A earth station calling another station sends a link setting-up a request to a control station. The control station memorizes in a transformed reference system the contour of a global geographical coverage including all the earth stations together with the earth positions of the latter. Subsequent to the request, the control station simulates the optimum evolution of the radioelectric coverages of the satellite so as to include, both on emitting and receiving, the calling and called stations in respective coverages with guaranteed minimum antenna gains. The total power of the satellite and the positions of the stations are notably considered in this simulation. If the result of simulation is positive, an emission authorization is sent by the control station to the calling station, and satellite antennae are reconfigured by phase shift and power control values emitted by the control station.

Antenna beam coverage reconfiguration

This work presents a detailed study of the forward link of a high-throughput satellite and proposes a novel methodology for the dimensioning of broadband communication satellites, based on the optimization of the capacity and/or the cost per capacity unit. The optimization process combines the characteristics (gain and interference) of the satellite antenna(e) with propagation effects, for a given set of technical and commercial parameters. The approach uses a spacecraft architecture implementing multibeam coverage based on frequency reuse, using a fixed payload power and targeting given user terminals. The methodology can be applied to any beam distribution, payload power distribution, or variable beam sizes, as these parameters are recalculated each time in the optimization process due to their impact on the interference environment or the available power for each beam. In this work, the method has been tested on single-feed-per-beam systems with a uniform power distribution. Among the input criteria, one can list the percentage of covered service area and the service availability. The proposed methodology is adaptable to any kind of service area and frequency band. A digital video broadcasting satellite second-generation air interface with adaptive coding and modulation is used as a reference. The method employs iterative link-budget calculations (including carrier-to-interference ratio and propagation attenuations) and provides the highest capacity or the best cost per capacity unit, for a fixed size of the antennae and a pragmatic feed design. The method is combined with the calculation of the channel capacity in order to be able to evaluate the difference between the theoretical performance and a realistic system.

Novel dimensioning method for high-throughput satellites: forward link

Hybrid antennas, the combination of a radiating or receiving aperture with an array feed, have been the subject of considerable recent interest because they offer some of the versatility of phased array antennas at a much lower cost. Adaptive nulling in hybrid antennas has not received as much attention as other important aspects, such as compensation for reflector surface distortion, scanning, pattern calculation, and the design of multibeam antennas. In this report we investigate adaptive nulling in hybrid reflector antennas using the Generalized Sidelobe Canceller algorithm. A general framework is presented for the computer simulation of narrow band adaptive nulling in hybrid reflector antennas that takes account of the details of reflector scattering and polarization. The general framework is then illustrated by the results of calculations performed for an offset paraboloid with a planar feed located in the focal plane of the paraboloid.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a275797.pdf

Adaptive Nulling in Hybrid Reflector Antennas

This work describes a novel methodology for the dimensioning of a Ka-Band high throughput satellite (HTS) for broadband communications. The method is based on the optimization of performance for a forward link, as a function of a set of input criteria and a given envelope of available power. This approach is based on a spacecraft architecture using a multi-beam coverage implementing frequency re-use. Among the input criteria, we use the percentage of covered service area with a certain type of earth stations, the service availability and the cost and mass of the system. The proposed methodology is adaptable to any kind of service area. A digital video broadcasting satellite second generation (DVB-S2) air interface with adaptive coding and modulation (ACM) is used as a reference. The method, employing iterative advanced link budget calculations including carrier-to-interference at antenna level, provides the highest capacity given a batch of antenna and pragmatic feed design.

/pdf/a-novel-dimensioning-method-for-high-throughput-satellite-2vrkxloo9d.pdf

A novel dimensioning method for high throughput satellite design

This work describes an interference study of the return link (user terminals to gateways) of a high throughput satellite (HTS) for broadband services. The aim is to identify a statistical behavior of the inter-spot interferences due to frequency re-use so as to estimate the carrier over interference ratio (C/I) on the uplink segment of the return link for a multi frequency time division multiple access (MF-TDMA) technique. The characterization of the interference will be done based on a mathematical model and validated through empirical observations for different transmission scenarios and satellite systems. In this work, we use the C/I performance at satellite antenna level as a benchmark parameter, in order to find the most faithful statistical law for the generated interferences. The satellite architecture itself uses a multi-beam coverage implementing frequency re-use and spatial separation.

/pdf/statistical-characterization-of-the-interference-on-the-3ybe7hgtqk.pdf

Statistical characterization of the interference on the return link of a broadband satellite system

: High-gain spacecraft antennas with multiple beams and contoured beams are key components in satellite communications and direct broadcast systems. This is reflected on the latest generation of communications satellites, where the antenna subsystem is the largest subsystem with its weight of more than 300 kg. The antennas achieve a large communications capacity through multiple frequency re-uses and may be reconfigured to serve different coverage areas. The paper overviews the current multi-beam and contoured-beam antenna technology. Different implementations, reflector or lens with feed array or direct radiating array, are considered. The emphasis is placed upon systems with offset paraboloidial reflectors. The limitations of the offset reflector with respect to beam scanning and cross polarization are reviewed. computer-aided design procedures and design examples are presented.

P Balling

Papers

Spacecraft Multi-Beam and Contoured-Beam Antennas