that if the primary PGW is unavailable, a backup PGW can be automatically selected to maintain service continuity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the MME uses a single VIP address for PGW selection, then the system is simple to operate, but the reliability is insufficient and total network outages cannot be prevented

Engineering Contradiction:

Improvenetwork availabilityVSAvoidPGW selection mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The MME performs preliminary actions by obtaining multiple PGW IP addresses (primary and backup) in advance during the PDN connection establishment process, before any failure occurs. This allows the system to have pre-prepared alternative PGWs ready for immediate use if the primary PGW becomes unavailable, thereby improving network reliability without adding complex real-time decision mechanisms.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements beforehand cushioning by configuring backup PGWs in advance. When the primary PGW fails, the backup PGW is already positioned and ready to take over, providing a cushion against network outages. This pre-positioning of backup resources ensures service continuity while maintaining operational simplicity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the MME selects only one PGW for PDN connection, then the device complexity is low, but the reliability is insufficient when the selected PGW becomes unavailable

Engineering Contradiction:

Improveservice continuityVSAvoidPGW selection and management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The MME performs preliminary actions by obtaining multiple PGW IP addresses (primary and backup) in advance during the PDN connection establishment process, before any failure occurs. This allows the system to have pre-prepared alternative PGWs ready for immediate use if the primary PGW becomes unavailable, thereby improving network reliability without adding complex real-time decision mechanisms.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a copy of the PGW selection by obtaining multiple PGW IP addresses (primary and backup) for the same PDN connection. This copying approach ensures that if the primary PGW fails, a backup copy (alternative PGW) is already available to maintain service continuity, improving reliability while keeping the selection mechanism relatively simple.

Inventive Principle:

Principle #26Copying

3Reliability

If the MME cannot determine PGW availability, then the system is easier to operate, but PDN connection requests may fail due to selecting unavailable PGWs

Engineering Contradiction:

ImprovePDN connection success rateVSAvoidPGW availability detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The MME performs preliminary actions by obtaining multiple PGW IP addresses (primary and backup) in advance during the PDN connection establishment process, before any failure occurs. This allows the system to have pre-prepared alternative PGWs ready for immediate use if the primary PGW becomes unavailable, thereby improving network reliability without adding complex real-time decision mechanisms.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by monitoring PDN connection request outcomes. When a PDN connection request fails (indicating the selected PGW is unavailable), the system learns from this feedback and can switch to using backup PGWs for subsequent connection requests, improving the success rate without requiring complex real-time availability detection.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8554933B2Dynamic selection of packet data network gateways

Publication Date: 2013.10.08 VERIZON PATENT & LICENSING INC

AI summary

A device receives a PDN connection request from a UE, and exchanges, with a HSS, authentication and authorization information associated with the UE. The device also constructs an APN FQDN based on the authentication and authorization information, and sends a query, that includes the APN FQDN, to a DNS server. The device further receives, from the DNS server, PGW FQDNs that contain the APN FQDN, and compares the PGW FQDNs with a FQDN associated with a SGW. The device determines, based on the comparison, a PGW, associated with a PGW FQDN that is a closest match to the FQDN associated with the SGW, to be a primary PGW for the PDN connection request. The device also determines, based on the comparison, one or more PGWs, residing within a predetermined distance of the SGW, to be one or more backup PGWs for the PDN connection request.