Técnicas de processamento MIMO para sistemas 4G

摘要

The theme of this dissertation work is focused in one of the key technologiesspecified in the last 4G cellular standards, which are the MIMO systems. In thiscontext, the MIMO (Multiple Input Multiple Output) acronym is used to define acommunication system where multiple antennas are used, therefore using thistype of systems jointly with specific signal processing techniques, we can usethe spatial dimension in order to generate multiplexing, diversity andbeamforming gains.The aim of this work is to show the type of signal processing techniques thatmust be applied in order to achieve the gains referenced above, as well theoptimal channel conditions in which these gains are maximized.Therefore,beyond the presentation of the theoretical background related with these type oftechniques, we will present the MIMO transmission modes specified on 4G-LTE,having not only the aiming of show the type of practical constraints verified in apractical implementation, but also present the solutions used to solve that kindof constraints.In the last part of this work is presented a simulation platform implemented forone of the spatial multiplexing modes specified on LTE, which is the mode 4.The numerical results obtained allowed to see the advantage in the use of SIC(Successive Interference Cancelation) equalizers for multi-layer transmissionmodes, as well as the performance limitations related with the transmissionthrough a channel where high spatial correlation conditions are verified. With theuse of multiple precoding matrices, we understand the importance of perform acorrect precoding selection in order to improve the transmission through achannel with this type of conditions.Beyond the observations referred above, wealso saw the diversity cost related with the increase of spatial multiplexing gain.