Smart antennas for wireless communications systems

The fundamental idea behind smart antennas is to improve the performance of the wireless communication system by increasing the gain in a chosen direction. This can be achieved by pointing the main lobes of the antenna-beam patterns towards the desired users. Smart antenna system combines multiple antenna elements with a signal processing capability to automatically optimise its radiation and/or reception pattern in response to the signal environment. In addition to pointing the direction of the main lobe towards a chosen user the smart antenna system can automatically steer one or more nulls of the directivity pattern towards one or several sources of interferences. There are several benefits of using a smart antenna system for a wireless system and among these are the following: larger covering area, increased SNR and capacity, saving energy for the same performances, providing spatial diversity etc. In this paper both switched and adaptive beamforming techniques are analysed in order to point out the advantages of using smart antenna technique in wireless communications systems.