This paper deals with reconstruction of nonuniformly sampled bandlimited continuous-time signals using time-varying discretetime finite-length impulse response (FIR) filters. The main theme of the paper is to show how a slight oversampling should be utilized for designing the reconstruction filters in a proper manner. Based on a time-frequency function, it is shown that the reconstruction problem can be posed as one that resembles an ordinary filter design problem, both for deterministic signals and random processes. From this fact, an analytic least-square design technique is then derived. Furthermore, for an important special case, corresponding to periodic nonuniform sampling, it is shown that the reconstruction problem alternatively can be posed as a filter bank design problem, thus with requirements on a distortion transfer function and a number of aliasing transfer functions. This eases the design and offers alternative practical design methods as discussed in the paper. Several design examples are included that illustrate the benefits of the proposed design techniques over previously existing techniques.

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This paper considers the problem of reconstructing a class of nonuniformly sampled bandlimited signals of which a special case occurs in, e.g., time-interleaved analog-to-digital converter (ADC) systems due to time-skew errors. To this end, we propose a synthesis system composed of digital fractional delay filters. The overall system (i.e., nonuniform sampling and the proposed synthesis system) can be viewed as a generalization of timeinterleaved ADC systems to which the former reduces as a special case. Compared with existing reconstruction techniques, our method has major advantages from an implementation point of view. To be precise, 1) we can perform the reconstruction as well as desired (in a certain sense) by properly designing the digital fractional delay filters, and 2) if properly implemented, the fractional delay filters need not be redesigned in case the time skews are changed. The price to pay for these attractive features is that we need to use a slight oversampling. It should be stressed, however, that the oversampling factor is less than two as compared with the Nyquist rate. The paper includes error and quantization noise analysis. The former is useful in the analysis of the quantization noise and when designing practical fractional delay filters approximating the ideal filters. Index Terms-Bandlimited signals, digital filters, fractional delay filters, nonuniform sampling, time-interleaved analog-to-digital converters, time-skew errors. 1053-587X/02$17.00 © 2002 IEEE Authorized licensed use limited to: Technion Israel School of Technology. Downloaded on April 13, 2009 at 02:32 from IEEE Xplore. Restrictions apply. Håkan Johansson (M'02) was born in Kumla, Sweden, in 1969. He received the M.Sc. degree in computer science and the Lic., Doctoral, and Docent degrees in electronics systems from Linköping

A crucial issue in the next-generation satellite-based communication systems is the satellite on-board reallocation of information which requires digital flexible frequency-band reallocation (FBR) networks. This paper introduces a new class of flexible FBR networks based on variable oversampled complex-modulated filter banks (FBs). The new class can outperform the previously existing ones when all the aspects flexibility, low complexity and inherent parallelism, near-perfect frequency-band reallocation, and simplicity are considered simultaneously.