Enrico M. Vitucci

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

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.

Analysis and Modeling on co- and Cross-Polarized Urban Radio Propagation for Dual-Polarized MIMO Wireless Systems

Cross-polarization coupling is an important radio propagation characteristic in dual-polarized multiple-input multiple output (MIMO) systems. Still, few studies analyze the polarimetric properties of the radio channel in relation to the actual propagation conditions and processes taking place in urban environment. The topic is studied in the present paper with the aid of dual-polarized MIMO measurements and ray tracing simulations. Several scenarios are considered, and the impact of the different propagation characteristics (LOS, NLOS, link-distance, presence of diffuse-scattering, angular distribution of the signal, etc.) on cross-polarization coupling is analyzed. Generally, a fairly high degree of coupling is observed due to multipath propagation and especially to diffuse scattering. Surprisingly, it does not appear to depend on link distance.

Ray-Tracing-Based mm-Wave Beamforming Assessment

The use of large-size antenna arrays to implement pencil-beam forming techniques is becoming a key asset to cope with the very high throughput density requirements and high path-loss of future millimeter-wave (mm-wave) gigabit-wireless applications. Suboptimal beamforming (BF) strategies based on search over discrete set of beams (steering vectors) are proposed and implemented in present standards and applications. The potential of fully adaptive advanced BF strategies that will become possible in the future, thanks to the availability of accurate localization and powerful distributed computing, is evaluated in this paper through system simulation. After validation and calibration against mm-wave directional indoor channel measurements, a 3-D ray tracing model is used as a propagation-prediction engine to evaluate performance in a number of simple, reference cases. Ray tracing itself, however, is proposed and evaluated as a real-time prediction tool to assist future BF techniques.

Polarimetric Properties of Diffuse Scattering From Building Walls: Experimental Parameterization of a Ray-Tracing Model

Dense multipath components may represent an important part of wireless transmission channels, yet little is known about their physical properties. For this reason, we parameterize an ad hoc diffuse scattering model, which can be easily included in ray-tracing tools. The work, focusing on the polarimetric properties of diffuse contributions scattered off building walls, relies on experimental data. By means of a joint post-processing of the data in conjunction with ray-tracing simulations, characteristic parameters of diffuse scattering are extracted. The analysis reveals that diffuse scattering represents an crucial part of the received power. Regarding depolarization caused by diffuse scattering, our work highlights that depolarization appears to be small for homogeneous brick walls, but is far from negligible for more complex wall structures.

Directional characterization of the 60 GHz indoor-office channel

Directional, dual-link, quad-polarized 60GHz channel measurements have been carried out in a small-office environment. Purpose of the measurements is to study the directional properties of the channel in view of future multi-gigabit system adopting beam-forming or macro-diversity solutions. The impact of polarization on the characteristics of the channel is also addressed in the study.

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.

Characterization of an Interleaved F-DAS MIMO indoor propagation channel

A key point in the deployment of new wireless services is the cost-effective extension and enhancement of the networks 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.

Analysis of Radio Propagation in Co- and Cross-Polarization in Urban Environment

The behaviour of radio propagation in co- and cross-polarization in urban environment is studied with the aid of both ray tracing simulation and MIMO measurements. A ray tracing (RT) model including diffuse scattering has been adopted, therefore allowing the tuning of the RT model and the analysis of the role of diffuse scattering in cross-polarization propagation. A high degree of cross-polarization coupling is observed, especially in NLOS cases, confirming the feasibility of efficient and compact MIMO schemes adopting dual polarized antennas.

Interleaved-MIMO DAS for Indoor Radio Coverage: Concept and Performance Assessment

Distributed antenna systems (DAS) represent a suitable method for extending multiple-operator radio coverage into indoor premises, tunnels, etc. With the advent of 4G (and beyond) mobile communications systems and of multiple input-multiple output (MIMO) transmission techniques, a common problem for wireless operators is how to upgrade existing DAS systems to the MIMO technology in a cost-effective way. In this paper novel indoor solutions based on the combination of DAS and MIMO transmission techniques (Interleaved-MIMO DAS solutions) are proposed, and their performance is investigated in realistic cases with the aid of measurements, ray tracing simulations, and LTE link-level simulations.