Radio propagation characteristics for line-of-sight microcellular and personal communications

Abstract

To acquire a knowledge of radio propagation characteristics in the microcellular environments for personal communications services (PCS), a comprehensive measurement program was conducted by Telesis Technologies Laboratory (nZ) in the San Francisco Bay area using three base station antenna heights of 3.2 m, 8.7 m, and 13.4 m and two frequencies at 900 MHz and 1900 MHz. Five test settings were chosen in urban, suburban, and rural areas in order to study propagation in a variety of environments. This paper reports the LOS measurements in different environments, all of which show variations of signal strength with distance that have distinct near and far regions separated by a break point. It was also found that the location of the break point for different frequencies and antenna heights can be calculated based on first Fresnel zone clearance.The regression analysis reveals a slope that is less than two before the break point, while it is greater than two after the break point. This break distance can be used to define the size of microcell and to design for fast hand-off. Beyond the first Fresnel zone break distance the base station antenna height gain was observed to approximately follow the square power law of antenna height.

Improving Propagation Modeling in Urban Environments for Vehicular Ad Hoc Networks

“…Adjustment is also made in simulation for the fact that a car is not a point but extends on either side of the crossover point. An equation [29] for the reflection coefficient is:…”

Propagation Aspects in Vehicular Networks

“…In (Green & Hata, 1991) (Xia et al, 1993). However, in practice the critical distance is related to the propagation characteristics environment, and of course, there are important differences among urban, suburban, highway and rural areas.…”

Following an RF trail to its source

“…In contrast, we use a moving RSS sensor to track a stationary source (evaluating and adapting the proposed algorithm for moving sources is an important topic for future work). Examples of prior work on modeling spatial variations in RSS include [7][8], which discuss methods to build RSS maps around a source using measurements by a group of robotic agents, and [9] [10], which use outdoor experiments to study the impact of factors such as distance, antenna orientation, and antenna height on RSS. However, the literature does not provide insight into the spatial variations of RSS at long ranges and as a function of angle, as required by the tracking problem considered here.…”