Amin A. Gohari

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—We investigate the structure of the polytope underlying the linear programming (LP) decoder introduced by Feldman, Karger, and Wainwright. We first show that for ex-pander codes, every fractional pseudocodeword always has at least a constant fraction of nonintegral bits. We then prove that for expander codes, the active set of any fractional pseudocodeword(More)
In this paper we investigate the structure of the fundamental polytope used in the Linear Programming decoding introduced by Feldman, Karger and Wainwright. We begin by showing that for expander codes, every fractional pseudocodeword always has at least a constant fraction of non-integral bits. We then prove that for expander codes, the active set of any(More)
—Spectrum sensing is a core problem in cog-nitive radio. Detecting the presence/absence of very weak primary users with a single antenna can be very difficult. Environmental uncertainties result in SNR walls that detectors cannot overcome. Multiple-antenna approaches show some potential gains, but we show here that single-user multiple-antenna detection(More)
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