Stefano Andrenacci

Energy efficient CPM waveforms for satellite mesh networks

This papers addresses the design of new energy-efficient Continuous Phase Modulation (CPM) waveforms suitable for being adopted in satellite mesh networks that are characterized by the absence of the Hub, and by small antennas and power amplifiers with moderate to low output saturated power at the user terminal. In particular, a CPM modulation format concatenated with a proper convolutional code for low spectral efficiency values has been selected to implement an efficient waveform for power-limited scenarios. Performance results show the gain obtained with respect to the DVB-RCS2 CPM waveforms at higher spectral efficiency also when transmission techniques, such as Burst Repetition, are considered, and confirm the suitability of the new designed CPM waveforms for satellite hub-less scenarios.

On Ground Beam Forming and Multi User Detection Proof of Concept

In the frame of the on-going ARTES-5.1 ESA project “On Ground Beam Forming Networks And Multi User Detection Proof Of Concept” different scenarios of interest for the OGBF with Multi user detection technique has been defined, based on a single S-Band GEO satellite. This paper is focused on the definition and design of a hardware test bed implementing a scaled version of an OGBF/MUD system in order to verify the achievable performance. The OGBF demonstrator test bed includes a traffic emulator with relevant channel impairments, a satellite emulator including frequency conversion and multiplexing of the feeds signals and HPA emulation, and a gateway emulator with on ground frequency conversion, digital demultiplexing and MMSE-SIC based Multi user detector.

Computationally and Energy Efficient Symbol-Level Precoding Communications Demonstrator

Abstract We demonstrate forward link interference mitigation techniques in a precoded multi-user communication scenario for the efficient frequency reuse. The developed test-bed provides an end-to-end precoding demonstration, which includes a transmitter, a multi-beam satellite channel emulator and user receivers. Precoded communications allow efficient frequency reuse in multiple-input multiple-output (MIMO) channel environments, where several coordinated antennas simultaneously transmit to a number of independent receivers. We implement and demonstrate the new Symbol-Level Precoding (SLP) technique and benchmark it against Zero-Forcing and MMSE techniques in realistic transmission conditions. We show performance of the SLP in various MIMO channel conditions and outline the impact of the modified constellation by the SLP on a conventional receiver.

Per-antenna power minimization in symbol-level precoding for the multibeam satellite downlink: Per-antenna power minimization in symbol-level precoding for the multibeam satellite downlink

This paper addresses the problem of multiuser interference in the forward downlink channel of a multibeam satellite system. A symbol-level precoding scheme is considered, to exploit the multiuser i ...

Optimized link adaptation for DVB-S2X precoded waveforms based on SNIR estimation

The present work deals with optimized strategies to address the issue of link adaptation (Adaptive Coding and Modulation — ACM) in a multi-user multi-beam satellite system employing precoding at the gateway side. Accordingly, the focus is on the forward link of a multi-beam satellite system employing a full frequency reuse configuration. In such an interference limited setting, the Super-Framing structure of DVB-S2X air interface (format specification 2 and 3) enables the use of precoding techniques. The aim herein is to investigate the Signal-to-Noise-plus-Interference (SNIR) estimation error given by the User Terminals (UTs) through the so-called P2 pilots is taken into account to optimize the ACM margins.

Future ground beamforming

This paper summarizes the outcome of a study aimed at analyzing the benefits and hence the potential role of On-Ground BeamForming (OGBF) techniques in future satellite systems. To this end the study analyzed different scenarios where OGBF could find applications to assess if use of such techniques can provide advantages in terms of system performances and costs. Given the impact of ground beamforming on the feeder link bandwidth requirements, solutions able to minimize the feeder bandwidth whilst allowing multiple gateways are considered. The issue of multi-gateway operation and its impact on system calibration is also considered.

Exploiting orthogonality in DVB-S2X through timing pre-compensation

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.