Search results for "FAD"
showing 10 items of 292 documents
Performance of LoRa technology: link-level and cell-level performance
2020
Abstract LoRa is a chirp spread spectrum technology that is becoming very popular for low-power wide-area networks, with high-density devices. In this chapter, we study the capacity of LoRa in rejecting different interfering signals. First, we analyze LoRa modulation numerically demonstrating that channel captures appear easily and that collisions between packets modulated with different spreading factors (SFs) are not uncommon. We validate such findings in experiments based on commercial devices and software-defined radios. Second, we model the network capacity obtainable in a typical LoRa cell: we show that high SFs can be seriously influenced by inter-SF collisions and that fading has a …
Channel estimation and transmit power control in wireless body area networks
2015
Wireless body area networks have recently received much attention because of their application to assisted living and remote patient monitoring. For these applications, energy minimisation is a critical issue since, in many cases, batteries cannot be easily replaced or recharged. Reducing energy expenditure by avoiding unnecessary high transmission power and minimising frame retransmissions is therefore crucial. In this study, a transmit power control scheme suitable for IEEE 802.15.6 networks operating in beacon mode with superframe boundaries is proposed. The transmission power is modulated, frame-by-frame, according to a run-time estimation of the channel conditions. Power measurements u…
Dissolvenze. Il corpo immaginario della fotografia
2020
Composto da fotografie appartenenti a tre progetti diversi – Lost in the K-Hole, Doppelgänger e Maelström – Human Surfaces è un diario visivo interpretativo che mette in luce, in modo originale, un’iconografia di varie e potenziali diversità individuali (l’alter ego, l’attore, il visionario) protagoniste di scene immaginarie ma non per questo meno obiettive. Di Donato si muove in un territorio non solo di osservazione ma di costruzione dell’immagine, a sancire che la fotografia, come tutte le forme visuali autoriali, è un’emanazione che contiene il suo artefice. Tessendo le fila delle sue visioni l’autore crea intersezioni, riconoscimenti, trasformazioni, vere e proprie descrizioni dense di…
Damasco dal profumo soave
2004
Damasco dal profumo soave – al fayha' in arabo, la più antica città della terra. Dalla soavità del profumo è derivata la sua intrigante continuità: l'essere città della seduzione e della poesia. I suoi giardini e il suo biondo fiume hanno spinto viaggiatori e geografi a cantare Damasco al-Sham come paradiso sulla terra. Le colline benedette che la sovrastano ricordano il dramma di Caino e Abele, i quaranta profeti, Maria e Gesù Bambino in fuga. La grande moschea degli Umayyadi riporta alla memoria il sacrificio di Giovanni Battista, il profeta del deserto. È la città menzionata nel Corano e ricordata più volte da Muhammad: il sigillo della profezia. Fu capitale dei califfi umayyadi e forse …
Performance Analysis of Cooperative V2V and V2I Communications Under Correlated Fading
2019
Cooperative vehicular networks will play a vital role in the coming years to implement various intelligent transportation-related applications. Both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications will be needed to reliably disseminate information in a vehicular network. In this regard, a roadside unit (RSU) equipped with multiple antennas can improve the network capacity. While the traditional approaches assume antennas to experience independent fading, we consider a more practical uplink scenario where antennas at the RSU experience correlated fading. In particular, we evaluate the packet error probability for two renowned antenna correlation models, i.e., cons…
Simultaneous harvest-and-transmit ambient backscatter communications under Rayleigh fading
2019
Ambient backscatter communications is an emerging paradigm and a key enabler for pervasive connectivity of low-powered wireless devices. It is primarily beneficial in the Internet of things (IoT) and the situations where computing and connectivity capabilities expand to sensors and miniature devices that exchange data on a low power budget. The premise of the ambient backscatter communication is to build a network of devices capable of operating in a battery-free manner by means of smart networking, radio frequency (RF) energy harvesting and power management at the granularity of individual bits and instructions. Due to this innovation in communication methods, it is essential to investigat…
Blind source separation for OFDM with filtering colored noise out
2011
Two blind algorithms that are developed with the intention of improving the symbol detection of Orthogonal Frequency Division Multiplexing (OFDM) techniques are proposed in this paper. OFDM systems are easy to equalize in implementations. The schemes are based on the theories of blind source separation (BSS). They are among the premier mechanisms used for extracting unobserved signals from observed mixtures in signal processing. In this study noise component of the received signal mixture is tried to be filtered out. A scalar energy function with the iterative fixed point rule for receive signal is used in determining the filter coefficients while taking the time correlation properties of t…
José Vidal-Beneyto/Autor de "Memoria democrática"/Entrevista. "Estamos empantanados en la corrupción"
2007
On the Consistency of Non-Stationary Multipath Fading Channels with Respect to the Average Doppler Shift and the Doppler Spread
2017
This paper is concerned with the consistency of non-stationary multipath fading channels. We introduce conditions under which a channel model is consistent w.r.t. the average Doppler shift and the Doppler spread. The conditions are applied to two classes of non-stationary channel models. The first class, which is termed Class A, is characterized by channel models based on an integral relationship between the path phases and the associated time-variant Doppler frequencies. The second class of models, called the Class B models, emerges from standard sum-of-cisoids (SOC) models by replacing the time-independent Doppler frequencies by time-dependent Doppler frequencies. It is shown that the Cla…
CCDC 137959: Experimental Crystal Structure Determination
2000
Related Article: A.Garcia-Raso, J.J.Fiol, S.Rigo, A.Lopez-Lopez, E.Molins, E.Espinosa, E.Borras, G.Alzuet, J.Borras, A.Castineiras|2000|Polyhedron|19|991|doi:10.1016/S0277-5387(00)00355-7