Search results for " Telecom"

The Effect of the Range of a Modulating Phase Mask on the Retrieval of a Complex Object from Intensity Measurements

2021

The authors have been supported by the postdoctoral project (1.1.1.2/16/I/001, 1.1.1.2/VIAA/1/16/199), the CAMART2 project (grant agreement ID 739508), the Latvian Investment and Development Agency (LIDA) project (KC-PI-2017/105), and the grant for the Latvian State Emeritus Scientists.

Sviluppo di dispositivi elettronici di misura innovativi per la gestione delle Smart Grid attraverso un'opportuna infrastruttura di comunicazione

2014

On the Flexibility of the IEEE 802.11 Technology: Challenges and Directions

2011

The original 802.11 standard, which is the de-facto standard for contention-based wireless data networks, has shown to give poor performance or to be scarcely suitable for dealing with new PHY-layer technologies, networking scenarios, or service contexts, thus boosting the proliferation of projects, technical solutions and dedicated task groups for extending the basic protocol operations. In this paper, starting from the evolution analysis of current 802.11 standard and de- vices, we propose an architectural solution for making the medium access protocol programmable. Our basic idea, pursued within the FP7 EU Project FLAVIA [1], started in July 2010, is changing the role of the wireless net…

Wireless card virtualization: from virtual NICs to virtual MAC machines

2012

Virtualization has been a hot topic in computer science this last 10 years, and a key enabler to the recent advances. By technically enabling the Cloud paradigm, virtualization is becoming an inspiring source for the whole IT industry. At the same moment the virtualization of commodity PC was envisioned, Software Defined Radio started as a huge promise of efficient wireless transmission hardware. Unfortunately, the pace of innovation has still to reach the one of the PC virtualization. Yet, there is a another option. The current state of the art of hardware and software of wireless adapter in standard PC reveals interesting capabilities in terms of unused wireless capacity, processing power…

Analysis of MAC-level throughput in LTE systems with link rate adaptation and HARQ protocols

2015

LTE is rapidly gaining momentum for building future 4G cellular systems, and real operational networks are under deployment worldwide. To achieve high throughput performance, in addition to an advanced physical layer design LTE exploits a combination of sophisticated mechanisms at the radio resource management layer. Clearly, this makes difficult to develop analytical tools to accurately assess and optimise the user perceived throughput under realistic channel assumptions. Thus, most existing studies focus only on link-layer throughput or consider individual mechanisms in isolation. The main contribution of this paper is a unified modelling framework of the MAC-level downlink throughput of …

Generalized wave propagation problems and discrete exterior calculus

2018

We introduce a general class of second-order boundary value problems unifying application areas such as acoustics, electromagnetism, elastodynamics, quantum mechanics, and so on, into a single framework. This also enables us to solve wave propagation problems very efficiently with a single software system. The solution method precisely follows the conservation laws in finite-dimensional systems, whereas the constitutive relations are imposed approximately. We employ discrete exterior calculus for the spatial discretization, use natural crystal structures for three-dimensional meshing, and derive a “discrete Hodge” adapted to harmonic wave. The numerical experiments indicate that the cumulat…

Optimal Resource Allocation in Multi-Hop Networks: Contention vs. Scheduling

2014

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is actually the most used method in ad-hoc networks for transmitting on a contending medium, even if it shows poor performance in presence of hidden nodes. To increase performance, we propose an algorithm that combines CSMA and TDMA (Time Division Multiple Access) approaches. The adopted solution consists of grouping contending nodes in non-interfering subsets and granting a different numbers of time slots to different groups, while using the CSMA to manage medium access among nodes belonging to the same subset. An optimization procedure to assign the time slots to each subset of nodes and to find an equilibrium between contention …

Io sono Gandhi, io sono Telecom. Intorno a uno spot istituzionale di Telecom Italia

2009

Cosa succede quando una marca dice “io”? E quando lo dice un testimonial? E se si dovesse trattare di un leader mondiale riconosciuto come Gandhi? Che differenza si pone fra discorso di marca e discorso politico? L’analisi dello spot della campagna “Se avesse potuto comunicare così” e “A voi comunicare” assume un ruolo di cartina di tornasole per i processi di costruzione dell’identità aziendale. Le due campagne pongono anche la questione del ruolo delle nuove tecnologie nel discorso di marca. Si riflette sul “dialogo” intorno agli spot della campagna e attraverso di essi fra la marca e la rete (comunità facenti riferimento al cosiddetto web 2.0). L’analisi quindi si costruisce come opportu…

Opportunistic Synchronization for Improving IEEE 802.15.4 MAC Performance in Chain Topologies

2010

The most effective solution for energy saving in low-rate wireless sensor networks is maintaining each node in a doze state as long as possible. In order to guarantee network connectivity, the intervals at which the network sensors are turned on and off have to be coordinated. Therefore, synchronization is a very critical function for sensor networks. In this paper, we analyze the IEEE 802.15.4 MAC performance in sensor networks deployed in a chain topology. For this topology, critical inefficiencies can arise in case of multi-hop packet deliveries. We evaluate the impact of different synchronization schemes on the network performance, both in terms of network throughput and in terms of ene…

Image inpainting using directional wavelet packets originating from polynomial splines

2020

The paper presents a new algorithm for the image inpainting problem. The algorithm is using a recently designed versatile library of quasi-analytic complex-valued wavelet packets (qWPs) which originate from polynomial splines of arbitrary orders. Tensor products of 1D qWPs provide a diversity of 2D qWPs oriented in multiple directions. For example, a set of the fourth-level qWPs comprises 62 different directions. The properties of the presented qWPs such as refined frequency resolution, directionality of waveforms with unlimited number of orientations, (anti-)symmetry of waveforms and windowed oscillating structure of waveforms with a variety of frequencies, make them efficient in image pro…