LTE Station VoLTE Capability Check for CSFB Voice
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Solution Overview
Problem
Older generation cellular phones lacking Voice over LTE (VoLTE) capabilities or with VoLTE turned off cannot conduct voice calls on LTE only radio access technologies, leading to repeated attach and detach processes that strain battery supply, network resources, and user time.
Innovation Solution
A method and station configuration to determine if a Public Land Mobile Network (PLMN) supports circuit switched fallback voice calls, and if not, to assess VoLTE properties to attach to the PLMN only when these properties meet predetermined conditions, prioritizing cells with neighbor cells supporting circuit switched fallback calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the station attaches to an LTE only RAT without checking VoLTE capability, then the attachment process is simple and fast, but the station cannot conduct voice calls and must repeatedly detach and reattach
Solution Approach 1:
The station performs preliminary checks before attaching to an LTE only RAT by evaluating VoLTE capability properties and determining whether the network supports circuit switched fallback. This preliminary assessment prevents attachment to networks that cannot support voice calls, eliminating the need for repeated detach and reattach cycles while maintaining reliable voice service.
2Reliability
If the station checks VoLTE capability and network support before attachment, then voice call reliability is improved, but the attachment process becomes more complex and time-consuming
Solution Approach 1:
The invention evaluates specific parameters such as VoLTE capability properties and network support for circuit switched fallback to determine attachment suitability. By changing the attachment decision from a simple connect action to a parameter-based evaluation, the system ensures voice call reliability while managing complexity through focused parameter assessment.
3Reliability
If the station repeatedly detaches and reattaches to find a suitable network, then it eventually locates a network supporting voice calls, but battery supply and network resources are strained
Solution Approach 1:
The station performs preliminary evaluation of VoLTE capability and network support before attachment, preventing attachment to networks that cannot support voice calls. This preliminary action eliminates repeated detach and reattach cycles, significantly reducing battery consumption and network resource strain while ensuring voice service availability.
4Loss of time
If the station performs preliminary VoLTE capability assessment before attachment, then repeated attach-detach cycles are reduced, but the initial attachment process requires additional processing
Solution Approach 1:
The station performs a preliminary assessment of VoLTE capability properties and network support for circuit switched fallback before initiating attachment. This preliminary action evaluates critical parameters to determine attachment suitability, reducing the need for repeated attach-detach cycles and saving time in the long run despite requiring additional processing during the initial attachment attempt.
Data Source
AI summary
A method performed by a station that includes receiving information from a cell of a Public Land Mobile Network (PLMN), determining whether the information indicates the cell supports circuit switched fallback (CSFB) voice calls, when the CSFB voice calls are not supported, determining whether at least one packet switched voice property of the station satisfies a predetermined condition and attaching to the cell of the PLMN when the predetermined condition is satisfied. A further method performed by a station connected to a PLMN that includes identifying cells of the PLMN available for the station to camp on, determining whether the station is capable of executing packet switched calls, when the station is not capable of executing packet switched calls, determining whether the identified cells have a neighbor cell that supports CSFB voice calls and prioritizing the cells that are identified as having neighbor cells that support CSFB voice calls.