The plans for a new satellite-based scientific experiment

The paper presents a new satellite-based propagation experiment, planned to start in the 2011, foreseeing the collection of simultaneous attenuation and depolarisation measurements during a 3-years period in Italy and possibly in many locations in Europe; the experiment, called TDP#5/Alphasat, is the initiator of a more comprehensive roadmap that will arrive to a Final Operational Mission (MOR) consisting in a very large Telecommunication infrastructure (called Broadband Distributed Users Access - BDUA) whose radio-bases will operate in the Q/V bands (service links) while the final users terminals in the ka bands (user links). This roadmap foresees a second milestone (after the TDP#5/Alphasat one) called "Missione Sperimentale Combinata" (MSC) whose task will be the one to test the critical technologies and techniques of the MOR. The whole program, called TRANSPONDERS, aims at demonstrating the effectiveness of a new TLC systems design philosophy foreseeing the application of a set of "propagation impairment mitigation techniques" to contrast the strong atmospheric attenuations foreseen at mm waves without resorting to excessive (and expensive) power expenditures. The present paper concentrates on the TDP#5/Alphasat mission which will carry on a set of significant propagation experiments. Its baseline design foresees a transmit-only payload radiating two beacon signals in the ka and Q bands from a geostationary platform; the coverage area will be the continental Europe and the North Africa; the polarization of the Q-band beacon will be circular and the reception shall be possible with antennas with diameter of the order of one meter. The coherency between the Ka and Q/V beacons will allow a wide dynamic range of measurements by facilitating the carrier recovering and will permit the assessment of the correlation of attenuation in distant sites, the correlation between attenuation and BER (measured separately), the attenuation frequency scaling error (for open-loop up-link power control) and will put the grounds for the implementation of future adaptive fade mitigation techniques. ASI assumed directly the commitment to realize the deployment and realization of the Earth terminals in Italy while ESA, on behalf and with the financial support of the ASI, is carrying out the realization of the payload. One of the Earth terminals will be located in the station of Spino d' Adda where the Operational Centre of the entire propagation experiment will be located as well. Another receiving station will be located in the Roma area (Tor Vergata) where also the coordination Centre for the Telecommunication experiments is foreseen; moreover, in order to enlarge the significance of this experiment, the development of one or a few prototypes of a propagation ground terminal is currently in the plans of the ESA with the aim of fostering the involvement of as many European experimenters as possible.