Selective Camping Bit for UE Voice Service Verification
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Solution Overview
Problem
The ambiguity in differentiating between a UE that powers up in a 2G/3G network and one that reselects to 2G/3G from E-UTRAN leads to potential failure in providing voice services, as the network cannot determine if the UE has a voice solution in E-UTRAN, resulting in incorrect assumptions about voice service availability.
Innovation Solution
Implementing a selective camping capability bit that is conditionally set by the UE only after determining E-UTRAN voice service availability, along with network tracking mechanisms and explicit NAS signaling to differentiate between power-up and reselection scenarios, ensuring accurate voice service provision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the network assumes a UE has a voice solution in E-UTRAN after reselection, then voice service provision is simplified, but voice service availability becomes unreliable due to incorrect assumptions
Solution Approach 1:
The network implements feedback mechanisms by tracking whether a UE powered up in GERAN/UTRAN or reselected from E-UTRAN. This feedback information is used to adjust handover decisions, ensuring that UEs with verified voice solutions in E-UTRAN are handed over appropriately while those without are kept on 2G/3G networks, thus resolving the contradiction between simplified service provision and reliable service availability
Solution Approach 2:
The network performs preliminary tracking of UE power-up location before making handover decisions. By determining in advance whether a UE powered up in GERAN/UTRAN or reselected from E-UTRAN, the network can proactively configure appropriate voice service parameters and handover policies, preventing voice service failures before they occur
2Productivity
If the network hands over all UEs to E-UTRAN, then data service performance is improved, but voice service quality deteriorates due to lack of verified voice solution
Solution Approach 1:
The network applies different quality treatments to different UE groups based on their power-up location. UEs that powered up in GERAN/UTRAN receive conservative handover policies prioritizing voice service reliability, while UEs that reselected from E-UTRAN receive aggressive handover policies optimizing data service performance. This local differentiation resolves the contradiction between data productivity and voice reliability
3Reliability
If the network tracks UE power-up location, then voice service reliability is improved, but network complexity increases due to additional tracking mechanisms
Solution Approach 1:
The network uses existing intermediate entities such as MME and SGSN to perform the tracking function. These intermediaries already handle UE context management and can be extended to track power-up location without requiring new dedicated tracking infrastructure. This approach improves voice service reliability while minimizing the increase in network complexity by leveraging existing network components
Data Source
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AI summary
A user equipment (UE) is provided that includes one or more processors configured to perform one of an attach procedure, Routing Area Update (RAU), or Tracking Area Update (TAU), and then cause the UE to provide an indication to a network, wherein the indication indicates whether the UE has determined a voice solution in an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (E-UTRAN).