Mobile Device Assisted Domain Selection for Call Termination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, the inability of IMS networks to determine if a terminating CS network is available when ISR is active can lead to dropped calls and poor user experiences, as IMS systems may mistakenly send calls to the PS domain instead of the CS domain.
Innovation Solution
A method for fall back procedures using mobile device-assisted terminating access domain selection, where a mobile device receives an invitation for a session, rejects it if necessary, and establishes a circuit-switched call, correlating it with IMS bearers to ensure proper domain selection and maintain communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If IMS network uses Idle mode Signaling Reduction (ISR) to reduce signaling overhead, then signaling efficiency is improved, but the network loses the ability to determine terminating CS network availability, leading to incorrect domain selection and dropped calls
Solution Approach 1:
The patent introduces an intermediary mechanism where the mobile device acts as a mediator between the IMS network and the CS network. The device receives session invitations from the IMS network, autonomously determines CS network availability, and manages the correlation between IMS sessions and CS calls. This intermediary role allows the network to maintain ISR while the device ensures reliable call termination by selecting the appropriate domain (PS or CS) based on its own network status assessment.
2Device complexity
If the network sends all terminating calls to the PS domain to simplify network architecture, then device complexity is reduced, but call reliability deteriorates when CS domain should be used
Solution Approach 1:
The patent implements self-service by enabling the mobile device to autonomously perform access domain selection without requiring complex network-side intelligence. The device independently evaluates whether to use PS or CS domain for call termination by checking its own network registration status and availability. This shifts the decision-making responsibility from the network to the device, maintaining simple network architecture while ensuring reliable call termination through device-level domain selection intelligence.
3Reliability
If the network implements sophisticated mechanisms to determine CS network availability, then call termination reliability is improved, but network complexity increases
Solution Approach 1:
The patent applies inversion by reversing the traditional approach: instead of the network determining CS network availability and directing calls accordingly, the mobile device itself performs the determination. The device checks its own registration status with the CS network and autonomously selects the appropriate domain (PS or CS) for call termination. This inverted approach maintains high call termination reliability while avoiding the need for complex network-side mechanisms, as the decision logic resides in the device that has direct knowledge of its network status.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Fall back using mobile device assisted terminating access domain selection is provided. A network entity forwards an invitation to a session to a mobile device. Session has packet switched bearers for media. Mobile device replies with a rejection of the invitation and a request for network entity to hold the session. Rejection is based on mobile device determining circuit switched bearers should be utilized. Mobile device sends a circuit switched call and network entity correlates the circuit switched call with the session. A dialog is set up over circuit switched domain bearers and Internet Protocol Multimedia Subsystem bearers.