The Analysis Of The Effect Of Correlation Between Array Elements On MIMO System Capacity

MIMO (multi-input and multi-output) technology has been used in mobile communications system for the increase in bandwidth efficiency, channel capacity, and high data rate. Due to this, it has gained great interests and been proposed as one of the key technologies for 3G and beyond systems. In this thesis, by exploiting the capacity of MIMO systems, we find that the capacity of MIMO systems is dependent on the communications scenarios as well as the correlation of the coupling between antenna array elements. The less the correlation, the greater in channel capacity will be obtained. Since this correlation is highly related to the antenna topologies, such as the element spacing and the antenna patterns, we suggest several antenna topologies in a typical micro-cell. The proposed element spacing and antenna pattern is able to greatly reduce the spatial correlation coefficient. The simulation has been conducted thereafter to verify the proposals.It is generally accepted that correlation reduces the capacity of the MIMO radio channel. The correlation mentioned here can be classified into two cases: first, the spatial correlation of the propagation scenarios; second, the mutual coupling between the antenna of the transceiver or the receiver. These two correlations will affect the capacity of the MIMO systems. The less the correlation, the less there will be the interference among the parallel sub-channels, and in turn, the greater the capacity of the superposition among the sub-channels, namely, the overall system capacity.Several factors affect the spatial correlation, such as the correlations of multi-path fading channels and the angular spread. The mutual coupling between the elements is dependent on the power azimuth spectrum (PAS), the direction of arrival (DOA) of the received signals, the element spacing, the size of the elements, the pattern of the array elements, and etc. While the spatial correlation could be obtained by the system feedback, the mutual coupling between the elements will be predetermined by calculation and measurements before hand. In this thesis, we focus on the impact of the element on correlation and hence explore the correlations between received signals in different cases.Obviously, the correlation between elements will be reduced by increasing the element spacing. In other words, the objective is 1.0 maintain a higher rank of the...