Roberto Garello

• Polytechnic University of Turin

Spectrum Sensing will play a pivotal role in 6G Cognitive Radio Networks, in which unlicensed users could dynamically use the spectrum and perform opportunistic transmission. In this paper, we focus on a multiple-antenna data-aided Spectrum Sensing algorithm and we compute the exact Moment Generating Function and probability density function under...

Quadratic forms with random kernel matrices are ubiquitous in applications of multivariate statistics, ranging from signal processing to time series analysis, biomedical systems design, wireless communications performance analysis, and other fields. Their statistical characterization is crucial to both design guideline formulation and efficient com...

In this paper we study spreading sequences for Code Division Multiplexing (CDM) generated from the AES algorithm in counter mode. These sequences are robust against jamming because they cannot be reconstructed from one of their segments. Additionally, they are flexible, have a large cardinality, and can be obtained from a small key. We show how the...

In this paper, we study the extension of 5G New Radio (NR) to Non-Terrestrial Networks (NTN). For terrestrial ones, Hybrid Automatic Repeat reQuest (HARQ) is the main retransmission solution used by 5G NR at the physical and MAC layers, enhancing decoding performance through diversity and coding gain. However, for NTN, its implementation faces chal...

This paper presents a framework for integrating Low-Earth Orbit (LEO) platforms with Non-Terrestrial Networks (NTNs) in the emerging 6G communication landscape. Our work applies the Mega-Constellation Services in Space (MCSS) paradigm, leveraging LEO mega-constellations’ expansive coverage and capacity, designed initially for terrestrial devices, t...

In this paper we introduce Serial Bicode and Serial Multicode Direct Sequence Spread Spectrum (DSSS) and we extend them to Code Division Multiple Access (CDMA). To each user are assigned two or more spreading codes. The information is associated to these codes, which are alternated within a single DSSS signal. The performance of the new techniques...

This paper studies the performance of the communication link between a ground station and the satellites of a LEO constellation, employing code division multiplexing and a non-linear high-power amplifier. The analysis shows that the input power selection at the high-power amplifier of the ground station has a significant impact on overall system pe...

Massive MIMO technology has significantly enhanced the performance of 5G networks, and its potential is poised for further expansion in the upcoming 6G standard. Large antenna arrays at the transmitter, combined with multiple antennas at each user can enable multi-user multi-layer MIMO data transmission. In this paper, we study the potential benefi...

This work studies the problem of secrecy energy efficiency maximization in multi-user wireless networks aided by reconfigurable intelligent surfaces, in which an eavesdropper overhears the uplink communication. A provably convergent optimization algorithm is proposed which optimizes the user’stransmit power, metasurface reflection coefficients, and...

This work studies the problem of secrecy energy efficiency maximization in multi-user wireless networks aided by reconfigurable intelligent surfaces, in which an eavesdropper overhears the uplink communication. A provably convergent optimization algorithm is proposed which optimizes the user's transmit power, metasurface reflection coefficients, an...

The number of applications of low-power wide-area networks (LPWANs) has been growing quite considerably in the past few years and so has the number of protocol stacks. Despite this fact, there is still no fully open LPWAN protocol stack available to the public, which limits the flexibility and ease of integration of the existing ones. The closest t...

We analyze the performance of enhanced spread spectrum Aloha (E-SSA) in the framework of unsourced multiple access (UMAC). The asynchronous, unframed transmission of E-SSA is modified to enable a direct comparison with framed UMAC schemes and with Polyanskiy’s achievability bound. The design of E-SSA is tailored to the UMAC setting, resorting to sh...

We consider a Low Earth Orbit (LEO) satellite hosting a 5G base station transmitting to a handheld device in L-band or S-band. This link is critical because it is characterized by a very low Signal-to-Noise Ratio and significant residual frequency offset due to imperfect Doppler compensation. Usual methods adopted to detect the Primary Synchronizat...

The 5G New Radio synchronization procedure is the first step that the user must complete to access the mobile network. It mainly consists of the detection of the primary and secondary synchronization signals (PSS and SSS, respectively) and the decoding of the physical broadcast channel (PBCH). Our goal is to provide a comprehensive study of the syn...

This paper presents a preliminary analysis on the impact of Reconfigurable Intelligent Surfaces (RISs) for the realization of multi-user Distributed multiple input multiple output (DMIMO) systems, where the distributed units are actually RISs. Assuming no direct link between the multi-antenna Access Point (AP) and the users, we design the joint tra...

Beyond 5G technologies promise groundbreaking advances on the performance of cellular networks, by taking advantage of Massive MIMO in mmWave scenarios. The aim of this study is to analyze and test the performance of a 5G cell site equipped with large antenna arrays. It is of particular interest the comparison between the typical trisector cell des...

Advances in machine learning have widened the range of its applications in many fields. In particular, deep learning has attracted much interest for its ability to provide solutions where the derivation of a rigorous mathematical model of the problem is troublesome. Our interest was drawn to the application of deep learning for channel state inform...

Satellite missions demand ever greater connectivity, especially in the LEO regime. In this paper, we introduce the new mega-constellation services in space paradigm: we show that mega-constellations, deployed to offer innovative services to Earth’s users, can provide excellent connectivity to LEO spacecrafts, too. First, we characterise the communi...

Recently, CRC-aided list decoding of convolutional codes has gained attention thanks to its remarkable performance in the short blocklength regime. This paper studies the convolutional and CRC codes of the Consultative Committee for Space Data System Telemetry recommendation used in space missions by all international space agencies. The distance s...

Mega-constellations are being deployed to offer innovative services to Earth's users. Our work shows how they can provide seamless connectivity to LEO spacecrafts too, and transform them into highly responsive nodes of a space-to-space network characterized by high throughput, low latency, and low cost. For realizing the new mega-constellation serv...

Mega-constellations are being deployed to offer innovative services to Earth's users. Our work shows how they can provide seamless connectivity to LEO spacecrafts too, and transform them into highly responsive nodes of a space-to-space network characterized by high throughput, low latency, and low cost. For realizing the new mega-constellation serv...

Mega-constellations are being deployed to offer innovative services to Earth’s users. Our work shows how they can provide seamless connectivity to LEO spacecrafts, too, and transform them into highly responsive space network nodes, thus enabling a myriad of innovative applications. For realizing the new mega-constellation services in space paradigm...

In this paper we introduce and design sparse constellations for Direct-to-Satellite Internet of Things (DtS-IoT). DtS-IoT does not require a ground infrastructure, because the devices are directly connected to Low Earth Orbit satellites acting as orbiting gateways. The key idea of sparse constellations is to significantly reduce the number of in-or...

The Consultative Committee for Space Data Systems, followed by all national and international space agencies, has updated the Telecommand Coding and Synchronization sublayer to introduce new powerful low-density parity-check (LDPC) codes. Their large coding gains significantly improve the system performance and allow new Telecommand services and pr...

This paper presents a thorough analysis of the spectral characteristics of space telemetry signals when randomizers are used to counter the power excess, that is, the increase of the power spectrum in some measurement bandwidths with respect to the transmission of an ideal random signal. We show that a long randomizer actually improves the spectral...

Bluetooth mesh is a recent technology built on the Bluetooth Low Energy protocol stack architecture, focusing on the Internet of Things. It represents an excellent solution for commercial and industrial lighting applications, though it is still evolving. One of the biggest challenges of the Bluetooth mesh network is the improvement of confirmation...

In this paper, we study the feasibility of coupling the PN ranging with filtered high-order modulations, and investigate the simultaneous demodulation of a high-rate telemetry stream while tracking the PN ranging sequence. Accordingly, we design a receiver scheme that is able to perform a parallel cancellation, in closed-loop, of the ranging and th...

Since their dawning, space communications have been among the strongest driving applications for the development of error correcting codes. Indeed, space-to-Earth telemetry (TM) links have extensively exploited advanced coding schemes, from convolutional codes to Reed-Solomon codes (also in concatenated form) and, more recently, from turbo codes to...

NEXCODE is a project promoted by the European Space Agency aimed at research design development and demonstration of a receiver chain for telecomm and links in space missions including the presence of new short low-density parity-check codes for error correction. These codes have excellent performance from the error rate viewpoint but also put new...

The article investigates the coverage achievable by three different network configurations for delivering high quality multicast video services to mobiles: conventional broadcast High Power High Tower (HPHT), mobile cellular Low Power Low Tower (LPLT), and mixed structures. Different spectrum efficiencies, transmitter distance and power, and receiv...

This paper presents a new location determination in an indoor environment is a contest that appearances the wireless communication. The concept of indoor cooperative positioning was established in order to provide the user's location inside buildings or laboratories during a necessity where Global Navigation Satellite System (GNSS) facilities are n...

In this paper, a performance analysis of multi-antenna spectrum sensing techniques is carried out. Both well known algorithms , such as Energy Detector (ED) and eigenvalue based detectors , and an eigenvector based algorithm, are considered. With the idea of auxiliary noise variance estimation, the performance analysis is extended to the hybrid app...

In this paper, a thorough comparison of multi-antenna spectrum sensing techniques is performed. We considered well known algorithms, such as Energy Detector (ED), eigenvalue based detectors, and an algorithm that uses the eigenvector associated to the largest eigenvalue of the covariance matrix. With the idea of auxiliary noise variance estimation,...

Non-line-of-sight (NLoS) propagation of radio frequency (RF) signal has proven to be challenging for the localization of unknown nodes in wireless networks. In particular, the blockage of RF signal can heavily affect the accuracy of range measurements performed between nodes and in turn may cause the position estimation diverging. This paper analyz...

Hosting multiple radio technologies in computing devices is becoming increasingly feasible, common, and widely-adopted by stakeholders to offer better services. Packet-loss analysis is essential for characterizing and evaluating the behavior of wireless systems, and thereby assists the procedures of delivering the required of quality of service lev...

We investigate and compare, over the additive white Gaussian noise channel, different options for updating the error correcting code currently used in space mission telecommand links. Besides some more consolidated proposals, using low-density parity-check codes, we characterize and assess the performance of alternative schemes, based on parallel t...

In this paper, we study the performance of telecommand space links affected by pulsed, continuous wave and pseudo-noise jamming. Countermeasures include coding, interleaving, and direct sequence spread spectrum. Binary and non-binary low-density parity-check codes, parallel turbo codes, and soft-decision decoded BCH codes are considered. We investi...

In this paper, we extend the concept of SNR Wall phenomenon for Energy Detection (ED) to the multi-sensor ED by using a hybrid approach with auxiliary noise estimation under a typical flat fading channel scenario. SNR Wall expression is derived for multi-sensor ED and proved to be independent of the number of sensors. The distribution of the uncert...

In this paper, semi-blind class of spectrum sensing algorithms, Energy Detection (ED) and Roy's Largest Root Test (RLRT), are considered under a typical flat fading channel scenario. The knowledge of the noise variance is imperative for the optimum performance of ED and RLRT. Unfortunately, the variation and unpredictability of noise variance is un...

Two particular semi-blind spectrum sensing algorithms are taken into account in this paper: Energy Detection (ED) and Roy's Largest Root Test (RLRT). Both algorithms require the knowledge of the noise power in order to achieve optimal performance. Since by its nature the noise power is unpredictable, noise variance estimation is needed in order to...

This chapter describes a set of spectrum sensing algorithms to be employed for the detection of Ortogonal Frequency Division Multiplexing transmissions in the TV bands (470–790 MHz), like DVB-T signals. Spectrum sensing techniques take a crucial role to support geo-referenced TV White-Spaces (TVWS) databases and to maintain them up-to-date over tim...

Cognitive radio networks operating in the digital television white spaces are of particular interest for their practical applications. In this paper, we review several parametric and non-parametric test statistics commonly used in spectrum sensing. Both single-antenna as well as multiple antenna techniques are considered. For a selected subset of t...

The aim of this paper is to study the performance of some coding schemes recently proposed for updating the TC channel coding standard for space applications, in the presence of jamming. Besides low-density parity-check codes, that appear as the most eligible candidates, we also consider other solutions based on parallel turbo codes and extended BC...

We investigate and compare different options for updating the error correcting code currently used in space mission telecommand links. Taking as a reference the solutions recently emerged as the most promising ones, based on Low-Density Parity-Check codes, we explore the behavior of alternative schemes, based on parallel concatenated turbo codes an...

We investigate and compare different options for updating the error correcting code currently used in space mission telecommand links. Taking as a reference the solutions recently emerged as the most promising ones, based on Low- Density Parity-Check codes, we explore the behavior of alternative schemes, based on parallel concatenated turbo codes a...

Multi-access networks are envisioned to guarantee a continuous service while addressing different application requirements in terms of data rate, coverage and power consumption. Different access technologies can be effectively combined in a multi-access scenario where the overall system is able to achieve a better performance leveraging on the diff...

Since Global Navigation Satellite Systems (GNSS) show degraded performance in dense urban and indoor areas, a positioning sensor based on Digital Video Broadcast-Terrestrial (DVB-T) systems is presented in this paper. DVB-T signals can be considered as signals-of-opportunity for positioning, due to their good properties. One of the challenges to ov...

This paper presents a novel cognitive and cooperative tracking (CCT) approach based on extended Kalman filter (EKF) to localize mobile nodes in wireless networks. The proposed algorithm shows three important features: energy efficient, cognitive and cooperative. More specifically, the tracking algorithm adaptively adjusts the transmission power to...

Dense urban areas are particularly challenging environments for global navigation satellite systems (GNSS) because the satellite visibility is heavily reduced due to the presence of the so called urban canyons, composed of a series of tall buildings and narrow streets. In order to improve GNSS performance in these environments, hybrid (GNSS/terrest...

In cognitive radio networks, systems operating in digital television white spaces are particularly interesting for practical applications. In this paper, we consider single- antenna and multi-antenna spectrum sensing of real DVB-T signals under different channel conditions. Some of the most important algorithms are considered and compared, includin...

This paper presents a novel processing technique which can be applied to corneal in vivo images obtained with optical coherence tomograms across the central meridian of the cornea. The method allows to estimate the thickness of the corneal sublayers (Epithelium, Bowman's layer, Stroma, Endothelium, and whole corneal thickness) at any location, incl...

This paper presents a novel 'Energy Efficient Tracking' (EET) algorithm that tries to meet the localization accuracy requirement, Pa, imposed by a generic location-based application while the energy consumption for ranging and communication is optimized. More specifically, given the set of range measurements performed by a mobile node with respect...

In DVB-T Single Frequency Networks (SFN) different emitters simultaneously transmit the same signal on the same frequency. These signals can be used for positioning, or to integrate GNSS in hostile environments, but SFN characteristics may induce a path ambiguity problem. This paper demonstrates two solutions for solving this problem: pseudorange c...

In this paper, we study a positioning method working in DVB-T single frequency networks (SFNs). These networks have several properties useful for positioning (synchronized emitters at fixed and known location, high SNR, OFDM signals containing pilot subcarriers). Thus, their signals may be used as signals-of-opportunity when the user enters a GNSS...

I n peer-to-peer (P2P) networks, com-munication nodes can communicate with their neighbors without central coordination. By exchanging data, the network can perform cooperative positioning: each node is helped by its neighbors to compute its position. If the devices contain both a GNSS receiver and a terrestrial ranging sys-tem for estimating the i...

In this paper we propose a decentralized approach for cooperative signal detection, based on peer-to-peer collaboration among sensor nodes. The proposed method combines belief propagation, implemented in a distributed fashion through the exchange of local messages to and from neighboring nodes, with a Neyman-Pearson framework, that allows control o...

m a r c h /a p r i l 2 0 1 2 InsideGNSS 55 A s part of an effort to find meth-ods that improve the perfor-mance of GNSS receivers in hostile environments, this article examines a cooperative position-ing, where receivers exchange data and information with their neighbors or peers. We focus on unstructured peer-to-peer (P2P) networks, without a cont...

We propose a novel cooperative positioning al- gorithm that fuses information from satellites and terrestrial wireless systems, suitable for GPS-challenged scenarios. The algorithm is fully distributed over an unstructured network, does not require a fusion center, does not rely on fixed terrestrial infrastructure, and is thus suitable for ad-hoc d...

In this paper we propose a novel hybrid and cooperative positioning approach based on extended Kalman filter (EKF) to localize mobile targets in indoors. The algorithm fuses both received signal strength (RSS) measurements performed by nodes of a wireless sensor network (WSN) and proximity information from radio frequency identification (RFID) devi...

In this paper we compare several popular and top performing spectrum sensing algorithms for cognitive radio under low signal to noise ratio scenario, namely the Energy Detection, the Cyclostationary Detection, and the Eigenvalue based Detection. Especially, when auxiliary sensing slots are available, we incorporate modified hybrid algorithms that c...

In this paper we consider signal detection in cognitive radio networks, under a non-parametric, multi-sensor detection scenario, and compare the cases of known and unknown noise level. The analysis is focused on two eigenvalue-based methods, namely Roy's largest root test, which requires knowledge of the noise variance, and the generalized likeliho...

Transition-edge sensors (TES) are detectors able to count single photons from x-ray to infrared, generating pulses with amplitudes proportional to the absorbed photon energy. The TES performance depends on the sensor parameters and also on the noise level. The evaluation of the energy resolution is thus dependent on the type of signal analysis appl...

This study addresses the problem of detecting signals characterised by a discontinuous presence in the detection window. This situation is of particular interest for applications of spectrum sensing in cognitive radio networks where, on the one hand, the sampling frequency may be limited by hardware capabilities and, on the other hand, the signal t...

Towards adaptive wireless personal area networks (WPANs)Introduction and motivationRecent years have witnessed a growing demand on wireless technologies, thanks to their convenience and the variety of services offered. This success is leading to an increasing adoption of wireless systems, especially the ones operating in the unlicensed 2.4 GHz indu...

Nowadays indoor positioning applications have received great attentions among short range wireless communication systems. In particular, Wireless Sensor Network (WSN) is the most widely used technology for indoor localization as it is cheap and easy to deploy. However, location accuracy is limited by the harsh propagation of the Radio Frequency (RF...

It is well known that many of the scientific and technological discoveries of the XXI century will depend on the capability of processing and understanding a huge quantity of data. With the advent of the digital era, a fully digital and automated treatment can be designed and performed. From data mining to data compression, from signal elaboration...

Truncated maximum-length binary sequences are studied in this paper. The impact of truncation on their autocorrelation properties and power spectral density is investigated. Several new analytical results are given and validated through simulation. The first- and second-order statistics of the periodic autocorrelation function and the spectral peak...

Cooperative positioning algorithms have been recently introduced to overcome the limitations of traditional methods, relying on GNSS or other terrestrial infrastructure. In particular, SPAWN (Sum- Product Algorithm over a Wireless Network) was shown to provide accurate position estimate even in challenged indoor environments, thanks to exchange of...

In this paper we address the problem of distributed Bayesian hypothesis testing in wireless networks where correlations among nodes are modeled as exponential Markov Random Fields (MRF). Applying distributed Belief Propagation (BP), we first derive message and belief update rules for the above model expressed under a likelihood ratio formulation. T...

Cooperative localization algorithms have been recently introduced to overcome the limitations of systems relying on GPS or other terrestrial infrastructure. The novel hybrid cooperative unscented Kalman filter (hcUKF) approach, which fuses ranging data from both satellites and terrestrial receivers, allows increased availability, robustness and acc...

This paper presents a demonstrator of a multi-hop 6LoWPAN provided with frequency-agility extensions. A reference architecture is presented along with the basic components introduced to build a distributed spectrum sensing and interference resolution service in a multi-hop environment. Moreover, a frequency-agility management plane is proposed for...

In this paper we propose a novel, versatile graph model to solve efficiently and in a fully distributed fashion problems of collaborative inference in Cognitive Networks. Specifically, we develop an algorithm that estimates the probabilities of channel occupation for secondary network nodes; the algorithm can be used either to compute multiple, loc...

Custom filtering structures have been studied and implemented on Field Programmable Gate Arrays (FPGA) to process signals coming from nuclear particle detectors. These algorithms will help to build new triggerless data acquisition systems of future generation experiments. In this paper the steps to optimize the filters implementation on hardware-pr...

Periodicities in a DNA sequence contain information about its function and structure. Frequency analysis can be used to reveal such periodicities. A definition of spectrum for DNA sequences is proposed, based on an entropy minimization criterion. It is shown that the properties of the proposed spectrum are those expected from the spectrum of a symb...

We investigate the effect of non idealities in the diagonalizing precoder vectoring technique used for cancellation of the far-end crosstalk in downstream VDSL networks. The contribution of the paper is twofold: on one hand we provide analytical formulas to estimate the average bit rates achievable as a function of both relative and absolute estima...

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