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Title: A random-phase-assisted ray-tracing technique for wireless channel modeling
Abstract: A random-phase-assisted ray-tracing technique for predicting spatio-temporal wireless channel parameters is presented. A two dimensional-three dimensional (2D-3D) hybrid ray-tracing algorithm is implemented in code for the prediction of channel parameters in outdoor micro- and pico- cellular urban enviornments. Meanwhile, a Random Phase Approach (RPA) is applied in the ray-tracing algorithm. The application of the RPA is intended for two purposes: 1) to account for the effects of inaccurate antenna positions; 2) to predict the range of short-term fading fluctuation. Several measurements carried out in pico-cell enviornments confirm the calculation accuracy of this techinque. It was found that measured fluctuation of path-loss and delay profiles are almost fully confined within the 90% confidence interval, providing that the approach can account for the effects mentioned above. In addition, the conventional verification of path-loss and delay profiles predicted by ray tracing was extended to include the verification of angle-of-arrival (AOA). The demonstrated calculation accuracy in spatial and terporal domain confirms the applicability of authors' technique to analyze system performance in real environments.
Author(s): Houtao Zhu, Junichi Takada, Kiyomichi Araki, Takehiko Kobayashi
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 4564 KB

Title: Nanocells Intrasystem Interference Realistic Worst Case Analysis for Open Site Personal Communication Scenarios
Abstract: The exponential growth in mobile communications is followed by the development of new generations of Personal Communication Systems (PCS). Numerous research activities and papers have been published on PCS but only a few deal with the Electromagnetic Interference (EMI) affecting those systems. This paper presents a realistic worst case analysis and computation of the PCS intrasystem interference effects on open site nanocell scenarios. The operation range is up to 200m, usually under Line of Sight (LOS) propagation conditions where intrasystem interefering signals are maximum. Analysis and computation results are provided for a typical second generation cordless PCS CT-2 telephone (telepoint) operating in the 900 MHz frequency band. The computations show that for most cases of nanocell open site, intrasystem interference can be neglected, except for a few cases of single tone spurious. The good perfomances is due to PCS advanced Digital Signal Processing (DSP) technology advantages using Adaptive Power Control (APC) to optimize transmitter power requirements and to Dynamic Channel Assignent (DCA) electing the best signal to noise and intereference channel available.
Author(s): J. Gavan
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 4587 KB

Title: Designing Embedded Antennas for Bluetooth Protocol
Abstract: In the near future, all kinds of portable devices ranging from laptops, PDAs, to cellular phones will be capable of communicating and inter-operate with each other using a new wireless technology networking protocol known as bluetooth. There are however, several hurdles that must be overcomed. One of these hurdles is to provide a communication link that is mostly interference free. The design of an appropriate antenna is important in providing a good communication between devices. In this paper we present the outline of an embedded antenna using the method of moments. This work is also extended to address generally other design issues in bluetooth technology that can be addressed using computational electromagnetics.
Author(s): Ray Perez
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 2605 KB

Title: Analysis and Design of Tapered Meander Line Antennas for Mobile Communications
Abstract: Small printed antennas are becoming one of the most popular designs in personal wireless communications systems. In this paper, the characterization and design of a novel printed tapered meander line antenna are presented using the finite difference time domain technique. Experimental verifications are applied to ensure the effectiveness of the numerical model, and excellent agreement is found between numerical analysis and prototype measurements. A new design of this antenna features an operating frequency of 2.55 GHz with a 230 MHz bandwidth, which supports future generations of mobile communication systems.
Author(s): Chun-Wen Paul Huang, Atef Z. Elsherbeni, Charles E. Smith
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 3447 KB

Title: A Cole-Cole Diagram Representation of Microstrip Structure
Abstract: A method for analyzing the performance of a microstrip line using the concept of Cole-Cole diagram, is proposed. Analogous to dieletric relaxation considerations of Cole-Cole diagrams as applied to dieletric materials, a "reactive relaxation" concept is introduced to represent the frequency-dependent characteristics of a microstrip. Also, included in the algorithm are relevant considerations pertinent to the substrate dieletric and strip-line conductor losses. The dynamic permittivity of the microstrip structure (deduced via Cole-Cole diagram) leads to a convenient and modified Smith-chart representation that includes the frequency-dependent influence of the fringing field and the lossy characteristics of the line cohesively. The efficacy of the model is illustrated with an example concerning a microstrip patch antenna in ISM band. Relevant algorithms are useful in computer-aided designs (CADs).
Author(s): S. Malisuwan, P.S. Neelakanta, V. Ungvichian
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 3192 KB

Title: Enhancement of Numerical Computation Methods Useful for Radio Communication Antenna Systems
Abstract: The radiation from a flanged parallel-plate waveguide is solved efficiently by the moment method, where the expansion functions contain the correct edge behavior of the fields. This computation method can be useful to optimize radiation of microwave transmitters and efficiency of receiver antenna and front end circuits. It is shown that three appropriate expansion functions are sufficient for an excellent accuracy and convergence rate of the solution.
Author(s): H. Matzner, N. Amir, U. Mahlab, J. Gavan
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 1967 KB

Title: Time and Frequency Domain Wave Propagators
Abstract: Is this paper, a new time-domain wave propagator (TDWP) that was recently introduced, is compared against a frequency-domain one that has been in use for more than a decade. The new time-domain wave propagator is built by a two-dimensional (2D) finite-difference time-domain (FDTD) algorithm. The frequency-domain wave propagator is the Split-step Parabolic Equation (SSPE), which is the solution of (one-wave) wave equation in parabolic form. These two techniques can be both used for different kinds of 2D propagation problems. In this paper, ground wave problems, which are difficult to solve, have been taken into consideration in order to compare the methods and show their power. Assuming an azimuthal symmetry, ground wave propagation and surface and/or elevated ducts may be represented via transverse and/or longitudinal refractivity and boundary perturbations in 2D space. The 2D propagation space extends from x=0 (bottom) to x->infinity (top), vertically and from z-> negative infinity (left) to z-> inifity (right) horizontally. Pulse propagation is simulated in TDWP and while a moving window escorts the transmitted waveform from one end to the other end within the FDTD computation space, time histories are accumulated at choses observation points. Any vertical and/or horizontal field profile at a desired frequency is extracted by applying off-line discrete Fourier transformation (DFT). On the other hand, a given field profile is longitudinally ppropagated by moving back and forth between the transverse spatial and wavenumber domains in SSPE. The results of TDWP and SSPE are compared on different ducting and anti-ducting refractivity profiles and their agreement is presented.
Author(s): Funda Akleman, Levent Sevgi
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 7191 KB

Title: RAY-TRACING TECHNIQUES FOR MOBILE COMMUNICATIONS
Abstract: In this paper an application for mobile communication of several ray-tracing techniques is presented. The techniques work in combination with deterministic propagation models based on GTD/UTD techniques. Several ray-tracing techniques are reviewed and some results applying one of them, the Angular Zeta Buffer (AZB) method for urban and indoor scenarios are shown, obtaining in all the cases good results comparing with measurements.
Author(s): O. Gutierrez, F. Saez de Adana, I. Gonzalez, J. Perez, M. E. Cetedra
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 2460 KB

Title: ON THE FEASIBILITY OF THE MULTIPATH FINGERPRINT METHOD FOR LOCATION FINDING IN URBAN ENVIROMENT
Abstract: The feasibility of the multipath fingerprint method wireless location finding in urban enviroments is examined using computational electromagnetics simulation. Fingerprints composed of time and angle of arrival data in urban environments are created using electromagnetic ray tracing. The fingerprints at specific locations within a simple four-by-four building model are studied to address issues including uniqueness of the fingerprints, repeatability due to environmental changes, and bandwidth limitations. A classifier based on template matching is also constructed using the simulation data from a 1-km city area of downtown Austin, Texas. Angle of Arrival (AOA) is found to be a stronger identifier than Time of Arrival (TOA). The classifier results demonstrate that good location-finding performance is achievable using both time of arrival and angle of arrival features.
Author(s): Ivy Y. Kelly, Hai Deng, Hao Ling
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 1424 KB

Title: NEW DESIGNS FOR DUAL BAND ANTENNAS FOR SATELLITE MOBILE COMMUNICATIONS HANDSETS
Abstract: The design of dual-band antennas for hand-held terminals (HHT) to be used in personal communications via a satellite network (SPCN) is investigated. The quadrifilar helical (QHA) is selected as the optimum design for futher study and new design for a QHA is derived and optimized using a standard Moment-Method program. A dual L-S band design with an input VSWR in its two operating bands of between 1 and 2 was developed, incorporating external shorted turns to achieve the desired passbands. The design of the required hybrid feed phasing network is derived. Experiments with physical realizations of the optimum designs showed good performance and confirmed the computational predictions
Author(s): S. M. Dannish, R. A. Abd-Alhameed, P. S. Excell
File Type: Journal Paper
Issue:Volume: 15      Number: 3      Year: 2000
Download Link:Click here to download PDF     File Size: 1680 KB