References of "Cioni, Stefano"
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See detailExploiting orthogonality in DVB-S2X through time pre-compensation
Andrenacci, Stefano UL; Chatzinotas, Symeon UL; Vanelli-Coralli, Alessandro et al

in Proceedings of 2016 8th Advanced Satellite Multimedia Systems Conference and the 14th Signal Processing for Space Communications Workshop (2016)

The superframing option of the recent DVB-S2X standard specifies, for the so-called SF-Pilot fields, the use of the orthogonal set of Walsh-Hadamard (WH) sequences. In order to exploit this orthogonality ... [more ▼]

The superframing option of the recent DVB-S2X standard specifies, for the so-called SF-Pilot fields, the use of the orthogonal set of Walsh-Hadamard (WH) sequences. In order to exploit this orthogonality, waveforms coming from different beams to the k-th User Terminal (UT) should be quasi perfectly aligned in time. While in the downlink part of a terrestrial system this is quite straightforward, in satellite system, having a satellite as a relay, this is not the case, especially when large baudrates are considered in the transmission. A procedure to compensate for timing misalignment amongst waveforms is here presented and the advantages are quantified through numerical simulations.In particular, Channel State Information (CSI) estimation errors, which are fundamental for precoding techniques, are evaluated. While the focus of the work is on systems which enable precoding techniques, the procedure can be applied in each scenario which uses the superframing structure of DVB-S2X in an interference limited scenario. [less ▲]

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See detailPerformance Analysis of Fractionally Spaced Equalization in Non-linear Multicarrier Satellite Channels
Piazza, Roberto UL; Shankar, Bhavani UL; Berheide, Tobias et al

in Proceedings of 32nd AIAA International Communications Satellite Systems Conference (ICSSC), (2014, August 05)

Joint amplification of multiple carriers with a single wideband high power amplifier (HPA) has been considered towards reusing the satellite resources among multiple links to reduce the mission cost. The ... [more ▼]

Joint amplification of multiple carriers with a single wideband high power amplifier (HPA) has been considered towards reusing the satellite resources among multiple links to reduce the mission cost. The non-linear characteristic of the HPA, especially near saturation, coupled with the on-board IMUX/ OMUX filters result in non-linear adjacent carrier interference (ACI) and inter-symbol interference (ISI) during multicarrier power amplification. To benefit from the advantages of multicarrier transmissions, on-ground techniques to mitigate the non-linear distortions need to be devised. These techniques include predistortion at the transmitter and equalization at the receiver. Several works have considered the use of multicarrier predistortion along with single carrier equalization. A symbol synchronous equalizer, while being simple to implement, may not necessarily provide for the optimum linear filter. Towards improving the performance, fractionally spaced equalizers (FSE) have been considered. Such receivers are shown to provide enhanced performance by effectively compensating for the group delay distortions. The objective of this work is to consider the use of FSE in the context of multicarrier transmissions over non-linear channels and illustrate their performance enhancements [less ▲]

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See detailSensitivity Analysis of Multicarrier Digital Pre-distortion/ Equalization Techniques for Non-linear Satellite Channels
Piazza, Roberto UL; Shankar, Bhavani UL; Zenteno, Efrain et al

in Proceedings of 31st AIAA International Communications Satellite Systems Conference (ICSSC), (2013)

On-board joint power amplification of multiple-carrier DVB-S2 signals using a single High-Power Amplifier (HPA) is an emerging configuration that aims to reduce flight hardware and weight. However ... [more ▼]

On-board joint power amplification of multiple-carrier DVB-S2 signals using a single High-Power Amplifier (HPA) is an emerging configuration that aims to reduce flight hardware and weight. However, effects specific to such a scenario degrade power and spectral efficiencies with increased Adjacent Channel Interference caused by non-linear characteristic of the HPA and power efficiency loss due to the increased Peak to Average Power Ratio (PAPR). The paper studies signal processing techniques that counteract for both aspects enabling efficient multicarrier on board amplification. Digital pre-distortion (DPD) at the gateway and equalization (EQ) at the User Terminal are the designed avenues of attack to mitigate the non-linear effects and improve power as well as spectral efficiencies. This paper builds on our initial work in Ref.1 that performed a survey on the adaptability of various compensation techniques to the considered scenario and short-listed the most favourable ones. Preliminary performance analysis of these techniques was undertaken with Signal to Interference Ratio (SINR) as the figure of merit. The contribution of this work over Ref. 1 includes : (a) a full DVB-S2 chain is simulated with the chosen techniques with Total Degradation (TD) as the figure of merit and (b) a sensitivity analysis is performed to study the dependence of the pre-distortion/ equalization performance ( measured as TD) on the channel parameters. [less ▲]

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