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As a remedy to multipath fading in land mobile communication, adaptive antenna arrays combined with equalizers have been proposed. For hardware realization and adaptive algorithm development in order to alleviate fading by temporal and spatial processing, it is necessary to clarify the spatiotemporal characteristics of the propagation channel such as the delay time and direction of arrival of multipath waves. In a microcell using a low antenna-height base station, the spatiotemporal propagation characteristics are measured for line-of-sight and non-line-of-sight propagation at 3.35 GHz. Characteristics of these channels have been presented. With regard to non-line-of-sight propagation, the measured spatiotemporal characteristics are modeled and the angular spread and the delay spread of the arriving waves are quantitatively evaluated. Also, when the transmission characteristics of fading prevention techniques by spatiotemporal processing are evaluated by computer simulation, an example of the delay-azimuth profiles that is usable as a reference for setting the conditions for fading is presented. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(7): 11–21, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10032 [ABSTRACT FROM AUTHOR]

Estimating the position of mobile terminals is an important problem for cellular networks. A low cost method of locating the mobile terminal is to use measurements of the radio path loss. The distribution of radio path loss is, unfortunately, a non-linear function of the mobile terminal location. The non-linearity results from large obstacles to radio-wave propagation such as buildings or hills. This paper demonstrates how the conditional density of the location given measured path loss can be approximated as a sum of kernel density functions based on radio propagation data collected from propagation surveys or estimated from computer models. Using these approximate density functions an accurate location estimate of a mobile terminal can be estimated from measured path loss values contaminated by measurement noise. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The problem of electromagnetic wave propagation in a two-dimensional tunnel with an arbitrary bending angle is numerically analyzed by the FVTD method. The FVTD representations for the electromagnetic field in a lossy medium and the PML absorbing boundary condition are formulated and a procedure for the numerical analysis of the two-dimensional tunnel is provided. Next, as specific numerical examples, the electromagnetic propagation characteristics near the bend of tunnels with bending angles of 30°, 45°, and 60° are computed. It is confirmed that the results agree well with those of the model experiment using microwaves. Detailed numerical calculations are performed for the case in which the width of the tunnel is much larger than the wavelength. In this way, the propagation characteristics are predicted for an electromagnetic wave in the mobile communication frequency band, used inside a tunnel. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(9): 1–9, 1999 [ABSTRACT FROM AUTHOR]