Uplink Timing Adjustment for Long-RTT Satellite Synchronization
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Solution Overview
Problem
In satellite communication systems, the round-trip time (RTT) is long, preventing terminal devices from completing timing advance processing within the duration of existing uplink transmission time, leading to challenges in ensuring uplink orthogonality and synchronization.
Innovation Solution
The terminal device adjusts uplink sending time based on target adjustment information and timing advance (TA) received from the network device, using various methods such as system information blocks (SIB), downlink control information (DCI), and random access responses, to ensure timely completion of timing advance and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the terminal device uses existing uplink transmission time for timing advance processing, then the processing can be completed within normal duration, but in satellite communication systems with long RTT, the timing advance processing cannot be completed within the existing time duration
Solution Approach 1:
The patent dynamically adjusts the uplink transmission time based on the round-trip time characteristics of the communication system. For satellite communication systems with long RTT, the terminal device is configured to use a longer time duration for timing advance processing, while terrestrial systems continue to use the standard shorter duration. This dynamic adaptation resolves the contradiction by allowing sufficient processing time for satellite systems without affecting the efficiency of terrestrial systems.
Solution Approach 2:
The patent changes the time parameter for uplink transmission based on the system type. By configuring different time durations for timing advance processing in satellite versus terrestrial communication systems, the patent enables terminal devices to complete timing advance operations within the appropriate time framework for each system type, thereby maintaining synchronization reliability across different deployment scenarios.
2Productivity
If the terminal device sends uplink signals immediately after receiving downlink data, then the transmission efficiency is high, but uplink orthogonality cannot be ensured due to timing misalignment
Solution Approach 1:
The patent applies preliminary timing advance processing before the terminal device sends uplink signals. The network device calculates the timing advance value based on the random access preamble and provides this information to the terminal device in advance. The terminal device then uses this timing advance value to adjust its uplink transmission time before actual data transmission, ensuring that uplink signals from different terminals arrive at the network device simultaneously. This preliminary action resolves the contradiction by maintaining both transmission efficiency and timing synchronization precision.
3Measurement precision
If the network device sends detailed timing adjustment information to each terminal device, then the timing synchronization accuracy is improved, but the signaling overhead and system complexity increase
Solution Approach 1:
The patent enables terminal devices to self-adjust their uplink transmission timing based on timing advance information provided by the network device. Instead of the network device continuously monitoring and controlling each terminal's timing, the terminal device autonomously applies the timing advance value to adjust its transmission time. This self-service approach maintains high timing synchronization accuracy while reducing the complexity of timing management in the system.
Data Source
AI summary
This application discloses a communication method. In one example method, a network device sends a first message, where the first message includes target adjustment information. The network device sends a second message, where the second message includes a timing advance (TA), the target adjustment information is used to determine a delay time, and the TA is used to determine a first uplink sending time. The network device receives an uplink transmission sent at an uplink sending time, where the uplink sending time is the first uplink sending time delayed by the delay time.