Random Access Timing Offset for Satellite Uplink Alignment
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Solution Overview
Problem
In satellite communication systems, the larger transmission delay and high-speed movement of satellites complicate the calculation of timing advance (TA) for slot alignment, leading to issues with uplink data transmission and demodulation, particularly in initial access procedures.
Innovation Solution
A communication method that determines an offset value for sending a random access request, considering factors like ephemeris information and error margins to ensure a positive timing advance adjustment value, thereby improving system robustness and alignment with the network side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal device calculates the timing advance based on position information and ephemeris information to send the random access request in advance, then the slot alignment can be achieved, but the timing advance adjustment value may become negative due to transmission delay and satellite movement, causing system robustness degradation
Solution Approach 1:
The terminal device performs preliminary calculation of the timing advance value before sending the random access request, using position information and ephemeris information to determine an appropriate advance time. This preliminary action allows the device to proactively adjust for expected delays, ensuring the network device receives the request at the correct timing while avoiding negative adjustment values that would compromise system robustness.
2Productivity
If the terminal device sends the random access request using a calculated timing advance value, then the uplink data transmission can be synchronized, but the high-speed satellite movement and large transmission delay make it difficult to ensure the timing advance adjustment value remains non-negative
Solution Approach 1:
The network device provides feedback information to the terminal device regarding the timing advance adjustment value. Based on this feedback, the terminal device can adjust its timing advance calculation to ensure the adjustment value remains non-negative. This feedback mechanism allows continuous optimization of the timing advance value, maintaining both uplink transmission efficiency and adjustment validity despite satellite movement and transmission delays.
Data Source
AI summary
A communication method is provided. In the method, after determining a first offset value, a terminal device decreases the first offset value, where the first offset value is used to send a random access request in advance; and the terminal device sends the random access request to a network device by using a decreased first offset value, and receives a random access response from the network device, where a timing advance adjustment value indicated by the random access response is greater than or equal to 0.