IMS Access Control via Subscription-Based RAT Restriction

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Solution Overview

Problem

Uncontrolled and undesired spurious signalling occurs between IP Multimedia Subsystem (IMS) networks and user devices that are capable of accessing IP multimedia services but are precluded due to lack of subscription, leading to network overload and increased costs.

Innovation Solution

A method that includes sending restriction information to user devices indicating allowed and not-allowed Radio Access Technologies (RAT) and IP multimedia services based on subscription information, causing the devices to stop requests to access prohibited services, thereby managing access and reducing spurious signalling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If user devices continuously attempt to access IP multimedia services despite being precluded, then the user device maintains service access capability, but spurious signalling increases and network load increases

Engineering Contradiction:

Improveuser device service access capabilityVSAvoidspurious signalling traffic

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The network performs preliminary actions by sending rejection messages to user devices before they can initiate continuous access attempts. The rejection message includes a timer value that pre-configures the user device to stop access attempts for a predetermined period, preventing spurious signalling before it accumulates

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by sending rejection messages with timer values to user devices, which then adjust their access behavior accordingly. This feedback loop allows the network to control and reduce spurious signalling by informing user devices when to stop access attempts

Inventive Principle:

Principle #23Feedback

2Reliability

If user devices retry access periodically or upon RAT change, then service availability is maintained, but network capacity is reduced due to continuous rejection handling

Engineering Contradiction:

Improveservice access reliabilityVSAvoidnetwork capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network sends rejection messages with timer values in advance, before user devices can initiate periodic retry attempts. This preliminary action establishes a predetermined period during which access attempts are suppressed, allowing the network to recover capacity while maintaining service reliability for authorized users

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts access control by implementing a timer-based mechanism that temporarily suspends access attempts from precluded user devices. This dynamic approach allows the network to adapt to changing conditions and manage capacity while maintaining service availability for authorized users

Inventive Principle:

Principle #15Dynamics

3Reliability

If the IMS network processes continuous access requests from unauthorized devices, then service access control is maintained, but network equipment requires oversizing and costs increase

Engineering Contradiction:

Improveservice access controlVSAvoidnetwork equipment capacity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and removes spurious signalling traffic from the system by implementing a timer-based suppression mechanism. Rejection messages with predetermined timer values are sent to precluded user devices, which then stop access attempts during the timer period, effectively removing the harmful signalling load from the network

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system converts the potentially harmful continuous access attempts into a beneficial reduction of network load. By sending rejection messages with timer values, the network transforms the persistent access behavior of precluded devices into a controlled temporary suspension, reducing signalling traffic and allowing for more efficient network equipment sizing

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11716624B2Method and system for avoiding spurious signalling in a communication system

Publication Date: 2023.08.01 TELECOM ITALIA SPA

AI summary

In a method for managing access by a user device to multimedia services delivered by a communication system, the user device accesses the multimedia services through a Radio Access Technology (RAT). An information element sent to the user device from the communication system includes restriction information that indicates the types of RAT that the user device may use to access the multimedia services. The restriction information also includes the types of RAT that the user device cannot use to access the multimedia services. The information element also includes additional restriction information indicating the multimedia services that can be accessed by the user device, and the multimedia services that cannot be accessed by the user device. The additional restriction information is based on subscription information for the user device.