SIP Fallback Indicators for 5G UE Network Control
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Solution Overview
Problem
In 5G cellular networks, the lack of backwards compatibility between the 5G core network and existing 4G technology leads to inefficient fallback procedures, causing resource wastage and network stress during outages, as 5G-compliant UEs repeatedly attempt to reestablish communication sessions on legacy RATs without network authorization.
Innovation Solution
Implementing a network-controlled fallback approach through Session Initiation Protocol (SIP) signaling, where User Equipment (UE) exchanges fallback indicators with an IMS node to determine authorized radio access technologies (RATs) for reattempting communication sessions, preventing futile attempts on unauthorized RATs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 5G-compliant UEs always retry failed sessions using legacy RATs, then session reestablishment capability is improved, but computing resources and network bandwidth are wasted
Solution Approach 1:
The network performs preliminary actions by sending fallback indication messages to UEs before session establishment fails, informing them whether legacy RAT fallback is authorized. This prevents UEs from wastefully attempting fallback when unauthorized, while still enabling them when permitted, thus resolving the contradiction between reliability and resource waste.
Solution Approach 2:
The system implements feedback mechanisms where the network monitors session establishment failures and sends authorized fallback indications to UEs in real-time. This feedback loop ensures UEs only attempt legacy RAT fallback when the network authorizes it, preventing resource waste while maintaining session reestablishment capability when needed.
2Reliability
If traditional fallback approach is adopted for 5G UEs, then session continuity is improved, but network stress increases during widespread outages
Solution Approach 1:
The network sends fallback authorization indications in advance to UEs, allowing them to proactively attempt fallback to legacy RATs only when authorized. This preliminary authorization prevents mass simultaneous fallback attempts during outages, reducing network stress while maintaining session continuity for authorized UEs.
Solution Approach 2:
The fallback authorization is dynamic rather than static - the network can adjust which UEs receive fallback authorization based on current network conditions, outage severity, and capacity availability. This dynamic control allows session continuity for critical UEs while limiting overall network stress during widespread failures.
3Ease of operation
If 5G core network is made backwards compatible with 4G technology, then fallback procedures are simplified, but 5G network architecture complexity increases
Solution Approach 1:
The patent introduces an intermediary fallback indication message as a mediator between the 5G core network and UEs. This message carries authorization information without requiring the 5G core to be directly backwards compatible with 4G protocols. The intermediary approach simplifies fallback procedures for UEs while maintaining the integrity and low complexity of the 5G network architecture.
Data Source
AI summary
A user equipment (UE) and an Internet Protocol (IP) Multimedia Subsystem (IMS) node may exchange fallback indicators in SIP signaling for purposes of controlling fallback procedures implemented by the UE. By sending fallback indicators to an IMS node in a SIP request, a UE is able to inform the IMS node of its capabilities in regards to particular fallback radio access technologies (RATs) that are supported by the UE. The IMS node may respond to the UE with a SIP response that includes information indicating which of the supported Fallback RATs the UE is authorized to use (if any), and which of the supported Fallback RATs the UE is not authorized to use (if any). In this way, the IMS node can control a fallback procedure at the UE by indicating which Fallback RATs are usable by the UE to reattempt communication sessions that cannot be established on an existing RAT.