Random access channel transmission method and device in low earth orbit satellite communication

Abstract

The invention provides a random access channel transmission method in low earth orbit satellite communication. The method comprises the following steps: selecting a PN sequence in a set sequence formfrom a set PN sequence set; mapping the PN sequence to a subcarrier according to a preset conversion mode; and performing inverse fast Fourier transform on the subcarrier mapped with the PN sequence,transforming the subcarrier mapped with the PN sequence to a time domain, and transmitting the subcarrier mapped with the PN sequence to a base station in a predetermined form. According to the method, the PN sequence in the set sequence form is adopted to bear the signal to be transmitted and replace the ZC sequence adopted by the existing Preamble sequence, so that the condition of a false peakin the transmission process is avoided, the main peak can be identified more effectively, the terminal can be accessed to the base station in time, and the base station can receive the signal effectively. According to the method provided by the embodiment of the invention, when the PN sequence is transmitted to the base station, the CP does not need to be transmitted, so that the time overhead issaved.

Description

technical field [0001] The invention relates to the field of low-orbit satellite communication, in particular to a random access channel transmission method and device in low-orbit satellite communication. Background technique [0002] With the development of communication technology, people's demand for real-time information is getting higher and higher. Relying on its many advantages such as wide coverage, large communication capacity, and good transmission quality, satellite communication has become an indispensable and important means of global communication. [0003] The random access channel PRACH in satellite communication is mainly used for estimating the uplink transmission timing error, estimating uplink frequency offset error and estimating SNR when the user accesses. The channel characteristics of the satellite channel are that the coverage of the satellite beam is very large, with an area of ​​60km*1000km. Before the uplink timing, the uplink timing error will ...

AI Technical Summary

Problems solved by technology

After research on the existing transmission process, it is found that the ZC sequence will appear false peaks when there is a frequency offset. When the frequency offset exceeds half of the subcarrier spacing, the energy of the false peaks is even greater than the energy of the main peak, making it impossible to determine the transmission. The main peak of the signal, unable to effectively receive the signal

[0007] The frequency deviation of satellite communication is as high as ±30kHz. Under this frequency deviation, even if the preamble configuration with 60kHz subcarrier spacing is used, the main peak cannot be correctly judged.

At the same time, when the subcarrier spacing is larger, more RBs in the frequency domain are occupied, resulting in an increase in the overhead for PRACH

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