In the paper various issues in personal satellite communications are addressed. Basic geostationary and non-geostationary satellite constellations are considered. The narrowband and wideband characterization of the mobile satellite channel and related system implications are discussed. Satellite diversity is presented as a measure to overcome signal shadowing. The capacity of TDMA and CDMA mult...

A circle at an altitude of approxmately 35 786km above the equator is known as the geostationary arc. Geostationary orbit, or GEO as it is called, is discovered because of its advantegs. It is situated circular in the equatorial plane, moving tn step with the earth rotation. The geostationary orbit time is close to a solar day which has some advantageous properties. The orbit covers the most of...

| We examine the design of a communication link involving the data transfer from a small, low-orbit satellite to a ground station, but through a geostationary satellite. The advantage of this approach is that a single ground station , which tracks only the geostationary satellite, may be shared by a multiplicity of small satellites. Our goal is to select certain small satellite parameters { sig...

Geostationary satellite links have characteristics that can degrade the performance of TCP. The propagation time for a geostationary satellite link is on the order of 0.25 seconds. Thus a satellite can add approximately 0.5 seconds to the round trip time experienced by a TCP packet and the corresponding acknowledgement. This delay time is the primary cause of TCP inefficiency over satellites. T...

|We compare CDMA and FDMA (or TDMA) schemes in multi-beam non-geostationary satellite systems, taking the e ects of antenna patterns on inter-cell interference into consideration. The maximum acceptable number of users per cell in uplink is employed as a measure of the system capacity. We have found that in FDMA (or TDMA) systems the maximum acceptable number of users varies according to the al...

Earth-observing satellites carrying multispectral sensors are widely used to monitor the physical and biological states of atmosphere, land, oceans. These have different vantage points above Earth spectral imaging bands resulting in inconsistent imagery from one another. This presents challenges building downstream applications. What if we could generate synthetic for existing union all domains...

This paper investigates the performance of two TCP enhancements (i.e., Scalable TCP and HighSpeed TCP), recently proposed for high-speed backbone networks with a very large bandwidth-delay product, in a geostationary satellite environment. Both persistent and elastic traffic patterns are considered, performance being evaluated in terms of TCP throughput and mean session delay, respectively. The...

Thermal infrared (TIR) remote sensing of landsurface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetation amount (e.g., as quantified by the Normalized Difference Vegetation Index; NDVI) have demonstra...

The term nowcasting reflects the need of timely and accurate predictions of risky situations related to the development of severe meteorological events. In this work the objective is the very short term prediction of the rainfall field from geostationary satellite imagery entirely based on neural network approach. The very short-time prediction (or nowcasting) process consists of two steps: fir...

Satellite communications are the outcome of research in the area of communications and space technologies whose objective is to achieve ever increasing ranges and capacities with the lowest possible costs. The Second World War stimulated the expansion of two very distinct technologies—missiles and microwaves. The expertise eventually gained in the combined use of these two techniques opened up ...