AbstractThe Advanced Communication Technology Satellite (ACTS) is an experimental communications satellite system launched in September 1993. ACTS introduces many new technologies, including operation in the Ka frequency band. ACTS uses multiple hopping narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for a bit-error-rates of 5x10 or be...

Satellite transmissions have an important role in telephone communications, television broadcasting, computer communications, maritime navigation, and military command and control. Moreover, in many situations they may be the only possible communication set-up. Recent trends in telecommunications indicate that four major growth market/service areas are: messaging and navigation services (wirele...

We present a wide-field (4.5 deg2) photometric and spectroscopic survey of the Leo I dwarf spheroidal (dSph) galaxy to explore its extended morphology and dynamics. As in previous papers in this series, we take advantage of photometry in the M, T2, and DDO51 filter system to select Leo I red giant branch star candidates, and, so far, this selection technique has proven 100% reliable in selectin...

In this paper the problem of sending a spacecraft from Low Earth Orbit (LEO) to the Moon with minimum fuel consumption is considered. It is assumed that the "Two-Body model" approximation is valid in all phases of the mission and that the final orbit around the Moon is polar. The first part deals with impulsive maneuvers, and obtain a set of values for fuel expenditure and trip time for several...

Despite immense progress along different tracks, wireless connectivity for machine applications in remote areas is still very challenging. To address this vital need, article, we discuss and advocate the convergence between low-pow-er wide area network (LPWAN) grade massive machine-type communication (mMTC) technologies satellite (especially low Earth orbit, LEO) systems. In alternative impleme...

Abstract In Low Earth Orbit (LEO), atmospheric drag is the largest contributor to trajectory prediction error. The current thermospheric density model used in operations, High Accuracy Satellite Drag Model (HASDM), applies corrections an empirical every 3 hr using observations of 75+ calibration satellites. This work aims improve global estimation by utilizing a physics‐based space environment ...

Due to the rapid development of space–air–ground integrated network (SAGIN), a satellite communication system has advantages wide coverage and low requirements for geographical environment is gradually becoming main competitive technology 6G. The low-earth-orbit (LEO) characteristics transmission delay, small propagation loss, global coverage, its exploration become research object contemporary...

In this paper we focus on the modeling and evaluation of next generation satellite communications technologies to support future aeronautical communications. Recent studies has identified the delivery of real-time high resolution weather maps to the cockpit as an important future aeronautical application. Focusing on this application, we investigate the use of Lowand GeosynchronousEarth Orbit (...

Low earth orbit (LEO) satellite has been considered as a potential supplement for the terrestrial Internet of Things (IoT). In this paper, we consider grant-free non-orthogonal random access (GF-NORA) in orthogonal frequency division multiplexing (OFDM) system to increase capacity and reduce latency LEO satellite-IoT. We focus on joint device activity detection (DAD) channel estimation (CE) pro...

In this paper, an analytical framework is developed to evaluate the performance of complete sharing (CS) with two different handover priority schemes for multi-class traffic in Low Earth Orbit-Mobile Satellite Systems (LEO-MSS). In the first priority scheme, the handover requests are given the higher priority using queuing scheme with also taking into consideration the priority between classes ...