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ABSTRACT: A key point in the deployment of new wireless services is the cost-effective extension and enhancement of the network's radio coverage in indoor environments. Distributed Antenna Systems using Fiber-optics distribution (F-DAS) represent a suitable method of extending multiple-operator radio coverage into indoor premises, tunnels, etc. Another key point is the adoption of MIMO (Multiple Input-Multiple Output) transmission techniques which can exploit the multipath nature of the radio link to ensure reliable, high-speed wireless communication in hostile environments. In this paper novel indoor deployment solutions based on Radio over Fiber (RoF) and distributed-antenna MIMO techniques are presented and discussed, highlighting their potential in different cases.
Antennas and Propagation Conference (LAPC), 2010 Loughborough; 12/2010
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ABSTRACT: Environmental effects may seriously threaten the performance of UHF RFID systems and reduce the rate of successful reading; many applications aiming at the so-called item-level tagging (ILT) can be therefore compromised. In order to preserve the reliability of the tag acquisition the so-called near field (NF) UHF RFID has been recently considered. In this paper, the main properties and the performance of NF UHF RFID systems are investigated by means of electromagnetic analyses based on both theoretical evaluations on simple but representative radiating elements and measurements carried out also on real UHF RFID devices.
IEEE Transactions on Antennas and Propagation 06/2010; · 2.15 Impact Factor
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ABSTRACT: In this paper a novel model for forward diffuse scattering of indoor walls is presented which is suitable for integration in ray-based prediction tools for indoor environment. The model extends the already-available Effective-Roughness (ER) diffuse-scattering model in a straight-forward way and allows for a different scattering behaviour of the wall in the backward and forward half-spaces to be described. The model is checked against measurements on a wall sample and it is shown to sensibly improve the accuracy of the prediction of the overall scattering pattern of the wall.
Antennas and Propagation (EuCAP), 2010 Proceedings of the Fourth European Conference on; 05/2010
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ABSTRACT: Despite their good performance, the widespread diffusion of ray tracing field-prediction models is still limited due to their high complexity and high computation time. In this paper, two different classes of methods for speeding up ray tracing urban field prediction are proposed, aimed at reducing the size of the input database and the number of rays to be handled by the algorithm. With the proposed techniques, a great computation time reduction can be achieved without sensibly affecting the accuracy of the prediction.
IEEE Transactions on Antennas and Propagation 06/2009; · 2.15 Impact Factor
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ABSTRACT: Recent studies highlighted the important role of diffuse (or distributed) scattering in determining the actual time- and angle-dispersion of the radio channel in urban environment. Diffused scattering however, is inherently a ldquodistributedrdquo phenomenon, i.e. it takes origin from every single surface spot, and therefore its prediction requires a great deal of computational resources. In the present paper a novel formulation is presented which allows the fast computation of the power-angle profile related to distributed scattering from a single wall adopting simple analytical formulas.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
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ABSTRACT: A multidimensional analysis of multipath propagation in urban micro- and macro-cellular environment has been carried out. Multidimensional measurement data, including path-loss, delay spread and direction-of-arrival are compared with simulations performed with a 3D ray tracing model which takes diffuse scattering into account. The results are analyzed highlighting the dominant propagation mechanisms in the different cases and model performance/shortcomings. In particular, the results show that diffuse scattering plays a key role in urban propagation, with an impact on both narrowband and wideband parameters in most cases. Also, the accuracy and the characteristics of environment representation can have a significant impact on prediction even in simple topologies.
IEEE Transactions on Antennas and Propagation 04/2008; · 2.15 Impact Factor
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ABSTRACT: The performance of UHF-RFID systems are particularly exposed to environmental effects, such as multipath propagation and electromagnetic coupling. This sensitivity to the electromagnetic properties of the environment is peculiar of systems operating in the UHF band and therefore has not been completely investigated, since many RFID systems still work at HF frequencies. In this letter, the possible impairments due to the most usual environmental effects are considered, with particular reference to the impact on the bit error rate (BER) at the reader side in the Uplink stage of the RFID system.
IEEE Antennas and Wireless Propagation Letters 02/2008; · 1.37 Impact Factor
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ABSTRACT: The investigation of the modulated, backscattered contribution from UHF RFID Transponders is a crucial issue for the reliable evaluation of the behavior and the performance of RFID systems. The backscattered, radiated field by a UHF Transponder is described by means of a simple and complete analytical expression. The tag radar cross section (RCS) and the bit error rate (BER) at the Reader are evaluated by means of the achieved formula, and the results are in perfect agreement with previous available publications.
IEEE Antennas and Wireless Propagation Letters 02/2008; · 1.37 Impact Factor
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ABSTRACT: The co- and cross-polarization behaviour of the urban propagation channel has been studied through both MIMO measurements and ray tracing (RT) simulation. A ray tracing model including diffuse scattering has been adopted, allowing the role of diffuse scattering to be highlighted through comparison between measurement and simulation. The high degree of cross-polarization power transfer observed in both measurement and simulation seems to be partly due to multipath propagation (and to diffuse scattering in particular), and partly due to the polarization behaviour of the antennas.
Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on; 12/2007
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ABSTRACT: The recent widespread diffusion of radio-frequency identification (RFID) applications operating in the UHF band have been supported by both the request for greater interrogation ranges and larger and faster data exchange. UHF-RFID systems, exploiting a physical interaction based on Electromagnetic propagation, introduce many problems that have not been explored (or only partially) for the previous generations of RFID systems (e.g. HF). Therefore, the availability of reliable tools for modelling and evaluating the radio-communication between Reader and Tag within an RFID radio-link are needed. The paper discuss the impact of real environment (e.g. Electromagnetic Coupling, Multipath propagation) on system performance in terms of error- probability and received powers, showing some relevant effects and trade-offs in transponder and reader design.
Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on; 12/2007
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ABSTRACT: The results of a measurement campaign aimed at determining the far-field diffuse scattering pattern of typical building walls are shown in the paper. Such results are then used to determine and tune simple diffuse scattering models based on the effective roughness approach, to be embedded into ray tracing simulators. It is shown that by adopting an appropriate single-lobe scattering pattern the agreement between simulation and measurement is very good
IEEE Transactions on Antennas and Propagation 02/2007; · 2.15 Impact Factor
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ABSTRACT: Ray tracing (RT) models are now widely adopted for field prediction in urban environment. Nevertheless, conventional RT tools still suffer for excessive central processing unit (CPU) time and inaccuracy in wide-band prediction. By increasing the maximum number of successive interactions (reflections, diffractions) little improvement in wide-band results can be usually achieved while CPU time increases exponentially. In the present paper, it is shown that by integrating reflection/diffraction with diffuse scattering, good narrow-band and wide-band results can be obtained with a low number of interactions. The adopted scattering model is a simple ray-based model, which has been embedded in a three-dimensional (3-D) RT program. The impact of diffuse scattering on narrowband and wide-band parameters is analyzed in the paper and the complete model is compared with measurements in a variety of cases, showing the validity of the approach.
IEEE Transactions on Antennas and Propagation 08/2004; · 2.15 Impact Factor
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ABSTRACT: The performance and the usability of deterministic field prediction tools for the urban environment is heavily limited by the high computing time, which depends exponentially on the size of the input urban database. A simple technique for urban database simplification, aimed at speeding up deterministic field prediction is presented in the paper. Such a technique, based on a sort of heuristic preprocessing of the city map, identifies the buildings which are 'likely' to have an impact on the multipath propagation mechanism taking place between the radio terminals, and discards the rest of the map. Using this pre-processing technique, the CPU time can be decreased by orders of magnitude in typical ray tracing prediction cases, while the accuracy of the results only marginally degrades, as shown in the results section of the paper.
Antennas and Propagation Society International Symposium, 2004. IEEE; 07/2004
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ABSTRACT: A novel statistical model for over rooftop (ORT) propagation in an urban environment is presented in this paper. The proposed algorithm is based on an automatic extraction of the relevant environment parameters from the urban map. These parameters are used to build up a statistical description of the environment geometry through analytical pdf functions from which statistical estimates of the propagation loss are derived by mathematical processing and the use of simple, deterministic ORT models. Finally, analytical formulas for the direct derivation of the average ORT loss and its variance from the environment parameters are proposed.
IEEE Transactions on Antennas and Propagation 02/2004; · 2.15 Impact Factor
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ABSTRACT: A statistical approach to the study and the prediction of urban propagation is presented. The method is based on a "statistical ray tracing" approach where the statistical characteristics of the multipath are derived by analytical processing from the statistical characteristics of the environment. Thanks to the adopted approach, the model does not require a detailed, site-specific description of the environment, nor a high computation time as required by methods such as traditional ray tracing tools. Also, it is more complete and accurate than conventional models such as Hata-like models.
Antennas and Propagation Society International Symposium, 2002. IEEE; 02/2002
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ABSTRACT: A novel statistical method for field prediction in an urban
environment is presented. The method is based on a sort of "statistical
ray tracing", that is, the main parameters of the generic ray
(orientation, number of reflections, path length etc.) are evaluated
through their statistical distribution on the basis of the
characteristics of the environment. These characteristics can be
extracted from a sample map by means of an automatic graphical algorithm
Vehicular Technology Conference, 2001. VTC 2001 Spring. IEEE VTS 53rd; 02/2001
