ADAPTIVE MULTIPLE INPUT MULTIPLE OUTPUT (MIMO) ANTENNA SYSTEM BASED ON DIVERSITY TECHNIQUES

Abstract

Over the last few decade or so, the need for high speed communication is increased by a great extent. This requirement of high data rate communication motivated the extensive research in the application of Multiple Input and Multiple Output (MIMO) antenna systems. Under the multipath and dense environment, these systems have been proved to provide excellent throughput and error performance compared to Single Input and Single Output (SISO) antenna systems. The major limitation of the MIMO antenna systems is requirement of multiple number of signal processing units such as low noise amplifiers (LNA), power amplifiers (PAs), signal mixers, digital to analog converters (DAC) and analog to digital converters (ADC) etc. at the transmitter and receiver sides of the communication system. So to tackle this limitation, adaptive selection of these analog chains without compromising the performance of the system has been proved to be the best solution. In the present dissertation work, we studied the MIMO antenna system and its performance characteristics thoroughly. Different adaptive selection techniques based on antenna pattern diversity, frequency diversity and polarisation diversity have been surveyed. A metaheuristic based approach for antenna selection has been studied and implemented using Particle Swarm optimization (PSO) technique. Laboratory implementation of the MIMO antenna system using National Instruments Universal Software Defined Radio (NI-IJSRP) powered with LabVIE\V programming is studied and the system is designed. One more approach of antenna configuration selection without the exhaustive search technique is studied and implemented. The search technique of optimal configuration without exhaustive search is extended by including the polarisation diversity.