Beamforming solutions for interference reduction for high altitude airborne CDMA systems

Interference reduction is vital for being able to effectively communicate with mobile users in rugged terrain and mountainous regions.¹² It is proposed to outfit a high flying airborne node with a Code Division Multiple Access (CDMA) base station in order to provide line of sight communications and continual coverage to the remote users. One approach to increasing capacity and coverage zones for the servicing wireless station is to use smart antennas. Smart antenna systems offer an efficient way to limit the interference by canceling out potential jammers. Sophisticated adaptive beamforming techniques can be applied to point the array´s beam in the desired look direction while simultaneously nulling out the interfering signal. This paper will investigate the application of the Least Mean Squares (LMS) algorithm and its key challenges in a highly congested environment. The results will demonstrate the utility of the LMS algorithm as a solution to interference rejection.