This paper presents a novel direction-finding (DF) system based on a 3-axis crossed antenna array in combination with threedimensional Unitary ESPRIT. The application and design considerations are discussed and the implemented antenna array is shown. The 3-D Unitary ESPRIT algorithm is modified to solve a rank-deficiency problem in order to obtain better estimation results. The improved resolut...

In the presentation the most important proprieties of the radio wave propagation in the ionosphere are explained and its impact on the high performance radio transmissions is discussed. The principles of the orthogonal frequency division multiplexing is explained and new digital radio system based on this principle is presented. Then some experimental data registered in Cracow in Poland are sho...

The accuracy of time of arrival (ToA) estimation using wide band signals is characterized. The Cramér-Rao Lower Bound (CRLB) for ToA estimation in multipath conditions is presented in terms of the Ricean K-factor, the ratio of direct to diffuse multipath components. The validity of the CRLB is demonstrated using thousands of measurements, where the K-factor is estimated in the spectral domain. ...

The Weibull distribution is a flexible statistical model for describing multipath fading channels in both indoor and outdoor radio propagation environments. A new closed-form expression is derived for the moment generating function of the Weibull distribution, valid when its fading parameter assumes integer values. The performance of digital linear modulations operating on Weibull channels is s...

Linear space-time equalization is shown to be effective in coping with the complicated propagation conditions for wireless broadband communication in an industrial indoor environment. This is demonstrated by realistic simulations that use real channel measurement data obtained from a vector channel sounder for modeling the influence of the radio channel. The system parameters are similar to the...

In this study, torsional wave propagation is investigated in a rod that are made of one and two dimensional functionally graded material. Firstly, the governing equations of the wave propagation in the functionally graded cylinder derived in polar coordinate. Secondly, finite difference method is used to discretize the equations. The Von Neumann stability approach is used to obtain the time ste...

In this paper, a global optimization technique is applied to solve the optimal transmitter placement problem for indoor wireless systems. An efficient pattern search algorithm—DIRECT (DIviding RECTangles) of Jones, Perttunen, and Stuckman (1993)—has been connected to a parallel 3D radio propagation ray tracing modeler running on a 200-node Beowulf cluster of Linux workstations. Surrogate functi...

To support the continuously increasing number of mobile telephone users around the world, mobile communication systems have become more advanced and sophisticated in their designs. As a result of the great success with the second generation mobile radio networks, deployment of the third and development of fourth generations, the demand for higher data rates to support available services, such a...

Evidence is presented which indicates that, notwithstanding the change in sign made by Sommerfeld in his 1926 paper on radio wave propagation, the radiation field of a vertical electric dipole may be separated into space and surface wave components. Sommerfeld's original concepts as to the characteristics of two such waves in radio transmission are largely substantiated. It is shown that a spac...