An Efficient Adaptive Beamforming Technique for Operation in Frequency-Selective Channels

This paper presents an efficient adaptive beam forming technique for Quadrature Amplitude Modulation (QAM) receivers operating in frequency-selective channel environments. In order to mitigate the Inter-Symbol Interference (ISI) resulted from the wireless channel´s frequency-selectivity, the proposed method adopts multi-tap filters at all receiver branches, and converts the weight matrix into a long vector to facilitate efficient weight update using a recently proposed beam forming algorithm, which automatically generates a time-varying weight update at each iteration. Computer simulations are performed in MATLAB to validate the effectiveness of the proposed technique, which successfully suppresses frequency selectivity-induced ISI, while single-tap beam forming algorithms fail to converge in the presence of ISI.