Session Context Preservation During Inter-RAT Failover
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Solution Overview
Problem
Current wireless communication systems lack a mechanism to gracefully suspend and switch from a packet-switched network to a circuit-switched network without risking data loss or context loss, especially when a service fails over a packet-switched network.
Innovation Solution
A method where user equipment sends an extended service request to suspend the communication session with the packet-switched network, allowing it to retry the data transmission over a circuit-switched network while preserving session context, and subsequently resume the session with the packet-switched network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE switches from LTE packet-switched network to circuit-switched network to retry service, then service delivery can be achieved, but session context is lost and incoming pages are lost
Solution Approach 1:
The UE performs a tracking area update procedure before switching networks, which proactively refreshes the network's location information and maintains session context. This preliminary action ensures that when the UE returns to the LTE network after circuit-switched fallback, the session can be quickly reestablished without context loss.
Solution Approach 2:
The tracking area update procedure acts as an intermediary mechanism that bridges the gap between packet-switched and circuit-switched networks. By performing this update before network switching, the UE maintains a reference to its session context through the core network, allowing seamless return to the original packet-switched network without losing service context.
2Loss of information
If the UE remains on LTE packet-switched network, then session context is maintained, but service delivery fails when service is unavailable
Solution Approach 1:
The system dynamically switches between packet-switched and circuit-switched networks based on service availability. The UE monitors service delivery status and can transition from LTE network to circuit-switched network when service fails, then return when service is restored, making the network selection dynamic rather than static.
Solution Approach 2:
The UE changes network parameters by switching radio access technologies based on service availability conditions. When service delivery fails on LTE, the UE changes the active network parameter to circuit-switched network, and can revert when conditions improve, allowing adaptive service delivery without permanent session context loss.
3Reliability
If the UE abandons LTE connection to switch networks, then service can be delivered over circuit-switched network, but incoming pages are lost
Solution Approach 1:
The UE performs a tracking area update before leaving the LTE network, which proactively notifies the network of its temporary absence and preserves paging information. This preliminary action prevents loss of incoming pages by ensuring the network retains knowledge of the UE's session context during the circuit-switched network switch.
Data Source
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AI summary
A method is provided for facilitating preservation of session context information during an inter-radio access technology service retry. A user equipment (UE) may initiate a data transmission for a first service over a wireless communication session with a first network. Upon ascertaining that the first service has failed over the first network, a failover procedure is initiated by sending a service request for a second service to the first network. The second service may be distinct from the first service and has the effect of suspending the wireless communication session with the first network. The UE then resends the data transmission for the first service over a second network. The UE then resumes use of the wireless communication session over the first network after resending the data transmission over the second network. This resumption is done by using context information for the wireless communication session preserved prior to the suspension.