Marc Darmon

A hybrid FEC-ARQ communication system for zero-error digital transmissions on the troposcatter channel

The results of a study defining an error-correcting scheme that permits very-high-reliability links for digital data transmissions over the troposcatter (Rayleigh) channel are presented. When the transmission channel is unidirectional, transmission error correction is made by means of a forward error correction (FEC). An automatic repeat request (ARQ) strategy feedback channel is used to reduce the complexity of the coding scheme and the interleaving depth. A hybrid ARQ and FEC system is proposed using a long constraint length convolutional code and sequential decoding algorithm, associated with a modified go-back-N ARQ protocol, able to cope with a two-way noisy channel. The protocol control is achieved by a modified high-level data link control (HDLC) structure. The system is tested on a simulated Rayleigh channel. The simulations have shown no transmission errors, corresponding to a binary error rate lower than 10/sup -9/.<<ETX>>

Alcatel 732: a new generation of very light and tactical satellite terminal for voice, data and multichannel trunk communications

Major progress has been made for military communications by satellite, especially due to the multiplication of allied interventions on foreign territories (Somalia, Bosnia, etc.). The purpose of this article is to show how transmission of different services (voice, data, etc.) or trunks may now be made using very light military ground stations (easy to transport in a light vehicle) which are fully tactical (disembarkable, sealed, resistant to environmental constraints of a battlefield, etc.). In fact, the various designs incorporated a demountable antenna (sectionalized reflector), modularity using different ergonomic tactical cabinets, and frequency band interchangeability, etc.) making it possible to combine high tacticity, COMSEC, TRANSEC and a low transponder occupancy.<<ETX>>

New trends on high bit rate troposcatter links: a trade-off between tacticity and performance

The authors describe how to build a very mobile troposcatter station with a radio and a modem which can handle up to 4 Mb/s transmission. This is achieved by the combination of equalization and differential demodulation, and by a patented technique for getting a high diversity order with only one amplifier and one antenna.<<ETX>>

A hybrid FEC-ARQ communication system using sequential decoding

This paper presents the results of a study which aimes at defining an error correcting scheme matched to the troposcatter (Rayleigh) channel, which would permit to insure very high reliability links for digital data transmissions.