EFFECT OF ANTENNA ARRAY GEOMETRY AND ULA AZIMUTHAL ORIENTATION ON MIMO CHANNEL PROPERTIES IN URBAN CITY STREET GRID

Abstract

Propagation environment and antenna array configuration have significant effect on spatial correlation properties of multiple- input multiple-output (MIMO) wireless communications channels. In this paper the effect of different antenna array geometries on MIMO channel properties is investigated in urban city street grid propagation environment. Four antenna array geometries with the same number of antenna elements and fixed inter-element spacing are considered, namely, uniform linear array (ULA), uniform circular array (UCA), uniform rectangular array (URA) and uniform cubic array (UCuA). The effect of ULA orientation in azimuthal plane on MIMO channel ergodic capacity is also investigated. Varying orientation angle from 0 to π at the two communication ends is considered. The investigation is carried out based on three dimensional (3D) spatial multi-ray realistic propagation channel model covering different propagation types. It is shown that the antenna array geometry have significant impact on MIMO channel properties. Under different propagation scenarios the ULA shows superiority to the other considered geometries in terms of the ergodic channel capacity and number of spatial parallel channels. However, this superiority depends largely on the array azimuthal orientation.