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IEEE Signal Processing Letters

Issue 6 • Date June 2002

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Displaying Results 1 - 6 of 6
  • Semidefinite positive relaxation of the maximum-likelihood criterion applied to multiuser detection in a CDMA context

    Publication Year: 2002, Page(s):165 - 167
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB) | HTML iconHTML

    Many signal processing applications reduce to solving combinatorial optimization problems. Semidefinite programming (SDP) has been shown to be a very promising approach to combinatorial optimization, where SDP serves as a tractable convex relaxation of NP-hard problems. We present a nonlinear programming algorithm for solving SDP, based on a change of variables that replaces the symmetrical, posit... View full abstract»

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  • A short proof of the equivalence of LCMV and GSC beamforming

    Publication Year: 2002, Page(s):168 - 169
    Cited by:  Papers (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (173 KB) | HTML iconHTML

    Charles Jim (1977) showed the conditions under which a linearly constrained minimum-variance (LCMV) beamformer produces outputs equivalent to a generalized sidelobe canceller (GSC). Buckley (1986) has stated that the proof of equivalence extends to general multilinear constraints. In this article a short proof based on complementary subspaces is presented. View full abstract»

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  • Multiframe resolution-enhancement methods for compressed video

    Publication Year: 2002, Page(s):170 - 174
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB) | HTML iconHTML

    Multiframe resolution enhancement ("superresolution") methods are becoming widely studied, but only a few procedures have been developed to work with compressed video, despite the fact that compression is a standard component of most image- and video-processing applications. One of these methods uses quantization-bound information to define convex sets and then employs a technique called "projecti... View full abstract»

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  • A novel full-search vector quantization algorithm based on the law of cosines

    Publication Year: 2002, Page(s):175 - 176
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (168 KB) | HTML iconHTML

    Vector quantization (VQ) is an essential tool in signal processing. Although many algorithms for vector quantizer design have been developed, the classical generalized Lloyd algorithm (GLA) is still widely used, mainly for its simplicity and relatively good performance. Using law of cosines this letter presents a simple improved method for nearest-neighbor search in GLA. Experiments show that the ... View full abstract»

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  • Conditions for nonnegative independent component analysis

    Publication Year: 2002, Page(s):177 - 180
    Cited by:  Papers (39)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (230 KB) | HTML iconHTML

    We consider the noiseless linear independent component analysis problem, in the case where the hidden sources s are nonnegative. We assume that the random variables si are well grounded in that they have a nonvanishing probability density function (PDF) in the (positive) neighborhood of zero. For an orthonormal rotation y=Wx of prewhitened observations x=QAs, under certain reasonable conditions we... View full abstract»

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  • Stochastic discrete scale invariance

    Publication Year: 2002, Page(s):181 - 184
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (222 KB) | HTML iconHTML

    A definition of stochastic discrete scale invariance (DSI) is proposed and its properties studied. It is shown how the Lamperti (1962) transformation, which transforms stationarity in self-similarity, is also a means to connect processes deviating from stationarity and processes which are not exactly scale invariant: in particular we interpret DSI as the image of cyclostationarity. This theoretica... View full abstract»

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Aims & Scope

The IEEE Signal Processing Letters is a monthly, archival publication designed to provide rapid dissemination of original, cutting-edge ideas and timely, significant contributions in signal, image, speech, language and audio processing.

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Editor-in-Chief
Peter Willett
University of Connecticut
Storrs, CT 06269
peter.willett@uconn.edu