Terminal Timing Advance Reporting for NTN Uplink Synchronization
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Solution Overview
Problem
In non-terrestrial networks, especially in LEO scenarios, the timing advance (TA) values between terminal devices and network devices change rapidly and greatly, leading to frequent uplink out-of-synchronization issues, which result in increased signaling overhead and resource consumption due to the inability of the network device to update TA values in real time.
Innovation Solution
Terminal devices determine and adjust their own TA values based on self-positioning capabilities and report them to the network device using periodic, aperiodic, or semi-persistent reporting modes through specific physical channels, ensuring real-time updates and adjustments to avoid frequent uplink out-of-synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network device determines and updates TA values by measuring uplink transmission, then uplink synchronization can be maintained, but in NTN scenarios with rapidly changing TA values, the network device cannot update TA values in real time, leading to frequent uplink out-of-synchronization
Solution Approach 1:
Instead of having the network device measure and determine TA values (traditional approach), the terminal device autonomously determines its own TA value based on downlink signal timing and self-positioning capabilities. This inversion of the determination subject enables real-time TA updates without network device intervention, solving the contradiction between synchronization reliability and update speed in NTN scenarios
Solution Approach 2:
The terminal device performs self-service by autonomously calculating and adjusting its own TA value using downlink signal timing measurements and positioning information. This self-determination mechanism eliminates the bottleneck of network device processing, allowing real-time TA updates while maintaining uplink synchronization, thus resolving the technical contradiction
2Reliability
If the terminal device frequently updates TA values to maintain synchronization, then uplink synchronization is improved, but signaling overhead and random access resource consumption increase
Solution Approach 1:
The terminal device performs preliminary action by proactively determining and adjusting its TA value based on downlink signal timing and positioning information before uplink transmission occurs. This advance preparation eliminates the need for frequent synchronization correction signaling, reducing signaling overhead while maintaining continuous uplink synchronization
Solution Approach 2:
The terminal device uses feedback from downlink signal timing measurements and positioning data to continuously adjust its TA value. This closed-loop feedback mechanism at the terminal side enables real-time synchronization maintenance without requiring frequent network-device-initiated TA updates, thereby reducing signaling overhead and random access resource consumption
Data Source
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AI summary
Provided in embodiments of the present invention are a communication method and device, and an apparatus. A terminal apparatus receives configuration information from a network apparatus, and transmits TA information to the network apparatus according to the configuration information. The above process ensures that a TA value of a terminal apparatus can be timely updated and adjusted, thereby preventing frequent occurrence of uplink out-of-synchronization.