Propagation in urban microcells with high rise buildings (original) (raw)
Related papers
Two-dimensional ray-tracing modeling for propagation prediction in microcellular environments
IEEE Transactions on Vehicular Technology, 1997
The application of diffraction theory and geometrical optics for modeling the propagation in microcellular urban environments is investigated. The model simplifies the reality by considering only a two-dimensional (2-D) geometry, where the building walls are modeled by segments and the buildings are considered infinitely high. The model can handle arbitrary layouts of buildings according to an efficient algorithm briefly described in this paper. Comparisons between several predictions and measurements in two different cities in Switzerland are presented. A detailed investigation of the two main parameters considered in the predictions, i.e., the reflection and diffraction coefficients, is also provided. The study shows that the ray tracing model is appropriate for path-loss coverage prediction even in complex environments.
A UTD propagation model in urban microcellular environments
IEEE Transactions on Vehicular Technology, 1997
This paper presents a three-dimensional (3-D) propagation model for path-loss prediction in a typical urban site, based on geometrical optics (GO) and uniform theory of diffraction (UTD). The model takes into account numerous rays that undergo reflections from ground and wall surfaces and diffraction from corners or rooftops of buildings. The exact location of reflection and diffraction points is essential in order to calculate the polarization components of the reflected and diffracted fields and their trajectories. This is accomplished by local ray-fixed coordinate systems in combination with appropriate dyadic reflection and diffraction coefficients. Finally, a vector addition of the received fields is carried out to obtain the total received field strength and, subsequently, the path loss along a predetermined route. The model computes the contributions of various categories of rays, as selected, in a flexible manner. Several results-path loss versus distance and power-delay profile-are given, and comparisons with measured data are presented.
A high-speed 2.5D ray-tracing propagation model for microcellular systems, application: Smart cities
2017 11th European Conference on Antennas and Propagation (EUCAP), 2017
This paper introduces a new high-speed 2.5D deterministic radio propagation model. This model is suitable for outdoor urban configurations where transmitter and receiver nodes are below the rooftop level of the surrounding buildings. This model can provide narrow-band and wide-band predictions. In this paper we combine three acceleration strategies in order to achieve a high-speed site-specific urban microcellular model. The first strategy is an efficient implementation of a ray-tracing model based on the visibility tree technique. The second strategy is to consider only a limited portion of the propagation environment that has a significant contribution on the received signal estimation. The third strategy is based on a pre-calculation of the exact 2D visibility trees, in order to be used to reconstruct very quickly all the possible paths between a transmitter and a receiver. Simulation results for the implemented ray-tracing model with the first acceleration technique are presented and compared with measurements. Then, the other acceleration techniques were combined to further reduce the overall execution time to the minimum extent with a small impact on the accuracy.
Lateral, full-3D and vertical plane propagation in microcells and small cells
1998
When the height of the transmitter is close to building heights, over-rooftop contributions, i.e. full-3D rays or rays in the vertical plane, become relevant in propagation. In this paper, full-3D propagation, vertical plane propagation and lateral propagation are compared, both mutually and against measurements in Munich (Germany) and Rosslyn (VA, USA). To perform our study we made use of a full-3D ray tracing tool. In addition, a deterministic vertical plane prediction model was implemented based on a literature review of the most recent published models. In Munich, which has a regular mixture of building heights with virtually no high rise buildings, our deterministic vertical plane model was found to be accurate in predicting the average measured power for receivers far from the transmitter. Deterministic models require, in general, less calibration with measurements than empirical models. The wedge representation of buildings in the vertical plane was found to give better agreement with measurements than the classical knife-edge representation.
Influence of database accuracy on two-dimensional ray-tracing-based predictions in urban microcells
IEEE Transactions on Vehicular Technology, 2000
Ray-tracing-based predictions in urban microcellular environments require databases for building layouts, electrical characteristics of buildings, and base stations (locations, antennas, power, etc.). The aim of this paper is to provide help in selecting the appropriate level of accuracy required in these databases in order to achieve the best tradeoff between database costs and prediction accuracy. The effects of inaccuracies in these databases are presented and analyzed by comparing predictions and measurements. The results presented here show to what extent errors, which are due to automatic vectorization of scanned maps, could lead to erroneous predictions. Furthermore, an analysis of the influence of random errors in a building vector database was performed to quantify the prediction error as a function of the accuracy in the building vector databases. Ray-tracing prediction models implementing a reflection and diffraction phenomena were found to be sensitive to the choice of the reflection coefficient attributed to building walls. This dependence can be used to fit the measurements as the complexity of real building walls does not allow one to easily derive their electrical parameters from which a reflection coefficient could be computed. It was also found that, in general and in agreement with measurements, ray-tracing-based prediction models are not sensitive to small variations on a base-station location. Finally, the sensitivity study also lead to gained insight of the propagation phenomena involved in urban microcell environments.
Fast computer tool for the analysis of propagation in urban cells
1997
FASPRO is an accurate and extremely efficient tool that is used to perform deterministic analyses of propagation in urban picocells and microcells. A fully 3D propagation model is considered. The topographical input data are based on a 3D plane-facets model of the urban environment which is given in terms of DXF files. FASPRO is able to read DXF files from AUTOCAD, Microsystem, CADDS and other CAGD and topographical tools. In addition, FASPRO has its own facility which allows it to create new urban scenes. FASPRO visualizes the geometry on the screen as a 2D map of the urban scene or a 3D isoparametric view. The electromagnetic analysis is performed using UTD techniques. First order coupling mechanisms (direct reflected and edge-diffracted rays), second order coupling mechanisms (double reflected diffracted-reflected, diffracted-reflected, double diffracted, etc.) and third order mechanisms (e.g. reflected-diffracted-reflected, etc.) are included. It must be noted that, thanks to the incorporation of diffraction in all the edges of the 3D model, coverage in areas in the deep shadow of the transmitter antenna can be predicted well. A new ray-tracing algorithm is used to speed-up the computations. This ray-tracing algorithm is based on a modification of the Z-Buffer and the “Bounding Volumes” schemes, in which the elements are arranged in an angular map (AZB, Angular Z-Buffer)
An efficient two-dimensional ray-tracing algorithm for modeling of urban microcellular environments
Aeu-international Journal of Electronics and Communications
In this work, an efficient ray-tracing approach based on decomposition of visibility-tree into sub-tree has been compared with the conventional approach. The comparison is done in the context of both the computational complexity and accuracy of the ray-tracing algorithm. Three independent urban scenarios are considered for this comparison. It is observed that the efficient approach based on use of sub-tree reduces the computational complexity significantly. Further, the proposed ray-tracing algorithm is applied to a microcellular environment to compute rms delay spread and the results are compared with available measurements.
A 3-D ray tracing model for macrocell urban environments and its verification with measurements
This paper presents verification results of an advanced 3-D ray tracing model in a macrocell urban environment. The verification is based on wide-band double-directional channel measurements at a center frequency of 5.2 GHz and a bandwidth of 120 MHz. For the verification two site-specific measurement routes in the city center of Karlsruhe, Germany are used. Both, the wide-band and the directional prediction of the ray tracing are evaluated. For the verification of the directional prediction the maximum-likelihood channel parameter estimation framework RIMAX is applied to the measurement data. Results show a strong level of agreement of delay spread and azimuth spread.
IEEE Journal on Selected Areas in Communications, 2000
Due to the site specific nature of microcellular operational environments, propagation models are required to take into account the exact position, orientation and electrical properties of individual buildings, and hence, ray tracing techniques have emerged as the dominant methods to predict propagation in such environments. A novel hybrid three-dimensional (3-D) ray tracing algorithm which can evaluate scenarios incorporating many thousands of objects by utilising the concept of "illumination zones," is presented in this paper.
Comparison of predictions from a ray tracing microcellular model with narrowband measurements
1997 IEEE 47th Vehicular Technology Conference. Technology in Motion
In this paper predictions from a 3-D 'image-based' ray tracing model for microcellular environments are compared with three sets of narrowband measurements performed in a typical urban area. The comparisons illustrate that good agreement can be obtained, with RMS errors less than 3.7dB, even for deep shadow areas. In order to analyse the inherent discrepancies that result from the limited averaging of the measurements along the route, predictions were also obtained by producing slow fading envelopes similar to those measured.