Alban Duverdier

Systems and Services

After several science fiction papers and books, satellite telecommunications appeared with the paper titled “Extraterrestrial Relays” authored by Arthur Clarke and published on Wireless World in October 1945. In that paper, the orbital configuration of a satellite constellation utilizing a Geostationary Earth Orbit (GEO), an orbit located at 35800 km over the Earth surface coplanar with the equatorial plane, was proposed. In that configuration, three manned satellites, fixed with respect to a point on the Earth surface, were equally spaced in angle of 120° each and covered one third of the world. The second milestone was represented by the paper published in 1954, titled “Telecommunication Satellites”, authored by John Pierce where also Low Earth Orbit (LEO) were proposed using unmanned satellites. Latter, Highly Elliptical Orbit (HEO) and Medium Earth Orbit (MEO) have been considered.

Design and Simulation of a DVB-S2-like Adaptive Air interface Designed for Low Bit Rate Emergency Communications Satellite Link in Ku/Ka/Q/V Bands

Access to information is of paramount importance in emergency situations when a disaster or a natural catastrophe (earthquakes, landslides, tsunamis, tidal wave, volcanic eruptions, floods, cyclones, other tornados or forest fires) occurs in a given place. The rescuers must have access to telecommunications means in order to be able to transmit critical information (such as the number of victims, of persons needing medical assistance or to be transported towards care centers, hospital locations, the nature of injuries, etc.) to the center that is in charge of coordinating the heavy logistical rescue operations. However, when an extensive area is affected (in developing countries in particular, but this holds true in first world countries also), it is most often impossible to use some telecommunications equipments, because of a destruction of the base stations or an unavailability of electric power. Thus, it is an absolute priority, in order to manage a situation of post-disaster, to restore the communications infrastructure. Three distinct and consecutive phases can be distinguished (Pech et al., 2008):

Introduction of Additional Elements in DVB­S2 for New System Applications

‡This paper proposes toxa0improve the DVBxadS2 standard, developed for thexa0new generation of satellite broadcasting, in casexa0of lowxa0cost and mobilexa0equipments.xa0Itxa0presents in details the DVBxadS2xa0air interfacexa0andxa0associated receiver architecture.xa0It is shown howxa0the latter can be conserved giving better performances at low signalxa0to noisexa0ratioxa0when a regular framing and low efficient coding rates are introduced. The authors conclude that DVBxadS2 can be usedxa0withxa0mobilexa0portablexa0orxa0handxadheldxa0terminals, withxa0slightxa0additionsxa0inxa0thexa0standard.

Performance of an Adaptive Multicast System with Mobile DVB-S2

The adaptation of a satellite telecommunication standard to mobile environments implies taking into account the impairments associated to the propagation channel. In a railway scenario erasures can occur more or less regularly caused by the presence of catenaries, electrical trellis and posts. A possible countermeasure to this phenomenon is the use of a FEC coding scheme directly at the application level. This paper presents the use of this technique associated with interleaving and the novel GSE encapsulation. Through simulations we will evaluate the performance gain of a multicast DVB-S2 transmission for streaming services that is able to adapt in terms of packet level FEC scheme and interleaving depth and physical layer parameters to the mobile channel characteristics.