Study On Smart Antenna Array In MIMO System

Smart antenna and multiple-input multiple-output (MIMO) are two widely usedtechnologies in WCS(wireless communication system). Smart antenna array can improvethe anti-interference performance of WCS by directing the main lobe in the direction ofusers while the sidelobe in the direction of interference. MIMO can increase the capacityof WCS by placing multiple antenna in transmitter and receiver, taking full advantage ofmulti-path property in wireless channel.Although plenty of antenna array have been proposed for smart antenna system andMIMO system respectively, antenna array which can support both several MIMO datastreams and smart antenna technology are rarely stduied. It is meaningful for stduying inhow to make antenna array fulfil demand of increasing the capacity and enhancing theanti-interference performance of the system.Starting from the principle of smart antenna and MIMO, the thesis analyzes theinfluence of element radiation pattern, element polarization, coupling between elements,configuration of antenna array and connectivity structure of elements on the performanceof MIMO and smart antenna system. Then, the design idea of the MIMO smart antennaarray based on beam switching strategy and the key technology used in the process ofantenna design are proposed.According to the proposed design idea and key technology, dual-band element hasbeen presented for the design of MIMO smart antenna array. The dual-band element hasbeen optimized by high frequency structure simulator (HFSS). After that, the element cancover the two band provided by802.11n agreement, meanwhile, shows high gain andreasonably good front-to-back ratios.Based on the dual-band element, dual-band dual-polarization antenna array used inMIMO system which supports beam switching strategy simultaneously has been proposed.With this antenna array, the beam generated by the array can switch automatic along withthe change of communication environment so that the beam can direct users. With the helpof HFSS, coupling between elements and coverage area of the proposed array have beenanalysed, the improvement on the performance of the system which employ the proposedarray has been also qualitatively analysed in this thesis.At the end of this thesis, the problem in the study and the research orientation havebeen pointed out.