IMS Interworking Entity for GRUU Addressing

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Solution Overview

Problem

User Equipment (UE) lacking Globally Routable User Agent URI (GRUU) support cannot be integrated into Session Initiation Protocol (SIP) systems due to addressing limitations, as existing solutions rely on GRUU support for routing, which is not guaranteed across all UE devices.

Innovation Solution

A core network is designed to provide a binding between Globally Routable User Agent URI (GRUU), public user ID (SIP URI), and International Mobile Subscriber Identity (IMSI), allowing arbitrary network entities to address specific UE devices, even if they do not support GRUU functionality, by simulating GRUU support through entities like Proxy-Call State Control Function (P-CSCF) or Serving-Call State Control Function (S-CSCF).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If addressing is based on public user IDs (AOR) in SIP systems, then multiple user agents can be referenced by the same identifier, but it becomes impossible to address a single specific user agent instance

Engineering Contradiction:
ImproveAbility to address specific user agent instancesVSAvoidAddressing mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The public user ID (AOR) is segmented into two components: the stable public identifier and the instance-specific GRUU identifier. This segmentation allows the system to maintain both the ability to address multiple user agents collectively and the ability to address specific instances individually, resolving the contradiction between versatility and precision in addressing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension to the addressing system by adding the GRUU identifier that includes instance-specific information (such as device identifiers, IP addresses, or other unique characteristics). This additional dimension enables precise targeting of specific user agent instances while preserving the original public user ID for general addressing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If User Equipment does not support GRUU functionality, then the device cannot be integrated into SIP systems requiring instance-specific addressing, but forcing GRUU support increases device complexity

Engineering Contradiction:
ImproveCompatibility with SIP systemsVSAvoidUE device complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The network infrastructure (specifically the IMS core network elements) acts as an intermediary that generates and manages GRUU identifiers on behalf of User Equipment that lacks native GRUU support. The network translates between public user IDs and instance-specific GRUUs, enabling legacy devices to participate in GRUU-based addressing without modifying the devices themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtual representation of GRUU functionality in the network that mirrors what would exist in the UE. By generating GRUU identifiers network-side and maintaining the binding between public user IDs and instance identifiers, the system effectively copies the GRUU addressing capability at the network layer, allowing devices without native support to function as if they did.

Inventive Principle:
Principle #26Copying

3Ease of operation

If explicit IP addresses are used in Contact header field to achieve instance-specific addressing, then direct routing to specific user agents is possible, but compatibility with NATs and firewalls deteriorates

Engineering Contradiction:
ImproveDirect routing capabilityVSAvoidNAT and firewall compatibility
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

Instead of using raw IP addresses in the Contact header, the patent transforms the addressing parameters into URIs that follow SIP standards. The GRUU identifier is constructed as a properly formatted SIP URI that includes instance-specific information in a standardized manner, maintaining both direct routing capability and compatibility with NATs and firewalls that expect standard SIP addressing formats.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2478684B1Method for supporting a user equipment lacking globally routable user agent URI - GRUU support in an internet protocol multimedia subsystem - IMS.
Publication Date: 2018.11.07 DEUTSCHE TELEKOM AG
  • EP2478684B1 patent drawingFigure 1
  • EP2478684B1 patent drawingFigure 2~3
  • EP2478684B1 patent drawingFigure 4

AI summary

The invention relates to a Core Network for supporting a User Equipment (UE) lacking Globally Routable User Agent URI (GRUU) support in an Internet Protocol Multimedia Subsystem (IMS) of a communication network, the Core Network comprising an interworking entity, - wherein the User Equipment (UE) sends first Session Initiation Protocol (SIP) messages to the interworking entity, the first messages lacking a Globally Routable User Agent URI (G RU Unrelated data, and the interworking entity modifying the first messages by adding Globally Routable User Agent URI (GRUU)-related data, - and wherein the interworking entity receives second Session Initiation Protocol (SIP) messages to be sent to the User Equipment (UE), the second messages having a Globally Routable User Agent URI (GRUU)-related data, and the interworking entity modifying the second messages by removing the Globally Routable User Agent URI (GRUU)-related data.