Cell search, cell access method and device in satellite communication

Abstract

An embodiment disclosed by the invention relates to a cell search method, a cell access method, a cell search device and a cell access device in satellite communication. The cell search method comprises the steps of calculating distances between a mobile terminal and a plurality of satellite base stations, and calculating Doppler frequency shifts of the plurality of satellite base stations relative to the mobile terminal; selecting, from the plurality of satellite base stations, N satellite base stations which are closest to the mobile terminal; for the N satellite base stations , adopting theDoppler frequency shifts of the plurality of satellite base stations relative to the mobile terminal to perform frequency offset compensation; and selecting cells covered by the satellite base stations with the best signal quality from the N satellite base stations for resident. Correspondingly, the cell access method comprises the steps of: calculating a distance between the mobile terminal anda satellite base station to which a target is accessed; calculating propagation delay according to the distance between the mobile terminal and the satellite base station to which the target is accessed; and bringing forward PRACH according to the propagation delay and the frequency shifts, and performing cell access on the satellite base station to which the target is accessed. According to the cell search method, the cell access method, the cell search device and the cell access device, the application of LTE in satellite communication is realized by adopting an in-advance compensation method.

Description

technical field [0001] The invention relates to the communication field, in particular to cell search and cell access methods and devices in satellite communications. Background technique [0002] Satellite communication is the use of artificial earth satellites as relay stations to forward radio waves, thereby realizing communication between two or more earth stations. Satellite communication is characterized by large Doppler frequency shift (maximum 70KHz) and long uplink and downlink delays and signal fading caused by long communication distance (above 500Km). [0003] The synchronization sequence and frame structure of LTE (Long Term Evolution) limit the maximum Doppler frequency shift that the current LTE protocol can work within ±7.5KHz, and the maximum delay difference between uplink and downlink within 0.7ms ( That is, the maximum distance between the base station and the mobile terminal is limited to about 100km). Therefore, at present, the LTE system cannot be di...

AI Technical Summary

Problems solved by technology

[0003] The synchronization sequence and frame structure of LTE (Long Term Evolution) limit the maximum Doppler frequency shift that the current LTE protocol can work within ±7.5KHz, and the maximum delay difference between uplink and downlink within 0.7ms ( That is, the maximum distance between the base station and the mobile terminal is limited to about 100km)

Therefore, at present, the LTE system cannot be directly used in satellite communication

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