Radio propagation measurements and modelling for line-of-sight microcellular systems

Abstract

A knowledge of radio propagation characteristics in the microcell environment is recognized to be essential for future frequency allocation and system implementation of proposed personal communications services (PCS). A comprehensive radio propagation measurement program in the San Francisco Bay area is discussed. Measurements were performed using three transmitting antenna heights of 3.2 m, 8.7 m, and 13.4 m and two frequencies in the 900 MHz and 1900 MHz bands. Five test settings were chosen in urban, suburban, and rural areas in order to study propagation in a variety of environments. For all LOS measurements even in different environments, the variation of signal strength with distance was found to show distinct ear 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 could be calculated based on first Fresnel zone clearance. The regression analysis shows 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 the microcell and to design for fast hand-off. >