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Hesham El Gamal

  1. Proactive Resource Allocation: Harnessing the Diversity and Multicast Gains.

    Mon, 10/24/2011 - 15:01 — SomNambul
    Authors: Hesham El Gamal, John Tadrous, Atilla Eryilmaz
    Subjects: Information Theory
    Abstract

    This paper introduces the novel concept of proactive resource allocation
    through which the predictability of user behavior is exploited to balance the
    wireless traffic over time, and hence, significantly reduce the bandwidth
    required to achieve a given blocking/outage probability. We start with a simple
    model in which the smart wireless devices are assumed to predict the arrival of
    new requests and submit them to the network T time slots in advance.

  2. ARQ Security in Wi-Fi and RFID Networks.

    Tue, 10/19/2010 - 15:01 — SomNambul
    Authors: Moustafa Youssef, Hesham El Gamal, Mohamed Elsabagh, Yara Abdallah
    Subjects: Cryptography and Security
    Abstract

    In this paper, we present two practical ARQ-Based security schemes for Wi-Fi
    and RFID networks. Our proposed schemes enhance the confidentiality and
    authenticity functions of these networks, respectively. Both schemes build on
    the same idea; by exploiting the statistical independence between the multipath
    fading experienced by the legitimate nodes and potential adversaries, secret
    keys are established and then are continuously updated.

  3. The Two Way Wiretap Channel: Theory and Practice.

    Mon, 06/07/2010 - 15:01 — SomNambul
    Authors: Moustafa Youssef, Hesham El Gamal, Aly El Gamal, O. Ozan Koyluoglu
    Subjects: Information Theory
    Abstract

    This work considers the two way wiretap channel in which two legitimate
    users, Alice and Bob, wish to exchange messages securely in the presence of a
    passive eavesdropper Eve. In the full duplex scenario, where each node can
    transmit and receive simultaneously, we obtain new achievable secrecy rate
    regions based on the idea of allowing the two users to jointly optimize their
    channel prefixing distributions and binning codebooks; in addition to key
    sharing. The new regions are shown to be strictly larger than the known ones
    for a wide class of discrete memoryless and Gaussian channels.

  4. Keys through ARQ: Theory and Practice.

    Fri, 05/28/2010 - 15:01 — SomNambul
    Authors: Moustafa Youssef, Hesham El Gamal, Ahmed Sultan, Yara Abdallah, Mohamed Abdel Latif
    Subjects: Information Theory
    Abstract

    This paper develops a novel framework for sharing secret keys using the
    Automatic Repeat reQuest (ARQ) protocol. We first characterize the underlying
    information theoretic limits, under different assumptions on the channel
    spatial and temporal correlation function. Our analysis reveals a novel role of
    "dumb antennas" in overcoming the negative impact of spatial correlation on the
    achievable secrecy rates.

  5. On Secrecy Capacity Scaling in Wireless Networks.

    Tue, 04/13/2010 - 15:03 — SomNambul
    Authors: Hesham El Gamal, O. Ozan Koyluoglu, C. Emre Koksal
    Subjects: Information Theory
    Abstract

    This work studies the achievable secure rate per source-destination pair in
    wireless networks. First, a path loss model is considered, where the legitimate
    and eavesdropper nodes are assumed to be placed according to Poisson point
    processes with intensities $\lambda$ and $\lambda_e$, respectively. It is shown
    that, as long as $\lambda_e/\lambda=o((\log n)^{-2})$, almost all of the nodes
    achieve a perfectly secure rate of $\Omega(\frac{1}{\sqrt{n}})$ for the
    extended and dense network models.

  6. Polar Coding for Secure Transmission and Key Agreement.

    Tue, 03/09/2010 - 16:01 — SomNambul
    Authors: Hesham El Gamal, O. Ozan Koyluoglu
    Subjects: Information Theory
    Abstract

    Wyner's work on wiretap channels and the recent works on information
    theoretic security are based on random codes. Achieving information theoretical
    security with practical coding schemes is of definite interest. In this note,
    the attempt is to overcome this elusive task by employing the polar coding
    technique of Ar{\i}kan. It is shown that polar codes achieve non-trivial
    perfect secrecy rates for binary-input degraded wiretap channels while enjoying
    their low encoding-decoding complexity.

  7. A New Class of TAST Codes With A Simplified Tree Structure.

    Wed, 01/20/2010 - 16:01 — SomNambul
    Authors: Hesham El Gamal, Mohamed Oussama Damen, Ahmed A. Badr
    Subjects: Information Theory
    Abstract

    We consider in this paper the design of full diversity and high rate
    space-time codes with moderate decoding complexity for arbitrary number of
    transmit and receive antennas and arbitrary input alphabets. We focus our
    attention to codes from the threaded algebraic space-time (TAST) framework
    since the latter includes most known full diversity space-time codes. We
    propose a new construction of the component single-input single-output (SISO)
    encoders such that the equivalent code matrix has an upper triangular form.

  8. Randomization for Security in Half-Duplex Two-Way Gaussian Channels.

    Thu, 08/27/2009 - 13:23 — SomNambul
    Authors: Moustafa Youssef, Hesham El Gamal, Aly El Gamal
    Subjects: Information Theory
    Abstract

    This paper develops a new physical layer framework for secure two-way
    wireless communication in the presence of a passive eavesdropper, i.e., Eve.
    Our approach achieves perfect information theoretic secrecy via a novel
    randomized scheduling and power allocation scheme. The key idea is to allow
    Alice and Bob to send symbols at random time instants. While Alice will be able
    to determine the symbols transmitted by Bob, Eve will suffer from ambiguity
    regarding the source of any particular symbol. This desirable ambiguity is
    enhanced, in our approach, by randomizing the transmit power level.

  9. ARQ Secrecy: From Theory to Practice.

    Tue, 08/18/2009 - 11:53 — SomNambul
    Authors: Yara Omar, Moustafa Youssef, Hesham El Gamal
    Subjects: Information Theory
    Abstract

    Inspired by our earlier work on Automatic Repeat reQuest (ARQ) secrecy, we
    propose a simple, yet efficient, security overlay protocol to existing 802.11
    networks. Our work targets networks secured by the Wired Equivalent Privacy
    (WEP) protocol because of its widespread use and vulnerability to a multitude
    of security threats. By exploiting the existing ARQ protocol in the 802.11
    standard, our proposed opportunistic secrecy scheme is shown to defend against
    all known passive WEP attacks.

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