The Design And Implementation Of Channel Simulator For Satellite

Satellite communications play an irreplaceable role in the military,maritime,disaster relief and so on.With the development of spatial information technology,simple satellite communication system is evolved into a complex spatial information network.The spatial information network,which fused with ground system,is the threedimensional network based on satellite as the main information processing node.Not only does it deal with traditional voice and low speed data services,but also other high speed date services such as broadband multimedia.Satellite communication is characterized by large signal attenuation,long delay,obvious Doppler effect and channel fading.In the planning of spatial information network,we need channel simulation being close to the real scenario to assist receivers and associated design and evaluation of transport protocols.If we rent actual satellite to simulate,it is time-consuming and money-consuming.Traditional channel simulator focuses on point-to-point wireless signal transmission,but fails to simulate the multiplelink and high dynamic topology structure in spatial information network.This paper designs an extensible channel simulator which may achieve link transmission and dynamic topology changes in spatial information network.This system is composed of simulation platform and control platform.Control platform simulates running status of spatial information network;simulation platform can simulates digital base-band and medium frequency signal respectively according to different applications.The main work is shown as follows:(1)A satellite channel simulator is designed,which can not only simulate link characteristics and dynamic topology changes in spatial information network,but also increase or decrease hardware resources according to simulation scale.(2)Design and implementation of the two sets of simulation platform for digital and analog are given.Based on digital base-band residual error model,digital simulation platform supports digital base-band characteristics simulation of satellite channel,which sustains 8 to 256 digital base-band signal simulation nodes with a maximum data rate of 100 Mbps and link delay of 1 second.Based on Corazza model,channel simulator backs up medium frequency characteristics simulation in satellite channel simulation,which bolsters up 8 to 128 70 MHz medium frequency simulation nodes with a maximum signal bandwidth of 20 MHz,Doppler of 2MHz and propagation delay of 2 seconds.(3)On account of Qt/C++,channel simulator system control platform is achieved,which not only simulates running status of spatial information network by software,but also transmits these statuses to simulation platform in real time and simulates high dynamic topology structure of spatial information network.Meanwhile,possessing friendly user interface,this control platform can display running status of spatial information network in real time by using two-dimentional or three-dimentional animation.In conclusion,this channel simulator overcomes the weaknesses of traditional channel simulators that focus on single-link simulations,and can simulate the spatial information network which have multi-link and high dynamic topology characteristic.