User Terminal Network Selection for Circuit-Switched Services
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Solution Overview
Problem
Mobile communication networks face inefficiencies when user terminals need to switch between different radio access technologies to access voice or speech services, particularly when the preferred circuit-switching RAT is not available, leading to a 'ping-pong' effect between PLMNs or inability to find suitable networks.
Innovation Solution
A method where user terminals detect the availability of predetermined services and monitor for alternative PLMNs or RATs, temporarily disabling EUTRAN capability only when necessary, and generating information elements to remember disabled RATs for subsequent selections, allowing efficient switching to alternative networks that support circuit-switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user terminal switches to an alternative PLMN or RAT to access circuit-switching services, then service availability is improved, but network selection complexity and re-registration frequency increase
Solution Approach 1:
The terminal performs preliminary detection of service availability on the current PLMN/RAT before attempting to access circuit-switching services. By checking whether the current network supports the required service in advance, the terminal can avoid unnecessary switching to alternative networks, thereby reducing network selection complexity while maintaining service availability.
Solution Approach 2:
The terminal implements a feedback mechanism that monitors service accessibility and network conditions. When circuit-switching services are unavailable on the current PLMN/RAT, the terminal receives feedback and automatically switches to alternative networks. This feedback-driven approach optimizes network selection by making decisions based on actual service availability rather than complex predetermined rules.
2Reliability
If the user terminal frequently switches between PLMNs or RATs to maintain service connectivity, then service access is ensured, but network re-registration overhead and time loss increase
Solution Approach 1:
The terminal performs preliminary service capability detection on the current PLMN/RAT before attempting to access circuit-switching services. By verifying service availability in advance, the terminal可以避免不必要的网络切换和重新注册, thereby reducing time loss while ensuring service connectivity when needed.
Solution Approach 2:
The terminal applies preliminary anti-action by detecting and avoiding PLMNs/RATs that do not support required services. By identifying unsuitable networks beforehand and preventing access attempts, the terminal avoids the time-consuming re-registration process while maintaining reliable service connectivity on appropriate networks.
3Productivity
If the user terminal attempts to access higher priority PLMNs that do not support required services, then network priority optimization is improved, but service access failure and re-registration cycles increase
Solution Approach 1:
The terminal performs preliminary detection of service support capability on higher priority PLMNs before attempting to access them. By verifying whether the priority network supports required services in advance, the terminal can make informed decisions about network selection, improving both selection efficiency and service access success by avoiding futile connection attempts to incompatible networks.
Data Source
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Figure 3A~4B
Figure 5~7A
AI summary
There is provided a method, comprising: detecting a preference of a user terminal for a predetermined service, detecting that the current RAT does not provide the predetermined service; monitoring whether or not another PLMN or another RAT of the first PLMN is available; upon detecting that no other PLMN and no other RAT of the first PLMN is available, maintaining connection to the first RAT of the first PLMN until another PLMN or another RAT in the first PLMN becomes available; upon detecting that another PLMN or another RAT is available, considering the first RAT of the first PLMN as disabled due to lack of the predetermined service from the first RAT, and generating an information element to a memory according to which the first RAT of the first PLMN has been marked as disabled, wherein the information element is valid until a predetermined criterion is met and at least beyond a point of time when the user terminal switches to another PLMN and/or to another RAT.