Research and Analysis of Promoting the Performance of LEO Satellite Communication

• Main Authors: Wang, Kai-Yuan, 王開源
• Other Authors: Li, Sheng-Yi
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/73322918602060520777

博士 === 國防大學理工學院 === 國防科學研究所 === 100 === The low-earth-orbiting (LEO) satellites prefer to geostationary (GEO) satellites because of their lower orbit altitude, shorter transmission delay, and relatively low launch expense. Seamless communication and good link quality can be achieved by using a satellite constellation. However, the scenarios of the visible LEO satellites to an earth station are varying with time, and channel fading state changes accordingly. From the past references about improving performance for a LEO satellite, we find the most researchers only focus on the fix or the finite channel state to develop algorithms or methods to promote and analyze the performance. It is a challenge to present exactly the effect of time varying scenario in LEO satellite communication environment. Thus, we focus on the research and analysis of promoting the performance of communication in the LEO satellite constellation. Based on the spherical geographic analysis, we use the probability density function of elevation-angle and the visibility probability of satellite to propose the algorithm of choosing the optimize earth station, and use the scenario PDF of LEO satellite to derive the probability density function of the satellite maximum elevation angle selection diversity and the probability density function of satellite path diversity. Through simulation and performance analysis in time varying elevation-angle- dependent channel and path-dependent channel, respectively, we obtain the optimized position of the earth station quickly and also have verified that only two low earth orbiting satellites can offer the optimal path diversity performance. We propose the models and methods which have the advantage of not involving orbital simulations for data collection, thus avoiding statistical processing as well as curve fitting. By the way, we would analyze the performance of diversity quickly in time varying scenario if we specified the parameters of a earth station and the LEO satellite constellation. So, that will be helpful for system designers to determine the receiver location or the satellite orbit parameters at the stage of designing satellite constellation.