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ARTES Elements
Tenders and Workplans
Last Update: 10 Aug 2007




The SkyPlexNet system architecture is based on very innovative technology, namely the Skyplex on board multiplexer, designed and developed by Alenia Spazio and presently operational on Eutelsat Hot Bird 5, placed at 13 0E. The basic idea is to avoid any kind of centralisation regarding the management of the space resource, making available the direct access to the satellite transponder operated in downlink in full compliance with the DVB (Digital Video Broadcasting) standard through up-link stations relatively simply and not expensive.

The key feature of Skyplex system is then the possibility to avoid the cost of the terrestrial tails to reach the master up-link station. Although Skyplex was initially designed for TV broadcasting it has revealed during the course of its development enormous advantages regarding the IP based applications due to MPEG2-Transport Stream inherent capability to transport also IP packets. The SkyPlexNet system specifically addresses such emerging potentialities thus disclosing the exploitation of WWW multimedia.

The SkyPlexNet system optimises separately, the two basic links of a generic satellite broadcasting system: the former between the earth station and the satellite and the latter between the satellite and the end user receiving station. This is because Skyplex is capable of re-combining different up-streams into a single 55 Mbps down-link stream compatible with DVB-S standard. End users do not perceive any difference between a Skyplex transmission and the one operated through a usual transparent transponder.

In the access to Skyplex repeater geographically distributed, the network management and control system have duties much different from those required in a usual satellite transparent DVB transponder. More specifically, the overall network management maintains functional control over the satellite access (co-ordination, spectrum management, etc.), but has many more responsibilities regarding the telecommunication transmission.

The adopted architectural solutions clearly address the commercial exploitation of multimedia services via satellite: specific emphasis will be placed on the definition of their strategic positioning, competitive advantages and market potentialities.


SkyPlexNet system architecture is composed of the following three major elements:

  1. The Network Operation Center (NOC), whose main role is to offer a set of services to manage the SkyPlexNet system so that the appropriate transponder quota is guaranteed to each up-link station. Basic services will include the monitoring and control of the subnetworks as well as a customer managent system.
  2. The Service Center (SC), co-located with the skyplex up-link station. It will be basically composed of two major components: the first strictly linked to service management, the second connected to all supervision and control functions which have to be considered common to all applications. Into the latter class can be also included, all the elements needed to handle the end user and the interactive channel interface. Main subsystem composing the SC will be: transaction server, content server, service scheduler and control, a conditional access system, an Interner server and a DVB mux (and/or a DVB/IP Gateway).
  3. The DVB Client Platform at the end user premises. It will be equipped with:                
  • A PC with a multimedia kit, enough powerful to join the services;
  • A Data Browser User System, with navigation Software and the data receiving card to put on the PC;
  • A modem to access the Internet, useful for those 'Spread Content' services both in Broadcast & Internet way.

The Data Browser manages the user station contents, spread both in Broadcast and Internet way, so that the user is able to freely navigate in one whole integrated environment.

Project Plan

SkyPlexNet Project has been split into two phases, namely phase 1 and 2:

  • Phase 1, defining in detail the system architecture, has been completed in June 1999
  • Phase 2, dealing with the platform development, integration and test is going to be completed by April 2000.

Test campaign, carried out in November 1999/March 2000, will face a real commercial case for the two typologies of services which the SkyPlexNet platform is going to vehiculate, namely the data broadcasting services and the interactive video-communication ones. Consequently two Service Centers will be developed one in Rome, providing the first kind of service and one in Naples (I) for the latter ones. In particular, interactive video-communication services will address a Remote Learning application , having as end users a set of five remote terminals located at the University of Lecce (I) premises.


The principal challenges which the project addresses are:

  • The skyplex TDMA access mode, which needs still to be fully commercially exploited.
  • The design, development and test of the complete NOC functionalities, pioneer system for a skyplex network developed around the Skyplex concept.
  • The Service Center integration and test, a novel concept for multimedia service provision.


SkyPlexNet will provide a consistent breakthrough on multimedia service provision across Europe: major benefits will be the independent and distributed up-lnk to the satellite resource (accordingly to DVB-S standard) and the availability of a near bandwidth on demand capability, associated with a very flexible up-link data-rates. The induced cost competitiveness of the DVB-S, high power connectivity, is considered an important key- factor.

Current Status (dated: 22 Jul 2002)

The Final Review meeting was held on September 18th, 2000. A description of development achievements and pilot trials results was provided to the participants. This involved the presentation of the results for Video Streaming platform (ITS), DBE (Skydata), SEMS (Newtec), NCMS (Marconi), Distance Learning trials (CMU), OSG (GCS). A session was held in the SkyPlexNet Network Operation Centre for a demonstration of the results of SEMS-NCMS integration.

During the review, Alenia Spazio presented the commercial achievements of SkyPlexNet that have recently been confirmed by three important contracts. The first is with ENEL.IT of Rome, a subsidiary of ENEL (the national electricity provider), to create the first corporate Intranet between their 1,200 plants where there will be a total of about 50,000 active users. The second is with Openet of Matera (Southern Italy), a new entrepreneurial body backed by a premier group of industrialists that have decided to pool their resources and adopt SkyPlexNet to improve their day-by-day business and offer services to external organisations such as public institutions. The third agreement is with the Catholic University, the leading private university, which is adopting the SkyPlexNet platform to connect its remote locations and deliver live interactive courses.

Further seven Service Centres are under development and will be operational by the end of this year in Rome, Naples, Milan, Trieste and Lecce.

In January 2001, ESA considered successfully completed the SkyPlexNet project. For more information are available the Alenia Spazio and the SkyPlexNet web sites: and .

Last Update: 10 Aug 2007
Project Plan
Current Status
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