Efficient Mobility Management of Earth Terminals for Low Earth Orbit (LEO) Satellite Systems

2006 ◽  
Author(s):  
Yasushi Wakahara ◽  
Hiroko Tsuchiya ◽  
Jun-ichi Mizusawa
Keyword(s):  
Mobility Management ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Satellite Systems ◽  
Leo Satellite

SUPPORTING DISTRESS SIGNALS OVER LOW EARTH ORBIT MOBILE SATELLITE SYSTEMS FOR EMERGENCY INFORMATION ACQUISITION

2013 ◽  
Vol 09 (03n04) ◽  
pp. 1350018
Author(s):  
GAMAL A. HUSSEIN ◽  
MOSTAFA A. NOFAL ◽  
MOAWAD I. DESSOUKY ◽  
OSAMA ALY ORABY ◽  
WALEED AL-HANAFY ◽  
...  
Keyword(s):  
Information Acquisition ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Rescue Operation ◽  
Satellite Systems ◽  
Leo Satellites ◽  
Mobile Satellite ◽  
Voice Data ◽  
Leo Satellite ◽  
Service Priority

Low earth orbit (LEO) satellite systems allow a broad range of services to be provided using small, lightweight, cellular-like portable telephones. Exploiting LEO satellites to support distress signals for aircrafts, ships and international travelers is explored in the current paper. A multi-service priority-oriented algorithm is proposed for handling voice, data and emergency signals over LEO satellites. The emergency signal is privileged with service priority so that rescue operation can be carried out as soon as possible. The priority mechanism includes channel reservation as well as joining a queue if no free channel is available as long as the request is roaming in the handover area. In addition, a simplified but efficient approach is suggested for locating the object of an imminent danger situation. As LEO satellites are non-geostationary, the visible period of each spot-beam is small. Consequently, a teletraffic model, that accommodates the mobility of spot-beams as well as the resulting handover rate, is developed in order to gauge the performance of the proposed algorithm. Numerical results for access denying and service-dropping rates are presented for nominal system parameters.

scholarly journals Simulation study of the plasma-brake effect

2014 ◽  
Vol 32 (10) ◽  
pp. 1207-1216 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ionospheric Plasma ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Breaking Force ◽  
Field Orientation ◽  
Particle In Cell ◽  
Leo Satellite ◽  
The Magnetic Field

Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

Performance of Low Earth Orbit Satellite Systems with a Gaussian Mixtures Traffic Distribution

Frequenz ◽  
2002 ◽  
Vol 56 (3-4) ◽  
Author(s):  
Hebatallah M. Mourad ◽  
Abd El-Aziz M. El-Basioni ◽  
Sherief S. Emam ◽  
Emad K. Al-Hussaini
Keyword(s):  
Low Earth Orbit ◽  
Earth Orbit ◽  
Gaussian Mixtures ◽  
Satellite Systems ◽  
Traffic Distribution ◽  
Orbit Satellite ◽  
Low Earth Orbit Satellite

A Comparative Study of Satellite Orbits as Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO)

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Sandeep Vishwakarma ◽  
Aradhana S. Chauhan ◽  
Shoeba Aasma
Keyword(s):  
Satellite Orbit ◽  
Low Earth Orbit ◽  
Geostationary Orbit ◽  
Earth Orbit ◽  
Satellite Orbits ◽  
Satellite Systems ◽  
Broadcast Television ◽  
Television Use ◽  
Gps System ◽  
Orbiting Systems

It is known facts that satellites are used to receive the signal at geostationary orbit by remaining stationary above a particular point on the Earth. The orbit that is chosen for a satellite depends upon its application. Those used for direct broadcast television use geostationary orbit. Many communication satellites similarly use geostationary orbit. Other satellite systems used for satellite phones use Low Earth orbiting systems. Similarly, satellite systems used for navigation like Nav-star or Global Positioning (GPS) system occupy a relatively Low Earth Orbit. There are also many other types of satellites : Weather satellites Research satellites and many others. Each will have its own type of orbit depending upon its application. The actual satellite orbit that is chosen will depend on factors including its function, and the area of serving. At some instances, the satellite orbit may be as low as 100 miles (160 km) for a Low Earth Orbit (LEO), whereas others may be over 22 000 miles (36000 km) high as in the case of a Geostationary Orbit (GEO). The satellite may even has an elliptical rather than a circular orbit.

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