Emergency Service Routing in IMS Networks

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Solution Overview

Problem

In the IMS communication network, emergency service requests often require special handling to prioritize calls and route them correctly, but existing systems involve unnecessary steps and entities, such as the S-CSCF, which can complicate and delay emergency service provisioning.

Innovation Solution

Implementing an emergency-related local service function (ERLSF) co-located with the application server (AS) that determines if a session is an emergency session and routes the request directly to the E-CSCF, bypassing the S-CSCF, allowing for click-to-dial services and location-based checks to ensure proper emergency service delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the S-CSCF is involved in routing emergency service requests, then proper session control and user authentication can be ensured, but the routing complexity and processing time increase

Engineering Contradiction:

Improvesession control reliabilityVSAvoidemergency service provisioning time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention extracts the emergency service detection function from the S-CSCF and places it in the P-CSCF. This allows emergency requests to be identified and routed directly to the E-CSCF without involving the S-CSCF, thereby reducing processing time while maintaining reliable session control through the dedicated emergency service handling path.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The P-CSCF acts as an intermediary that detects emergency service requests and redirects them to the E-CSCF. This mediator function allows the system to bypass the S-CSCF for emergency traffic while maintaining proper session control through the specialized E-CSCF handler, resolving the contradiction between reliability and speed.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the P-CSCF detects and routes emergency requests directly to E-CSCF, then emergency service delivery speed improves, but the complexity of the routing mechanism increases

Engineering Contradiction:

Improveemergency service delivery speedVSAvoidrouting mechanism complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The P-CSCF is designed to perform both its standard proxy call state control functions and the additional function of detecting emergency service requests. This multi-functionality allows the system to improve emergency service delivery speed without adding separate dedicated detection entities, thereby limiting the increase in overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of time

If emergency requests bypass the S-CSCF, then processing time is reduced, but the ability to apply visited network services may be compromised

Engineering Contradiction:

Improverequest processing timeVSAvoidvisited network service applicability

Core Design Contradiction:

Loss of timeVSAdaptability or versatility

Solution Approach 1:

The invention segments the emergency service handling path from the normal service path. By creating a dedicated route through P-CSCF to E-CSCF for emergency requests, the system reduces processing time while maintaining the ability to apply visited network services through the E-CSCF, which is configured to handle both emergency and visited network service requirements.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9277382B2Emergency service in communication system

Publication Date: 2016.03.01 NOKIA TECHNOLOGIES OY

AI summary

The invention relates to an apparatus, method and a computer program product for establishing a request for a session by an application server, determining by an emergency related local service function that the session includes an emergency session, wherein the emergency related local service function is co-located at the application server, and, transmitting the request for the session to an emergency call state control function of the internet protocol multimedia subsystem based on the determination.