Resource Allocation in Correlated MIMO Systems

Abstract

Antennas proximity produces the antennas correlation eff ect which impacts over the Multiple-Input Multiple-Output (MIMO) system performance. This PhD thesis evaluate the receiver-side antennas correlation e ffect and outputs the appropriate antennas set-up, showing simulation results for a (4 x 4) correlated MIMO channel with linear and non-linear uniformly spaced antennas. Therefore, optimal and sub-optimal resource allocation techniques for MIMO systems are compared. Bit and power allocation techniques have been investigated in order to fi nd out optimal algorithms to achieve the best bit-error rate (BER) performance. An optimal power allocation (PA) technique based on Lagrange multiplier method is compared against a sub-optimal PA based on an equal-SNR for uncorrelated and correlated channel pro files. Following the sub-optimal strategies, a novel iterative bit- and power allocation (IBPA) approach has been developed when transmitting a given bit/s/Hz data rate over a correlated frequency non-selective (4 x 4) MIMO channel. The iterative resources allocation algorithm developed in this investigation is aimed at the achievement of the minimum BER in a correlated MIMO communication system. In order to achieve this goal, the available bits are iteratively allocated in the MIMO active layers which present the minimum transmit power requirement per time slot. Finally, this single-user MIMO system has been extended to multi-user MIMO system.