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Rüdiger Urbanke

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Publications associées (85)

The Least Degraded and the Least Upgraded Channel with respect to a Channel Family

Rüdiger Urbanke, Seyed Hamed Hassani, Wei Liu

Given a family of binary-input memoryless output-symmetric (BMS) channels having a fixed capacity, we derive the BMS channel having the highest (resp.lowest) capacity among all channels that are degraded (resp. upgraded) with respect to the whole family. W ...

Ieee2013

Threshold Saturation in Spatially Coupled Constraint Satisfaction Problems

Nicolas Macris, Rüdiger Urbanke, Seyed Hamed Hassani

We consider chains of random constraint satisfaction models that are spatially coupled across a finite window along the chain direction. We investigate their phase diagram at zero temperature using the survey propagation formalism and the interpolation met ...

Springer Verlag2013

Displacement Convexity - A Useful Framework for the Study of Spatially Coupled Codes

Nicolas Macris, Rüdiger Urbanke, Rafah El-Khatib

Spatial coupling has recently emerged as a powerful paradigm to construct graphical models that work well under low-complexity message-passing algorithms. Although much progress has been made on the analysis of spatially coupled models under message passin ...

Ieee2013

Chains of mean field models

Nicolas Macris, Rüdiger Urbanke, Seyed Hamed Hassani

2012

How to Prove the Maxwell Conjecture Via Spatial Coupling - A Proof of Concept

Nicolas Macris, Rüdiger Urbanke, Andrei Giurgiu

Investigations on spatially coupled codes have lead to the conjecture that, in the infinite size limit, the average input-output conditional entropy for spatially coupled low-density parity-check ensembles, over binary memoryless symmetric channels, equals ...

Ieee2012

Universal bounds on the scaling behavior of polar codes

Rüdiger Urbanke, Seyed Hamed Hassani, Ali Goli

We consider the problem of determining the tradeoff between the rate and the block-length of polar codes for a given block error probability when we use the successive cancellation decoder. We take the sum of the Bhattacharyya parameters as a proxy for the ...

2012

Lossy source coding via spatially coupled LDGM ensembles

Nicolas Macris, Rüdiger Urbanke, Marc Vuffray, Vahid Aref

We study a new encoding scheme for lossy source compression based on spatially coupled low-density generatormatrix codes. We develop a belief-propagation guided-decimation algorithm, and show that this algorithm allows to approach the optimal distortion of ...

Ieee2012

Polar Codes: Robustness of the Successive Cancellation Decoder with Respect to Quantization

Rüdiger Urbanke, Seyed Hamed Hassani

Polar codes provably achieve the capacity of a wide array of channels under successive decoding. This assumes infinite precision arithmetic. Given the successive nature of the decoding algorithm, one might worry about the sensitivity of the performance to ...

Ieee2012

Chains of mean-field models

Nicolas Macris, Rüdiger Urbanke, Seyed Hamed Hassani

We consider a collection of Curie-Weiss (CW) spin systems, possibly with a random field, each of which is placed along the positions of a one-dimensional chain. The CW systems are coupled together by a Kac-type interaction in the longitudinal direction of ...

2012

Threshold Saturation via Spatial Coupling: Why Convolutional LDPC Ensembles Perform So Well over the BEC

Rüdiger Urbanke, Shrinivas Kudekar

Convolutional low-density parity-check (LDPC) ensembles, introduced by Felstrom and Zigangirov, have excellent thresholds and these thresholds are rapidly increasing functions of the average degree. Several variations on the basic theme have been proposed ...

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

Exchange of Limits: Why Iterative Decoding Works

Rüdiger Urbanke, Satish Babu Korada

We consider communication over binary-input memoryless output-symmetric channels using low-density parity-check codes and message-passing decoding. The asymptotic (in the length) performance of such a combination for a fixed number of iterations is given b ...

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

On the scaling of polar codes: II. The behavior of un-polarized channels

Rüdiger Urbanke, Seyed Hamed Hassani

We provide upper and lower bounds on the escape rate of the Bhattacharyya process corresponding to polar codes where transmission takes place over the the binary erasure channel. More precisely, we bound the exponent of the number of sub-channels whose Bha ...

IEEE2010

Threshold saturation via spatial coupling: Why convolutional LDPC ensembles perform so well over the BEC

Rüdiger Urbanke, Shrinivas Kudekar

Convolutional LDPC ensembles, introduced by Felstrom and Zigangirov, have excellent thresholds and these thresholds are rapidly increasing as a function of the average degree. Several variations on the basic theme have been proposed to date, all of which s ...

IEEE2010

Polar codes for Slepian-Wolf, Wyner-Ziv, and Gelfand-Pinsker

Rüdiger Urbanke, Satish Babu Korada

2010

An empirical scaling law for polar codes

Rüdiger Urbanke, Emre Telatar, Andrea Montanari, Satish Babu Korada

IEEE2010

Polar Codes are Optimal for Lossy Source Coding

Rüdiger Urbanke, Satish Babu Korada

We consider lossy source compression of a binary symmetric source using polar codes and the low-complexity successive encoding algorithm. It was recently shown by Arikan that polar codes achieve the capacity of arbitrary symmetric binary-input discrete mem ...

Institute of Electrical and Electronics Engineers2010

Polar Codes: Characterization of Exponent, Bounds, and Constructions

Rüdiger Urbanke, Satish Babu Korada, Eren Sasoglu

Polar codes were recently introduced by Arikan. They achieve the capacity of arbitrary symmetric binary-input discrete memoryless channels under a low complexity successive cancellation decoding strategy. The original polar code construction is closely rel ...

2010

Performance of Polar Codes for Channel and Source Coding

Rüdiger Urbanke, Satish Babu Korada, Nadine Hussami

Polar codes, introduced recently by Arikan, are the first family of codes known to achieve capacity of symmetric channels using a low complexity successive cancellation decoder. Although these codes, combined with successive cancellation, are optimal in th ...

2009

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