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Suhas Diggavi

  1. Wireless Network Information Flow: A Deterministic Approach.

    Fri, 09/17/2010 - 15:02 — SomNambul
    Authors: Suhas Diggavi, David Tse, Salman Avestimehr
    Subjects: Information Theory
    Abstract

    In a wireless network with a single source and a single destination and an
    arbitrary number of relay nodes, what is the maximum rate of information flow
    achievable? We make progress on this long standing problem through a two-step
    approach. First we propose a deterministic channel model which captures the key
    wireless properties of signal strength, broadcast and superposition. We obtain
    an exact characterization of the capacity of a network with nodes connected by
    such deterministic channels.

  2. Secret-key Agreement with Channel State Information at the Transmitter.

    Fri, 09/17/2010 - 15:01 — SomNambul
    Authors: Suhas Diggavi, Ashish Khisti, Gregory Wornell
    Subjects: Information Theory
    Abstract

    We study the capacity of secret-key agreement over a wiretap channel with
    state parameters. The transmitter communicates to the legitimate receiver and
    the eavesdropper over a discrete memoryless wiretap channel with a memoryless
    state sequence. The transmitter and the legitimate receiver generate a shared
    secret key, that remains secret from the eavesdropper. No public discussion
    channel is available. The state sequence is known noncausally to the
    transmitter. We derive lower and upper bounds on the secret-key capacity.

  3. Approximately achieving Gaussian relay network capacity with lattice codes.

    Mon, 05/10/2010 - 15:01 — SomNambul
    Authors: Suhas Diggavi, Ayfer Ozgur
    Subjects: Information Theory
    Abstract

    Recently, it has been shown that a quantize-map-and-forward scheme
    approximately achieves (within a constant number of bits) the Gaussian relay
    network capacity for arbitrary topologies. This was established using Gaussian
    codebooks for transmission and random mappings at the relays. In this paper, we
    show that the same approximation result can be established by using lattices
    for transmission and quantization along with structured mappings at the relays.

  4. Optimality and Approximate Optimality of Source-Channel Separation in Networks.

    Fri, 04/16/2010 - 15:01 — SomNambul
    Authors: Shlomo Shamai, Suhas Diggavi, Jun Chen, Chao Tian
    Subjects: Information Theory
    Abstract

    We consider the source-channel separation architecture for lossy source
    coding in general communication networks. It is shown that the separation
    approach is optimal in two general scenarios, and is approximately optimal in a
    third scenario.

  5. On the Capacity of Non-Coherent Network Coding.

    Tue, 01/12/2010 - 16:01 — SomNambul
    Authors: Suhas Diggavi, Christina Fragouli, Soheil Mohajer, Mahdi Jafari Siavoshani
    Subjects: Information Theory
    Abstract

    We consider the problem of multicasting information from a source to a set of
    receivers over a network where intermediate network nodes perform randomized
    network coding operations on the source packets. We propose a channel model for
    the non-coherent network coding introduced by Koetter and Kschischang in [5],
    that captures the essence of such a network operation, and calculate the
    capacity as a function of network parameters.

  6. Hierarchical Routing over Dynamic Wireless Networks.

    Tue, 09/15/2009 - 11:27 — SomNambul
    Authors: Dominique Tschopp, Suhas Diggavi, Matthias Grossglauser
    Subjects: Networking and Internet Architecture
    Abstract

    Wireless network topologies change over time and maintaining routes requires
    frequent updates. Updates are costly in terms of consuming throughput available
    for data transmission, which is precious in wireless networks. In this paper,
    we ask whether there exist low-overhead schemes that produce low-stretch
    routes. This is studied by using the underlying geometric properties of the
    connectivity graph in wireless networks.

  7. Approximate Nearest Neighbor Search through Comparisons.

    Mon, 09/14/2009 - 09:02 — SomNambul
    Authors: Dominique Tschopp, Suhas Diggavi
    Subjects: Data Structures and Algorithms
    Abstract

    This paper addresses the problem of finding the nearest neighbor (or one of
    the R-nearest neighbors) of a query object q in a database of n objects. In
    contrast with most existing approaches, we can only access the ``hidden'' space
    in which the objects live through a similarity oracle. The oracle, given two
    reference objects and a query object, returns the reference object closest to
    the query object. The oracle attempts to model the behavior of human users,
    capable of making statements about similarity, but not of assigning meaningful
    numerical values to distances between objects.

Math-arch

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