EPS Fallback Indicator Handling for SIP Signaling

Solution Overview

Problem

In 5G communication systems, EPS fallback for IMS voice services often results in SIP signaling loss due to the unavailability of default QoS flows or bearers during handovers, leading to increased call setup latency and potential call setup failures, especially when VoNR and EPS fallback are supported simultaneously.

Innovation Solution

A method and apparatus that enable early notification of EPS fallback events to policy charging nodes and call control nodes, allowing for optimized handling of SIP signaling, such as buffering or prolonging transmission times, to ensure successful call setup without impacting VoNR services.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If EPS fallback is triggered for IMS voice service, then voice service continuity is maintained, but SIP signaling loss occurs and call setup latency increases

Engineering Contradiction:

Improvevoice service continuityVSAvoidcall setup latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by notifying the policy charging node about the upcoming EPS fallback event before the actual fallback occurs. This allows the network to prepare appropriate handling mechanisms in advance, such as buffering SIP signaling or adjusting transmission parameters, thereby preventing signaling loss and reducing call setup latency when the fallback actually happens.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by establishing a notification mechanism where the session management node informs the policy charging node about EPS fallback events. This feedback loop enables the policy charging node to adapt its behavior dynamically, adjusting SIP signaling transmission and handling strategies based on the predicted fallback condition, thus resolving the contradiction between maintaining service continuity and avoiding signaling loss.

Inventive Principle:

Principle #23Feedback

2Reliability

If EPS fallback is triggered for IMS voice service, then voice service continuity is maintained, but SIP signaling loss occurs

Engineering Contradiction:

Improvevoice service continuityVSAvoidSIP signaling loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The system performs preliminary actions by notifying the policy charging node about the upcoming EPS fallback event before the actual fallback occurs. This allows the network to prepare appropriate handling mechanisms in advance, such as buffering SIP signaling or adjusting transmission parameters, thereby preventing signaling loss and reducing call setup latency when the fallback actually happens.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by establishing a notification mechanism where the session management node informs the policy charging node about EPS fallback events. This feedback loop enables the policy charging node to adapt its behavior dynamically, adjusting SIP signaling transmission and handling strategies based on the predicted fallback condition, thus resolving the contradiction between maintaining service continuity and avoiding signaling loss.

Inventive Principle:

Principle #23Feedback

3Reliability

If SIP signaling transmission is prolonged or buffered during EPS fallback, then signaling loss is avoided, but call setup time increases

Engineering Contradiction:

Improvesignaling delivery successVSAvoidcall setup time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by notifying the policy charging node about the upcoming EPS fallback event before the actual fallback occurs. This allows the network to prepare appropriate handling mechanisms in advance, such as buffering SIP signaling or adjusting transmission parameters, thereby preventing signaling loss and reducing call setup latency when the fallback actually happens.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies dynamics by making the SIP signaling handling strategy adaptive rather than static. The policy charging node dynamically adjusts its behavior based on the predicted EPS fallback event, selectively buffering or prolonging transmission only when necessary, and using normal transmission when the fallback is not predicted. This dynamic adaptation resolves the contradiction between avoiding signaling loss and minimizing call setup time.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20240276312A1Method and apparatus for call setup

Publication Date: 2024.08.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Various embodiments of the present disclosure provide a method for call setup. The method which may be performed by a session management node comprises receiving an evolved packet system (EPS) fallback indicator from a mobility management node. In an embodiment, the EPS fallback indicator may indicate that a fallback to an EPS for an Internet protocol multimedia subsystem (IMS) voice service is ongoing. The method further comprises reporting an EPS fallback event to a policy charging node, according to the EPS fallback indicator.