ICS UE Access Domain Switching for Bearer Setup
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Solution Overview
Problem
In IP multimedia subsystem (IMS) networks, especially in ICS networks, bearer establishment failures occur due to CS network busy conditions or UE roaming beyond CS network coverage, leading to call failures without re-establishment attempts.
Innovation Solution
A method and system where the ICS UE and SCC AS collaborate to select a new access network for bearer establishment when the current one fails, enabling the UE to change its access domain and retry the call, using T-ADS to select a new network and send corresponding messages for bearer setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses a single access network (CS or PS) for bearer establishment, then the call setup process is simple, but the call establishment fails when the selected access network is unavailable
Solution Approach 1:
The patent implements dynamic access network selection by enabling the UE to switch from a failed access network (CS or PS) to an alternative access network. The system dynamically adapts the bearer establishment path based on real-time network availability, transforming a static single-path approach into a dynamic multi-path approach that resolves the contradiction between simplicity and reliability.
Solution Approach 2:
The patent changes the access network parameter (CS/PS selection) based on establishment failure detection. When bearer establishment fails on the initially selected access network, the system modifies the access network parameter to select an alternative network type, thereby resolving the contradiction by allowing parameter adaptation without significantly increasing system complexity.
2Ease of operation
If the UE attempts to establish bearer in the original CS domain when roaming beyond coverage, then the SCC AS follows original access information, but the bearer establishment fails due to network asynchrony
Solution Approach 1:
The patent introduces a feedback mechanism where the UE monitors bearer establishment results and reports failure information back to the network. This feedback loop enables the SCC AS to detect when automatic bearer establishment fails due to roaming or network asynchrony, and triggers a re-evaluation of access network selection, thereby resolving the contradiction between automatic operation and establishment reliability.
Solution Approach 2:
The patent performs preliminary verification of access network availability before finalizing bearer establishment. By checking whether the selected access network (CS or PS) is actually available and synchronized with current UE location, the system prevents premature establishment attempts that would fail, thus improving reliability while maintaining automatic operation.
Data Source
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AI summary
A method, a device, and a system for the called party to access are provided. The method includes the following steps. A new bearer access network is selected when bearer establishment fails, and a bearer is established in the new bearer access network. The method enables a called terminal to change an access domain of the called terminal and try accessing again when the bearer establishment fails, thereby providing more guarantees for a successful call.