Henri Favaro

Fast convolution filter banks for satellite payloads with on-board processing

Filter banks able to demultiplex channels of different sizes are necessary on board the satellite when a single bit-rate channel is assigned to each user. In this paper, the method referred to as the fast convolution filter bank is analyzed for regenerative payloads. The size of the input fast Fourier transform (FFT) depends on the narrowest channel, while the inverse fast Fourier transform (IFFT) number of points is relative to the decimation ratio associated with each channel. In order to reduce the complexity, most of the frequency coefficients are forced to zero, leading to a violation of the overlap-and-save (OS) condition. It is shown that the resulting error can be modeled as a cyclostationary process, and an optimization method based on minimization of the associated mean-square error (MSE) is proposed. Fast convolution is then compared with multistage implementation in terms of flexibility, reconfigurability, and complexity.

Multicarrier demultiplexing in the frequency domain

Filtering by fast convolution is a well-known technique. The goal of this article is to apply the technique to filterbanks. The operation of filtering-decimation is analyzed in order to limit the number of points of the inverse discrete Fourier transforms, and a new filter optimization method allowing the reduction of the number of frequency coefficients is proposed. The use of these new filters is shown in examples, and some system implications are considered. (Author)