Search results for "Telecommunication"
showing 10 items of 1769 documents
<title>Safety problems in free space optical transmission</title>
2006
The paper is focused on safety of exploitation of optical transmission devices in free space. The subjects concerning propagation of "open" optical stream and its' possible dangerous influence on environment, mainly living organisms are discussed. An attempt to evaluate an installation and exploitation of transmitting devices was made, concerning dangers, requirements, recommendations and restrictions, concluding from accepted safety standards (IEC 60825- 1 :2005, EN 60825-1 :2005 and in Poland PN-EN 60825-1 :2005 "Safety of laser devices - Equipment classification, requirements and user's guide"; IEC 60825-12:2004, EN 60825-12:2005 and in Poland PN-EN 60825-12:2005 "Safety of free space op…
Static and Dynamic Comparative Study on the Cardanic Transmission
2015
This paper aims to make a comparative study between the static and the dynamic analysis in the cardanic transmission. The cardanic transmission is done at full scale and is charged as it is in practice, by means of the Solidworks and Cosmos programs. We observe the differences and the tension areas which appear in the cardanic transmission elements and present the findings and the given solutions, according to the study.
Enhanced LMMSE equalizer for high-speed single frequency network in HSDPA
2011
Currently, considerable interest has been shown in the research and standardization communities in multicell transmission schemes for HSPA, with a number of possible schemes under discussion that include Multiflow, Fast Cell Switching (FCS) and High-Speed Single Frequency Network (HS-SFN). In particular, HS-SFN is a promising technique that not only combines received energy from participating cells, but also reduces intercell interference with low UE complexity. In principle, HS-SFN can be implemented with a small modification to an LMMSE receiver at the UE. This paper introduces a more advanced LMMSE equalizer for High-Speed Single Frequency Network in HSDPA that achieves further performan…
Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation
2017
[EN] Duty cycling (DC) is a popular technique for energy conservation in wireless sensor networks (WSNs) that allows nodes to wake up and sleep periodically. Typically, a single-packet transmission (SPT) occurs per cycle, leading to possibly long delay. With aggregated packet transmission (APT), nodes transmit a batch of packets in a single cycle. The potential benefits brought by an APT scheme include shorter delay, higher throughput, and higher energy efficiency. In the literature, different analytical models have been proposed to evaluate the performance of SPT schemes. However, no analytical models for the APT mode on synchronous DC medium access control (MAC) mechanisms exist. In this …
Effect of Channel-Quality Indicator Delay on HSDPA Performance
2007
This paper evaluates the effect of the channel estimation inaccuracy on the performance of an HSDPA system. This study provides some results from system level simulations that have been conducted over a very complete dynamic simulator which models an HSDPA system full compliant with specifications. This emulator allows performing multi-user transmission and link adaptation with a limited modulation and coding scheme (MCS) selection based on the channel quality indicator (CQI) modes. Many factors such as the user equipment (UE) speed, the employed scheduling algorithm or the traffic load have been considered in the assessment. Moreover the intrinsic constraints of a WCDMA system like HSDPA h…
Efficiency of Split-Way CVT's. A simplified model
2007
ABSTRACT In this paper, a general formula is obtained for the efficiency of all types of Split-Way CVT, consisting of one or two epicyclic trains, a number of fixed ratio gears and one variable speed unit (CVU). It is based on the application of the principle of virtual works and on the simplifying hypothesis that all the dissipation is lumped inside the CVU. The comparison with some experimental results from the literature shows a surprisingly good fit, also in the neighbourhoods of zero speed ratio. INTRODUCTION The possibility of changing the speed ratio continuously between the primary and the secondary shaft of a mechanical transmission is a very interesting topic, mainly in the automo…
On the Problems of Symbol-Spaced Tapped-Delay-Line Models for WSSUS Channels
2007
Article from the journal: Wireless Communications and Mobile Computing The deposited fulltext is a preprint of the definitive article at Wiley Interscience http://dx.doi.org/10.1002/wcm.683 This paper analyzes the validity and statistical behavior of symbol-spaced tapped-delay-line (SSTDL) models for wide-sense stationary uncorrelated scattering (WSSUS) mobile radio channels. SSTDL models are obtained by sampling the channel impulse response (CIR) in delay domain at a rate equal to the reciprocal of the symbol duration. They were proposed more than four decades ago as canonical channel models for band-limited timevariant linear (TVL) systems, and are nowadays widely in use for assessing the…
Fuzzy topology discovery protocol for SDN-based wireless sensor networks
2017
Abstract The growing trend in pervasive systems forces traditional wireless sensor networks to deal with new challenges, such as dynamic application requirements and heterogeneous networks. One of the latest paradigms in this area is software defined wireless sensor network. According to the paradigm, the networks take care of managing topological information and forwarding decisions using a bipartite architecture in which a control plane decides the forwarding policies and the data plane (i.e. ordinary sensor nodes) executes them. Unfortunately, in highly dynamic networks, this approach generates an overhead of control packet exchange between the ordinary nodes and the control plane, that …
Wind Turbines to Power Telecommunication Systems: A Case Study in Sicily
2011
The ever increasing problems related to air pollution and the difficulties for power lines to reach inaccessible areas are pushing to find new solutions for powering telecommunications equipments (TLC). The renewable energy sys- tems, although relatively expensive, have the required characteristics. The purpose of this work is to find a solution based on a low power wind turbine to serve a real telecommunication site located near Palermo, the main city of Sicily (Italy).
Smart grid integrated green data centres as ancillary service providers
2015
In this paper a review of Green Data Centres facilities to support smart grids operation is proposed. The paper describes the ancillary services a Green Data Centre can provide both in terms of spinning reserve provision and different regulation services. In the application section, a real electrical grid hosting a data centre is considered. The infrastructure is owned by Engineering S.p.A. and is installed in northern Italy. The system has been considered as connected to the MV distribution grid in presence of other renewable energy sources. The impact of possible power management operations over the considered data centre has been studied by means of a simulation software and the spinning…