Conditional UE Reattachment to LTE via Broadcast Monitoring
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Solution Overview
Problem
In LTE networks, when a UE handovers from LTE to WLAN, it often gets disconnected, leading to issues with control signaling and resource management due to the conventional methods of AP selection and traffic steering, which can result in loss of service and inefficient resource utilization.
Innovation Solution
The introduction of an 'ATTACH-CONDITIONALLY' state in the UE allows it to monitor broadcast transmissions for signal and load levels, applying predefined rules to determine when to reattach to the LTE network, thereby optimizing reconnection without maintaining a dummy PDN connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy PDN connection is maintained to keep UE connected to LTE network, then network connectivity is ensured, but control signaling overhead and resource consumption increase
Solution Approach 1:
The network performs preliminary actions by storing UE context information (bearer contexts, QoS parameters, PCC rules) in the PDN Gateway before the UE detaches. This allows the network to quickly restore connectivity without requiring a dummy connection to maintain state, thereby reducing control signaling overhead while ensuring reliable reconnection.
Solution Approach 2:
The patent creates a copy of the UE's network context (bearer contexts, QoS profiles, PCC rules) and stores it in the PDN Gateway. This copied context enables the network to rapidly reestablish connections after detachment without needing the UE to maintain a dummy connection, thus reducing signaling overhead while preserving connectivity reliability.
2Adaptability or versatility
If RAN-based traffic steering moves all PDN connections to WLAN, then traffic routing flexibility improves, but control signaling capability is lost
Solution Approach 1:
The PDN Gateway acts as an intermediary that maintains control signaling capability independently of the access network. By storing UE context and managing bearer information in the core network rather than relying on RAN control, the system enables flexible traffic steering to WLAN while preserving the ability to send control signaling to the UE through any available access network.
Solution Approach 2:
The patent separates control plane functions (handled by MME and PDN Gateway in core network) from user plane functions (handled by RAN). This segmentation allows traffic steering decisions to be made flexibly at the RAN level while control signaling capability is maintained independently in the core network, resolving the contradiction between routing flexibility and control capability.
3Reliability
If dummy PDN connection is setup before handover to WLAN, then LTE network connection is maintained, but resource consumption in network nodes increases
Solution Approach 1:
The patent extracts the essential function of the dummy PDN connection (maintaining UE context in the network) and implements it separately through context storage in the PDN Gateway. This allows the UE to detach completely from LTE without requiring a dummy connection, thereby reducing network resource consumption while maintaining the ability to quickly restore connectivity when needed.
Data Source
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AI summary
A method implemented in a user equipment (UE) for establishing reattachment to a first network includes establishing a data connection to a second network. The method further includes detecting a detachment from the first network. The method further includes entering a conditional state after detecting the detachment from the first network. After entering the conditional state, the method further includes monitoring one or more broadcast transmissions from a network node, extracting broadcast data included in the broadcast transmissions of the first network, applying the extracted broadcast data in a predetermined rule, and if the predetermined rule is satisfied, establishing the reattachment to the first network.