| MIMO is a technology that can use multi-antenna in the end transceivers, and effectively overcome the adverse environmental impacts, in the same transmission conditions that provide better signal transmission quality than conventional antenna system, also the corresponding can effectively improve the capacity of the system. But between the MIMO channel is not independent of each other, they are correlated which will seriously affect the performance of MIMO antenna system to play. Therefore, spatial correlation technology has been the key technology in multi-antenna wireless communication systems.This article briefly study the spatial correlation of the linear and circular antenna arrays in typical angular energy distributions. We derived the approximate equation which calculation the spatial correlation easier based on the exact algorithm. Form the simulation, we found the main factors which impact the spatial correlation are spacing between the antennas and angular spread. Then the effect of spatial correlation between receive antennas on capacity is investigated for various scattering environments. The physics of signal propagation is combined with statistics of the scattering environment to derive a capacity expression in terms of spatial correlation, antenna spacings/placement, aperture size, and power distribution of scatters. This result is used to show that for a given aperture size, one can increase the capacity approximately linearly up to a certain value by increasing the number of antennas but further increase will not give any significant capacity gain. Last we study the performance impact of STBC in correlated and non-correlated Rayleigh fading channels.Using the equivalent SISO model, we derive the exact SER and BER of OSTBC with multiple modulations over flat uncorrelated and correlated Rayleigh fading channels, and we provide the impact of antenna correlation on the performance of OSTBC. |
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