UE SERVICE ACCEPT Reception Timer Mechanism
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Solution Overview
Problem
In LTE systems, it is not defined how long after a service request procedure is completed that a UE should accept a SERVICE ACCEPT message, leading to potential protocol errors due to unsynchronized bearer context status information.
Innovation Solution
A new timer is started when the service request procedure is determined complete, allowing the UE to treat the SERVICE ACCEPT message as successfully received within a defined time window, or an existing timer T3417/T3417ext is used to define this window, ensuring the UE remains in the correct protocol state until the timer expires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE considers the service request procedure completed immediately upon receiving SECURITY MODE COMMAND or radio bearer setup indication, then the service request procedure completion time is reduced, but the UE may receive SERVICE ACCEPT message in wrong protocol state causing protocol errors
Solution Approach 1:
The patent introduces a timer mechanism that is started when the service request procedure is completed (upon receiving SECURITY MODE COMMAND or radio bearer setup indication). This timer creates a predefined time window during which the UE remains in a transitional state and can still accept SERVICE ACCEPT messages. By performing this preliminary state extension action, the patent allows the SERVICE ACCEPT message to be received within the timer window without causing protocol errors, thus resolving the contradiction between quick procedure completion and reliable protocol state handling
2Reliability
If the UE extends the acceptance window for SERVICE ACCEPT message beyond immediate procedure completion, then message reception reliability is improved, but the protocol state management complexity increases
Solution Approach 1:
The patent changes the temporal parameter of the protocol state by introducing a timer with a predefined duration. Instead of maintaining a complex multi-state machine to handle the transitional period, the patent uses a simple timer mechanism that automatically manages the extended acceptance window. This parameter-based approach (time duration) simplifies the protocol state management while ensuring reliable SERVICE ACCEPT message reception within the allowed window
Data Source
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AI summary
A method of supporting reception of standalone SERVICE ACCEPT message is proposed. In one embodiment, a new timer is started when the UE determines successful completion of the service request procedure and has not received SERVICE ACCEPT during the procedure. In an alternative embodiment, an existing timer T3417 or T3417ext can be used to define the allowed time window for the reception of SERVICE ACCEPT. While the timer is running, the UE can treat the SERVICE ACCEPT message as successfully received and the message does not cause protocol error.