1,720,990 research outputs found
A performance analysis of PRMA considering speech/data traffic, co-channel interference and ARQ error recovery
No full textPRMA (packet reservation multiple access) is a multiple access protocol proposed for use in advanced TDM-based radio systems. While the basic properties of such a protocol are understood, a comprehensive analysis of the protocol performance under realistic operation conditions is missing. The authors consider aspects which are key to a comprehensive analysis, such as traffic source interference, mixture of services (voice and data) and ARQ (automatic repeat request) function
Convegno “Campi elettromagnetici e salute: le risposte della Scienza”, Venezia, 1 ottobre 2005
No full textQuesto volume contiene gli Atti del Convegno promosso da Elettra 2000 “Campi elettromagnetici e salute: le risposte della Scienza”, che si è svolto a Venezia il 1 ottobre 2005.
Il contenuto di questo libro intende fornire una panoramica sulle attuali conoscenze scientifiche in materia di esposizione ai campi elettromagnetici, al fine di costruire un dialogo sul tema e prevenire l’insorgere di allarmismi ingiustificati
Performance evaluation of a Differential-GPS ground station for high accurate satellite navigation services
No full textAnalysis of field strength levels near base station antennas
No full textA new hybrid algorithm to evaluate the field strength levels around base stations antennas of cellular mobile radio systems is presented in the paper. The method allow a correct evaluation of near and far radiated field by means of the combination of different propagation models. The field intensity level is compared with measurements for some typical urban base stations and an analysis of the impact of the presence of buildings or other objects is also performed. We identify the areas around the antennas where the field strength level exceeds the exposure limits specified in [1, 2]. As a result of this analysis we propose a preliminary classification of different installations based on few fundamental parameters related to the antenna characteristics and to the environment topology. © 1999 IEEE
Propagation effects and countermeasures analysis in vehicle-to-vehicle communication at millimeter waves
No full textIn the context of the European research projects, PROMETHEUS (EUREKA) and DRIVE, special attention has been paid to the possible implementation of short-range millimeter-wave communication systems. In fact, vehicle-to-vehicle communications represent one of the major areas of integrated road transport environment (IRTE) research. An analytical approach to the problem of defining and evaluating the performance limits when the system operates in an actual environment is presented. More precisely, the anomalous propagation due to road reflection and multipath propagation effects are considered in order to determine possible countermeasure techniques such as coding and diversity in order to define system availabilit
Secondo Convegno “Elettrosmog”: quali risposte? Campi elettromagnetici e salute: le risposte della scienza, della società, della comunicazione. Roma, 11 ottobre 2007
No full textQuesto volume contiene gli Atti del Secondo Convegno “Elettrosmog:quali risposte? Campi elettromagnetici e salute: le risposte della Scienza,della Società, della Comunicazione”, tenutosi a Roma l’11 ottobre 2007.
Il Convegno è stato promosso da Elettra 2000 con lo scopo di fare il punto su quali sono stati gli sviluppi delle ricerche scientifiche negli ultimi anni, con un’ampia e aggiornata panoramica sugli studi recenti affidata ai più qualificati esperti della Scienza del settore.
Una seconda sessione è stata dedicata alla discussione degli aspetti sociali e di comunicazione, in modo da offrire un’occasione di incontro tra mondo politico, mondo accademico e cittadini, a sottolineare come in questi anni la via dei processi partecipati sia stata quella di maggior successo per la diminuzione dei conflitti, che dalle origini ad oggi hanno caratterizzato la gestione del problema “campi elettromagnetici”
Occupational exposure assessment to static magnetic field in MRI environment
No full textThe aim of the present study is the evaluation of occupational exposure to static magnetic field in MRI environment, through direct measurements and relevant dosimetric parameters calculation
A new methodology for the identification of validity domains of prediction models in urban environment
No full textThe choice of a given propagation model has a major impact on the accuracy and effectiveness of cellular planning, especially in an urban environment, where a higher degree of detail is required. Rigorous models, such as those based on ray optics, are generally heavily time-consuming; furthermore, they are accurate only if high resolution data-bases (of buildings, land usage, etc.) are available, and the cost of these data-bases is increasingly affecting the operators' budget. Therefore, one should use them only in their "validity domain", i.e., the area where they are both reliable and necessary; using complex tools where it is not needed implies an overhead in terms of computation time and, above all, data-base cost. For this reason, increasing interest and effort are being devoted by operators, manufacturers, and system planners in general to determine the validity domains of propagation models in urban environment. In this paper we introduce a new methodology, based on objective indicators related to field strength statistics, to determine these domains
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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