![]() ; Andrenacci, Stefano ![]() ![]() in International Journal of Satellite Communications and Networking (2020) Detailed reference viewed: 125 (29 UL)![]() ; Andrenacci, Stefano ![]() ![]() in International Conference on Communications (2019, May) In this paper we propose a new measurement procedure for the amplitude response of a wideband transponder in an in-orbit testing (IOT) context. The proposed procedure resorts to a direct sequence spread ... [more ▼] In this paper we propose a new measurement procedure for the amplitude response of a wideband transponder in an in-orbit testing (IOT) context. The proposed procedure resorts to a direct sequence spread spectrum (DSSS) technique in order to limit the interference caused by the measurement signals to the traffic. Further, an adaptive approach exploiting the knowledge of the inband traffic power has been introduced. Such knowledge, acquired either a priori or by sensing the channel, allows to easily design measurement signals satisfying multiple performance requirements (i.e., accuracy, resolution, interference, duration, and complexity). The proposed procedure can be used as a design tool to optimize the dimensioning of the IOT system parameters, and to flexibly trade off a performance indicator against another. [less ▲] Detailed reference viewed: 45 (14 UL)![]() Krivochiza, Jevgenij ![]() ![]() ![]() in IEEE Access (2019) In this paper, we demonstrate an FPGA accelerated design of the computationally efficient Symbol-Level Precoding (SLP) for high-throughput communication systems. The SLP technique recalculates optimal ... [more ▼] In this paper, we demonstrate an FPGA accelerated design of the computationally efficient Symbol-Level Precoding (SLP) for high-throughput communication systems. The SLP technique recalculates optimal beam-forming vectors by solving a non-negative least squares (NNLS) problem per every set of transmitted symbols. It exploits the advantages of constructive inter-user interference to minimize the total transmitted power and increase service availability. The benefits of using SLP come with a substantially increased computational load at a gateway. The FPGA design enables the SLP technique to perform in realtime operation mode and provide a high symbol throughput for multiple receive terminals. We define the SLP technique in a closed-form algorithmic expression and translate it to Hardware Description Language (HDL) and build an optimized HDL core for an FPGA. We evaluate the FPGA resource occupation, which is required for high throughput multiple-input-multiple-output (MIMO) systems with sizeable dimensions. We describe the algorithmic code, the I/O ports mapping and the functional behavior of the HDL core. We deploy the IP core to an actual FPGA unit and benchmark the energy efficiency performance of SLP. The synthetic tests demonstrate a fair energy efficiency improvement of the proposed closed-form algorithm, also compared to the best results obtained through MATLAB numerical simulations. [less ▲] Detailed reference viewed: 258 (42 UL)![]() ![]() Krivochiza, Jevgenij ![]() ![]() ![]() Scientific Conference (2018, December) We present a convex optimization based Symbol-Level Precoding (SLP) for sum power minimization and propose the low-latency closed-form algorithm to find a heuristic solution to the optimization problem ... [more ▼] We present a convex optimization based Symbol-Level Precoding (SLP) for sum power minimization and propose the low-latency closed-form algorithm to find a heuristic solution to the optimization problem. The technique exploits constructive interference at the multi-user MIMO systems and minimizes the sum power of the transmitted precoded signal per each symbol slot. As a result, the received signals gain extra Signal-to-Noise Ratio (SNR), which leads to the improved data rate and energy efficiency. We benchmark the low-complexity algorithm for solving the optimization technique against the conventional Fast Non-Negative Least Squares algorithm (NNLS). The demonstrated design of the SLP technique combined with the proposed closed-form algorithm has low computational complexity and fast processing time, which is applicable in low-latency high-throughput satellite communication systems. [less ▲] Detailed reference viewed: 209 (25 UL)![]() ; Lagunas, Eva ![]() ![]() in IEEE Global Conference on Signal and Information Processing (GlobalSIP), Anaheim, California, USA (2018, November) Detailed reference viewed: 94 (13 UL)![]() Merlano Duncan, Juan Carlos ![]() ![]() ![]() Scientific Conference (2018, October) In this paper, we present a hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in the forward link of the multi-beam ultra-high throughput satellite systems ... [more ▼] In this paper, we present a hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in the forward link of the multi-beam ultra-high throughput satellite systems. The hardware demonstrator is a full-chain closed-loop communication system with a multi-beam DVB-S2X compliant gateway, a satellite payload and MIMO channel emulator and a set of DVB-S2X user terminals with real-time CSI estimation and feedback. We experimentally show the feasibility of Precoding implementation in satellite communications based on the superframe structure DVB-S2X standard. Using the test-bed we have a possibility to run real-time precoded DVB-S2X communication and benchmark its performance under realistic environment. The hardware demonstrator is suitable to perform realistic benchmarks of Block- and Symbol-level Precoding techniques for multicast and unicast user scheduling scenarios. [less ▲] Detailed reference viewed: 256 (40 UL)![]() Krivochiza, Jevgenij ![]() ![]() ![]() in Physical Communication (2018), 28 We present a precoded multi-user communication test-bed to demonstrate forward link interference mitigation techniques in a multi-beam satellite system scenario, which will enable a full frequency reuse ... [more ▼] We present a precoded multi-user communication test-bed to demonstrate forward link interference mitigation techniques in a multi-beam satellite system scenario, which will enable a full frequency reuse scheme. The developed test-bed provides an end-to-end precoding demonstration, which includes a transmitter, a multi-beam satellite channel emulator and user receivers. Each of these parts can be reconfigured accordingly to the desired test scenario. Precoded communications allow full frequency reuse in multiple-input multiple-output (MIMO) channel environments, where several coordinated antennas simultaneously transmit to a number of independent receivers. The developed real-time transmission test-bed assist in demonstrating, designing and benchmarking of the new Symbol-Level Precoding (SLP) techniques, where the data information is used, along with the channel state information, in order to exploit the multi-user interference and transform it into the useful power at the receiver side. The demonstrated SLP technique is designed in order to be computationally efficient, and can be generalized to others multi-channel interference scenarios. [less ▲] Detailed reference viewed: 254 (42 UL)![]() Spano, Danilo ![]() ![]() ![]() in International Journal of Satellite Communications and Networking (2018) This paper addresses the problem of multi-user interference in the forward downlink channel of a multi-beam satellite system. A symbol-level precoding scheme is considered, in order to exploit the multi ... [more ▼] This paper addresses the problem of multi-user interference in the forward downlink channel of a multi-beam satellite system. A symbol-level precoding scheme is considered, in order to exploit the multi-user interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, a per-antenna power minimization scheme is proposed, under Quality-of-Service constraints, for multi-level modulation schemes. The consideration of the power limitations individually for each transmitting RF chain is a central aspect of this work, and it allows to deal with systems using separate per-antenna amplifiers. Moreover, this feature is also particularly relevant for systems suffering non-linear effects of the channel. This is the case of satellite systems, where the non-linear amplifiers should be properly driven in order to reduce the detrimental saturation effect. In the proposed scheme, the transmitted signals are designed in order to reduce the power peaks, while guaranteeing some specific target signal-to-noise ratios at the receivers. Numerical results are presented in order to show the effectiveness of the proposed scheme, which is compared both to the state of the art in symbol-level precoding and to the conventional MMSE precoding approach. [less ▲] Detailed reference viewed: 243 (31 UL)![]() Kodheli, Oltjon ![]() ![]() ![]() in 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC), Berlin, Germany, 10-12 September 2018 (2018) Internet of things (IoT) over satellite is an attractive system architecture which has been proposed as a key-enabling technology, to extend the coverage in remote areas (e.g. desert, ocean, forest, etc ... [more ▼] Internet of things (IoT) over satellite is an attractive system architecture which has been proposed as a key-enabling technology, to extend the coverage in remote areas (e.g. desert, ocean, forest, etc), particularly where a terrestrial network is impossible or impractical to reach. One of the most promising technologies that fit the IoT vision of low-power, wide area networks (LPWAN) is the narrowband IoT (NB-IoT). While low earth orbit (LEO) satellites are favourable because of their lower round trip time (RTT) and lower propagation loss in the communication link, they come up with a significantly increased Doppler shift. In our NB-IoT over LEO satellite architecture, we identify the problem of high differential Doppler among channels of different users on Earth, which leads to the performance degradation of our system. In this paper, we propose a resource allocation approach in order to reduce the high values of differential Doppler under the maximum value supported by the standard itself. [less ▲] Detailed reference viewed: 231 (54 UL)![]() ; Andrenacci, Stefano ![]() ![]() in 2018 9th Advanced Satellite Multimedia Systems Conference and the 15th Signal Processing for Space Communications Workshop (ASMS/SPSC) (2018) The application of linear precoding at the gateway side enables broadband multibeam satellite systems to use more aggressive frequency reuse patterns increasing the overall capacity of future High ... [more ▼] The application of linear precoding at the gateway side enables broadband multibeam satellite systems to use more aggressive frequency reuse patterns increasing the overall capacity of future High Throughput Satellites (HTS). However, although some previous works about precoding consider imperfect CSIT (Chanel State Information at the Transmitter) adding some CSI estimation errors, that is not the main cause of CSI degradation. In practice, receivers can only detect and estimate a few coefficients of the CSI vector being the other nullified, replaced by zeros. This introduces errors in the SINR calculation by the gateway that lead to the assignment of Modulation and Coding Schemes (MCS) over the decoding possibilities of the users, increasing the rate of erroneous frames. In this work, the errors in the SINR calculation caused by the nullification of the CSI are analyzing statistically and geographically using a radiation diagram of 245 beams over Europe. Furthermore, a solution based on a link adaptation algorithm with a per user adaptive margin is proposed, helping to achieve the QEF (Quasi-error Free) target of DVB-S2X systems. [less ▲] Detailed reference viewed: 53 (2 UL)![]() Joroughi, Vahid ![]() ![]() ![]() in Global Conference on Signal and Information Processing (GlobalSIP) (2018) Detailed reference viewed: 97 (4 UL)![]() ; ; et al in IEEE Transactions on Vehicular Technology (2018) Satellite Communication systems are a promising solution to extend and complement terrestrial networks in unserved or under-served areas. This aspect is reflected by recent commercial and standardisation ... [more ▼] Satellite Communication systems are a promising solution to extend and complement terrestrial networks in unserved or under-served areas. This aspect is reflected by recent commercial and standardisation endeavours. In particular, 3GPP recently initiated a Study Item for New Radio-based, i.e., 5G, Non-Terrestrial Networks aimed at deploying satellite systems either as a stand-alone solution or as an integration to terrestrial networks in mobile broadband and machine-type communication scenarios. However, typical satellite channel impairments, as large path losses, delays, and Doppler shifts, pose severe challenges to the realisation of a satellite-based NR network. In this paper, based on the architecture options currently being discussed in the standardisation fora, we discuss and assess the impact of the satellite channel characteristics on the physical and Medium Access Control layers, both in terms of transmitted waveforms and procedures for enhanced Mobile BroadBand (eMBB) and NarrowBand-Internet of Things (NB-IoT) applications. The proposed analysis shows that the main technical challenges are related to the PHY/MAC procedures, in particular Random Access (RA), Timing Advance (TA), and Hybrid Automatic Repeat reQuest (HARQ) and, depending on the considered service and architecture, different solutions are proposed. [less ▲] Detailed reference viewed: 141 (11 UL)![]() Andrenacci, Stefano ![]() ![]() Book published by IET (2018) Detailed reference viewed: 93 (19 UL)![]() Lagunas, Eva ![]() ![]() ![]() in 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC), Berlin, Germany, 10-12 September 2018 (2018) Detailed reference viewed: 177 (30 UL)![]() Merlano Duncan, Juan Carlos ![]() ![]() ![]() in IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (2017, October) We present a precoded multi-user communication test-bed to demonstrate forward link interference mitigation techniques in a multi-beam satellite system scenario which will enable a full frequency reuse ... [more ▼] We present a precoded multi-user communication test-bed to demonstrate forward link interference mitigation techniques in a multi-beam satellite system scenario which will enable a full frequency reuse scheme. The developed test-bed provides an end-to-end precoding demonstration, which includes a transmitter, a multi-beam satellite channel emulator and user receivers. Each of these parts can be reconfigured accordingly to the desired test scenario. Precoded communications allow full frequency reuse in multiple-input multiple-output (MIMO) channel environments, where several coordinated antennas simultaneously transmit to a number of independent receivers. The developed real-time transmission test-bed assist in demonstrating, designing and benchmarking of the new Symbol-Level Precoding (SLP) techniques, where the data information is used, along with the channel state information, in order to exploit the multi-user interference and transform it into useful power at the receiver side. The demonstrated SLP techniques are designed in order to be computationally efficient, and can be generalized to others multi-channel interference scenarios. [less ▲] Detailed reference viewed: 236 (33 UL)![]() Andrenacci, Stefano ![]() ![]() 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 ▲] Detailed reference viewed: 184 (41 UL)![]() Andrenacci, Stefano ![]() ![]() in Asilomar Conference on Signals, Systems, and Computers 2016 (2016) 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 ... [more ▼] 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. [less ▲] Detailed reference viewed: 226 (12 UL)![]() ![]() ; Andrenacci, Stefano ![]() ![]() in Advanced Relay Technologies in Next Generation Wireless Communication, Telecommunications (2016) Detailed reference viewed: 192 (9 UL)![]() Spano, Danilo ![]() ![]() ![]() in 21st Ka Conference (2015, October) Linear precoding exploits the spatial degrees of freedom offered by multi-antenna transmitters to manage interferences between multiple co-channel users. The adoption of precoding in practical systems ... [more ▼] Linear precoding exploits the spatial degrees of freedom offered by multi-antenna transmitters to manage interferences between multiple co-channel users. The adoption of precoding in practical systems, however, entails a series of practical barriers. Amongst several issues, the focus herein is on the non-linear dependence of the input versus the output power of the efficient and reliable amplifiers that drive each transmit antenna, which limits the system performance. As a first step, the present work studies the impact of linear precoding on the peak-to-average power ratio (PAPR) of precoded waveforms in multibeam satellite systems using a finite alphabet. In this context, a sensitivity analysis of the PAPR at the input of each amplifier with respect to intrinsic system level parameters, such as the number of transmit feeds, is performed. Next, the performance of the whole non-linear satellite chain is analyzed with respect to the symbol-error-rate (SER) and the total degradation (TD) of the channel. Furthermore, two low-complexity solutions are considered for counteracting the effects of the non-linearities of the satellite channel on the precoded waveforms, namely an automatic gain control (AGC) operation and a non-linear equalization performed at the receiver side. [less ▲] Detailed reference viewed: 365 (49 UL) |
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