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Adaptive Modulation and Coding (AMC) is one of the most promising techniques to cope with the dynamic fading of wireless channels, adopted by emerging standards such as LTE and WiMAX. In satellite communications, the upper bound of AMC adjustment period is determined by both long round-trip delay and different channel coherence time. In this paper, the impact of AMC adjustment period in mobile satellite...
First, a new observation equation of a satellite from the intersatellite range-rate interpolation approach (IRRIA) is created by inserting the precise intersatellite range-rate measurements into the line-of-sight component of the orbital velocity difference vector. Second, by a comparison of the two-point, four-point, six-point, and eight-point interpolation formulas, the accuracy of the Earth's gravitational...
The Chlorophyll-a (Chl-a) concentrations in water is of great importance for the monitoring of water quality and ecosystem balance. Remote sensing offers a convenient and systematical tool for the observations of water at a long time scale. In this paper, we present a study of Chl-a estimation using the reflectance models (MOD3 and MOD2) derived from the Medium Resolution Spectral Image (MERSI) onboard...
The estimation of soil wetness variations is of considerable importance to improve the reliability of flood warning. In this paper, Polarization Ratio Variation Index (PRVI) is presented which, on the basis of long-term multi-temporal Special Sensor Microwave/Image (SSM/I) data, can monitor soil wetness variations at a large scale. Nearly 18-years long time series PRVI are calculated based on the...
In this paper a new scheme of attitude control with active magnetic torque and aerodynamic stabilization torque is proposed for low-orbit micro-satellite (orbit altitude lower than 500km), to take full advantage of environmental torque. Aerodynamic torque will be configured as stabilization torque by designing the relatively position of the center of pressure and the centroid. Simulation results show...
The issue of satellite operations in close proximity to a reference satellite is of interest for both civilian and military applications. One such operation is fast fly around formation in a time period less than the orbital period of the reference satellite. A control law based on continuous low thrust is derived in this paper to realize fast fly around space circle formation on circular orbit. The...
The focus of this paper is dynamic link allocation algorithms for sharing the limited link resources of the tracking and data relay satellites (TDRS) system among many burst users with varying quality of service (QoS) requirements. The task of scheduling communications between TDRS link and spacecraft is getting more and more critical since an increasing number of spacecraft must communicate with...
This paper proposes the complete QoS (quality of service) architecture for integration of space network with infrastructure networks. The technology, service differentiation mechanisms, network control mechanisms and user-to-networks mechanisms are discussed. The modules required in the network elements and its integration to provide end-to-end QoS in Space networks are presented. The proposed solution...
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