Prediction of radiowave propagation in urban microcell environments using ray tracing methods

The use of microcells has been proposed as a method of providing high capacity cellular radio systems. The cell base station antenna is positioned below the rooftop height of the surrounding buildings in order to constrain the radio coverage to a small area. The aim of the work described in this paper is to develop theoretical models which can predict received signal powers in urban microcells. Theoretical models should have wider applicability than empirical methods because they are not based on measurements in a particular situation. In this paper predictions from a computer program are compared with experiments to verify the program. The experiments are carried out at microwave frequencies in the laboratory using idealised scaled obstacles. The scaling factor arises because the experimental frequency of 29 GHz is higher than that used in current cellular radio systems and the experimental wavelength is correspondingly reduced. This means that the dimensions of the experiment are scaled down so that measurements can be taken in the laboratory. This experimental method cannot include the detail of a real urban environment but allows the controlled testing of the computer program and has the advantages of manageable dimensions, repeatability and flexibility. Individual parts of the propagation problem can be isolated and their effect studied.