Interference analysis for optical wireless communications in Network-on-Chip (NoC) scenarios

Optical wireless (OW) communications, besides being of great interest for indoor and outdoor applications, have been recently proposed as a powerful alternative to the existing wired and wireless radio frequency (RF) interconnects in network-on-chips (NoCs). Design and analysis of networks with OW links require a careful investigation of cross-link interference, which impacts considerably the efficiency of systems that reuse the same channel for multiple transmissions. Yet, there is no comprehensive analysis of interference for OW NoCs, and the analyses of crosstalk in optical waveguide communications usually rely on synchronous data transmissions. A novel framework for the analysis of on-chip OW communications in the presence of cross-link cochannel interference and noise is proposed, where asynchronous data transmissions are considered. Self-beating of interfering signals is also considered, which was often neglected in previous literature. The bit error probability (BEP) for arbitrary number of interfering sources is derived as a function of signal-to-noise ratio (SNR), interference powers, detection threshold and pulse shaping, using both exact and approximation methods. The proposed analysis can be applied to both noise- and interference-limited cases, and enables a system designer to evaluate reuse distance between links that share the same optical carrier for simultaneous communication in NoCs

Pragmatic Space-Time Codes for Cooperative Relaying in Block Fading Channels

We address the problem of construction of space-time codes for cooperative communications in block fading channels. More precisely, we consider a pragmatic approach based on the concatenation of convolutional codes and BPSK/QPSK modulation to obtain cooperative codes for relay networks, for which we derive the pairwise error probability, an asymptotic bound for frame error probability, and a design criterion to optimize both diversity and coding gain. Based on this framework, we set up a code search procedure to obtain a set of good pragmatic space-time codes (P-STCs) with overlay construction, suitable for cooperative communication with a variable number of relays in quasistatic channel, which outperform in terms of coding gain other space-time codes (STCs) proposed in the literature. We also find that, despite the fact that the implementation of pragmatic space-time codes requires standard convolutional encoders and Viterbi decoders with suitable generators and branch metric, thus having low complexity, they perform quite well in block fading channels, including quasistatic channel, even with a low number of states and relays

A cross-layer scheduling strategy for the downlink of a MIMO-OFDMA system with heterogeneous traffic

in this paper we propose and investigate a cross-layer multiuser scheduling strategy for the support of heterogeneous traffic in the downlink of a MIMO-OFDMA system. It jointly considers different objectives: maximize the sum-rate on the radio channel, ensure a fair allocation of resources among users belonging to the same traffic class, consider the dynamics of traffic sources by looking at the delay of data packets in the queues, contribute to maximize quality of service figures at the application level. To exploit temporal diversity and to reduce complexity, the ergodic weighted sum-rate is maximized and dual optimization with stochastic approximation is applied to derive on-line algorithms. The numerical results show the capability of the scheduler to allocate physical layer resources according to rate constraints imposed for each different traffic class and with fairness inside each class, even in presence of different channels conditions and different network loads.Postprint (published version

Polarization Effect on the Performance of On-Chip Wireless Optical Point-to-Point Links

Optical on-chip wireless interconnection is an emerging technology that aims to overcome the communication bottleneck in computing architectures and in which multiple processing units are exploited for data-intensive applications. In this work, we propose an integrated dielectric Vivaldi antenna, which exhibits the same gain performances for both TE and TM input polarizations. Point-to-point on-chip communication links between two Vivaldi antennas are analyzed. Moreover, the effect of wave polarization on the link performances is numerically studied in on-chip multilayer structures in connection with the multilayer characteristic parameters, i.e., cladding layer thickness and refractive index. The numerical results show that, with the same antenna gain, TM polarization is affected by lower propagation losses when suitable cladding layer thickness and refractive index are considered

Effects of relay position and power allocation in space-time coded cooperative wireless systems

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Influenza vaccination and absenteeism among healthy working adults: a cost-benefit analysis

Seasonal influenza is a highly contagious infection that might lead to serious clinical complications and incurs a conspicuous socio-economic impact. Influenza vaccination is currently recommended only for specific groups of healthy adults (such as healthcare workers) even though it was demonstrated to be effective in reducing absenteeism and decreased workers' productivity during flu epidemic period. The main purpose of this study is to analyse the extent of absences due to illness following a voluntary flu immunization program among the Komatsu Italia Manufacturing company's personnel during the flu season 2017-2018. Secondly, we aimed at performing a cost-benefit analysis of the vaccination campaign from the company's perspective

Multi-level analysis of on-chip optical wireless links

Networks-on-chip are being regarded as a promising solution to meet the on-going requirement for higher and higher computation capacity. In view of future kilo-cores architectures, electrical wired connections are likely to become inefficient and alternative technologies are being widely investigated. Wireless communications on chip may be therefore leveraged to overcome the bottleneck of physical interconnections. This work deals with wireless networks-on-chip at optical frequencies, which can simplify the network layout and reduce the communication latency, easing the antenna on-chip integration process at the same time. On the other end, optical wireless communication on-chip can be limited by the heavy propagation losses and the possible cross-link interference. Assessment of the optical wireless network in terms of bit error probability and maximum communication range is here investigated through a multi-level approach. Manifold aspects, concurring to the final system performance, are simultaneously taken into account, like the antenna radiation properties, the data-rate of the core-to core communication, the geometrical and electromagnetic layout of the chip and the noise and interference level. Simulations results suggest that communication up to some hundreds of \u3bcm can be pursued provided that the antenna design and/or the target data-rate are carefully tailored to the actual layout of the chip

Multi-level analysis of on-chip optical wireless links

Networks-on-chip are being regarded as a promising solution to meet the on-going requirement for higher and higher computation capacity. In view of future kilo-cores architectures, electrical wired connections are likely to become inefficient and alternative technologies are being widely investigated. Wireless communications on chip may be therefore leveraged to overcome the bottleneck of physical interconnections. This work deals with wireless networks-on-chip at optical frequencies, which can simplify the network layout and reduce the communication latency, easing the antenna on-chip integration process at the same time. On the other end, optical wireless communication on-chip can be limited by the heavy propagation losses and the possible cross-link interference. Assessment of the optical wireless network in terms of bit error probability and maximum communication range is here investigated through a multi-level approach. Manifold aspects, concurring to the final system performance, are simultaneously taken into account, like the antenna radiation properties, the data-rate of the core-to core communication, the geometrical and electromagnetic layout of the chip and the noise and interference level. Simulations results suggest that communication up to some hundreds of μm can be pursued provided that the antenna design and/or the target data-rate are carefully tailored to the actual layout of the chip

Active TB screening among homeless people attending soup kitchens in Verona (Italy)

BACKGROUND: The hard-to-reach populations, including the homeless, are particularly vulnerable to the development of active tuberculosis. According to the World Health Organization, tuberculosis rates among the homeless in industrialized Countries are up to 20 times higher if compared with the general population, representing a relevant public health problem. The aim of our study was to describe the results of an active tuberculosis screening applied in order to find out suspected active TB cases among the homeless in Verona.METHODS: As part of a partnership between the non-profit association Medici per la Pace and one of the Local Health Units of Veneto Region (ULSS 9 Scaligera) in 2018, a tuberculosis screening, based on thoracic radiographs, was offered to the homeless guests of two Verona's soup kitchens.RESULT: The studied population included 139 people, and three cases of suspected active tuberculosis, all in males, were observed. Among these, two received a diagnostic confirmation of active tuberculosis (a prevalence of 1.44% - CI: 0,17 - 5,1). Moreover, radiographic patterns of tuberculosis aftermaths were found in six additional subjects.CONCLUSION: Interventions specifically dedicated to hard-to-reach populations, can be useful in identifying tuberculosis active cases and controlling the disease in low tuberculosis burden countries. In particular, the active research of subjects, the screening carried out with mobile X-ray, and also the constant caring of the patients with active disease, could be the right method to keep under control this relevant public health problem