Various methods for kinematic and reduced-dynamic precise orbit determination (POD) of Low Earth Orbiters (LEO) were developed based on zeroand double-differencing of GPS carrier-phase measurements with and without ambiguity resolution. In this paper we present the following approaches in LEO precise orbit determination: – zero-difference kinematic POD, – zero-difference dynamic POD, – double-d...

The problem of handoffs in cellular networks is compounded in a low earth orbit (LEO) satellite-based cellular network due to the relative motion of the satellites with respect to a stationary observer on earth. Typically, the velocity of motion of mobiles can be ignored when compared to the very high velocity of the footprints of satellites. We exploit this property of LEO satellite systems an...

There is an increasing demand for interconnecting LAN's at high data rates, e.g. remote X-Applications. Due to the lack of B-ISDN before the second decade of the next century, satellite systems are the only alternative. We compare the End-to-End cell delay of a geostationary satellite system with a low earth orbit satellite system by means of simulation. The comparison shows that the use of LEO...

A completely geometric approach for precise orbit determination (POD) of low earth orbiter (LEO) spacecraft has been devised by the authors which does not use dynamic models, but only data from the GPS receiver onboard the LEO and the International GPS Service (IGS) precise GPS ephemeris product. The strategy relies on combining the time-continuous measurement strength of the pseudorange and ca...

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 ...

THE IMPACT project (Fig. 1), funded by an internal research and development process at Los Alamos National Laboratory (LANL), has the goal to develop an integrated modeling system for addressing current needs in space debris and conjunction analysis for resident space objects (RSOs) in low Earth orbit (LEO). Now, almost three years into the project, we have developed an integrated solution comb...

An experiment in Low Earth Orbit (LEO) is proposed to measure components of the Riemann curvature tensor using atom interferometry. We show that the difference in the quantum phase ∆φ of an atom that can travel along two intersecting geodesics is given bymR0i0j/~ times the spacetime volume contained within the geodesics. Our expression for ∆φ also holds for gravitational waves in the long wavel...

This paper presents the evaluation performance of a hybrid satellite constellation network which provides internet access based Transport Control Protocol (TCP). The evaluated satellite network uses the constellation topology operating on Low Earth Orbit (LEO). The COMMStellationTM satellite system implemented using network simulator 2 (NS-2). In this paper, we modified a congestion window cont...

Low-Earth Orbit (LEO) satellite systems are intended to have an important part of the future generation of mobile telecommunication systems. They aim to provide diierent services to various populations of users. Each class of users requires a certain Quality of Service (QoS) and thus a given part of the shared channel resource. In this paper, LEO satellite systems based on an earth-xed cell con...

The Namuru family of Field Programmable Gate Array (FPGA)-based GNSS receivers now includes a space-qualified design designated the Namuru V3.2A. This GPS L1 carrier phase receiver is suitable for low earth orbit (LEO) “cube” satellites. Actel flash-based FPGA’s are used along with latch-up detection circuitry and other standard techniques to provide resilience to the effects of radiation. The ...