Idle-State UE Timing Synchronization Through Random Access
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Solution Overview
Problem
User equipment (UE) in idle or inactive states faces challenges in obtaining accurate timing advance (TA) information for effective timing synchronization, which is crucial for meeting 5G timing synchronization accuracy requirements in time-sensitive network (TSN) services.
Innovation Solution
The UE triggers a random access (RA) procedure to obtain effective TA information, enabling propagation delay compensation and timing synchronization, regardless of its connected or unconnected state, through 2-step or 4-step RA processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE remains in idle or inactive state without triggering RA procedure, then power consumption is reduced and state complexity is minimized, but timing synchronization accuracy deteriorates and TA information becomes unavailable
Solution Approach 1:
The UE performs timing synchronization and obtains TA information through RA procedure in advance, before actual data transmission is needed. This preliminary action ensures that when the UE needs to transmit data in idle/inactive states, the timing synchronization is already established, eliminating the need for state transitions to connected mode just for synchronization purposes.
Solution Approach 2:
The UE independently performs the RA procedure to obtain TA information and maintain timing synchronization without requiring network intervention or state transitions. The UE serves itself by autonomously triggering RA when needed, obtaining synchronization independently, and maintaining timing alignment without becoming fully connected, thus reducing network signaling overhead and state management complexity.
2Measurement precision
If the UE triggers RA procedure to obtain TA information, then timing synchronization accuracy is improved, but signaling overhead increases and procedure complexity worsens
Solution Approach 1:
The UE performs a simplified RA procedure that focuses only on obtaining TA information for timing synchronization, without necessarily completing all steps of a full RA procedure. The UE can trigger RA with specific purposes (timing synchronization) and may not need to complete contention resolution or establish full data bearers, thus reducing the time and signaling overhead compared to a complete RA procedure.
3Reliability
If the UE performs propagation delay compensation with accurate TA information, then TSN service timing requirements are met, but the requirement for frequent synchronization increases system activity
Solution Approach 1:
The UE performs timing synchronization and obtains updated TA information in advance through RA procedure before TSN service data transmission is required. This preliminary synchronization ensures that when the UE does transmit, the timing is already accurate, allowing the UE to remain in low-power idle or inactive states between synchronization events rather than continuously monitoring or maintaining connected state.
Solution Approach 2:
The UE autonomously determines when to trigger RA procedures for timing synchronization based on its own needs for TSN service transmission, rather than being continuously commanded by the network. This self-service approach allows the UE to balance between maintaining timing accuracy and conserving power by independently deciding when synchronization updates are necessary.
Data Source
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AI summary
Methods for timing synchronization, a terminal device, and a network device are provided in the disclosure. The method for timing synchronization includes the following. The terminal device obtains timing advance (TA) information through a random access (RA) procedure. The terminal device performs timing synchronization through using the TA information. By triggering the RA procedure by the terminal device, it can be ensured that the terminal device can obtain effective TA information in various scenarios, and perform propagation delay compensation, to perform timing synchronization.