Enhanced-Least-Mean Square Algorithm Based Weight Optimization for Concentric Circular Antenna Array

Abstract

In the field of wireless communication, interfering signals impose critical problems during the transmission of signals. Signal to noise ratio can be improved at the base station by proper selection of array antenna. In this paper, Enhanced- Least- Mean Square algorithm has been presented to be employed for Concentric Circular Antenna Array as it has the ability to provide symmetrical beam pattern in all 360 degree with lesser effect of mutual coupling compared to other array patterns. Enhanced- Least- Mean Square algorithm is the algorithm for adaptive-beamforming that optimizes the weight vector such that the direction of the main beam of the circular antenna is adjusted, mitigating the undesired interfering signals thereby enhancing the desired signal. Mean-square error is minimized between the output received from the array and the reference signal due to optimal weight obtained from Enhanced- Least- Mean Square algorithm. The proposed algorithm incorporates iterative procedure as it does computation with the current weights for the processed signal, thereby generating deviation between the signal obtained from processing and the desired signal. This information about new error is utilized in adjusting the weights using gradient-method thereby obtaining the optimized weights. The simulation of the proposed algorithm is done using MATLAB, which converges at about 10 iterations. Performance evaluation is done for various angles of arrival for the proposed algorithm. Implementation of Enhanced- Least- Mean Square algorithm is simple comparable to other techniques as it eliminates inversion of any matrix.