Giulio Colavolpe

• PhD
• Professor (Full) at University of Parma

In the context of signal detection in the presence of an unknown time-varying channel parameter, receivers based on the Expectation Propagation (EP) framework appear to be very promising. EP is a message-passing algorithm based on factor graphs with an inherent ability to combine prior knowledge of system variables with channel observations. This s...

We address the parallel implementation of a closed-loop symbol timing synchronizer in digital receivers. Starting from a serial timing recovery loop, we propose a low-complexity parallel architecture which, unlike parallel schemes available in the literature, employs a single numerically controlled oscillator, and is practically suitable for high-s...

In this letter, we propose a novel constellation design, specifically tailored to contrast the effect of nonlinear channels. The proposed constellations are based on a spiral expression, which, unlike other unstructured designs, makes them easy to build and optimize. Our design approach allows to optimize the distance between symbols in the angular...

We investigate the performance of free-space optical communication systems in the presence of atmospheric turbulence to assess the advantages that a coherent communication system can bring with respect to a conventional intensity modulation and direct detection (IM/DD) system. The perspective is an information-theoretic one, hence we evaluate the m...

This paper deals with the phase noise affecting communication systems, where local oscillators are employed to obtain reference signals for carrier and timing synchronizations. The most common discrete-time phase noise channel model is analyzed, with the aim to fill the gap between measurements and analytical models. In particular, the power loss a...

This letter addresses the problem of signal detection in flat-fading channels. In this context, receivers based on the expectation propagation framework appear to be very promising although presenting some critical issues. We develop a new algorithm based on this framework where, unlike previous works, convergence is achieved after a single forward...

Non-terrestrial networks will play a crucial role in future wireless 6G systems to ensure ubiquitous connectivity and to complement terrestrial networks. With reference to a LEO constellation, this letter performs a comparison in terms of pragmatic capacity between the OFDM and the OTFS modulation in a scenario where multi-satellite diversity is em...

Motivated by automotive applications, we consider joint radar sensing and data communication for a system operating at millimeter wave (mmWave) frequency bands, where a Base Station (BS) is equipped with a co-located radar receiver and sends data using the Orthogonal Time Frequency Space (OTFS) modulation format. We consider two distinct modes of o...

This paper aims at tackling the problem of signal detection in flat-fading channels. In this context, receivers based on the expectation propagation framework appear to be very promising although presenting some critical issues. We develop a new algorithm based on this framework where, unlike previous works, convergence is achieved after a single f...

The paper summarizes the recent investigation on feasibility of adapting state-of-the-art coherent fiber-optics (FO) systems for Free Space Optical (FSO) scenarios. This investigation is critically dependent on the intertwined aspects of architecture, as well as device and propagation impairments (including the channel) appearing in the aforementio...

We consider time-frequency-packed systems in an additive white Gaussian noise scenario. With respect to systems employing time packing, thus introducing intentional intersymbol interference only, a further improvement of the spectral efficiency is obtained by packing the adjacent carriers closer in frequency. The adoption of a multiuser detector ca...

In the frame of ongoing efforts between space agencies to define an on-off-keying-based optical low-Earth-orbit (LEO) direct-to-Earth (DTE) waveform, this paper offers an in-depth analysis of the Variable Data Rate (VDR) technique. VDR, in contrast to the currently adopted Constant Data Rate (CDR) approach, enables the optimization of the average t...

Motivated by automotive applications, we consider joint radar sensing and data communication for a system operating at millimeter wave (mmWave) frequency bands, where a Base Station (BS) is equipped with a co-located radar receiver and sends data using the Orthogonal Time Frequency Space (OTFS) modulation format. We consider two distinct modes of o...

Fast and reliable synchronization in free-space optical (FSO) communications is a crucial task that has received little attention so far. Since in these applications the data rate is much higher than in traditional radio-frequency (RF) systems, novel technological constraints may arise in the design of the synchronization algorithms, as for example...

Many recent works in the literature declare that Orthogonal Time-Frequency-Space (OTFS) modulation is a promising candidate technology for high mobility communication scenarios. However, a truly fair comparison with its direct concurrent and widely used Orthogonal Frequency-Division Multiplexing (OFDM) modulation has not yet been provided. In this...

Gait and jump anomalies are often used as indicators to identify the presence and state of disorders that involve motor symptoms. Physical tests are often performed in specialized laboratories, which offer reliable and accurate results, but require long and costly analyses performed by specialized personnel. The use of inertial sensors for gait and...

In the frame of ongoing efforts between space agencies to define an on-off-keying-based optical low-Earth-orbit (LEO) direct-to-Earth (DTE) waveform, this paper offers an in-depth analysis of the Variable Data Rate (VDR) technique. VDR, in contrast to the currently adopted Constant Data Rate (CDR) approach, enables the optimization of the average t...

In the frame of ongoing efforts between space agencies to define an on-off-keying-based optical low-Earth-orbit (LEO) direct-to-Earth (DTE) waveform, this paper offers an in-depth analysis of the Variable Data Rate (VDR) technique. VDR, in contrast to the currently adopted Constant Data Rate (CDR) approach, enables the optimization of the average t...

We consider the phase noise affecting communication systems, where local oscillators are employed to obtain a reference signal for frequency and timing synchronizations. We try to fill the gap between measurements and analytical models, in case of free-running and phase-locked oscillators. In particular, we propose a closed form expression for the...

In this paper, we address the problem of the decoding of variable length physical layer header (PLH) codes. We take as a case study the DVB-S2X standard, and, after selecting a suitable PLH code with variable codeword length, we propose two alternative noncoherent decoding strategies. The proposed decoding strategies allow to estimate the length of...

In this paper, we address the problem of the decoding of variable length physical layer header (PLH) codes. We take as a case study the DVB-S2X standard, and, after selecting a suitable PLH code with variable codeword length, we propose two alternative noncoherent decoding strategies. The proposed decoding strategies allow to estimate the length of...

Featured Application The communications scenario analyzed in this paper is typical of environments affected by strong electromagnetic interference (EMI), such as, e.g., power line communications or power substations. The transmission of random correlated samples with continuous values, which we analyze, can be seen both as a rough model for multica...

The 5G ecosystem is radically shifting Information and Communication Technologies (ICT) towards a system directly tailored and optimised to support vertical markets and services. In order to design and implement the ambitious 5G network, Satellite Communications (SatCom) have been recognised as a promising solution to extend and complement terrestr...

Impulsive noise is the main limiting factor for transmission over channels affected by electromagnetic interference. We study the estimation of (correlated) Gaussian signals in an impulsive noise scenarios. In this work, we analyze some of the existing as well as some novel estimation algorithms. Their performance is compared, for the first time, f...

Motivated by future automotive applications, we study some joint radar target detection and parameter estimation problems where the transmitter, equipped with a mono-static MIMO radar, wishes to detect multiple targets and then estimate their respective parameters, while simultaneously communicating information data using orthogonal time frequency...

The 5G ecosystem is radically shifting Information and Communication Technologies (ICT) towards a system directly tailored and optimised to support vertical markets and services. In order to design and implement the ambitious 5G network, Satellite Communications (SatCom) have been recognised as a promising solution to extend and complement terrestr...

We consider a joint radar parameter estimation and communication system using orthogonal time frequency space (OTFS) modulation. The scenario is motivated by vehicular applications where a vehicle (or the infrastructure) equipped with a mono-static radar wishes to communicate data to its target receiver, while estimating parameters of interest rela...

We compare the main multicarrier modulation formats when employed over channels with nonlinear amplification. Using a general and unified discrete‐time model that encompasses orthogonal frequency division multiplexing (OFDM) and its most popular alternatives, we perform a comparison using the achievable spectral efficiency, computed in the presence...

Motivated by future automotive applications, we study the joint target detection and parameter estimation problem using orthogonal time frequency space (OTFS), a digital modulation format robust to time-frequency selective channels. Assuming the transmitter is equipped with a mono-static MIMO radar, we propose an efficient maximum likelihood based...

In this paper, the detection of LoRa signals from a low-earth orbit (LEO) satellite is considered. The use of a LEO satellite to collect messages from the terminals, as an alternative to terrestrial base stations in rural areas, represents a major challenge due to the specific impairments of this scenario, e.g., Doppler effects and interfering sign...

We propose a decoding algorithm for tail-biting convolutional codes over phase noise channels. It can be seen as a reduced complexity approximation of maximum-likelihood decoding. We target short blocks and extend the wrap-around Viterbi algorithm to trellises describing the random evolution of the phase impairment, for which we adopt two different...

We consider the estimation of correlated Gaussian samples in (correlated) impulsive noise, through message-passing algorithms. The factor graph includes cycles and, due to the mixture of Gaussian (samples and noise) and Bernoulli variables (the impulsive noise switches), the complexity of messages increases exponentially. We first analyze a simple...

We consider a joint radar estimation and communication system using orthogonal time frequency space (OTFS) modulation. The scenario is motivated by vehicular applications where a vehicle equipped with a mono-static radar wishes to communicate data to its target receiver, while estimating parameters of interest related to this receiver. In a point-t...

This work considers the design of short non-binary low-density parity-check (LDPC) codes over finite fields of order m, for channels with phase noise. In particular, m-ary differential phase-shift keying (DPSK) modulated code symbols are transmitted over an additive white Gaussian noise (AWGN) channel with Wiener phase noise. At the receiver side,...

We propose a framework, based on the combined use of single- and multiuser detection, to jointly optimize the achievable rates of two signals sharing the same frequency in the forward link of a multibeam satellite system. We propose then the application of the described framework to two different scenarios of interest. First, we consider a uniform...

The aim of this tutorial is to introduce a new air interface that inherits concepts from the DVB-S2X, while providing similar or better performance with higher flexibility for UniCast systems. The new air interface is based on a new framing numerology, a set of new optimized constellations and new FEC schemes derived from the 5G LPDC codes.

The integration of satellite and terrestrial networks is a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure, as also demonstrated by recent commercial and standardisation endeavours. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to t...

Recent investigations show that high-rate telemetry systems, based on the CCSDS 131.2-B-1 standard and employed in Earth observation missions, do not fully exploit the available capacity. We thus propose and discuss possible ways to improve the data return of these systems that can be considered for a revision of the current standard. Some of them...

The integration of satellite and terrestrial networks is a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure, as also demonstrated by recent commercial and standardisation endeavours. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to t...

In this letter, we investigate the lattice staggered multicarrier faster-than-Nyquist (MFTN) signaling. Specifically, we consider the time-frequency packing and optimal hexagonal lattice over additive white Gaussian noise channels. Firstly, an efficient implementation of the lattice staggered MFTN based on the fast Fourier transform algorithm is pr...

This paper presents results on the achievable spectral efficiency and on the energy efficiency for a wireless multiple-input-multiple-output (MIMO) link operating at millimeter wave frequencies (mmWave) in a typical 5G scenario. Two different single-carrier modem schemes are considered, i.e., a traditional modulation scheme with linear equalization...

This paper presents results on the achievable spectral efficiency and on the energy efficiency for a wireless multiple-input-multiple-output (MIMO) link operating at millimeter wave frequencies (mmWave) in a typical 5G scenario. Two different single-carrier modem schemes are considered, i.e., a traditional modulation scheme with linear equalization...

We consider the multicarrier faster-than-Nyquist (MFTN) signaling under low complexity symbol-by-symbol detection, where the lattice structure and time-frequency spacing play key roles in determining the system performance. Specifically, the energy of intersymbol interference (ISI) and intercarrier interference (ICI) introduced by time-frequency pa...

3GPP is finalising the first release of the 5G New Radio physical layer. To cope with the demanding 5G requirements on global connectivity and large throughput, Satellite Communications might be a valuable resource to extend and complement terrestrial networks. In this context, we introduce an integrated architecture for 5G-based LEO mega-constella...

LTE-based satellite systems in LEO constellations are a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to a traditional LTE system. In this paper, two architectures are proposed for a...

In this paper, the performance of a reference Medium Earth Orbit (MEO) satellite constellation system operating at Ka-band and employing single links to ground is compared with next generation advanced systems in higher RF or optical bands employing multiple diversity links. The fill rate of existing MEO constellations offering broadband and trunki...

In this paper, we study digital transmission over an additive white Gaussian noise (AWGN) channel with m-ary differential phase-shift keying (DPSK) modulation in the presence of phase noise. At the receiver side, non-coherent iterative detection and decoding is assumed. We present a non-binary low-density generator matrix (LDGM) code design which i...

We consider the rates achievable by a user in a multibeam satellite system for unicast applications, and propose alternatives to the conventional single-user symbol-by-symbol detection applied at user terminals. Single-user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area of a beam...

We study the benefits arising from the exploitation of interference in two satellite communications scenarios. We show that promising gains, with respect to the classical interference avoidance approach, can be achieved by applying non-orthogonal transmission schemes together with advanced transceiver architectures. We demonstrate that the non-orth...

We consider the rates achievable by a user in a multibeam satellite system for unicast applications, and propose alternatives to the conventional single-user symbol-by-symbol detection applied at user terminals. Single-user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area of a beam...

We investigate the problem of increasing the spectral efficiency of current high rate telemetry systems in two different scenarios, which exploit one and two channels, respectively. We will analyze several techniques aimed at improving different stages of the transceiver scheme. We will optimize the transmission parameters and apply advanced receiv...

This chapter reviews some of the best recently proposed alternatives to orthogonal frequency division multiplexing (OFDM). It gives mathematical models and block&;#x02010;schemes of the transmitter for all the alternatives considered. The chapter provides a comparative analysis of these modulations, highlights their pros and cons, and discusses the...

Future wireless networks will extensively rely upon bandwidths centered on carrier frequencies larger than 10GHz. Indeed, recent research has shown that, despite the large path-loss, millimeter wave (mmWave) frequencies can be successfully exploited to transmit very large data-rates over short distances to slowly moving users. Due to hardware compl...

We consider detection over intersymbol interference channels that are unknown at the receiver. For such a kind of systems, we consider an alternative approach to the design of a reduced-complexity receiver based on channel shortening without the explicit estimation of the channel impulse response. The proposed solution allows a simplification of th...

We design new continuous phase modulation (CPM) formats which are based on the combination of a proper precoder with binary input and a ternary CPM. The proposed precoder constrains the signal phase evolution in order to increase the minimum Euclidean distance, and to limit the bandwidth expansion due to the use of a ternary CPM. The resulting sche...

We consider the use of multiple co-located satellites to improve the spectral efficiency of broadcast transmissions. In particular, we assume that two satellites transmit on overlapping geographical coverage areas, with overlapping frequencies. We first describe the theoretical framework based on network information theory and, in particular, on th...

We consider binary continuous phase modulation (CPM) signals used in some recent low-cost and low-power consumption telecommunications standard. When these signals are generated through a low-cost transmitter, the real modulation index can end up being quite different from the nominal value employed at the receiver and a significant performance deg...

We consider binary continuous phase modulation (CPM) signals used in some recent low-cost and low-power consumption telecommunications standard. When these signals are generated through a low-cost transmitter, the real modulation index can end up being quite different from the nominal value employed at the receiver and a significant performance deg...

We investigate different techniques to improve the spectral efficiency of systems based on the DVB-S2 standard, when the transmitted signal bandwidth cannot be increased because it has already been optimized to the maximum value allowed by transponder filters. We will investigate and compare several techniques involving different sections of the tr...

We develop a robust multiuser detector for a Frequency Division Multiplexing (FDM) system where each user employs a binary continuous phase modulation (CPM) generated through a low-cost transmitter, thus characterized by a significant modulation index uncertainty, and sent over a channel affected by phase noise. In this FDM system the spectral effi...

In this work, we derive the maximum a posteriori (MAP) symbol detector for a multiple-input multiple-output system in the presence of Wiener phase noise due to noisy local oscillators. As in single-antenna systems, the computation of the optimum receiver is an analytically intractable problem and is unimplementable in practice. In this purview, we...

The second-generation specification of the digital video broadcasting for satellite (DVB-S2) was developed in 2003 with the aim of improving the existent broadcasting standard DVB-S. The main new features introduced by DVB-S2 included increased baud rates, higher cardinality constellations (up to 32 points), and more efficient binary codes. The ext...

It has been about 40 years since Gottfried Ungerboeck published his paper [1] on an alternative maximum-likelihood (ML) detector for intersymbol interference (ISI) channels. The ISI model used by Ungerboeck is commonly referred to as the Ungerboeck model. Ungerboeck?s ML detector has equivalent performance compared to Forney?s detector, which was p...

We study the achievable rates by a single user in multibeam satellite scenarios. We show alternatives to the conventional symbol-by-symbol detection applied at user terminals. Single user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area, and when aggressive frequency reuse is adopt...

We consider soft-output detection of a binary continuous phase modulation (CPM) generated through a low-cost transmitter, thus characterized by a significant modulation index uncertainty, and sent over a channel affected by phase noise. The proposed detector is designed by adopting a simplified representation of a binary CPM signal with the princip...

Flexible grid optical networks allow a better exploitation of fiber capacity, by enabling a denser frequency allocation. A tighter channel spacing, however, requires narrower filters, which increase linear intersymbol interference (ISI), and may dramatically reduce system reach. Commercial coherent receivers are based on symbol by symbol detectors,...

Time-frequency packing (TFP) transmission provides the highest achievable spectral efficiency with a constrained modulation format and detector complexity. In this work, the application of the TFP technique to fiber-optic systems is investigated and experimentally demonstrated. The main theoretical aspects, design guidelines, and implementation iss...

We discuss a few promising applications of the faster-than-Nyquist (FTN) signaling technique. Although proposed in the mid 70s, thanks to recent extensions this technique is taking on a new lease of life. In particular, we will discuss its applications to satellite systems for broadcasting transmissions, optical long-haul transmissions, and next-ge...

Fifth-generation (5G) cellular communications promise to deliver the gigabit experience to mobile users, with a capacity increase of up to three orders of magnitude with respect to current long-term evolution (LTE) systems. There is widespread agreement that such an ambitious goal will be realized through a combination of innovative techniques invo...

An innovative receiver architecture for the satellite-based automatic identification system has been recently proposed. In this paper, we describe a few modifications that can be introduced on the algorithms for synchronization and detection, which provide an impressive performance improvement. The receiver architecture has been designed for an on-...

An innovative receiver architecture for the satellite-based Automatic Identification System (AIS) has been recently proposed. In this paper, we describe a few modifications that can be introduced on the algorithms for synchronization and detection, that provide an impressive performance improvement with respect to the previous system. The receiver...

5G cellular communications promise to deliver the gigabit experience to mobile users, with a capacity increase of up to three orders of magnitude with respect to current LTE systems. There is widespread agreement that such an ambitious goal will be realized through a combination of innovative techniques involving different network layers. At the ph...

In this tutorial paper, we first review the main information–theoretic results on channels affected by a time-varying phase noise. The main maximum a posteriori symbol detection algorithms to be employed in such a challenging scenario are then described considering linear modulations and advanced coding schemes based on iterative detection and deco...