5G SA Registration Denial for Voice Fallback
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Solution Overview
Problem
As 5G standalone (SA) networks become more prevalent, UEs capable of using 5G SA for data but not for voice may struggle to maintain voice connectivity when 4G coverage is unavailable, leading to failed voice calls due to reliance on Evolved Packet System Fallback (EPSFB) that fails without 4G availability.
Innovation Solution
Implementing a mechanism in 5G network nodes, such as gNB and AMF, to determine the availability of 4G coverage for UEs attempting to connect. If 4G coverage is not available, the network node denies the UE's registration request for 5G SA coverage, prompting the UE to fail over to alternative radio access technologies like 3G, ensuring voice-centric logic is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UEs are allowed to register for 5G SA coverage regardless of 4G availability, then data connectivity is improved, but voice connectivity reliability deteriorates
Solution Approach 1:
The network node performs preliminary determination of 4G coverage availability before allowing 5G SA registration. By checking whether 4G coverage is available in advance, the system prevents UEs from registering on 5G SA when they would be unable to fall back to 4G for voice services, thus ensuring voice connectivity reliability while still allowing data connectivity when 4G is available.
2Reliability
If 5G SA coverage is denied when 4G is unavailable, then voice connectivity reliability is improved, but network resource utilization deteriorates
Solution Approach 1:
The system applies different registration acceptance criteria based on the local availability of 4G coverage. In areas where 4G is available, 5G SA registration is accepted for data services. In areas where 4G is unavailable, 5G SA registration is denied to preserve voice connectivity through 3G fallback. This localized differentiation optimizes both voice reliability and network resource utilization.
3Reliability
If UEs fall back to 3G networks when 4G is unavailable, then voice connectivity is maintained, but service quality deteriorates
Solution Approach 1:
By determining 4G coverage availability before 5G SA registration, the system prevents UEs from being forced into 3G fallback. UEs can register on 5G SA when 4G is available, maintaining higher service quality. Only when 4G is truly unavailable does the system allow 3G fallback as a last resort, minimizing service quality degradation while ensuring voice connectivity.
Data Source
AI summary
Described herein are device(s) of a Fifth Generation (5G) network configured to receive, from a user equipment (UE) a registration request for 5G standalone (SA) coverage and to determine that Fourth Generation (4G) coverage from the telecommunications network is not available to the UE. The device(s) of the 5G network are further configured to deny the registration request in response to determining that the 4G coverage is not available to the UE and regardless of whether 5G SA coverage is available to the UE.