GGSN PDP Context Reactivation for IMS Overload
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Solution Overview
Problem
The adoption of IMS for real-time services in mobile telecommunications leads to a paradoxical situation where always-on PDP Contexts consume IP resources without actual traffic, causing network overload and increasing call setup delays due to the need for constant availability of SIP signaling contexts, even during user inactivity.
Innovation Solution
A method that separates the PDP Context status from the IMS network by using a layer separation approach, where the GGSN sends Accounting Request messages to an AAA server with IP addresses, and upon inactivity, the association is not eliminated, allowing for reactivation of PDP Contexts using Network-Requested PDP context activation procedures, minimizing signaling and resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the GGSN closes inactive PDP Contexts to save IP resources, then resource efficiency is improved, but user reachability and service availability deteriorate
Solution Approach 1:
The network performs preliminary actions by maintaining the association record in the AAA server before the PDP Context is fully deactivated. This allows the system to quickly reactivate the context when needed without going through full authentication and registration procedures, thus maintaining user reachability while enabling resource cleanup.
Solution Approach 2:
The AAA server acts as an intermediary that stores the association between IP address, GGSN, and SGSN even after PDP Context deactivation. This intermediary record enables rapid context reactivation by providing the necessary routing information without requiring complete re-authentication, resolving the contradiction between resource saving and service availability.
2Reliability
If the PDP Context is kept always-on for IMS users, then service availability is improved, but network overload increases
Solution Approach 1:
The system dynamically adjusts the PDP Context state based on activity patterns. Instead of a static always-on approach, the context can be deactivated after inactivity while maintaining reactivation capability through the AAA server association record. This dynamic state management reduces network load while preserving service availability when needed.
Solution Approach 2:
The system changes the parameter of PDP Context liveness by introducing a hybrid state where the context is formally deactivated but its association record remains active in the AAA server. This parameter change allows the system to reduce resource consumption while maintaining the ability to quickly restore service, balancing network load and service availability.
3Loss of energy
If the GGSN closes PDP Contexts after inactivity, then resource efficiency is improved, but call setup delay increases
Solution Approach 1:
The association record is maintained in the AAA server as a preliminary action before full context deactivation. This pre-prepared information allows the network to skip time-consuming re-authentication and re-registration steps during context reactivation, significantly reducing call setup delay while still allowing resource cleanup during inactivity.
Data Source
AI summary
A method for preventing overload in telecommunications networks with IMS by always-on for a call received by a user. The user sends a request message in order to activate a new PDP Context to his SGSN, which sends it to a GGSN. The GGSN sends an Accounting Request message to an AAA server. If the GGSN is going to deactivate the user PDP Context for having been inactive, the association is not eliminated from an AAA server in which this association has been saved and, when an incoming call is received: the status of the user PDP Context is verified by an indicator, and if it is not active, the PDP Context is reactivated, and if the IP address has not been assigned to another user, an attempt is made to reactivate the PDP Context; and if said IP address has already been assigned, a restart is carried out after the failure of the call.