Mobile UE Fallback Switching After SIP Failure in 5G Voice
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Solution Overview
Problem
Mobile terminating (MT) voice calls in 5G NR networks experience prolonged service disruptions due to SIP failure messages, leading to users unknowingly missing incoming calls when network or global failures occur, as NR UEs cannot perform circuit-switched fallback and are unaware of the originating number for redialing.
Innovation Solution
A UE connected to a 5G network maintains a hierarchy of fallback networks (LTE, Wi-Fi, 3G, 2G) to systematically attempt connections upon receiving SIP failure messages, incrementing a counter to bar NR communication for increasing durations with each failure, ensuring voice services are maintained through alternative networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If NR UEs operate on 5G network without circuit-switched fallback capability, then network simplicity is improved, but voice service reliability deteriorates during SIP failures
Solution Approach 1:
The patent introduces an intermediary fallback mechanism where the UE maintains connectivity to alternative networks (LTE, Wi-Fi, 3G, 2G) as intermediate solutions when the primary 5G NR network experiences SIP failures. This mediator layer allows voice services to continue through alternative paths without requiring complex circuit-switched architecture in the 5G core network.
Solution Approach 2:
The UE performs preliminary actions by maintaining a hierarchy of fallback networks ready for immediate switching. When SIP failures are detected, the UE can rapidly transition to pre-configured alternative networks without waiting for network reconfiguration, thus maintaining voice service continuity while keeping the primary 5G architecture simple.
2Reliability
If UE systematically attempts connections to fallback networks upon SIP failures, then voice service reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the network selection process into a hierarchical structure with multiple levels of fallback networks (LTE, Wi-Fi, 3G, 2G). This segmentation allows the UE to systematically attempt connections in a predefined order, reducing the complexity of managing all possible network transitions simultaneously while ensuring comprehensive voice service coverage.
3Reliability
If UE bars NR communication for increasing durations with each SIP failure, then service disruption time is reduced, but loss of time for network recovery increases
Solution Approach 1:
The patent implements periodic action through incrementally increasing barring durations for NR communication after each SIP failure. This periodic reinforcement strategy allows the UE to gradually extend the exclusion period for the primary network, giving it time to recover while ensuring that voice services remain available through fallback networks. The incremental approach balances network recovery time with service availability.
Data Source
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AI summary
An apparatus for wireless communication of a user equipment (UE) is disclosed. The apparatus may include a memory and at least one processor coupled to the memory. The at least one processor may be configured to receive a paging signal associated with an mobile terminating (MT) internet protocol (IP) multimedia subsystem (IMS) voice session. The at least one processor may be further configured to send a session initiation protocol (SIP) message in response to the paging signal. The at least one processor may be further configured to receive a second SIP message indicating SIP failure. The at least one processor may be further configured to determine whether the second SIP message indicates a network failure or a global failure. The at least one processor may be further configured to establish a connection with a different RAT network when the second SIP message indicates a network failure or a global failure.