College of Electronic Science, National University of Defense Technology, Changsha 410073, China.
Sensors (Basel). 2019 Oct 29;19(21):4700. doi: 10.3390/s19214700.
Low Earth Orbit (LEO) is of great benefit for the positioning performance of Global Navigation Satellite System (GNSS). To realize the system of LEO-augmented GNSS, three methods to integrate communication and navigation signal for LEO communication system with the least influence on the communication performance are analyzed. The analysis adopts the parameters of IRIDIUM signal as restrictions. This paper gives quantitative comparison of these methods considering CN0(carrier noise power spectral density rate) margin, pseudorange accuracy, Doppler accuracy, and communication loss. For method 1, a low-power navigation signal is added to the communication signal. For method 2, the navigation signal is launched in one or more frames. For method 3, the navigation signal is launched in the frequency band separated to the communication signal. The result shows that the pseudorange accuracy of method 2 is far below method 1 and method 3. However, the difference of Doppler accuracy among the three methods can be emitted. Detailed analysis shows that method 1 is practicable when the communication and navigation signal power rate is 15 dB. It achieves the balance of pseudorange accuracy and bit error rate (BER) performance under this condition. Comprehensive comparison of these methods is given in the last. The result shows that the CN0 margin of the navigation signal for method 3 can be 13.04 dB higher than method 1, based on the accuracy threshold considered in this paper. Methods 1 and 3 have the advantage of high accuracy and high CN0 margin respectively. However, method 3 causes high communication capacity loss. Considering that the main disadvantage of GNSS signals is low CN0, method 3 is a good choice for the LEO-augmented GNSS system. Methods 1 and 3 can be combined to realize both high accuracy and high CN0 margin if possible.
低地球轨道 (LEO) 对全球导航卫星系统 (GNSS) 的定位性能有很大的好处。为了实现 LEO 增强型 GNSS 系统，分析了三种将通信和导航信号集成到 LEO 通信系统中的方法，以对通信性能的影响最小。该分析采用 IRIDIUM 信号的参数作为限制。本文考虑 CN0（载波噪声功率谱密度率）裕量、伪距精度、多普勒精度和通信损耗，对这三种方法进行了定量比较。对于方法 1，在通信信号中添加低功率导航信号。对于方法 2，导航信号在一个或多个帧中发射。对于方法 3，导航信号在与通信信号分离的频带中发射。结果表明，方法 2 的伪距精度远低于方法 1 和方法 3。然而，三种方法的多普勒精度差异可以忽略不计。详细分析表明，当通信和导航信号功率比为 15dB 时，方法 1 是可行的。在这种情况下，它实现了伪距精度和误码率（BER）性能之间的平衡。最后对这些方法进行了综合比较。结果表明，在本文考虑的精度阈值下，方法 3 的导航信号的 CN0 裕量可以比方法 1 高 13.04dB。方法 1 和 3 分别具有高精度和高 CN0 裕量的优势。然而，方法 3 会导致通信容量的巨大损失。考虑到 GNSS 信号的主要缺点是低 CN0，方法 3 是 LEO 增强型 GNSS 系统的一个不错的选择。如果可能的话，方法 1 和 3 可以结合起来实现高精度和高 CN0 裕量。
