Impact of Antenna array Geometry on the Capacity of MIMO Communication System

MIMO systems, employing array of antennas at both ends of the transmission link, provide significant increase in the achievable capacity. The ability of achieving this high capacity is greatly influenced by the geometry of antenna array used and the correlation between the channel gains on each antenna element in the array. In this paper, the impact of different array configurations have on capacity is observed and compared. Five different array configurations - uniform linear array, non-uniform linear array, uniform circular array, hexagonal array and star array are used to compare their performances. The expression of capacity of the communication system, derived from information-theoretic approach, is altered to introduce the impact of channel matrix on the system capacity. The influence of different array geometry is modelled by using the concept of 'array manifold vector' in the expression of channel matrix and in turns in the expression of capacity. Using this expression, capacities with different antenna array geometries are compared.