Iterative Beamforming Technique for Interference Cancellation

Abstract

Adaptive beamforming is used in many applications such as radar, sonar and wireless communications for separating desired signals from other unwanted signals. Beamforming is essentially applied to direct the pattern of the receiving antenna system towards the desired direction as well as to attenuate the received signals from unwanted directions. The process of adaptive beamforming is performed in two steps. The first step is assigned to estimate the direction of arrival of signals at the field of view of the receiving system. The second step is assigned to nullify the beam pattern in the directions of unwanted signals. To improve the performance of the adaptive beamforming, the number of array elements as well as the number of snapshots should be increased. However, this increase in both numbers of elements and snapshots leads to increase in the cost and the processing time. In this paper, a proposed iterative adaptive digital beamforming technique is presented to improve the array capability of interference cancellation while reducing the processing time. The proposed technique is based on the Jacobi theorem for iterative solution of a system of linear equation to determine the optimum weight vector at the array output. The proposed technique is compared with the optimal Minimum Variance Distortionless Response (MVDR) beamformer technique. Computer simulation is applied to verify the mathematical analysis that presented in the paper. The paper results show that the proposed technique can provide effective Co-Channel Interference (CCI) suppression better than MVDR, while increasing the strength of the desired signal.