Satellite Random Access Timing Advance Estimation
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Solution Overview
Problem
Existing random access procedures in LTE and NR are not suitable for satellite communications systems due to long propagation delays and large differential delays, which are not accounted for in terrestrial-based designs.
Innovation Solution
Adapting random access procedures to include open-loop timing advance estimation and closed-loop feedback to determine accurate timing advances for uplink transmissions in satellite networks, allowing for successful random access even with significant propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If terrestrial random access procedures are used in satellite networks, then device complexity is reduced, but reliability deteriorates due to long propagation delays
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure multiple timing advance values and corresponding random access preamble groups before the random access procedure. The wireless device selects an appropriate preamble group based on its estimated propagation delay, allowing the system to preemptively accommodate long delays in satellite networks without increasing procedural complexity during actual access.
Solution Approach 2:
The patent changes the timing advance parameter by introducing multiple pre-configured timing advance values (first, second, third timing advance values) corresponding to different propagation delay scenarios. This allows the system to adapt to varying satellite orbit conditions (LEO, MEO, GEO) by selecting appropriate timing parameters without redesigning the entire random access procedure.
2Reliability
If timing advance estimation is performed to handle propagation delays, then random access reliability improves, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the wireless device to autonomously estimate its propagation delay and select the appropriate random access preamble group based on pre-configured thresholds. The device independently determines which timing advance value to use without requiring complex network coordination or additional signaling, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The network performs preliminary configuration by providing the wireless device with multiple timing advance values and their corresponding threshold ranges before the random access procedure. This pre-prepared information allows the device to quickly determine the appropriate timing advance without performing complex real-time calculations, reducing the actual computational burden during random access.
3Adaptability or versatility
If multiple timing advance values are pre-configured to handle differential delays, then adaptability improves, but information overhead increases
Solution Approach 1:
The patent segments the timing advance values into distinct groups (first, second, third timing advance values) with corresponding threshold ranges. This segmentation allows the network to provide adaptability for different satellite orbit types without overwhelming the device with a single large set of parameters. The segmented approach enables efficient selection based on measured propagation delay thresholds.
Solution Approach 2:
The patent changes the information representation by encoding multiple timing advance values and their associated threshold ranges as pre-configured parameters. This parameterization approach allows the network to convey extensive timing information efficiently, enabling the device to adapt to different satellite conditions without requiring excessive signaling overhead during runtime.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables successful random access in satellite communications by accurately handling long propagation delays and differential delays, improving the reliability and efficiency of satellite network operations.
Implementation Method 1
The two main physical phenomena that affect satellite communications system design are the long propagation delay and Doppler effects.
Implementation Method 2
The two main physical phenomena that affect satellite communications system design are the long propagation delay and Doppler effects. The Doppler effects are especially pronounced for LEO satellites.
Data Source
AI summary
Systems and methods are disclosed for random access in a wireless communication system such as, e.g., a wireless communication system having a non-terrestrial (e.g., satellite-based) radio access network. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method performed by a wireless device for random access comprises performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station. The method further comprises transmitting a random access preamble using the open-loop timing advance estimate. In this manner, random access can be performed even in the presence of a long propagation delay such as that present in a satellite-based radio access network. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed.