A random walk model of wave propagation (original) (raw)
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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.
Propagation Model for Small Urban Macro Cells
IEEE Transactions on Vehicular Technology, 2009
This paper presents the MOPEM 1 propagation model for dense urban areas in the frequency band from 850 to 900 MHz. This work is based on the COST 231-WI model, but the hypothesis of infinite screen blocks is replaced by finite screens, taking into account the street crossings, predicting the signal attenuation along the block. The dependence of the propagation loss with the terrain height is reviewed and optimized by considering an absolute reference, whereas the dependence on the angle between the street and the wave propagation is modified to obtain a continuously differentiable loss function. The standard deviation obtained with this model is 5.1 dB, and the mean error is 0 dB versus 6.6 and 6.2 dB, respectively, for the COST 231-WI model, with validation measurements from two areas in Montevideo, Uruguay.
Propagation in urban microcells with high rise buildings
Proceedings of Vehicular Technology Conference - VTC
In this paper 2D and 3D ray-tracing-predictions based on UTD are compared to measurements in urban microcellular environments characterized by an irregular mixture of building heights due to the presence of relatively high rise buildings. It is shown that the 2D ray-tracing underestimates the measurement in area far from the transmitter. The theoretical study and the preliminary comparisons with measurements in Rotterdam (NL) showed that the 3D backward diffraction by high rise buildings might account for the propagation in area far from the transmitter and overcome the limitation of the 2D model in these areas. Trees were found to influence heavily the 2D prediction. Taking into account the same 3D contributions becomes even more important when there are obstructions such as trees in the 2D plane. A reasonable agreement with measurement can be obtained with a combined 3D and 2D (considering the absorption effects of trees) predictions.
Microcellular propagation measurements and simulation at 1.8 GHz in urban radio environment
IEEE Transactions on Vehicular Technology, 1998
This paper presents the results of measurements performed at 1.8 GHz in a microcellular environment in a city center (Athens, Greece). Studies have shown that the microcellular environment is dissimilar to the conventional macrocell area, therefore, accurate knowledge of propagation characteristics is essential. The aim of the measurement campaign is to provide a clear understanding of the propagation parameters affecting the design of a personal communication system (PCS) in a city center. Theoretical predictions developed using ray tracing techniques and measurement-based models are plotted versus distance for alternative configurations. The measurement procedure, data analysis, and comparison between theoretical and experimental results are in the following sections.
Characterization of Indoor Small Cells Propagation
2021 24th International Symposium on Wireless Personal Multimedia Communications (WPMC), 2021
The characterization of the wireless medium in indoor small cell networks is essential to obtain appropriate modeling of the propagation environment. Universal Software Radio Peripherals (USRPs) and simple dipole antennas can emulate LTE-Advanced networks. In this work, we verify WINNER II propagation modeling for the indoor femtocell environment by considering different classrooms of 7.32 × 7.32 square meters near a common University Department corridor while measuring the power received in UEs placed in a grid of 49 points (radiated by the small eNodeB in the centre of the classroom of the own cell). These measurements have been carried out either by using the Software Radio Systems LTE that emulates the LTE-Advanced network and its UEs, or by measuring the received power in the UES with a Rohde & Schwarz FSH8 spectrum analyzer. In room 1, by varying the UE position, the highest values of the received power have occurred close to the central BS, and then in the opposite wall, further away from the interferer. Nevertheless, it was verified that the received power does not decrease suddenly because of the effect of the radiation pattern of the BS and UE antennas for large angles of apertures, as well as due to the non-omnidirectional horizontal antenna pattern. In addition, it was demonstrated that there is an effect of "wall loss" proven by the fact that path loss increases between room 2 and room 1 (or between room 3 and 2). If we consider an attenuation for each wall of circa 7-9 dB the behavior of the WINNER II model at 2.625 GHz for the interference coming across different walls is verified.
Radio coverage prediction method in urban microcellular environment using electromagnetic techniques
A simulation method for the calculation of the radio propagation in urban area sites is presented, based on analytical electromagnetic techniques. First of all we summarize the basic theory of Physical Optics (PO) and Physical Theory of Diffraction (PTD) for the definition of first and second order reflected and diffracted fields in the far field area. We are also presenting formulas that calculate either numerically or analytically the near scattered electric field., because in a typical urban environment the scattered near field from walls occupies a large percentage of the area. Near field simulation results which are either in the form of potential coefficienits or electric field vector appear for various data inputs, resu'lting in a more accuLrate calculation of the electric field near the scattered surfaces.
1994
This paper presents results of wide-band path loss and delay spread measurements for five representative microcel-Mar environments in the San Francisco Bay area at 1900 MHz. Measurements were made with a wide-band channel sounder using a 100-ns probing pulse. Base station antenna heights of 3.7 m, 8.5 m, and 13.3 m were tested with a mobile receiver antenna height of 1.7 m to emulate a typical microcellular scenario. The results presented in this paper provide insight into the satistical distributions of measured path loss by showing the validity of a double regression model with a break point at a distance that has first Fresnel zone clearance for line-of-sight topographies. The variation of delay spread as a function of path loss is also investigated, and a simple exponential overbound model is developed. The path loss and delay spread models are then applied to communication system design allowing outage probabilities, based on path loss or delay spread, to be estimated for a given microcell size.
Model for urban and indoor cellular propagation using percolation theory
Physical Review E - PHYS REV E, 2000
A method for the analysis and statistical characterization of wave propagation in indoor and urban cellular radio channels is presented, based on a percolation model. Pertinent principles of the theory are briefly reviewed, and applied to the problem of interest. Relevant quantities, such as pulsed-signal arrival rate, number of reflections against obstacles, and path lengths are deduced and related to basic environment parameters such as obstacle density and transmitter-receiver separation. Results are found to be in good agreement with alternative simulations and measurements.
An Analysis of a Stochastic Urban Propagation Model Using Ray Tracing Generated Results
MILCOM 2007 - IEEE Military Communications Conference, 2007
A stochastic urban electromagnetic propagation model for non-line-of-sight (NLOS) paths was critically examined by comparing model behavior to ray tracing simulations in four city environments. We focus on the quality of model/data fit and the ability to a priori set model parameters based on city geometry and building materials. The stochastic model was found to fit simulated data well in typical cities. However, relating model parameters to city geometry metrics met with limited success. This is most likely due to the difficulty in characterizing city geometry, and the underlying physics of the model. The complex process of electromagnetic propagation is modeled as a simple one-dimensional random work, leading to diffusion-like behavior. The model does possess utility in its ability to provide easily computed estimates of urban propagation path losses and is an improvement over other empirical models.
IEEE Journal on Selected Areas in Communications, 1997
Engineers designing and installing outdoor and indoor wireless communications systems need effective and practical tools to help them determine base station antenna locations for adequate signal coverage. Computer-based radio propagation prediction tools are now often used in designing these systems. In this paper, we assess the performance of such a propagation tool based on ray-tracing and advanced computational methods. We have compared its predictions with outdoor experimental data collected in Manhattan and Boston (at 900 MHz and 2 GHz). The comparisons show that the computer-based propagation tool can predict signal strengths in these environments with very good accuracy. The prediction errors are within 6 dB in both mean and standard deviation. This shows that simulations, rather than costly field measurements, can lead to accurate determination of the coverage area for a given system design.