Juan Pascual-Garcia

Deterministic and Experimental Indoor mmW Channel Modeling

This letter presents an extensive multidimensional analysis of line-of-sight (LOS) experimental data and simulations at 60 GHz over a 9-GHz bandwidth. Numerical versions of the measured multiple-input-multiple-output (MIMO) channel transfer functions were obtained with a ray-tracing engine that includes single-order diffuse scattering. The received power, RMS delay spread (DS), and maximum excess delay (MED) computed from both measured and simulated data indicate that diffuse scattering improves ray-tracing-based modeling. Moreover, the multipath components (MPCs) extracted from both sets of data using the high-resolution estimator RiMAX were statistically compared. The analysis of the results shows that even a raw description of the environment can be used to predict millimeter-wave (mmW) propagation with ray tracing.

On the Importance of Diffuse Scattering Model Parameterization in Indoor Wireless Channels at mm-Wave Frequencies

In this paper, the impact of considering diffuse multipath components at mm-wave frequencies as well as the significance of selecting appropriate diffuse scattering model parameters is shown. Two different diffuse models, namely, the Lambertian model and the directive model, have been parameterized for several materials typically present in indoor environments. These models are formulated to embed the diffuse scattering phenomenon easily into ray tracing tools. The estimation of the parameters has been performed by comparing measurements and simulations using the models. Once the best fitting parameters have been estimated, they are included in the diffuse components simulation section of a general ray tracing tool. This tool has been used to simulate the power delay profile at 60 GHz in an indoor scenario, including single and double bounce diffuse components. Thanks to the estimated model parameters, the wireless channel at the 60-GHz band can be analyzed, including the diffuse scattering phenomenon, without the need for any previous measurement or simulation. Thus, the channel analysis with ray tracing tools, including dense components, becomes easier, faster, and more reliable.

Experimental comparison between centimeter- and millimeter-wave ultrawideband radio channels

This paper analyzes radio wave propagation phenomena at two very different frequency bands: 2–10 GHz (centimeter wave) and 57–66 GHz (millimeter wave (mm-W)). The two frequency bands have been measured using the same equipment and under similar propagation conditions, such as path loss, root-mean-square delay spread, maximum excess delay, and Rician K factor, and their respective correlations compared. Obstructed line of sight situations have also been considered by using metal and cardboard obstructions. The statistical distributions, main specular reflections, and decay factors have been found similar for the two bands. However, the measured path loss, correlation in terms of electrical distances, and the K factor are higher for the millimeter-wave frequency band. Indeed, the importance of propagation mechanism changes from one band to the other, which must be considered in the design of future mm-W systems.

ANALYSIS OF INDUCTIVE WAVEGUIDE MICROWAVE COMPONENTS USING AN ALTERNATIVE PORT TREATMENT AND EFFICIENT FAST MULTIPOLE

This paper presents a simple and alternative approach for the analysis of inductive waveguide microwave components. The technique uses a surface integral equation formulation, in which the contours of the waveguide walls and of the inner obstacles are all discretized using triangular basis functions. In order to avoid the relative convergence problem of other techniques based on mode matching, an alternative port treatment is used. The technique is based on the application of the extinction theorem using the spatial representation of the Greens functions in the terminal waveguides. In addition, the Fast Multipole Method is proposed in order to reduce the computational cost for large problems. Different complex structures are analyzed, including microwave bandpass filters with elliptic transfer functions, waveguide bends and T-junctions. Results show the high accuracy and versatility of the technique derived.

Comparison of a UTD-PO Formulation for Multiple-Plateau Diffraction With Measurements at 62 GHz

A hybrid uniform theory of diffraction-physical optics (UTD-PO) formulation for the analysis of multiple-diffraction of spherical waves by a series of rectangular plateaux is compared with measurements performed at 62 GHz. The comparison shows a solid agreement between predicted and measured results. Therefore, since the array of plateaux under investigation can be considered as a scaled-model of an urban environment, the results support the validity of the proposed UTD-PO formulation in the analysis of urban radiowave propagation.

Numerical evaluation of the Green's functions for arbitrarily shaped cylindrical enclosures and their optimization by a new spatial images method

This work has been developed with support from the Spanish National Project (CICYT) with reference TEC2004-04313-C02-02/TCM, and the Regional Seneca Project with reference 02972/PI/05

A novel leaky-wave antenna combining an image NRD guide and a strip circuit

This letter presents a novel leaky-wave antenna which combines an image NRD (nonradiative dielectric) guide and a printed strip circuit. The proposed structure allows for an easier, cheaper and more flexible tapering mechanism than all previous leaky-wave antennas in NRD technology. The working mechanism is explained, and two different tapering strip-circuit topologies are proposed. Cosine tapered illuminations are designed using a two-dimensional leaky-mode analysis technique. Simulations with high-frequency structure simulator (HFSS) three-dimensional analysis are presented for validation purposes. Also, the influence of the feeding transitions for each printed-circuit design is studied. Results show the feasibility of one of the proposed designs, leading to a tapered radiation pattern with sidelobes level below -20 dB.

Experimental comparison of UWB against mm-Wave indoor radio channel characterization

This paper presents an experimental comparison between two very different frequency bands: 2-10 GHz and 57-66 GHz. A line of sight indoor environment has been selected, and both bands have been measured under the same conditions and equipment; path loss, delay spread and statistical distributions have been properly compared.

UTD-PO Solution for Estimating the Propagation Loss due to the Diffraction at the Top of a Rectangular Obstacle When Illuminated From a Low Source

A new method based on a hybrid uniform theory of diffraction-physical optics (UTD-PO) formulation for the analysis of the propagation loss due to the diffraction that takes place at the top of a rectangular obstacle that is illuminated from a low source (i.e., the transmitter height is smaller than the obstacle height) is presented. The receiver is considered to be located at the shadow boundary of the second wedge of the plateau so that the solution is valid to estimate the mentioned diffraction loss in order to be incorporated into more general propagation models. In such models, for example, both the free space losses and the typical urban final diffraction loss down to street level (occurring at the receiving point due to an eventual final diffracting obstacle) will be considered. In this sense, it should be noted that the proposed formulation is not a general formalism to estimate radiowave propagation over plateaux (as the receiver is not arbitrarily located). The method, which is mathematically less complex than existing techniques, applies Babinets principle, and is validated through the solid agreement obtained with measurements at 60 GHz and the comparison with a method which is based on the evaluation of a Fresnel surface integral.

Numerical Evaluation of the Green's functions for Arbitrarily Shaped Enclosures

In this paper, a new spatial method has been implemented for the efficient calculation of the mixed potential Greens functions associated to electrical sources, when they are placed inside arbitrarily-shaped cylindrical cavities. The technique consists of placing electric dipole images and charges outside the cavity, imposing, at discrete points of the metallic wall, the appropriate boundary conditions for the potentials. Results show that the numerical convergence is attained fast. The cut-off frequencies and potential patterns for a trapezium-shaped waveguide are compared to those obtained by a standard finite elements technique, showing excellent agreement. Furthermore, a printed planar filter shielded in a square cavity has been analyzed with the new Greens functions, showing the practical value of the new theory.