Search results for "Computer network"
showing 10 items of 1634 documents
Exploiting EDCA for Feedback Channels in Hybrid VLC/WiFi Architectures
2021
In this paper, we consider integrating VLC and WiFi technologies in a scenario in which Light-Emitting-Diodes (LEDs), acting as network access points (APs) for ultra-dense Internet of Things applications, are deployed into an indoor lighting infrastructure. In such a scenario, RF-links can be exploited for complementing VLC-links in dealing with mobility and bidirectional communications, which can be problematic due to the limited coverage areas and self-generated interference of VLC APs. In particular, we consider the possibility of supporting a technology-based duplexing scheme, in which downlink and uplink transmissions are performed by means, respectively, of VLC and WiFi interfaces int…
Flood frequency analysis for an urban watershed: comparison between several statistical methodologies simulating synthetic rainfall events
2016
To obtain the flooding frequency distribution for an urban watershed, different methods based on simulations of synthetic rainfall events were compared with an empirical analysis of the flooding data and with the results of long-term simulations. A copula-based multivariate statistical analysis of the main hydrological variables was proposed to generate synthetic hyetographs. Two different approaches were adopted to assess a temporal pattern to the synthetic rainfall: one analyses all available historical rainfall patterns, and another adopts the cluster analysis in three different variants to reduce the computational effort of the analysis. To test the methodology reliability, the analysis…
Maximizing network capacity in an heterogeneous macro-micro cellular scenario
2011
The problem of resource allocation in cellular networks has been traditionally faced at two different levels: at the network level, in terms of frequency planning and reuse pattern design, and at the cell level, in terms of cell capacity optimizations based on channel-dependent scheduling, link adaptation, power control, and so on. While this second aspect has been deeply investigated in literature, the first aspect has been mainly faced with static or semi-dynamic reuse utilization solutions. In this paper we deal with the problem of multi-cellular resource allocation in heterogeneous OFDMA environments with reuse factor equal to 1, where base stations with different power constraints coex…
Optimum pulse shape for minimum spectral occupancy in FSK signals
1984
The characteristics of a frequency shift keying (FSK) signal giving rise to maximum power within a prescribed frequency band are determined. The baseband pulse shape extends over any integer number of bit periods. An integral equation for the optimum pulse shape is derived and some simple properties of the solution are investigated. The equation has been solved for some values of the product of the prescribed band times the pulse duration and the signal shape is shown. Our results for the particular case of pulses only one bit period long are presented for purpose of comparison with results known in the literature. Plots of out-of-band power for some values of the prescribed band and of pul…
Deploying Virtual MAC Protocols Over a Shared Access Infrastructure Using MAClets
2013
Network virtualization has been extensively researched in the last years as a key enabler for improving the network performance. However, virtualization in wireless networks pose some unique challenges: first, the usual over-provisioning approach for providing isolation between multiple virtual entities is not viable; second, the partitioning criteria are often ambiguous, since the actual resources perceived by each entity depend on many external (and time-varying) factors. In this demo, we show an effective virtualization solution for wireless local area networks, solving the problem of isolation and flexible resource paritioning, based on the concept of MAClets. MAClets are software progr…
An object-oriented development platform for transport layer protocols
2002
Transport layer protocols have become a necessary communication element for new and classical real-time applications. The implementation of these protocols has never been structured and the designers of transport layer protocols have always developed without following any pattern. The library we have designed tries to avoid this. We propose a C++ library which could be used to develop transport layer protocols, considering every generic element inside a protocol as an object. At the end we apply the library to a well known transport layer protocol known as SNR.
Protection Motivation Theory in Information Systems Security Research
2021
Protection motivation theory (PMT) is one of the most commonly used theories to examine information security behaviors. Our systematic review of the application of PMT in information systems (IS) security and the comparison with its application for decades in psychology identified five categories of important issues that have not yet been examined in IS security research. Discussing these issues in terms of why they are relevant and important for IS security, and to what extent IS research has not considered them, offers new research opportunities associated with the study of PMT and IS security threats. We suggest how future studies can approach each of the open issues to provide a new roa…
Weighted Fuzzy Clustering for Online Detection of Application DDoS Attacks in Encrypted Network Traffic
2016
Distributed denial-of-service (DDoS) attacks are one of the most serious threats to today’s high-speed networks. These attacks can quickly incapacitate a targeted business, costing victims millions of dollars in lost revenue and productivity. In this paper, we present a novel method which allows us to timely detect application-layer DDoS attacks that utilize encrypted protocols by applying an anomaly-based approach to statistics extracted from network packets. The method involves construction of a model of normal user behavior with the help of weighted fuzzy clustering. The construction algorithm is self-adaptive and allows one to update the model every time when a new portion of network tr…
GPRS Security for Smart Meters
2013
Part 1: Cross-Domain Conference and Workshop on Multidisciplinary Research and Practice for Information Systems (CD-ARES 2013); International audience; Many Smart Grid installations rely on General Packet Radio Service (GPRS) for wireless communication in Advanced Metering Infrastructures (AMI). In this paper we describe security functions available in GPRS, explaining authentication and encryption options, and evaluate how suitable it is for use in a Smart Grid environment. We conclude that suitability of GPRS depends on the chosen authentication and encryption functions, and on selecting a reliable and trustworthy mobile network operator.
Distributed medical images analysis on a Grid infrastructure
2007
In this paper medical applications on a Grid infrastructure, the MAGIC-5 Project, are presented and discussed. MAGIC-5 aims at developing Computer Aided Detection (CADe) software for the analysis of medical images on distributed databases by means of GRID Services. The use of automated systems for analyzing medical images improves radiologists’ performance; in addition, it could be of paramount importance in screening programs, due to the huge amount of data to check and the cost of related manpower. The need for acquiring and analyzing data stored in different locations requires the use of Grid Services for the management of distributed computing resources and data. Grid technologies allow…