The effect of finite antenna separation on the performance of spatial diversity receivers

The wireless communications channel is commonly modelled as imposing a Rayleigh distributed envelope onto any incumbent signals. Antenna arrays have long been recognised as enabling exploitation of signal spatial diversity in such an environment based upon the assumption of uncorrelated signals at the different antennas. However, it is precisely the relative positions of the antennas which determine the extent of the correlation. We consider the effects on receiver output SNR performance, of the maximum ratio combining and equal gain combining diversity schemes, of the relative positions of antennas in a uniform linear array compared with the standard Rayleigh fading model. Such a comparison is possible via a spatially based SIMO model. The insights gained allow the possibility of determining optimal antenna configurations for given output performance measures.