Analysis of maximum traffic intensity under pre-set quality of service requirements in low earth orbit mobile satellite system for fix channel reservation with queueing handover scheme

2015 ◽  
Vol 9 (13) ◽  
pp. 1575-1582 ◽  
Author(s):  
Mingxia Liao ◽  
Yuan'an Liu ◽  
Hefei Hu ◽  
Dongming Yuan
Keyword(s):  
Quality Of Service ◽  
Satellite System ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Traffic Intensity ◽  
Channel Reservation ◽  
Mobile Satellite ◽  
Handover Scheme

scholarly journals An In-Depth Assessment of the New BDS-3 B1C and B2a Signals

2021 ◽  
Vol 13 (4) ◽  
pp. 788
Author(s):  
Qinghua Zhang ◽  
Yongxing Zhu ◽  
Zhengsheng Chen
Keyword(s):  
Carrier Phase ◽  
Density Ratio ◽  
Signal Strength ◽  
Satellite Orbit ◽  
Satellite System ◽  
Earth Orbit ◽  
Base Line ◽  
Signal Characteristics ◽  
Better Than

An in-depth and comprehensive assessment of new observations from BDS-3 satellites is presented, with the main focus on the Carrier-to-Noise density ratio (C/N0), the quality of code and carrier phase observations for B1C and B2a signal. The signal characteristics of geosynchronous earth orbit (GEO), inclined geosynchronous satellite orbit (IGSO) and medium earth orbit (MEO) satellites of BDS-3 were grouped and compared, respectively. The evaluation results of the new B1C and B2a signals of BDS-3 were compared with the previously B1I/B2I/B3I signals and the interoperable signals of GPS, Galileo and quasi-zenith satellite system (QZSS) were compared simultaneously. As expected, the results clearly show that B1C and B2a have better signal strength and higher accuracy, including code and carrier phase observations. The C/N0 of the B2a signal is about 3 dB higher than other signals. One exception is the code observation accuracy of B3I, which value is less than 0.15 m. The carrier precision of B1C and B2a is better than that of B1I/B2I/B3I. Despite difference-in-difference (DD) observation quantity or zero-base line evaluation is adopted, while B1C is about 0.3 mm higher carrier precision than B2a. The BDS-3 MEO satellite and GPS, Galileo, and QZSS satellites have the same level of signal strength, code and phase observation accuracy at the interoperable frequency, namely 1575.42 MHz and 1176.45 MHz which are very suitable for the co-position application.

scholarly journals Detecting Targets above the Earth’s Surface Using GNSS-R Delay Doppler Maps: Results from TDS-1

2019 ◽  
Vol 11 (19) ◽  
pp. 2327 ◽  
Author(s):  
Changjiang Hu ◽  
Craig Benson ◽  
Hyuk Park ◽  
Adriano Camps ◽  
Li Qiao ◽  
...  
Keyword(s):  
Specular Reflection ◽  
Satellite System ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Navigation Satellite ◽  
Reflection Point ◽  
Leo Satellites ◽  
Gnss Reflectometry ◽  
Global Navigation Satellite ◽  
Remotely Sense

Global Navigation Satellite System (GNSS) reflected signals can be used to remotely sense the Earth’s surface, known as GNSS reflectometry (GNSS-R). The GNSS-R technique has been applied to numerous areas, such as the retrieval of wind speed, and the detection of Earth surface objects. This work proposes a new application of GNSS-R, namely to detect objects above the Earth’s surface, such as low Earth orbit (LEO) satellites. To discuss its feasibility, 14 delay Doppler maps (DDMs) are first presented which contain unusually bright reflected signals as delays shorter than the specular reflection point over the Earth’s surface. Then, seven possible causes of these anomalies are analysed, reaching the conclusion that the anomalies are likely due to the signals being reflected from objects above the Earth’s surface. Next, the positions of the objects are calculated using the delay and Doppler information, and an appropriate geometry assumption. After that, suspect satellite objects are searched in the satellite database from Union of Concerned Scientists (UCS). Finally, three objects have been found to match the delay and Doppler conditions. In the absence of other reasons for these anomalies, GNSS-R could potentially be used to detect some objects above the Earth’s surface.

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