scholarly journals Simulation Results of the Global Coverage Area of the Medium Earth Orbit Segment of the COSPAS–SARSAT System

2017 ◽  
Vol 4 ◽  
pp. 24-34
Author(s):  
D. V. Antonov ◽  
◽  
A.A. Romanov ◽  
Keyword(s):  
Earth Orbit ◽  
Coverage Area ◽  
Orbit Segment ◽  
Global Coverage ◽  
Simulation Results

Hierarchical Supervisor and Agent Routing Algorithm in LEO/MEO Double-layered Optical Satellite Network

2016 ◽  
Vol 37 (3) ◽  
Author(s):  
Yongjun Li ◽  
Shanghong Zhao
Keyword(s):  
Routing Algorithm ◽  
Single Layer ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Satellite Network ◽  
Coverage Area ◽  
Topology Changes ◽  
Global Coverage ◽  
Is Integration ◽  
Leo Satellite

AbstractA novel routing algorithm (Hierarchical Supervisor and Agent Routing Algorithm, HSARA) for LEO/MEO (low earth orbit/medium earth orbit) double-layered optical satellite network is brought forward. The so-called supervisor (MEO satellite) is designed for failure recovery and network management. LEO satellites are grouped according to the virtual managed field of MEO which is different from coverage area of MEO satellite in RF satellite network. In each LEO group, one LEO satellite which has maximal persistent link with its supervisor is called the agent. A LEO group is updated when this optical inter-orbit links between agent LEO satellite and the corresponding MEO satellite supervisor cuts off. In this way, computations of topology changes and LEO group updating can be decreased. Expense of routing is integration of delay and wavelength utilization. HSARA algorithm simulations are implemented and the results are as follows: average network delay of HSARA can reduce 21 ms and 31.2 ms compared with traditional multilayered satellite routing and single-layer LEO satellite respectively; LEO/MEO double-layered optical satellite network can cover polar region which cannot be covered by single-layered LEO satellite and throughput is 1% more than that of single-layered LEO satellite averagely. Therefore, exact global coverage can be achieved with this double-layered optical satellite network.

scholarly journals A Sensor Deployment Approach Using Improved Virtual Force Algorithm Based on Area Intensity for Multisensor Networks

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Jiahao Xie ◽  
Daozhi Wei ◽  
Shucai Huang ◽  
Xiangwei Bu
Keyword(s):  
Sensor Deployment ◽  
Local Optimum ◽  
Detection Model ◽  
Coverage Optimization ◽  
Virtual Force ◽  
Global Coverage ◽  
Optimal Deployment ◽  
Coverage Quality ◽  
Simulation Results ◽  
Sensor Detection

Sensor deployment is one of the major concerns in multisensor networks. This paper proposes a sensor deployment approach using improved virtual force algorithm based on area intensity for multisensor networks to realize the optimal deployment of multisensor and obtain better coverage effect. Due to the real-time sensor detection model, the algorithm uses the intensity of sensor area to select the optimal deployment distance. In order to verify the effectiveness of this algorithm to improve coverage quality, VFA and PSOA are selected for comparative analysis. The simulation results show that the algorithm can achieve global coverage optimization better and improve the performance of virtual force algorithm. It avoids the unstable coverage caused by the large amount of computation, slow convergence speed, and easily falling into local optimum, which provides a new idea for multisensor deployment.

scholarly journals Design Coverage Optimization Based on Position of Constellations and Cost of the Launch Vehicle

2021 ◽  
Vol 17 ◽  
pp. 1160-1190
Author(s):  
Saeid Kohani ◽  
Peng Zong ◽  
Fengfan Yang
Keyword(s):  
Genetic Algorithms ◽  
Optimal Design ◽  
Launch Vehicle ◽  
Multiple Objective ◽  
Satellite Constellations ◽  
Coverage Optimization ◽  
Satellite Constellation ◽  
Constellation Design ◽  
Global Coverage ◽  
Simulation Results

This research will analyze the tradeoffs between coverage optimization based on Position dilution of precision (PDOP) and cost of the launch vehicle. It adopts MATLAB and STK tools along with multiple objective genetic algorithms (MOGA) to explore the trade space for the constellation designs at different orbital altitudes. The objective of optimal design solutions is inferred to determine the economic and efficient LEO, MEO, HEO or hybrid constellations and simulation results are presented to optimize the design of satellite constellations. The benefits of this research are the optimization of satellite constellation design, which reduces costs and increases regional and global coverage with the least number of satellites. The result of this project is the optimization of the number of constellation satellites in several orbital planes in LEO orbit. Validations are based on reviewing the results of several simulations. The results of graphs and tables are presented in the last two sections and are taken from the results of several simulations.

scholarly journals Digital Connectivity and Low Earth Orbit Satellite: Constellations Opportunities for Asia and the Pacific

2021 ◽  
Author(s):  
John Garrity ◽  
Arndt Husar
Keyword(s):  
Satellite Communication ◽  
Low Earth Orbit ◽  
Small Island ◽  
Earth Orbit ◽  
Satellite Constellations ◽  
Mobile Cellular ◽  
Cable Networks ◽  
The Pacific ◽  
Mobile Cellular Networks ◽  
Global Coverage

Satellite communication plays an important role in the global connectivity ecosystem. It connects rural and remote populations, provides backhaul connectivity to mobile cellular networks, and enables rapid communications for emergency and disaster responses. Low Earth orbit constellations may prove to be transformational to the connectivity landscape based on their global coverage and their suitability for areas not served by fiber optic cable networks. The Asian Development Bank’s developing member countries are well placed to benefit from this expansion of internet connectivity. It will be particularly valuable for small island developing states and landlocked developing countries with limited international bandwidth internet.

scholarly journals Study on Zero-Doppler Centroid Control for GEO SAR Ground Observation

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yicheng Jiang ◽  
Bin Hu ◽  
Yun Zhang ◽  
Meng Lian ◽  
Zhuoqun Wang
Keyword(s):  
Control Method ◽  
Elliptical Orbit ◽  
Earth Orbit ◽  
New Approach ◽  
Orbital Parameters ◽  
Ground Observation ◽  
The Earth ◽  
Satellite Platform ◽  
Simulation Results ◽  
The Look

In geosynchronous Earth orbit SAR (GEO SAR), Doppler centroid compensation is a key step for imaging process, which could be performed by the attitude steering of a satellite platform. However, this zero-Doppler centroid control method does not work well when the look angle of radar is out of an expected range. This paper primarily analyzes the Doppler properties of GEO SAR in the Earth rectangular coordinate. Then, according to the actual conditions of the GEO SAR ground observation, the effective range is presented by the minimum and maximum possible look angles which are directly related to the orbital parameters. Based on the vector analysis, a new approach for zero-Doppler centroid control in GEO SAR, performing the attitude steering by a combination of pitch and roll rotation, is put forward. This approach, considering the Earth’s rotation and elliptical orbit effects, can accurately reduce the residual Doppler centroid. All the simulation results verify the correctness of the range of look angle and the proposed steering method.

scholarly journals Max–Min Fairness Optimization for D2D Communications Coexisting with Cellular Networks

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1422
Author(s):  
Hoai Giang Nguyen ◽  
Xuan Tung Nguyen ◽  
Van Son Nguyen ◽  
Trinh Van Chien ◽  
Tien Hoa Nguyen ◽  
...  
Keyword(s):  
Spectral Efficiency ◽  
Multiple Access ◽  
Optimization Problem ◽  
Mutual Interference ◽  
D2d Communications ◽  
Power Budget ◽  
Good Service ◽  
Coverage Area ◽  
Channel Condition ◽  
Simulation Results

This paper considers a system consisting of a nonorthogonal multiple access (NOMA)-based device-to-device (D2D) communication system within a cellular network, in which the time and frequency resources are shared by everyone. In particular, D2D groups that constitute different pairs are assigned to the subchannels that the cellular users occupy. A max–min fairness optimization problem with power budget constraints is formulated and solved in this paper to reduce the mutual interference between the cellular users and D2D devices that substantially impacts that with the worst channel condition. For a low computational complexity solution, we propose the use of the bisection method together with the solution of a system of linear equalities. The proposed algorithm can provide uniformly good service to all of the cellular users and D2D devices in the coverage area by utilizing the minimal total transmit power. The simulation results indicate the effectiveness of the proposed algorithm in the improvement of the spectral efficiency of the worst user under the different widely used subchannel assignments and pairing techniques.

Study of MVDR Adaptive Beam High Resolution Bearing Estimation Algorithms Based on SMI

2014 ◽  
Vol 926-930 ◽  
pp. 1840-1845
Author(s):  
Hao Zhou ◽  
Zhi Jie Huo
Keyword(s):  
High Resolution ◽  
Matrix Inversion ◽  
Beam Forming ◽  
Strongly Correlated ◽  
Music Algorithm ◽  
Coverage Area ◽  
Estimation Algorithms ◽  
Sample Covariance ◽  
Bearing Estimation ◽  
Simulation Results

This dissertation systematically studies beam space high resolution bearing estimation algorithms. The solution to target resolving and bearing estimation is proposed to remove the contribution from interferes outside the beam coverage area. MVDR adaptive beam based on sample covariance matrix inversion (SMI) is demonstrated for the condition under which strong interferes and signals are weakly correlated. For the situation that strong interferes and signals are strongly correlated, MVDR beam forming algorithm based on virtual interferes is proposed to suppress strong interferes. Simulation results indicate that the beam space MUSIC algorithm based on MVDR is an effective way to resolve multiple targets in small angle domain.

scholarly journals The Parameters Comparison of the “Starlink” LEO Satellites Constellation for Different Orbital Shells

2021 ◽  
Vol 2 ◽  
Author(s):  
Shkelzen Cakaj
Keyword(s):  
The United States ◽  
Low Earth Orbit ◽  
Point Of View ◽  
Earth Orbit ◽  
Coverage Area ◽  
Integrated Network ◽  
Broadband Internet ◽  
Orbital Parameters ◽  
Ground Station ◽  
Broadband Services

Communications-integrated satellite-terrestrial networks used for global broadband services have gained a high degree of interest from scientists and industries worldwide. The most convenient structures for such use are low Earth orbit satellites, since they fly closer to the Earth compared to the other orbits, and consequently provide significantly lower latency, which is essential for reliable and safe communications. Among these efforts is the Starlink satellites constellation, developed and partly deployed by the United States Company SpaceX. The constellation is planned to be organized in three spatial shells, each of them made up of several hundreds of small-dimensioned and light-weighted low Earth orbit specially designed satellites to provide broadband services, intending to offer global Earth coverage through their interoperability, combined also with the ground stations as a part of the satellite-terrestrial integrated network. By October 24, 2020, 893 satellites are situated in orbit of altitudes of 550 km under different inclinations, determining the first Starlink orbital shell. Two next generations are planned to be situated at altitudes of 1,110 and 340 km, to complete the appropriate infrastructure of three Starlink satellite shells, toward a global presence of broadband internet services. These three orbital shells offer different space views seen from the ground station (user) because of their different altitudes, thus in this paper a few parameters which describe the satellite’s behavior considered from the ground station’s (user’s) point of view are compared. These parameters in fact stem from the space orbital parameters and are defined as: horizon plane wideness, slant range, latency, and coverage area. A comparison is given for the three Starlink orbit layers, with identification of appropriate drawbacks and advantages as performance indicators. By the end, these parameters are applied to geometrically interpret and confirm the handover process among satellites. This paper may serve to highlight the new challenges of the satellite-terrestrial integrated network, providing some theoretical analysis and performance comparisons for the satellites in different orbit layers seen from the ground station (user) perspective.

scholarly journals Improvement and Simulation of an Autonomous Time Synchronization Algorithm for a Layered Satellite Constellation

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Feijiang Huang ◽  
Xiaochun Lu ◽  
Guangcan Liu ◽  
Liping Sun ◽  
Wang Sheng ◽  
...  
Keyword(s):  
Time Synchronization ◽  
Earth Orbit ◽  
Satellite Constellations ◽  
Satellite Constellation ◽  
Ground Station ◽  
Synchronization Algorithm ◽  
Satellite Visibility ◽  
Simulation Results ◽  
Simulation Errors ◽  
System Time

Autonomous time synchronization for satellite constellations is a key technology to establish a constellation system time without the use of a ground station. The characteristics of satellite visibility time for layered satellite constellations containing geostationary earth orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) satellites are simulated by establishing a visible satellite model. Based on the satellite visible simulation results for a layered constellation, this study investigates the autonomous time synchronization algorithm that corresponds to the layered constellation structure, analyzes the main error of the time synchronization algorithm, and proposes methods to improve the characteristics of satellite movement in the constellation. This study uses an improved two-way time synchronization algorithm for autonomous time synchronization in the GEO-MEO satellite layer of a layered satellite constellation. The simulation results show that in a condition with simulation errors, the time synchronization precision of this improved algorithm can be controlled within 5 ns and used in high-precision autonomous time synchronization between layered satellite constellations.

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