Adaptive Beamforming With Software-Defined-Radio Arrays

Digital beamforming is the holy grail of antenna array technologies, however implementing digital beamforming into practical antenna arrays has been slow due to hardware complexity and cost. We propose a relatively inexpensive new approach to digital beamforming using software defined radios. Using this system, we carried out experiments on adaptive interference cancellation. We present detailed description of the beamformer system along with the developed control software and experimentally verify the beamformer performance. Our results show that in high-interference and high-multipath environments, where carrier frequency offsets cannot be measured, conventional interference cancellation algorithms fail. We propose two new robust solutions to this problem and compare the results with multiple techniques, including the minimum variance distortionless response beamformer, which outputs the highest possible signal-to-interference-plus-noise-ratio (SINR). We experimentally demonstrate that both our approaches work well in the face of these types of signal corruptions and are capable of interference cancellation without degrading SINR or other system performance factors, and without the need for transmitter and receiver synchronization.