CG-SDT Timer Control for Timing Advance in RRC Inactive UEs
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Solution Overview
Problem
In the 5G NR system, there is no definite solution for the running mechanism of the timer for uplink small data transmission (SDT) and the method for maintaining the valid timing advance during the timer, leading to unnecessary power consumption and signaling overhead for UEs in the RRC_INACTIVE state with infrequent data transmission.
Innovation Solution
A timer running method is proposed, involving the reception of a first message for a Configured Grant (CG) resource used for inactive state data transmission, with operations on a first timer to maintain the validity of a first timing advance, including start/restart conditions and dynamic updates based on network messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a timer mechanism is introduced to maintain timing advance validity for CG-SDT, then uplink small data transmission capability is improved, but device complexity increases due to additional timer management
Solution Approach 1:
The patent applies preliminary action by pre-configuring the SDT-TAT timer and timing advance parameters through RRC release messaging before the UE enters inactive state. This allows the timer mechanism to be ready for immediate use when CG-SDT is needed, enabling uplink small data transmission without requiring complex real-time negotiations, thus improving adaptability while controlling device complexity.
2Reliability
If the UE maintains timing advance validity through timer operations, then uplink transmission reliability is improved, but power consumption increases due to continuous timer monitoring
Solution Approach 1:
The patent implements periodic action through the SDT-TAT timer which periodically monitors timing advance validity rather than continuous monitoring. The timer operates in discrete intervals, expiring at predetermined periods to trigger timing advance validation checks. This periodic mechanism maintains uplink transmission reliability by ensuring timing advance remains valid while significantly reducing power consumption compared to continuous monitoring approaches.
3Reliability
If the SDT-TAT timer is started or restarted upon receiving CG resource configuration, then timing advance validity is maintained, but signaling overhead increases due to additional timer control messages
Solution Approach 1:
The patent applies merging by combining the SDT-TAT timer start/restart operation with the existing CG resource configuration messaging流程. The timer is initiated or restarted as part of the RRC release message that already contains CG resource configuration, rather than requiring separate dedicated timer control messages. This integration maintains timing advance validity while minimizing additional signaling overhead by reusing existing message structures.
4Speed
If the UE performs timer operations based on RRC release message, then connection restoration speed is improved, but device complexity increases due to message parsing and timer coordination
Solution Approach 1:
The patent applies preliminary action by including all necessary timer configuration parameters (SDT-TAT duration, timing advance values) within the RRC release message before the UE needs to restore connection. The UE parses these pre-configured parameters and initiates the SDT-TAT timer immediately upon receiving the message, enabling fast connection restoration without requiring additional round-trip communications or complex real-time calculations, thus improving speed while managing device complexity.
Data Source
AI summary
Embodiments of the present application relate to a timer operating method, a terminal device, and a network device. The method comprises: a terminal device receives a first message, the first message being directed against a pre-configured (CG) resource for inactive state data transmission; and the terminal device performs a corresponding operation on a first timer according to the first message, the first timer being used for maintaining the validity of first timing advance. According to the embodiments of the present application, the terminal device may specify a timer mechanism of data transmission and maintained timing advance.