The effect of lamppost scatterers on direction finding by cylindrical arrays of dipoles intended for smart antenna application in wireless communications

Abstract

Smart antennas are widely used to enhance the capacity of the wireless communication systems in urban areas. To enhance the capacity by increasing the signal to noise ratio, one should estimate the angle of arrival precisely. In urban areas, the scattering from the lampposts in a boulevard or a highway is not negligible and its effect should be considered in direction finding algorithms. In this paper the lampposts are modelled by thick and long cylindrical scatterers and the scattered electric field is computed in terms of the cylindrical harmonics analytically. Then the total electric field is evaluated to estimate the angle of arrival by MUSIC direction finding algorithm. The computed total electric field with the proposed method shows a good agreement with precise HFSS simulation results for different incident angles. Monte-Carlo simulations are conducted to evaluate the RMS error values using cylindrical array of dipole antennas for direction finding and the results show that the proposed method can model the effects of the finite number of the lampposts in a wireless propagation scenario adequately, with reduced burden of computations. This fact contributes to a better planning of the beamforming in smart antennas with corresponding resolution.