Satellite Random Access Trip Time Compensation
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Solution Overview
Problem
Current satellite communication systems face challenges in performing random access due to the longer signal trip times, which result in preamble reception failures and collisions, and inefficient response window configurations, especially when using LTE configurations over satellite links.
Innovation Solution
A method for a user equipment (UE) device to determine the signal trip time from received reference signals, allowing for timely compensation of random access preambles and individualized response time intervals, enabling almost synchronous reception and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE random access configuration is used over satellite links, then the system can maintain compatibility with existing LTE standards, but preamble reception fails and collisions occur due to longer signal trip times
Solution Approach 1:
The patent changes the random access configuration parameters specifically for satellite links. It introduces satellite-specific parameters including extended response window durations (e.g., 8ms, 16ms, 32ms instead of standard LTE values), adjusted preamble formats, and modified timing advance values to compensate for the longer propagation delays in satellite communication, thereby maintaining compatibility while ensuring reliable preamble reception
Solution Approach 2:
The patent segments the random access procedure into satellite-specific configurations. It creates separate parameter sets for satellite links versus terrestrial links, allowing independent optimization of response window timing, preamble formats, and timing advance mechanisms for each link type without affecting the other
2Device complexity
If standard LTE response window timing is used, then the configuration remains simple and consistent with terrestrial networks, but the response timing does not account for longer satellite trip times causing access failures
Solution Approach 1:
The patent modifies the response window timing parameters for satellite links. It extends the response window duration from standard LTE values (e.g., 2-10ms) to satellite-appropriate values (8ms, 16ms, 32ms or longer) to accommodate the extended round-trip propagation delays, while maintaining the same procedural structure to minimize complexity increases
3Device complexity
If timing advance is not compensated for satellite distance, then the system maintains simplicity, but preambles from UEs at different distances arrive at different times causing collisions and reception failures
Solution Approach 1:
The patent introduces satellite-specific timing advance parameters that compensate for the longer propagation delays. It configures extended timing advance values and adjusted timing relationships between preamble transmission and response reception based on satellite distance, ensuring that preambles from UEs at different distances arrive synchronized at the satellite receiver
Solution Approach 2:
The patent performs preliminary timing synchronization by calculating and applying satellite-specific timing advance values before the random access procedure begins. It pre-configures the timing relationships based on expected satellite distances and orbital parameters, allowing UEs to transmit preambles that will arrive synchronized at the satellite without requiring complex real-time adjustments
Data Source
AI summary
The present invention provides a method of performing by a UE device a random access attempt in a communication system comprising at least one non-terrestrial transmission station, the method comprising receiving reference signals transmitted by the non-terrestrial transmission station; determining from the received reference signals a trip time between the UE device and the non-terrestrial transmission station; and using the trip time to control the random access attempt.