UE Service Request Handling for Circuit Switch Rejection
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Solution Overview
Problem
In LTE wireless communication systems, when a UE receives a service rejection message with EMM cause #39 'CS service temporarily not available' and a non-zero timer value, it is not allowed to send an EXTENDED SERVICE REQUEST message for circuit switch service, leading to delays in mobile originating data services.
Innovation Solution
The method involves receiving a service reject message with a non-zero timer value indicating the UE cannot send an extended service request for circuit switch service, starting this timer, and sending an extended service request for packet service even when the timer is running, allowing mobile originating packet service requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE sends an EXTENDED SERVICE REQUEST message for mobile originating services when timer T3442 is running, then the UE can maintain circuit switch service availability, but the network may experience service rejection and signaling overload
Solution Approach 1:
The patent changes the parameter state by introducing a distinction between two timer states: T3442-running (where EXTENDED SERVICE REQUEST is blocked) and T3442-stopped (where it is allowed). This parameter change enables the UE to send service requests for packet services even when T3442 is running, thereby resolving the contradiction between maintaining circuit switch service availability and preventing data service delay
Solution Approach 2:
The patent makes the service request behavior dynamic by conditionally allowing EXTENDED SERVICE REQUEST messages based on the timer state. When T3442 is stopped, the UE can send both circuit switch and packet service requests. When T3442 is running, only packet service requests are allowed. This dynamic adjustment resolves the contradiction by adapting the service request behavior to the current network state
2Reliability
If the UE is not allowed to send EXTENDED SERVICE REQUEST message when timer T3442 is running, then the network can control service rejection, but mobile originated data service is delayed
Solution Approach 1:
The patent changes the parameter by introducing a new condition for sending EXTENDED SERVICE REQUEST messages: the UE checks whether the service type is packet service and whether T3442 is running. If both conditions are met, the message is sent despite the timer running. This parameter change resolves the contradiction by allowing data service requests while maintaining network control over circuit switch service rejection
3Productivity
If the UE sends EXTENDED SERVICE REQUEST message for packet services when T3442 is running, then data service delay is prevented, but service rejection handling becomes complex
Solution Approach 1:
The patent segments the service request handling into two distinct paths: one for when T3442 is stopped (allowing all service requests) and one for when T3442 is running (allowing only packet service requests). This segmentation resolves the contradiction by providing clear, differentiated handling logic that reduces overall complexity despite the additional conditional check
Data Source
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AI summary
A method of handling service rejection for circuit switch service for a mobile device in a wireless communication system is disclosed. The method comprises receiving a service reject message with not available circuit switch service cause and a non zero timer value for a timer whose running state indicates that the mobile device is not allowed to send a extended service request message for a circuit switch service, from a network of the wireless communication system, starting the timer with the non zero timer value, and sending the extended service request message for a packet service to the network even when the timer is running.