Mobile Device Radio Access Capability Management for Emergency Calls
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Solution Overview
Problem
In wireless communication systems, particularly in LTE networks, multi-mode UEs with invalid USIMs face difficulties in selecting non-LTE cells during cell selection, leading to failed emergency call establishments due to the prioritization of LTE cells over other RATs, resulting in inaccessible emergency services.
Innovation Solution
A method and apparatus for setting radio access capability in mobile communication devices that allows them to disable an invalid RAT capability upon receiving a reject message, enabling the device to switch to and establish connections using alternative RATs, thereby ensuring successful emergency call establishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE always selects LTE cell based on measurement algorithm prioritization, then the LTE service quality is improved, but the emergency call establishment fails when USIM is invalid
Solution Approach 1:
The UE dynamically adjusts RAT selection behavior based on network response. When a reject message is received from the LTE network, the UE transitions from LTE-prioritized selection to alternative RAT selection, enabling adaptive emergency call establishment while maintaining normal LTE operation under valid USIM conditions
Solution Approach 2:
The UE changes the measurement algorithm parameters and cell selection criteria based on service type and network response. For emergency calls after reject message, the UE modifies selection parameters to favor non-LTE cells, while maintaining LTE prioritization for normal services, thus resolving the contradiction between LTE quality and emergency access
2Adaptability or versatility
If the eNB requests handover to non-LTE cell for emergency call, then emergency service access is enabled, but the handover is rejected due to invalid USIM capability
Solution Approach 1:
The UE proactively selects non-LTE cells for emergency call establishment before LTE handover is requested, based on detecting invalid USIM status. This preliminary action bypasses the need for LTE handover and directly establishes emergency service on alternative RATs, avoiding the reject message issue
Solution Approach 2:
Instead of following the conventional path of LTE-first selection and then handover to non-LTE, the UE inverts the approach by directly selecting non-LTE cells for emergency services when USIM is invalid, thus achieving emergency access without encountering the handover rejection problem
3Adaptability or versatility
If the UE disables invalid RAT capability upon reject message, then alternative RAT access is enabled for emergency call, but the LTE connection establishment is abandoned
Solution Approach 1:
The UE applies different connection establishment strategies to different service types and RATs. For emergency calls with invalid USIM, the UE disables LTE capability and enables non-LTE access. For normal services with valid USIM, the UE maintains LTE capability. This localized quality adjustment resolves the contradiction by tailoring the connection approach to specific conditions
Data Source
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AI summary
A method of setting radio access capability for a mobile device (12) capable of a plurality of radio access technologies, hereinafter called RATs is disclosed. The method includes utilizing a first RAT of the plurality of RATs to send subscribing information of the mobile device to a network (14) (410), and disabling capability of one of the plurality of RATs when a reject message corresponding to the subscribing information is received from the network (14) (420).