Autonomous Radio Access Technology Selection for Circuit Switched Fallback
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Solution Overview
Problem
In mobile communication networks, circuit switched fallback (CSFB) service requests often fail due to network-controlled radio access technology changes not being performed effectively, leading to inefficient selection of alternative radio access technologies by user terminals, resulting in service failures.
Innovation Solution
User terminals detect CSFB failures and autonomously select a second radio access technology from stored information associating PLMNs with capable RATs, using PLMN selector lists and coverage data to ensure fast and efficient selection of RATs capable of providing circuit switching services, thereby maintaining connection and ensuring service continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user terminals wait for network-controlled RAT changes to be performed, then service continuity is maintained, but service failure occurs when network-controlled changes fail
Solution Approach 1:
The user terminal performs preliminary actions by detecting CSFB failure conditions and preparing alternative RAT selection strategies in advance. The terminal stores PLMN selector lists and coverage data beforehand, enabling autonomous RAT selection when network-controlled changes fail, thus maintaining service continuity without waiting for network intervention.
Solution Approach 2:
The user terminal implements self-service by autonomously detecting CSFB failures and independently selecting alternative RATs without requiring network-controlled RAT changes. The terminal uses stored PLMN selector lists and coverage data to make independent decisions, reducing dependency on network actions and eliminating service failures caused by network-controlled changes.
2Reliability
If user terminals autonomously select alternative RATs, then service failure is reduced, but selection efficiency decreases without stored PLMN-RAT association information
Solution Approach 1:
The network performs preliminary action by providing the user terminal with PLMN selector lists and coverage data in advance. This stored information associates PLMNs with capable RATs, enabling the terminal to efficiently select alternative RATs autonomously when CSFB fails, thus improving both reliability and selection efficiency.
Solution Approach 2:
The patent introduces intermediary elements (PLMN selector lists and coverage data) that mediate between the network and user terminal. These intermediaries store PLMN-RAT association information, enabling the terminal to make informed autonomous RAT selections without requiring real-time network intervention, thus improving selection efficiency while maintaining reliability.
3Reliability
If network-controlled RAT changes are performed, then service continuity is maintained, but flexibility for alternative RAT selection is reduced
Solution Approach 1:
The system implements dynamics by allowing the user terminal to adapt its behavior based on CSFB failure conditions. The terminal dynamically switches from waiting for network-controlled RAT changes to autonomous RAT selection when failures are detected, providing flexibility while maintaining service continuity through adaptive response to network conditions.
Solution Approach 2:
The network performs preliminary action by pre-configuring PLMN selector lists and coverage data with alternative RAT options. This enables the user terminal to have pre-prepared flexibility for RAT selection, allowing it to adapt to CSFB failures by selecting from pre-stored alternative RATs associated with PLMNs, thus maintaining both service continuity and selection flexibility.
Data Source
AI summary
There is provided a method, including detecting, by a user terminal connected to a public land mobile net-work, PLMN, via a first radio access technology and having requested a circuit switched fallback service procedure, that a network controlled radio access technology change related to the circuit switched fallback service procedure is not performed; and selecting a second radio access technology to be applied on the basis of stored information, wherein the second radio access technology to be applied is capable to provide circuit switched services and the stored information associates at least one PLMN with at least one radio access technology.