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Cell search, cell access method and device in satellite communication

A technology of satellite communication and cell search, applied in the field of communication

Active Publication Date: 2018-07-03
SPREADTRUM COMM (SHANGHAI) CO LTD
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  • Abstract
  • Description
  • Claims
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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

Method used

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  • Cell search, cell access method and device in satellite communication
  • Cell search, cell access method and device in satellite communication
  • Cell search, cell access method and device in satellite communication

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Embodiment Construction

[0061] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0062] LTE (Long Term Evolution, long-term evolution) is the long-term evolution of the UMTS (Universal MobileTelecommunications System, Universal Mobile Communications System) technical standard formulated by 3GPP (The 3rd Generation Partnership Project, Third Generation Partnership Project), which was launched in December 2004 The project w...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04W4/02H04W48/16H04W48/18H04W84/06H04J11/00H04L27/00H04B7/185
CPCH04W84/06H04W48/04H04W48/20H04W74/0833H04W56/004
Inventor 董宇刘文明汪波
Owner SPREADTRUM COMM (SHANGHAI) CO LTD
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