Satellite PRACH Random Access Timing for Lower Channel Overhead
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Solution Overview
Problem
The existing random access processes in Non-Terrestrial Networks (NTN) systems, such as satellite communication, face inefficiencies due to increased PRACH channel overhead and reduced transmission efficiency caused by the need for longer cyclic prefixes (CP) to counteract relative transmission delays, which are not adequately addressed by current 5G NR-based closed-loop random access methods.
Innovation Solution
An open-loop random access process is introduced, where terminals determine uplink transmission timing positions based on cell public delay information, compensating for relative and public transmission delays, allowing for smaller CP lengths and reducing PRACH channel overhead by sending PRACH Preamble sequences in advance, thus improving transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the closed-loop random access process based on NR is reused, then the existing random access procedure can be maintained, but the overhead of the PRACH channel increases and transmission efficiency decreases
Solution Approach 1:
The patent changes the timing parameter by determining uplink transmission timing position based on cell public delay information, allowing terminals to send PRACH Preamble sequences in advance. This parameter change reduces the required CP length and decreases PRACH channel overhead while maintaining reliable random access procedure.
2Reliability
If the CP length is increased to counteract relative transmission delay, then uplink synchronization is improved, but the PRACH channel overhead increases
Solution Approach 1:
The patent applies preliminary action by having terminals determine uplink transmission timing position in advance based on cell public delay information. This allows the PRACH Preamble sequence to be sent before the actual uplink transmission, achieving uplink synchronization without requiring a long CP to counteract relative transmission delay, thus reducing PRACH channel overhead.
3Adaptability or versatility
If the PRACH Preamble format is redesigned to support larger CP lengths, then satellite communication requirements are met, but device complexity increases
Solution Approach 1:
The patent uses parameter changes by modifying the timing position parameter rather than the CP length parameter. Terminals determine uplink transmission timing position based on cell public delay information, which allows the existing PRACH Preamble format to be used without redesign, thereby supporting satellite communication requirements while avoiding increased device complexity.
Data Source
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AI summary
Embodiments of the present application relates to a method and device for random access, for use in resolving the problem that no current random access process can satisfy requirements of a satellite communication system. The method of the embodiments of the present application comprises: receiving and obtaining a related parameter in a configuration message, the related parameter comprising common cell delay information; generating a physical random access channel random access preamble (PRACH Preamble) sequence, and determining an uplink sending timing location according to the common cell delay information; and sending the PRACH Preamble sequence on a time-frequency resource corresponding to the uplink sending timing location. A relative transmission delay and a multi-path channel delay from a terminal, to a satellite, and to a base station are compensated according to the determined uplink sending timing location, thereby reducing overheads of a PRACH channel.