Terminal RAT Switching Timing Control via PS Session Status
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Solution Overview
Problem
The existing methods for switching between radio access technologies (RATs) face challenges, particularly in the fast return scheme, where a terminal may fail to successfully transition back to an LTE network due to unresolved packet switched sessions, leading to voice call and data communication failures.
Innovation Solution
A method and terminal for controlling the timing of switching between RATs by determining the status of packet switched signaling connections, controlling the transmission of signaling connection release indications, and requesting a switch to another network based on these conditions, allowing for a stable and fast transition to LTE even without explicit LTE redirection information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the terminal transmits SCRI message to close PS session during fast return to LTE, then the switching speed to LTE network is improved, but the location registration may fail causing communication failures
Solution Approach 1:
The terminal determines whether to transmit the SCRI message in advance by checking if a PS session for location registration exists before initiating the fast return procedure. This preliminary check prevents premature session closure that would cause location registration failures, while still enabling fast return when safe to do so.
Solution Approach 2:
The terminal monitors the status of PS sessions and uses this feedback information to dynamically decide whether to transmit the SCRI message. By continuously checking session status and adjusting behavior accordingly, the system maintains both fast switching capability and location registration reliability.
2Reliability
If the terminal waits for PS session termination before switching to LTE, then the switching reliability is improved, but the switching time increases
Solution Approach 1:
The terminal performs a preliminary check to determine whether a PS session for location registration exists before initiating the fast return procedure. This advance determination allows the terminal to take appropriate action (transmit or withhold SCRI message) to enable fast switching while maintaining reliability.
Solution Approach 2:
The system changes the behavioral parameter of SCRI message transmission based on the detected PS session status. When no location registration PS session exists, the parameter changes from 'wait for session termination' to 'transmit SCRI immediately,' enabling fast return without compromising reliability.
3Speed
If the terminal transmits SCRI message without checking PS session status, then the switching speed is improved, but the PS session management becomes problematic
Solution Approach 1:
The terminal performs a preliminary determination of PS session status before transmitting the SCRI message. This simple advance check prevents the complexity of managing unresolved sessions while maintaining fast switching capability, by only transmitting SCRI when it is safe to do so.
Data Source
AI summary
A method includes determining whether a packet switched (PS) signaling connection is released, the PS signaling connection being associated with a first network corresponding to a first radio access technology (RAT), controlling a switching timing to a second network corresponding to a second RAT according to a type of the PS signaling connection, and transmitting a request for switching to the second network. A terminal includes a controller to determine whether a packet switched (PS) signaling connection is released, the PS signaling connection being associated with a first network corresponding to a first radio access technology (RAT), and to control a switching timing to a second network corresponding to a second RAT according to a type of the PS signaling connection, and a transmitter to transmit a request for switching to the second network.