New adaptive beamforming algorithms for smart antennas in DS-CDMA mobile communication systems

The increasing capacity and quality demands for mobile communication services, without a corresponding increase in RF spectrum allocation, motivate the need for new techniques to improve spectrum utilization. The CDMA and SDMA (spatial division multiple access) technologies are two solutions that show real promise for increasing spectrum efficiency. This work investigated smart antenna adaptive beamforming algorithms to implement and combine the CDMA and SDMA techniques in DS-CDMA systems. In the paper, three blind adaptive algorithms: DR-LMS (de-spread re-spread-least mean square), DR-SMI (de-spread re-spread-sample matrix inversion) and DR-RLS (de-spread re-spread-recursive least square), are introduced and simulated in Matlab 6.1. These blind algorithms are based on the conventional LMS, SMI, and RLS algorithms.