SYSTOLIC DESIGN OF FREQUENCY-DOMAIN BLOCK LMS ADAPTIVE DIGITAL-FILTERS

Adaptive filtering in the frequency domain can be achieved by Fourier transformation of the input signal and independent weighting of the co ntents of each frequency bin. In certain applications, filtering in th e frequency domain results in great improvements in convergence rate o ver the conventional time-domain adaptive filtering. In this paper, th e use of word-level systolic arrays to implement frequency-domain adap tive filters based on the complex least mean square (I,MS) algorithm i s described, The transform employed is the discrete Fourier transform (DFT). The proposed architecture operates on a block-by-block basis an d makes use of the parallelism inherent in the computational problem u nder consideration. The input and output data flow sequentially and co ntinuously into and out of the systolic arrays at the system clock rat e. During each clock period, processing elements of three different ty pes operate in parallel. The most computationally demanding among them performs only three consecutive multiplications and two addition/subt ractions per clock period thereby allowing a very high throughput and very fast block signal processing to be achieved at the expense of a d elay of 2L + 1 samples between the input and the output, L being the b lock size. (C) 1998 Elsevier Science Ltd. All rights reserved.