Gabriele Falciasecca

Measurement and Modelling of Scattering From Buildings

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

Analytical Approach to the Backscattering from UHF RFID Transponder

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.

Speed-Up Techniques for Ray Tracing Field Prediction Models

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.

A spectrum- and power-efficient EHF mobile satellite system to be integrated with terrestrial cellular systems

An EHF satellite system for land-mobile applications to be integrated with a terrestrial cellular system is described. An approach to evaluate the carrier-to-cochannel interference occurring in multispot satellite coverage adopting frequency reuse is introduced, and results from the analysis are shown. Criteria for spectrum efficiency evaluation are also outlined along with traffic and link budget estimates. Possible options for payload implementation and mobile terminal design are presented. >

On the performance of packet reservation multiple access with fixed and dynamic channel allocation

The evaluation of packet reservation multiple access (PRMA) is extended from a single cell case, investigated in several previous papers, to a cellular environment characterized by user mobility and by the interference from other cells. The analysis is based on a comparison of PRMA performances with those of classical circuit switching schemes. The comparison methodology is defined, and the comparison, performed by means of a simulation program based on a dynamic traffic model, is discussed. >

Investigation on a dynamic channel allocation for high capacity mobile radio systems

The potential of a dynamic channel-allocation scheme is described, in particular, to increase the system capacity and to counteract the traffic bursts typically experienced in cellular mobile radio systems as a consequence of traffic jam, accidents, traffic lights, etc. In order to accomplish these improvements, an effective procedure, monitoring the link quality of all the active calls, is required. Practical considerations necessitate implementation such a control just at the base station. The affordability of this approach is considered, assuming as input parameters the correlation among wanted and interfering signals in both mobile-to-base and base-to-mobile directions. A software simulation of cellular systems with a broad range of applications has been used to evaluate the feasibility of such a channel assignment method.<<ETX>>

Electromagnetic Analyses of Near Field UHF RFID Systems

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.

Advanced planning criteria for cellular systems

This article provides a review of the most up-to-date frequency planning techniques suitable for current digital cellular systems. Frequency planning is becoming a key issue in the current scenario, with exceedingly high growth rates in many countries which compel operators to re-configure networks virtually on a monthly basis. Therefore, the search for smart techniques, which may considerably alleviate planning efforts (and associated costs) becomes extremely important for operators in a competitive market. Although reference is made particularly to a market leader (GSM and its offspring), the considerations reported are quite general, and can be applied to any TDMA/FDMA system. The article examines such well-known concepts as fractional loading, frequency hopping, and intelligent antennas in order to elaborate on them and show how they may impact conventional planning methodology and deprive complex dynamic channel allocation methods of any practical interest. The evaluation of this impact is extended to mixed cellular architectures, starting from a real case for the city of Munich and finally identifying some basic guidelines for cell planning.

Evaluation of exposure levels generated by cellular systems: methodology and results

During the past years, the number of antenna installations has considerably increased mainly as a consequence of the great diffusion of cellular systems. While the emissions of mobile terminals principally concern cellular system users, the exposure due to base stations (BSs) is permanent and spread over the entire territory. In this paper, a flexible approach for the evaluation of exposure levels generated by cellular systems BSs is proposed. Both a conceptual method for the evaluation of the overall exposure level and a site specific method for the computation of the field in the surroundings of BS antennas are proposed. This last method is based on a combination of three different propagation models which enable an accurate evaluation of the field both close to the antenna and farther off. The validity of the approach is checked by comparison with measurements in single-antenna and multiantenna cases.

Ray tracing propagation modeling for future small‐cell and indoor applications: A review of current techniques

Applied for the first time to mobile radio propagation modeling at the beginning of the nineties, ray tracing is now living a second youth. It is probably the best model to assist in the design and planning of future short-range, millimeter-wave wireless systems, where the more limited propagation environment with respect to UHF frequencies allows to overcome traditional high-CPU time limitations while the higher operating frequency makes ray-optics approximations less drastic and allows to achieve an unprecedented level of accuracy. An overview of ray tracing propagation modeling is given in this paper, with a special attention to future prospects and applications. In particular, frontiers of ray-based propagation modeling such as extension to diffuse scattering, multidimensional channel characterization, multiple-input multiple-output (MIMO) capacity assessments, and future applications such as real-time ray tracing are addressed in the paper with reference to the work recently carried out at the University of Bologna.