Impact of the Angular Spread and Antenna Spacing on the Capacity of Correlated MIMO FadingChannels

It has been shown that the capacity of a multiple-input multiple-output system increases linearly with the number ofantennas, provided that the environment is rich scattering. However, this increase in the capacity is substantially degraded ifthe multiple input multiple output channels are correlated. In this paper, the capacity of correlated multiple input multipleoutput fading channel is investigated for laplacian and uniform angular energy distributions that implicitly represent twodifferent scatterer distributions. The effect of the spatial correlation of a uniform circular antenna array is considered. Optimalpower allocation is implemented to maximize the capacity. Through extensive Monte Carlo simulations, the results show thatmultiple input multiple output channel capacity is a function of the angle spread and antenna spacing. These two parametersplay a major role in dictating the spatial correlation which in turn affects on the capacity. Large angle spread leads to lowercorrelation between the antenna elements and consequently higher capacity. The degradation in the capacity can be reduced byincreasing the spacing between the antenna elements