UE RAT Selection Policy for Wi-Fi to LTE Voice Handover
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Solution Overview
Problem
Current systems lack a suitable mechanism to influence user equipment (UE) to switch from non-3GPP access to LTE/EPS when Voice over New Radio (VoNR) is unavailable, resulting in undesirable multi-step handovers from Wi-Fi to NR and then to LTE.
Innovation Solution
Implementing User Equipment (UE) policies, specifically UE Route Selection Policies (URSP) rules that dynamically associate applications with preferred radio access technologies (RAT) for handovers, allowing the network to override static SIM-based settings and prioritize LTE/EPS when VoNR is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE automatically selects NR as the preferred RAT type for 3GPP access, then 5G connectivity is prioritized, but unnecessary multi-step handovers occur when VoNR is unavailable
Solution Approach 1:
The patent applies dynamics by making the UE's RAT selection preference changeable based on network conditions and application requirements. Instead of a fixed preference for NR, the system dynamically adjusts the preferred RAT type through UE policies that can be updated by the network, allowing the UE to switch between preferring NR or LTE/EPS depending on VoNR availability and other factors.
Solution Approach 2:
The patent changes the parameter of preferred RAT type from a static configuration to a dynamic one that can be modified through UE policies. The network can update the preferred RAT type parameter in the UE policy, enabling the system to adapt to changing network capabilities and requirements without requiring manual intervention or fixed configurations.
2Device complexity
If the UE uses static SIM-based RAT selection settings, then device simplicity is maintained, but network flexibility to optimize mobility is limited
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of UE policies that act as a mediator between the UE's static SIM settings and the network's dynamic optimization requirements. These policies serve as a flexible layer that can be updated by the network without changing the UE's fundamental configuration, enabling network-initiated adaptations while maintaining UE simplicity.
Solution Approach 2:
The patent transforms the static SIM-based selection into a dynamic system where UE policies can be updated by the network. This dynamic mechanism allows the network to optimize mobility scenarios without requiring changes to the UE's core configuration, balancing simplicity with adaptability.
3Productivity
If the network forces UE to switch to NR for handover, then 5G deployment priorities are met, but service disruption occurs when VoNR is not supported
Solution Approach 1:
The patent implements feedback mechanisms where the network can detect VoNR availability and application requirements, then adjust the UE policy accordingly. The network provides feedback about network capabilities and conditions, allowing the UE to make informed decisions about RAT selection that ensure reliable service continuity while supporting 5G deployment.
Solution Approach 2:
The patent applies preliminary action by allowing the network to pre-configure UE policies with preferred RAT types before handover scenarios occur. The network can anticipate VoNR availability and set appropriate preferences in advance, preventing service disruption before it occurs rather than reacting after issues arise.
Data Source
AI summary
In one illustrative example, a user equipment (UE) policy may be communicated to a UE. The UE policy may be a UE Route Selection Policy (URSP) which includes a policy rule that associates an application and/or traffic thereof with a routing policy comprising an indicated radio access technology (RAT) type for 3GPP access. When the UE operates to communicate the traffic in a communication session for the application via non-3GPP access, a message which indicates an attach request with a request type indicating “handover” may be received from the UE via a selected radio access network (RAN) corresponding to the indicated RAT type. The message is for triggering a handover of the communication session for the application from the non-3GPP access to the 3GPP access. In one scenario, when Voice over NR (VoNR) is unavailable, the indicated RAT type of the routing policy may be set to indicate an E-UTRAN.