Satellite PRACH Preamble Configuration for Large Delay Variation
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Solution Overview
Problem
The existing random access preamble formats defined in terrestrial communication protocols are inadequate for satellite communication systems, particularly in non-geostationary satellite orbits, due to the large variation in transmission delays among users, leading to inefficiencies in time domain resource usage and signaling overheads.
Innovation Solution
A random access preamble configuration method is introduced for satellite networks that includes a sequence part and a guard time, without a cyclic prefix, allowing for flexible signaling and efficient resource utilization by minimizing time domain resources, and utilizing a frequency domain enhanced detection method to determine uplink timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing random access preamble formats defined in terrestrial communication protocols are used, then the system can maintain compatibility with standard protocols, but the system cannot handle large transmission delay variations in satellite communication scenarios
Solution Approach 1:
The patent changes the parameter of cyclic prefix length to adapt to satellite communication scenarios. By configuring different cyclic prefix lengths (first length for first uplink signals, second length for second uplink signals), the system can handle large transmission delay variations while maintaining protocol compatibility. This parameter adjustment allows the random access preamble to function reliably in satellite environments with varying round-trip delays.
2Reliability
If a cyclic prefix is added to cover maximum round-trip transmission delay range, then the system can accommodate transmission delay variations, but the time domain resources occupied by random access preamble increase
Solution Approach 1:
The patent implements dynamic cyclic prefix configuration where the length of cyclic prefix adapts to the specific uplink signal type and transmission conditions. First uplink signals use a first cyclic prefix length while second uplink signals use a second cyclic prefix length. This dynamic adjustment ensures adequate coverage for transmission delay variations without unnecessarily occupying excessive time domain resources in all scenarios.
Solution Approach 2:
Different cyclic prefix lengths are applied to different uplink signals based on their specific requirements. First uplink signals (e.g., random access preambles) use one cyclic prefix length, while second uplink signals (e.g., PUSCH) use another length. This localized quality adjustment optimizes resource usage for each signal type individually rather than using a uniform cyclic prefix length for all signals.
3Device complexity
If unified time domain resource allocation is used for different uplink signals, then the system can simplify resource management, but the system cannot optimize resource usage for signals with different transmission characteristics
Solution Approach 1:
The patent segments time domain resources by configuring different cyclic prefix lengths for different uplink signal types. First uplink signals and second uplink signals are allocated resources with different cyclic prefix configurations, allowing optimized resource usage for each signal type's specific transmission characteristics while maintaining manageable resource allocation through standardized configuration procedures.
Data Source
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AI summary
This application discloses a random access preamble configuration method applicable to a satellite network and a communication apparatus. In the method, a random access preamble location offset and duration of a PRACH occasion can be flexibly configured based on features of a satellite system. The method includes: A receiving apparatus receives first indication information, where the first indication information includes indication information used to identify the random access preamble location offset at the physical random access channel PRACH occasion. The receiving apparatus transmits a random preamble based on the first indication information, where the random preamble includes a sequence part and a guard time. Because a communication distance is relatively long and a transmission delay difference between users is relatively large in a satellite communication system, time domain resources occupied by the PRACH occasion can be minimized by using this method.