Giacinto Losquadro

Requirements of multiregional mobile broadband satellite networks

Chiefly as a result of the phenomenal worldwide growth in the use of the Internet, a number of geostationary satellite systems have been proposed for provision of broadband multimedia-type services. The vast majority of these systems address the needs of fixed users; however, satellites can also play an important role in the deployment of mobile networks. This article describes the requirements of a multiregional network of interconnected geostationary satellites capable of providing multimedia-type services to ubiquitous and mobile users.

An advanced satellite system to provide interactive multimedia mobile services

Provision of wideband services up to the final user anywhere is a challenging task for terrestrial technologies unless the satellite is included as an essential system component. This objective is even more difficult to be met if at least a limited degree of user interactivity and mobility is required. Satellite multimedia applications will require wide bandwidths, high degree of flexibility on-board and intelligence at terminal level. The combined use of Ka band (20 - 30 GHz) and EHF (in the range 40 - 45 GHz) can extend interactive multimedia and personal services to ubiquitous and mobile users. This paper discusses the main interactive multimedia services and applications that may be provided via satellite. Particularly, it describes a new project, the SECOMS project, that is under way in the framework of a programme of the European Union. The paper provides some indications on the main SECOMS assumptions and requirements, and system design elements.

Space/Terrestrial Mobile Networks: Internet Access and QoS Support

Preface.1. Introduction.2. Multi-Segment Access Network.3. GMBS Multi-Mode Terminal.4. Service Requirements.5. End-to-End Qquality of Service Support.6. Mobility Support.7. Network Protocol Design.8. Performance Validation.Appendix A: Related Publications.Index.

Digital transmission of HDTV on satellite channels

The perspectives for digital HDTV on satellite channels are examined at the light of the recent progress on bit-rate reduction algorithms and on modulation and channel coding techniques. The experimental HDTV transmissions at 70 Mbit/s carried out by the RAI during the «1990 Football Worldcup» are shortly described. A preliminary configuration of the future HDTV network architecture has been identified, including terrestrial and satellite links. Two advanced modulation and coding systems, suitable for operating in the 30/20 GHz frequency range, have been studied by computer simulations: a) QPSK modulation and concatenated convolutional and Reed-Solomon coding, and b) Trellis-coded 8-PSK modulation and concatenated Reed-Solomon coding. The satellite channel has been optimized as regards the transmitting and receiving filters partitioning and the TWTA operating point. An example of design of a complete satellite chain at 30/20 GHz shows the feasibility of a 140 Mbit/s HDTV transmission system based on the described techniques.

Transmission issues for HDTV satellite systems

The transmission of digital HDTV signals on satellite channels in the 20-30 GHz band is studied with the aim of designing an Italian domestic satellite, both for the exchange of pro- grams among production centers and for direct broadcasting to end-users. Previous work on the definition of the system architecture and of the payloads is first briefly summarized. The transmis- sion impairments due to the interfered environment are then analyzed in detail and simulation studies are reported. The results confirm the choices made for the link budgets during the system configuration design. Experimental tests carried out both with laboratory simulators and with the Olympus European satellite are finally described.

End-to-End Telecommunication Satellite System with On-board IP Routing

Several fields of application of satellite systems may benefit from having on-board processing units able to route IP packets. Network Centric Operations (NCO) for dual-use applications, space exploration and Low Earth Orbit (LEO) communication satellite constellations are among them. This paper describes an end-to-end (E2E) telecommunication (TLC) satellite system with on-board IP routing functionality. The on-board IP routing is performed at IP packet level by means of a ground-board system currently under study in Thales Alenia Space - Italia.

The SECOMS Broadband Satellite Network in the Multimedia Services and Multi-environment Coverage Scenario

Providing multimedia services is one of the major key issues in the world of telecommunications. If mobility and ubiquity is required, the satellite assumes an essential role due to its flexibility and to the possibility of global coverage. The paper briefly describes the SECOMS satellite system aiming at providing multimedia services to ubiquitous and mobile users. This will be fully addressed in a wide range of environments, from the open country to heavily dense cities and built-up areas as well as the indoor environment. The possibility to create a global broadband mobile communication system consisting of multiple system components with different characteristics will be investigated.

Letter: Impact of RFI Detection in DRS Links on the Performance of Coding Schemes

This paper deals with Data Relay Satellite systems operating in the S-band environment and using Binary Phase Shift Keying modulation with concatenated Forward Error Correction data protection. One of the major sources of their performance degradation is radar generated Radio Frequency Interference in the same band. Transmission channel performance would certainly be improved if RFI positions (called erasures) were detected and passed to the decoders. By allowing the codes to handle about twice as many erasures as errors, this information would significantly reduce the effects of RFI deterioration. A novel technique for RFI detection is developed. It is based on a bank of simple “moving windows” associated with a detection algorithm and a method for the removal of ambiguous RFI detections. The use of this erasure information in the Viterbi decoding process is then illustrated and a new rule for updating the decoding metric is proposed. The residual correlation on the errors at the Viterbi decoder output makes the outer code useless, unless a further interleaving is introduced. Extensive simulation results highlighting the good performance of the joint RFI detection and modified Viterbi decoding schemes are presented. Simulation is also used to assess the outer code behavior.