Uplink synchronization method in satellite communication system

A satellite communication system and timing system technology, applied in the field of uplink synchronization, can solve the problems of frequent update of terminal initial information, high maintenance cost, frequent ground base station construction, etc., so as to avoid air interface overhead and complex terminal processing, simplify terminal operation, reduce Effect of Receive Window Length

Pending Publication Date: 2022-05-31
北京九天微星科技发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For the on-board transparent forwarding processing mode, the terminal needs to obtain the location information of the ground base station and the ephemeris information, and the error of the ephemeris and geographical location information needs to be controlled in a small range, and the ground base station is frequently constructed, and the initial information of the terminal needs to be updated frequently, maintenance very expensive

Method used

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  • Uplink synchronization method in satellite communication system
  • Uplink synchronization method in satellite communication system
  • Uplink synchronization method in satellite communication system

Examples

Experimental program
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Effect test

Embodiment 1

[0027] In this embodiment, both the base station and the terminal are synchronized with the global navigation satellite system GNSS, and the same reference time point is used as the frame start time T1, and the base station sends a downlink synchronization signal at the reference time point. After receiving the downlink synchronization signal, the terminal calculates the time difference T_offset=T2-T1 between the arrival time T2 of the downlink synchronization signal and the reference time point T1 to obtain the transmission delay from the base station on the ground or base station on the satellite to the terminal. The terminal sends T_offset in advance according to the receiving time requirements of the base station, so that the signal reaches the base station at the specified time T3, and the base station can complete signal reception within a small detection window, please refer to figure 2 . The main steps include:

[0028] Step 1. Both the base station and the terminal ...

Embodiment 2

[0038] Embodiment 2: Uplink synchronization method of on-board processing base station

[0039] For the schematic diagram of the synchronization method proposed in this embodiment, please refer to image 3 . Including the following steps:

[0040] Both the base station and the terminal are synchronized with GNSS to obtain 1PPS timing, and the timing accuracy can generally meet the 1us deviation;

[0041] Both base station and terminal generate 10ms frame boundary timing based on 1PPS information:

[0042] The base station assigns an even frame number to the first 10ms wireless frame after 1PPS timing, and an odd frame number to the second 10ms wireless frame. The subsequent frame numbers are accumulated sequentially. The frame number ranges from 0 to 1023. After the accumulation reaches 1023, the Start numbering from 0 again;

[0043] The terminal reference timing system defaults that the first 10ms wireless frame after 1PPS is an even frame, and subsequent even frames and...

Embodiment 3

[0047] Embodiment 3: Uplink synchronization method of transparent forwarding base station

[0048] Please refer to Figure 4 , in this embodiment, the on-board part is only used for transparent forwarding of data. Uplink synchronization at this time mainly includes the following steps:

[0049] Both the ground base station and terminal are synchronized with GNSS or 1588V2 to obtain 1PPS timing, and the transparent forwarding unit on the star does not need to be synchronized with GNSS.

[0050] Both the ground base station and the terminal generate 10ms frame boundary timing based on 1PPS information: the ground base station assigns an even frame number to the first 10ms wireless frame after 1PPS timing, and assigns an odd frame number to the second 10ms wireless frame, and the subsequent frames accumulate frame numbers sequentially , the frame number range is 0 to 1023. After the accumulation reaches 1023, it needs to start numbering from 0 again; the terminal reference timi...

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Abstract

The invention provides an uplink synchronization method in a satellite communication system, which comprises the following steps of: keeping time synchronization between a base station and a terminal and the same time service system, and mapping a downlink frame reference moment through the same rule; the terminal automatically measures the deviation between the arrival time of the downlink frame and the reference time, and the deviation is used as one-way transmission time delay from the base station to the terminal; and the terminal sends an uplink signal in advance according to the one-way transmission time delay, so that the uplink signal reaches a base station side in an expected receiving time window. Transmission delay measurement from the base station to the terminal can be completed without depending on any ephemeris and geographic position information, and air interface overhead and terminal complex processing caused by base station position updating are avoided; for the base station in a transparent forwarding processing mode, the terminal does not need to be processed differently, and terminal operation is simplified; the accurate terminal uplink time delay pre-compensation mechanism can greatly reduce the RACH receiving window length, thereby reducing the uplink overhead and shortening the access time delay.

Description

technical field [0001] The invention relates to the field of satellite communication, in particular to an uplink synchronization method in a satellite communication system. Background technique [0002] A key issue in the satellite communication system is uplink synchronization. Satellite communication uplink synchronization means that the terminal adjusts the signal transmission time so that the signal arrives at the base station on the star at a specified time. The general steps include: the ground terminal sends out a RACH signal for random access; the base station on the star By detecting the arrival time of the RACH signal, the signal transmission delay from the terminal to the base station is calculated; the base station sends a timing adjustment TA command to the terminal; the terminal adjusts the signal transmission time so that the signal arrives at the base station on the star at a specified time point. [0003] According to the terrestrial 5G solution, the length ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04W56/00H04W84/06
CPCH04W56/0005H04W56/004H04W84/06Y02D30/70
Inventor 张俊庆兴发
Owner 北京九天微星科技发展有限公司
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