CG-SDT Time Alignment Timer Management for Wireless Latency
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Solution Overview
Problem
In wireless communication systems, managing time alignment timers (TAT) for small data transmission (SDT) is challenging due to limited resources and the need to efficiently handle uplink/downlink data and control information, particularly in overcoming latency issues.
Innovation Solution
A method and apparatus for a User Equipment (UE) in a wireless communication system that starts a configured grant-based small data transmission (CG-SDT) time alignment timer upon receiving configuration, transmits data during the timer's operation in the RRC INACTIVE state, and restarts the timer based on a timing advance command (TAC) if the CG-SDT procedure is ongoing, while not restarting if the procedure is not ongoing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CG-SDT TAT is restarted every time a TAC is received, then the data transmission timing alignment is maintained, but the timer management complexity increases and latency increases
Solution Approach 1:
The patent applies dynamics by making the TAT restart behavior conditional rather than fixed. The timer is restarted only when specific conditions are met (CG-SDT procedure is ongoing and TAC is received), allowing the system to adapt its timing management strategy based on the current operational state, thereby reducing unnecessary timer restarts while maintaining alignment reliability when needed.
Solution Approach 2:
The patent changes the parameter of TAT restart behavior based on the procedural state. By distinguishing between different states of the CG-SDT procedure (ongoing vs. not ongoing), the system dynamically adjusts the timer management parameters to optimize both reliability and complexity, restarting the timer only when the procedure is ongoing.
2Device complexity
If the CG-SDT TAT is not restarted when TAC is received, then the timer management is simplified, but the timing alignment may be lost
Solution Approach 1:
The patent implements feedback mechanisms where the UE monitors the procedural state of CG-SDT and uses this feedback to determine whether to restart the TAT upon receiving a TAC. This feedback loop ensures that the timer management strategy adapts to the actual operational conditions, maintaining timing alignment reliability only when the procedure is ongoing while simplifying management when it is not.
3Reliability
If multiple timers are managed for different SDT types, then comprehensive timing control is achieved, but the resource consumption and processing overhead increase
Solution Approach 1:
The patent applies universality by creating a unified approach to timer management that can handle different SDT types (CG-SDT and RA-SDT) through a single timer structure. The CG-SDT TAT is designed to operate in conjunction with RA-SDT procedures, allowing one timer mechanism to serve multiple functions and reducing the need for separate timer management for each SDT type, thereby lowering processing overhead while maintaining comprehensive timing control.
Data Source
AI summary
The present disclosure relates to a method managing a time alignment timer (TAT) for small data transmission (SDT) in a wireless communication system. In particular, the method includes the steps of: starting a configured grant based small data transmission (CG-SDT) time alignment timer (TAT) upon receiving CG-SDT configuration; transmitting at least one data unit based on the CG-SDT configuration in RRC INACTIVE state during the CG-SDT TAT is running; and restarting the CG-SDT TAT based on a timing advance command (TAC) being received and based on a CG-SDT procedure being ongoing, wherein, based on the TAC being received and based on the CG-SDT procedure not being ongoing, the CG-SDT TAT is not restarted.