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Christina Fragouli

Cette personne n’est plus à l’EPFL

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Publications associées (117)

Simple schedules for half-duplex networks

Christina Fragouli, Siddhartha Brahma

We consider the diamond network where a source communicates with the destination through N non-interfering half-duplex relays. Deriving a simple approximation to the capacity of the network, we show that simple schedules having exactly two states and avoid ...

Ieee2012

Feedback-based coding algorithms for broadcast erasure channels with degraded message sets

Christina Fragouli, Shirin Saeedi Bidokhti

We consider single-hop broadcast packet erasure channels (BPEC) with degraded message sets and instantaneous feedback regularly available from all receivers, and demonstrate that the main principles of the virtual-queue-based algorithms in [1], which were ...

2012

Feedback-based Coding Algorithms for Braodcast Erasure Channels with Degraded Message Sets

Christina Fragouli

2012

Degraded two-message multicast over graphs

Christina Fragouli, Shirin Saeedi Bidokhti

We consider communication of two degraded mes- sage sets over graphs where a common source sends two prioritized messages (a common and a private message) to several receivers. All receivers require the common message and a subset of the receivers require ...

2011

A mobile world of security

Rüdiger Urbanke, Christina Fragouli, Christine Neuberg, Panagiotis Papadimitratos

We propose a novel approach to establish crypto- graphic keys among mobile users and a networking infrastruc- ture. Our approach comes at a low cost and can either be used as an alternative to existing solutions or can be employed in a complementary way. O ...

2011

Network simplification: the Gaussian diamond network with Multiple Antennas

Christina Fragouli, Ayfer Özgür Aydin, Javad Ebrahimi Boroojeni

We consider the N-relay Gaussian diamond network when the source and the destination have ns ≥ 2 and nd ≥ 2 antennas respectively. We show that when ns = nd = 2 and when the individual MISO channels from the source to each relay and the SIMO channels from ...

2011

Algebraic Algorithms for Vector Network Coding

Christina Fragouli, Javad Ebrahimi Boroojeni

We develop new algebraic algorithms for scalar and vector network coding. In vector network coding, the source multicasts information by transmitting vectors of length L, while intermediate nodes process and combine their incoming packets by multiplying th ...

Institute of Electrical and Electronics Engineers2011

Maximum likelihood estimation for multiple-source losss tomography with network coding

Christina Fragouli

Loss tomography aims at inferring the loss rate of links in a network from end-to-end measurements. Previous work in [1] has developed optimal maximum likelihood estimators (MLEs) for link loss rates in a single-source multicast tree. However, only sub-opt ...

2011

Reliability of clustered vs. declustered replica placement in data storage systems

Rüdiger Urbanke, Christina Fragouli

The placement of replicas across storage nodes in a replication-based storage system is known to affect rebuild times and therefore system reliability. Earlier work has shown that, for a replication factor of two, the reliability is essentially unaffected ...

2011

Approximate Capacity of a Class of Gaussian Interference-Relay Networks

Suhas Diggavi, Christina Fragouli, Soheil Mohajerzefreh

In this paper, we study a Gaussian relay-interference network, in which relay (helper) nodes are to facilitate competing information flows between different source-destination pairs. We focus on two-stage relay-interference networks where there are weak cr ...

Institute of Electrical and Electronics Engineers2011

A network coding approach to the shipper detection problem

Lorenzo Keller, Christina Fragouli, Abdulkadir Karaagaç

This paper experimentally studies the reliability and delay of flooding based multicast protocols for a sniper detection application. In particular using an emulator it studies under which conditions protocols based on network coding deliver performance im ...

2011

Secure key exchange in wireless networks

Christina Fragouli, László Czap

We investigate the problem of exchanging a se- cret key within a group of wireless devices. In particular, we are interested in information theoretically secure key exchange schemes that enable honest nodes of a multi-hop network to establish a secret grou ...

2011

Group secret key agreement over state-dependent wireless broadcast channels

Suhas Diggavi, Christina Fragouli, Mahdi Jafari Siavoshani

We consider a group of m trusted nodes that aim to create a shared secret key K, using a state-dependent wireless broadcast channel that exists from one of the honest nodes to the rest of the nodes including a passive eavesdropper Eve. All of the trusted n ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

On the capacity of non-coherent network coding

Suhas Diggavi, Christina Fragouli, Soheil Mohajerzefreh, Mahdi Jafari Siavoshani

We consider the problem of multicasting information from a source to a set of receivers over a network where interme- diate network nodes perform randomized linear network coding operations on the source packets. We propose a channel model for the noncoher ...

2011

Secret message capacity of erasure broadcast channels with feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

We characterize the secret message capacity of a wiretapped erasure channel where causal channel state informa- tion of the honest nodes is publicly available. In doing so, we establish an intimate connection between message secrecy and secret key generati ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

Network Coding: Beyond Throughput Benefits

Christina Fragouli

Network coding enables novel network functionalities and thus offers a wider canvas of choices when optimizing an information flow problem. In this paper, we examine the simplest possible information flow problem, a unicast connection, and explore what we ...

2011

Silence-Based Communication

Christina Fragouli

Communication complexity---the minimum amount of communication required---of computing a function of data held by several parties is studied. A communication model where silence is used to convey information is introduced. For this model the worst-case and ...

2010

Function computation over linear channels

Lorenzo Keller, Christina Fragouli, Nikhil Karamchandani

We consider multiple non-colocated sources commu- nicating over a network to a common sink. We assume that the network operation is fixed, and its end result is to convey a fixed linear deterministic transformation of the source data to the sink. This line ...

2010

Effect of replica placement on the reliability of large scale data storage systems

Robert Haas, Xiao-Yu Hu, Christina Fragouli, Vinodh Venkatesan

Replication is a widely used method to protect large- scale data storage systems from data loss when storage nodes fail. It is well known that the placement of replicas of the different data blocks across the nodes affects the time to rebuild. Several syst ...

2010

Erased Secrets: Practical Information-Theoretic Group Secrecy

Suhas Diggavi, Christina Fragouli, Mahdi Jafari Siavoshani, Aikaterini Argyraki, Uday Kiran Pulleti

We consider the scenario where a group of wireless nodes want to exchange a secret key, such that no eavesdropper can guess the key. Today, this can be achieved using publickey cryptography, e.g., the Diffie-Hellman or the RSA keyexchange algorithms. Howev ...

2010

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