運用低軌衛星星系場景機率密度函數分析衛星路徑分集之接收效能

Application of LEO Satellite Constellation Scenario PDF to Analyze the Satellite Path Diversity Performance

10.7049/JCHCTC.201210.0001

王開源(Kai-Yuan Wang)；李勝義(Sheng-Yi Li)

低軌道衛星 ； 仰角遮罩 ； 星下點 ； 機率密度函數 ； 分集 ； LEO satellite ； elevation mask ； sub-satellite point ； PDF ； diversity

健行學報

32卷4期（2012 / 10 / 26）

1 - 10

繁體中文

在低軌道衛星星系中，地面站於衛星仰角遮罩範圍內結合多顆可視衛星形成衛星分集後，可有效克服衛星通道衰落情形，以提昇通信傳輸效能。由於低軌衛星相對地面站之傳輸場景具有時變性，為求得有效衛星分集的傳輸效能，運用低軌衛星星系場景機率密度函數分析所有可視衛星的場景機率，並結合每一場景下多顆可視衛星分集後之接收信號機率密度函數，進而得到整體平均接收信號機率密度函數。經以類全球星（Globalstar- like）Walk T/P/F=48/8/1低軌衛星星系架構，採k顆衛星分集模擬，經由接收信號機率密度函數與位元錯誤率分析後，證明該星系架構運用衛星路徑分集，所需衛星數目二顆即可達到最佳的傳輸效能提升。因此，運用本文所提出新的、快速又正確的方法，不需軌道模擬與統計資料處理，可指定任一地面觀測站位置與低軌衛星星系架構參數後，快速有效分析k顆低軌衛星分集傳輸效能。

In the low earth orbiting satellite constellation, satellite diversity will promote communication quality and overcome the channel fading situation if we combine all the visible satellites in the range of the satellite elevation mask. However, the scenario of satellite communication from low earth orbiting satellite to the earth station is time varying. In order to obtain the performance of the satellite diversity, a new method is proposed to quickly and exactly evaluate the probability of scenarios of low earth orbiting satellite constellation observed from the earth station location to all visible satellites in the satellite elevation mask. Through the simulation for the Globalstar-like Walk T/P/F=48/8/1 low earth orbiting satellite constellation, we have verified that only two low earth orbiting satellites can offer the optimal diversity performance. The development does not need any orbital simulations and statistical data processing. Results are used to evaluate the probability density function of the received signal with k-fold combining diversity for any user-specified earth station locations and low earth orbiting satellite constellation parameters.