Antenna array and feed-backward equalizer as single adaptive device




adaptive antenna array, AAA, feed-forward equalizer, feed-backward equalizer, interference suppression, multipathing


This paper considers an adaptive antenna array (AAA) with its weight factors combined with those of Feed-Forward (FF) part of a channel equalizer, while the array output signal is combined with that of Feed-Backward (FB) part of the equalizer. Such an array and distributed equalizer operate as a single multichannel adaptive filter providing the possibility of receiving a useful signal under conditions of its multipathing and in the presence of signals of external interference sources. The paper presents the architecture of antenna array/equalizer and the mathematical description of its multichannel adaptive algorithms, such as recursive least-squares (RLS) algorithm based on the Matrix Inversion Lemma (MIL), QR-decomposition and Householder’s transformation with quadratic computational complexity, and also simple algorithms based on the least squares (LS) criterion, normalized LS (NLS) and affine projection (AP) algorithms with linear computational complexity. The simulation results of the linear antenna array with eight antennas/channels, which receives a useful 16-PSK signal having passed through a two-ray communication channel in the presence of one to four interference sources with signal-to-interference ratio (SIR) of –30 dB for each interference and the signal-to-noise ratio (SNR) of 10–30 dB in the array channels, demonstrate the efficiency of the solution proposed.


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Constellations of input and output signals