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Farokh Marvasti

  1. Compensating Interpolation Distortion by Using New Optimized Modular Method.

    Ср, 04/18/2012 - 15:01 — SomNambul
    Authors: Farokh Marvasti, Mohammad Tofighi, Ali Ayremlou
    Subjects: Computer Vision and Pattern Recognition
    Abstract

    A modular method was suggested before to recover a band limited signal from
    the sample and hold and linearly interpolated (or, in general, an
    nth-order-hold) version of the regular samples. In this paper a novel approach
    for compensating the distortion of any interpolation based on modular method
    has been proposed. In this method the performance of the modular method is
    optimized by adding only some simply calculated coefficients. This approach
    causes drastic improvement in terms of signal-to-noise ratios with fewer
    modules compared to the classical modular method.

  2. Fast Impulse Noise Removal from Highly Corrupted Images.

    Втр, 05/17/2011 - 15:01 — SomNambul
    Authors: Farokh Marvasti, Hossein Hosseini
    Subjects: Multimedia
    Abstract

    In this paper, we suggest a general model for the fixed-valued impulse noise
    and propose a two-stage method for high density noise suppression while
    preserving the image details. In the first stage, we apply an iterative impulse
    detector, exploiting the image entropy, to identify the corrupted pixels and
    then employ an Adaptive Iterative Mean filter (AIM) to restore them. The filter
    is adaptive in terms of the number of iterations, which is different for each
    noisy pixel, according to their Euclidean distance from the nearest uncorrupted
    pixel.

  3. Multiple Access Channels with Cooperative Encoders and Channel State Information.

    Пт, 10/01/2010 - 15:01 — SomNambul
    Authors: Farokh Marvasti, Reza Khosravi-Farsani
    Subjects: Information Theory
    Abstract

    The two-user Multiple Access Channel (MAC) with cooperative encoders and
    Channel State Information (CSI) is considered where two different scenarios are
    investigated: A two-user MAC with common message (MACCM) and a two-user MAC
    with conferencing encoders (MACCE). For both situations, the two cases where
    the CSI is known to the encoders either non-causally or causally are studied.
    Achievable rate regions are established for both discrete memoryless channels
    and Gaussian channels with additive interference.

  4. PAPR reduction of space-time and space-frequency coded OFDM systems using active constellation extension.

    Втр, 02/09/2010 - 16:01 — SomNambul
    Authors: Farokh Marvasti, Mahmoud Ferdosizadeh Naeiny
    Subjects: Information Theory
    Abstract

    Active Constellation Extension (ACE) is one of techniques introduced for Peak
    to Average Power Ratio (PAPR) reduction for OFDM systems. In this technique,
    the constellation points are extended such that the PAPR is minimized but the
    minimum distance of the constellation points does not decrease. In this paper,
    an iterative ACE method is extended to spatially encoded OFDM systems. The
    proposed methods are such that the PAPR is reduced simultaneously at all
    antennas, while the spatial encoding relationships still hold.

  5. A New Decoding Scheme for Errorless Codes for Overloaded CDMA with Active User Detection.

    Втр, 01/26/2010 - 16:01 — SomNambul
    Authors: Farokh Marvasti, Ali Mousavi, Pedram Pad
    Subjects: Information Theory
    Abstract

    Recently, a new class of binary codes for overloaded CDMA systems are
    proposed that not only has the ability of errorless communication but also
    suitable for detecting active users. These codes are called COWDA [1]. In [1],
    a Maximum Likelihood (ML) decoder is proposed for this class of codes. Although
    the proposed scheme of coding/decoding show impressive performance, the decoder
    can be improved.

  6. Deterministic Construction of Binary, Bipolar and Ternary Compressed Sensing Matrices.

    Чт, 08/20/2009 - 23:06 — SomNambul
    Authors: Arash Amini, Farokh Marvasti
    Subjects: Information Theory
    Abstract

    In this paper we establish the connection between the Orthogonal Optical
    Codes (OOC) and binary compressed sensing matrices. We also introduce
    deterministic bipolar $m\times n$ RIP fulfilling $\pm 1$ matrices of order $k$
    such that $\frac{\log m}{\log k}\approx \frac{\log(\log_2 n)}{\log(\log_2 k)}$.
    The columns of these matrices are binary BCH code vectors where the zeros are
    replaced by -1.

Math-arch

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