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This paper describes the evolution of the ETSI S-band mobile interactive multimedia protocol to support fixed satellite interactive multimedia (F-SIM) services exploiting existing Ku-band and Ka-band satellites. The key F-SIM protocol differences for both physical and upper layers are described and justified. The F-SIM protocol has been adopted by the recently deployed Eutelsat Broadcast Interactive System whose architecture, key system parameters, link budget examples and key composing elements are also described. Finally, a summary of laboratory and field trials results over the Eutelsat KA-SAT multibeam satellite are illustrated.

An open ITS platform combining interactive satellite services with other communication channels is being developed and evaluated in field trials within the SafeTRIP project [1]. Prototyping and in-field validation of a novel waveform for messaging return channel over satellite for land mobile is an important objective of the project. The overall system architecture has recently been standardized by ETSI under the name of S-MIM (S-band Mobile Interactive Multimedia). The messaging protocol, described in the Part 3 of the standard, is based on the Enhanced Spread Spectrum Aloha (E-SSA). Its main asset resides in the low power required at the transmitter, which will allow the reuse of off-the-shelf power amplifiers and low-cost omnidirectional antennas. This paper will present a comprehensive summary of previous E-SSA performance analysis from simulations and the first field trials results using the E-SSA waveform. The presented results have been derived from static and mobile field trials carried out in Germany with fully functional E-SSA modulator and demodulator prototypes and the EUTELSAT10A satellite. Results for the static and mobile performance of the E-SSA demonstrator with an omni-directional antenna under Line-of-sight (LOS) conditions are presented. The measured Packet Error Rates of transmissions via satellite at different terminal power levels confirm the theoretical link budget calculations for single and multiple simultaneously transmitting terminals. The degradation due to fading effects of the transmission channel under mobile conditions has been measured during the trials to approx. 3 dB. The resulting overall required transmitter power in the multi-user scenario of the trials setup has been only -3 dBW to reach a high QoS under mobile conditions. This value confirms the suitability of the E-SSA waveform for interactive mobile services for the mass market

SUMMARYThis paper describes the implementation of the first enhanced spread spectrum aloha demodulator, based on an innovative architecture which combines software-defined radio with processing via commercial graphics processing units. The validation tests performed both in laboratory conditions and directly on the satellite EUTELSAT 10A are presented. The performance assessment results obtained via satellite validate the theoretical results to a sufficient degree to make enhanced spread spectrum aloha technology a viable option for low-power mobile and fixed terminals, thus encouraging the growth of satellite mass market applications.

In this paper we describe a statistical and a physically based approaches to retrieve 2D rainfall fields exploiting the attenuation measurements made along satellite links at K a and K u bands, in the framework of the research project NEFOCAST. The retrieval algorithms, the main results obtained so far, and the on going test campaign are presented and discussed.