Minimum-Cost Multicast Over Coded Packet Networks (2009)
Desmond S. Lun, Student Member, Niranjan Ratnakar, Student Member, Muriel Médard, Senior Member, ...
Abstract—We consider the problem of establishing minimum-cost multicast connections over coded packet networks, i.e., packet networks where the contents of outgoing packets are arbitrary, causal...
On Counteracting Byzantine Attacks in Network Coded Peer-to-Peer Networks (2009)
Kim, MinJi, Lima, Luísa, Zhao, Fang, Barros, Joao, Medard, Muriel, Koetter, Ralf, ...
Random linear network coding can be used in peer-to-peer networks to increase the efficiency of content distribution and distributed storage. However, these systems are particularly susceptible to...
A Low Complexity Algorithm and Architecture for Systematic Encoding of Hermitian Codes (2008)
Rachit Agarwal, Ralf Koetter, Emanuel M. Popovici
Abstract — We present an algorithm for systematic encoding of Hermitian codes. For a Hermitian code defined over GF (q 2), the proposed algorithm achieves a run time complexity of O(q 2) and is...
On the block error probability of LP decoding of LDPC codes (2008)
Abstract — In his thesis, Wiberg showed the existence of thresholds for families of regular low-density parity-check codes under min-sum algorithm decoding. He also derived analytic bounds on these...
Tracey Ho, Muriel Médard, Ralf Koetter, David R. Karger, Michelle Effros, Jun Shi, ...
random linear network coding approach to multicast
A Rank-Metric Approach to Error Control in Random Network Coding (2008)
Danilo Silva, Frank R. Kschischang, Ralf Koetter
It is shown that the error control problem in random network coding can be reformulated as a generalized decoding problem for rank-metric codes. This result allows many of the tools developed for...
A Framework for the Design of Good Watermark Identification Codes (2008)
The fundamental difference between the data-hiding and watermark signature verification problems was highlighted in a 2001 paper by Steinberg and Merhav. In data hiding, the maximum number of...
Unwrapping of MR phase images using a markov random field model (2008)
Lei Ying, Zhi-pei Liang, David C. Munson, Ralf Koetter, Brendan J. Frey
Abstract—Phase unwrapping is an important problem in many magnetic resonance imaging applications, such as field mapping and flow imaging. The challenge in two-dimensional phase unwrapping lies in...
1 Byzantine Modification Detection in Multicast Networks using Randomized Network Coding (2007)
Tracey Ho, Ben Leong, Ralf Koetter, Muriel M Edard, Michelle Effros, David R. Karger
Abstract--- Distributed randomized network coding is a flexible and robust approach to transmitting and compressing information in multi-source multicast networks. In this paper, we show how the path...
Brendan J. Frey, Ralf Koetter, Nemanja Petrovic
loopy belief propagation for unwrapping phase images
Design of Space Time Spreading Matrices # (2007)
Yibo Jiang, Ralf Koetter, Andrew Singer
In this paper, we study the design of space time spreading matrices that are modulation matrices for communications over multiple-antenna block fading channels. We assume the channel is known to the...
Wheel Codes: Turbo-like Codes on Graphs of Small Order (2007)
Abstract — In this paper, we investigate a specific class of codes on graphs called wheel codes, where the underlying graph of a wheel code is constructed by the wheel construction. Wheel codes...
Ralf Koetter, Siddharta Mallik
Abstract--- We study modulation and code design for underspread time-varying fading channels. For a coherent receiver employing maximum-likelihood (ML) decoding, we derive the code design criteria...
Yibo Jiang, Ralf Koetter, Andrew Singer
In this paper, we study the property of space time spreading matrices that are modulation matrices for communications over multiple-antenna block fading channels. We assume the channel is known to...
Ralf Koetter, Alexander Vardy, Arshad Ahmed
Algebraic soft-decision decoding of Reed-Solomon codes delivers promising coding gains over conventional hard-decision decoding. The main computational steps in algebraic soft-decoding (as well as...
FOR SUBMISSION TO THE IEEE TRANS. ON VLSI SYSTEMS (2007)
Arshad Ahmed, Ralf Koetter, Naresh R. Shanbhag
Soft-decision decoding of Reed-Solomon codes delivers significant coding gains over classical minimum distance decoding. In this paper, we present architectures for polynomial interpolation and...
1 Turbo Equalization: Principles and New Results (2007)
Abstract | We study the turbo equalization approach to coded data transmission over channels with intersymbol interference. In the original system invented by Douillard et al., the data is protected...
1 Minimum Mean Squared Error Equalization Using A-priori Information (2007)
Abstract | A number of important advances have been made in the area of joint equalization and decoding of data transmitted over intersymbol interference channels. Turbo equalization is an iterative...
e-marl: {trace, medard}mit.edu (2007)
Tracey Ho, Muriel Mdard, Ralf Koetter
A coding view of network recovery and management
Simulation results for algebraic soft-decision decoding of Reed-Solomon codes (2007)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
Abstract — The Koetter-Vardy algorithm is an algebraic softdecision decoder for Reed-Solomon codes. The algorithm is based on an extension to the Guruswami-Sudan list-decoding algorithm with...
Brendan J. Frey, Ralf Koetter, Nemanja Petrovic
loopy belief propagation for unwrapping phase images
Mustafa Kesal, M. Kvanc Mhcak, Ralf Koetter, Pierre Moulin
The problem of information hiding or watermarking is investigated. Based in an information theoretic analysis of the watermarking task we investigate a strategy to employ binary codes to robustly...
Reduced Complexity Interpolation for (2007)
Arshad Ahmed, Ralf Koetter, Naresh R. Shanbhag
An algorithm for algebraic soft-decision decoding of Reed-Solomon codes based on bivariate polynomial interpolation and factorization [1] has been presented in [2]. A key step in [2] is a greedy...
Ralf Koetter, Andrew C. Singer
models for coded data transmission over inter-symbol interference channels
Network Coding in a Multicast Switch (2007)
Jay Kumar Sundararajan, Muriel Médard, Minji Kim, Atilla Eryilmaz, Devavrat Shah, Ralf Koetter
Abstract—We consider the problem of serving multicast flows in a crossbar switch. We show that linear network coding across packets of a flow can sustain traffic patterns that cannot be served if...
Coding for errors and erasures in random network coding (2007)
Abstract — The problem of error-control in a “noncoherent” random network coding channel is considered. Information transmission is modelled as the injection into the network of a basis for a...
Network Coding in a Multicast Switch (2007)
Jay Kumar Sundararajan, Muriel Médard, Minji Kim, Atilla Eryilmaz, Devavrat Shah, Ralf Koetter
Abstract — We consider the problem of serving multicast flows in a crossbar switch. We show that linear network coding across packets of a flow can sustain traffic patterns that cannot be served if...
An analysis of finite-memory random linear coding on packet streams (2006)
Desmond S. Lun, Payam Pakzad, Christina Fragouli, Muriel Médard, Ralf Koetter
Abstract — We consider the following packet coding scheme: The coding node has a fixed, finite memory in which it stores packets formed from an incoming packet stream, and it sends packets formed...
Minimum-cost multicast over coded packet networks (2006)
Desmond S. Lun, Niranjan Ratnakar, Muriel Médard, Ralf Koetter, David R. Karger, Tracey Ho, ...
We consider the problem of establishing minimum-cost multicast connections over coded packet networks, i.e. packet networks where the contents of outgoing packets are arbitrary, causal functions of...
A systematic approach to network coding problems using conflict graphs (2006)
Jay Kumar Sundararajan, Ralf Koetter
Abstract — We present a new approach to network coding problems that could lead to a systematic method for deciding solvability of a given network. The approach is based on a graph theoretic...
On Error Exponents of Modulo Lattice Additive Noise Channels (2006)
Tie Liu, Pierre Moulin, Ralf Koetter
Modulo lattice additive noise (MLAN) channels appear in the analysis of structured binning codes for Costa’s dirty-paper channel and of nested lattice codes for the additive white Gaussian noise...
A random linear network coding approach to multicast (2006)
Tracey Ho, Muriel Médard, Ralf Koetter, David R. Karger, Associate Member, Michelle Effros, ...
Abstract—We present a distributed random linear network coding approach for transmission and compression of information in general multisource multicast networks. Network nodes independently and...
Characterizations of pseudo-codewords of LDPC codes (2006)
Ralf Koetter, Pascal O. Vontobel, L. Walker
Abstract. An important property of high-performance, low complexity codes is the existence of highly efficient algorithms for their decoding. Many of the most efficient, recent graph-based...
Multilevel Codes for OFDM-Like Modulation over Underspread Fading Channels (2006)
Siddhartha Mallik, Ralf Koetter
We study the problem of modulation and coding for doubly dispersive, that is, time and frequency selective, fading channels. Using the recent result that underspread linear systems are approximately...
Minimal network coding for multicast (2005)
Kapil Bhattad, Niranjan Ratnakar, Ralf Koetter, Krishna R. Narayanan
Abstract — We give an information flow interpretation for multicasting using network coding. This generalizes the fluid model used to represent flows to a single receiver. Using the generalized...
An Information-Theoretic View of Network Management (2005)
Tracey Ho, Muriel Médard, Senior Member, Ralf Koetter
Abstract—We present an information-theoretic framework for network management for recovery from nonergodic link failures. Building on recent work in the field of network coding, we describe the...
Exponential error bounds for algebraic softdecision decoding of Reed-Solomon codes (2005)
Niranjan Ratnakar, Ralf Koetter
This work follows recent developments in e#cient soft decision decoding of Reed Solomon codes [1, 2, 3] building on the weighted-interpolation and factorization algorithms pioneered
Achieving Minimum-Cost Multicast: ADecentralized Approach Based on Network Coding (2005)
Desmond S. Lun, Niranjan Ratnakar +, Niranjan Ratnakar, Ralf Koetter, Muriel Médard, Ebad Ahmed, ...
We present decentralized algorithms that compute minimum-cost subgraphs for establishing multicast connections in networks that use coding. These algorithms, coupled with existing decentralized...
How good is random linear coding based distributed networked storage (2005)
Szymon Acedański, Supratim Deb, Muriel Médard, Ralf Koetter
Abstract — We consider the problem of storing a large file or multiple large files in a distributed manner over a network. In the framework we consider, there are multiple storage locations, each...
This tutorial paper reviews the theory and design of codes for hiding or embedding information in signals such as images, video, audio, graphics, and text. Such codes have also been called...
Network coding for wireless applications: A brief tutorial (2005)
Supratim Deb, Michelle Effros, Tracey Ho, David R. Karger, Ralf Koetter, Desmond S. Lun, ...
Abstract — The advent of network coding promises to change many aspects of networking. Network coding moves away from the classical approach of networking, which treats networks as akin to physical...
Extremal problems of information combining (2005)
Yibo Jiang, Alexei Ashikhmin, Ralf Koetter, Andrew C. Singer
Abstract — In this paper we study moments of soft-bits of binary-input symmetric-output channels and solve some extremal problems of the moments. We use these results to solve the extremal...
Achieving minimum-cost multicast: A decentralized approach based on network coding (2005)
Desmond S. Lun, Niranjan Ratnakar, Ralf Koetter, Muriel Médard, Ebad Ahmed, Hyunjoo Lee
Abstract — We present decentralized algorithms that compute minimum-cost subgraphs for establishing multicast connections in networks that use coding. These algorithms, coupled with existing...
Minimal network coding for multicast (2005)
Kapil Bhattad, Niranjan Ratnakar, Ralf Koetter, Krishna R. Narayanan
Abstract — We give an information flow interpretation for multicasting using network coding. This generalizes the fluid model used to represent flows to a single receiver. Using the generalized...
Exponential error bounds for algebraic softdecision decoding of Reed-Solomon codes (2005)
Niranjan Ratnakar, Ralf Koetter
This work follows recent developments in efficient soft decision decoding of Reed Solomon codes [1, 2, 3] building on the weighted-interpolation and factorization algorithms pioneered by [4, 5]. A...
Achieving minimum-cost multicast: A decentralized approach based on network coding (2005)
Desmond S. Lun, Niranjan Ratnakar, Ralf Koetter, Muriel Médard, Ebad Ahmed, Hyunjoo Lee
We present decentralized algorithms that compute minimum-cost subgraphs for establishing multicast connections in networks that use coding. These algorithms, coupled with existing decentralized...
On the utility of network coding in dynamic environments (2004)
Tracey Ho, Ben Leong, Muriel Médard, Ralf Koetter, Yu-han Chang, Michelle Effros
Abstract — Many wireless applications, such as ad-hoc networks and sensor networks, require decentralized operation in dynamically varying environments. We consider a distributed randomized network...
Byzantine modification detection in multicast networks using randomized network coding (2004)
Tracey Ho, Ben Leong, Ralf Koetter, Muriel Médard, Michelle Effros, David R. Karger
Abstract — We show how distributed randomized network coding, a robust approach to multicasting in distributed network settings, can be extended to provide Byzantine modification detection without...
Feasibility analysis of stochastic sensor networks (2004)
Shi Chao Zhang, F. Irem Koprulu, Ralf Koetter, Douglas L. Jones
Abstract — A stochastic wireless sensor network consisting of low-duty-cycle, unsynchronized nodes offers a simple, robust, and ultra-low-power solution for many sensor network applications. We...
Byzantine modification detection in multicast networks using randomized network coding (2004)
Tracey Ho, Ben Leong, Ralf Koetter, Muriel Médard, Michelle Effros, David R. Karger
This paper gives an information theoretic approach for detecting Byzantine modifications in networks employing random linear network coding. Each exogenous source packet is augmented with a flexible...
Rong-rong Chen, Bruce Hajek, Ralf Koetter, Upamanyu Madhow
It is well-known that independent and identically distributed Gaussian inputs, scaled appropriately based on the Signal-to-Noise Ratio (SNR), achieve capacity on the Additive White Gaussian Noise...
Lower Bounds on the Minimum Pseudo-weight of Linear Codes (2004)
Pascal O. Vontobel, Ralf Koetter, X ||x
Abstract — We discuss two techniques for obtaining lower bounds on the (AWGN channel) pseudo-weight of binary linear codes. Whereas the first bound is based on the largest and second-largest...
Network Coding for Correlated Sources (2004)
Tracey Ho, Muriel Médard, Michelle Effros, Ralf Koetter
Abstract — We consider the ability of a distributed randomized network coding approach to multicast, to one or more receivers, correlated sources over a network where compression may be required....
Graphical Models for Coded Data Transmission over Inter-Symbol Interference Channels (2004)
Michael Tüchler, Ralf Koetter, Andrew C. Singer
We derive graphical models for coded data transmission over channels introducing inter-symbol interference. These models are factor graph descriptions of the transmitter section of the communication...
Optimal Sparse-Qim Codes (2004)
Pierre Moulin, Anil K. Goteti, Ralf Koetter, In R
The problem of blind watermarking of an arbitrary host signal in R under squared-error distortion constraints and Gaussian attacks is considered in this paper. While distortion-compensated lattice...
Ralf Koetter, Andrew C. Singer, Michael Tüchler
Capitalizing on the tremendous performance gains of turbo codes and the turbo decoding algorithm, turbo equalization is an iterative equalization and decoding technique that can achieve equally...
Soft-Decision Decoding of Linear Block Codes (2004)
Using Preprocessing Yingquan, Yingquan Wu, Ralf Koetter, Christoforos Hadjicostis
this paper we develop two universally applicable preprocessing rules to improve iterative recoding algorithms that utilize the MRB, while focusing on order-w reprocessing
Network Coding with a Cost Criterion (2004)
Desmond S. Lun, Muriel Médard, Tracey Ho, Ralf Koetter
We consider applying network coding in settings where there is a cost associated with network use.
Network Coding with a Cost Criterion (2004)
Desmond S. Lun, Muriel Médard, Tracey Ho, Ralf Koetter
We consider applying network coding in settings where there is a cost associated with network use. We show that, while minimum-cost multicast problems without network coding are very di#cult except...
Osium On Information, Desmond S. Lun, Tracey Ho, Ralf Koetter
We consider applying network coding in settings where there is a cost associated with network use. We show that, while minimum-cost multicast problems without network coding are very di#cult except...
Byzantine Modification Detection in Multicast Networks using Randomized Network Coding (2004)
Tracey Ho, Ben Leong, Ralf Koetter, Muriel Medard, Michelle Effros, David R. Karger
We show how distributed randomized network coding, a robust approach to multicasting in distributed network settings, can be extended to provide Byzantine modification detection without the use of...
On Source and Channel Codes for Multiple Inputs and Outputs (2004)
Michelle Effros, Ralf Koetter, Andrea J. Goldsmith, Muriel Médard
Abstract — We compare two strategies for lossy source description across a pair of unreliable channels. In the first strategy, we use a broadcast channel code to achieve a different rate for each...
Pseudo-codewords of cycle codes via zeta functions (2004)
Abstract — Cycle codes are a special case of lowdensity parity-check (LDPC) codes and as such can be decoded using an iterative message-passing decoding algorithm on the associated Tanner graph....
On Source and Channel Codes for Multiple Inputs and Outputs (2004)
Michelle Effros, Ralf Koetter, Andrea J. Goldsmith, Muriel Médard
Abstract — We compare two strategies for lossy source description across a pair of unreliable channels. In the first strategy, we use a broadcast channel code to achieve a different rate for each...
Network Coding with a Cost Criterion (2004)
Desmond S. Lun, Tracey Ho, Ralf Koetter
We consider applying network coding in settings where there is a cost associated with network use. We show that, while minimum-cost multicast problems without network coding are very difficult except...
Toward a random operation of networks (2004)
Tracey Ho, Muriel Médard, Ralf Koetter, David R. Karger, Michelle Effros, Jun Shi, ...
We present a distributed randomized network coding approach for transmission and compression of information in general multi-source multicast networks. Network nodes independently and randomly select...
On coding for reliable communication over packet networks (2004)
D. Medard, R Effros, Subaward No. S, Office Of, Desmond S. Lun, Muriel Médard, ...
We present a capacity-achieving coding scheme for unicast or multicast over lossy packet networks. In the scheme, intermediate nodes perform additional coding yet do not decode nor even wait for a...
Network Coding from a Network Flow Perspective (2003)
Tracey Ho, David R. Karger, Muriel Médard, Ralf Koetter
Abstract — We make precise connections between algebraic network coding and network flows. Our combinatorial formulations offer new insights, mathematical simplicity, and lead to a substantially...
The benefits of coding over routing in a randomized setting (2003)
Tracey Ho, Ralf Koetter, Muriel Médard, David R. Karger, Michelle Effros
Abstract — We present a novel randomized coding approach for robust, distributed transmission and compression of information in networks. We give a lower bound on the success probability of a...
Towards a VLSI architecture for interpolation-based soft-decision Reed-Solomon decoders (2003)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
The Koetter-Vardy algorithm is an algebraic soft-decision decoder for Reed-Solomon codes which is based on the Guruswami-Sudan list decoder. There are three main steps: 1) multiplicity calculation,...
Linear turbo equalization for parallel ISI channels (2003)
Jill Nelson, Student Member, Andrew Singer, Ralf Koetter
Abstract—We propose a method for exploiting transmit diversity using parallel independent intersymbol interference channels together with an iterative equalizing receiver. Linear iterative turbo...
The benefits of coding over routing in a randomized setting (2003)
Tracey Ho, Ralf Koetter, Muriel Médard, David R. Karger, Michelle Effros
Abstract — We present a novel randomized coding approach for robust, distributed transmission and compression of information in networks. We give a lower bound on the success probability of a...
Algebraic soft-decision decoding of Reed-Solomon codes (2003)
A polynomial-time soft-decision decoding algorithm for Reed-Solomon codes is developed. This list-decoding algorithm is algebraic in nature and builds upon the interpolation procedure proposed by...
A complexity reducing transformation in algebraic list decoding of Reed-Solomon codes (2003)
Abstract — The main computational steps in algebraic soft-decoding, as well as Sudan-type list-decoding, of Reed-Solomon codes are interpolation and factorization. A series of transformations is...
An algebraic approach to network coding (2003)
Ralf Koetter, Muriel Médard, Senior Member
Abstract—We take a new look at the issue of network capacity. It is shown that network coding is an essential ingredient in achieving the capacity of a network. Building on recent work by Li et...
An algebraic approach to network coding (2003)
We take a new look at the issue of network capacity. It is shown that network coding is an essential ingredient in achieving the capacity of a network. Building on recent work by Li et al., who...
Algebraic soft-decision decoding of Reed-Solomon codes (2003)
A polynomial-time soft-decision decoding algorithm for Reed-Solomon codes is developed. This list-decoding algorithm is algebraic in nature and builds upon the interpolation procedure proposed by...
The structure of tail-biting trellises: minimality and basic principles (2003)
Basic structural properties of tail-biting trellises are investigated. We start with rigorous denitions of various types of minimality for tail-biting trellises. We then show that biproper and/or...
Applications of algebraic soft-decision decoding of Reed-Solomon codes (2003)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
Efficient soft-decision decoding of Reed-Solomon codes is made possible by the Koetter-Vardy (KV) algorithm which consists of a front-end to the interpolation-based Guruswami-Sudan list decoding...
Towards a VLSI Architecture for Interpolation-Based Soft-Decision Reed-Solomon Decoders (2003)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
The Koetter-Vardy algorithm is an algebraic soft-decision decoder for Reed-Solomon codes which is based on the Guruswami-Sudan list decoder. There are three main steps: 1) multiplicity calculation,...
Graph-Covers and Iterative Decoding of Finite Length Codes (2003)
Ralf Koetter, Pascal O. Vontobel
Codewords in finite covers of a Tanner graph G are characterized. Since iterative, locally operating decoding algorithms cannot distinguish the underlying graph G from any covering graph, these...
An Information Theoretic View of Network Management (2003)
Tracey Ho, Muriel Médard, Ralf Koetter
We present an information theoretic framework for network management for recovery from non-ergodic link failures. Building on recent work in the field of network coding, we describe the input-output...
Linear Network Codes: A Unified Framework for Source, Channel, and Network Coding (2003)
Michelle Effros, Muriel Medard, Tracey Ho, Siddharth Ray, David Karger, Ralf Koetter, ...
We examine the issue of separation and code design for network data transmission environments. We demonstrate that source-channel separation holds for several canonical network channel models when...
Applications of Algebraic (2003)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
E#cient soft-decision decoding of Reed-Solomon codes is made possible by the Koetter-Vardy (KV) algorithm which consists of a front-end to the interpolation-based Guruswami-Sudan list decoding...
An Information Theoretic View of Network Management (2003)
Tracey Ho, Muriel Médard, Ralf Koetter
We present an information theoretic framework for network management for recovery from non-ergodic link failures. Building on recent work in the field of network coding, we describe the input-output...
Network Coding from a Network Flow Perspective (2003)
Tracey Ho, David R. Karger, Muriel Medard, Ralf Koetter
The algebraic framework introduced in [4] gives an algebraic condition for the feasibility of a set of multicast connections in a network, that is equivalent to the max-flow min-cut condition of [1]....
Exponential Error Bounds for Algebraic Soft-Decision Decoding of Reed-Solomon Codes (2003)
Niranjan Ratnakar, Ralf Koetter
Algebraic soft decision decoding of Reed-Solomon codes is a promising technique for exploiting reliability information in the decoding process. While the algorithmic aspects of the decoding algorithm...
Joint Demodulation and Decoding for the Noncoherent Block Fading (2003)
Channel Practical Framework, Rong-rong Chen, Ralf Koetter, Dakshi Agrawal, Upamanyu Madhow
This paper contains a systematic investigation of practical coding strategies for noncoherent fading channels that is guided by explicit comparisons with information-theoretic benchmarks. Noncoherent...
Towards a VLSI architecture for interpolation-based soft-decision Reed-Solomon decoders (2003)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
The Koetter-Vardy algorithm is an algebraic soft-decision decoder for Reed-Solomon codes which is based on the Guruswami-Sudan list decoder. There are three main steps: 1) multiplicity calculation,...
The Benefits of Coding over Routing in a Randomized Setting (2003)
Tracey Ho, Ralf Koetter, Muriel Medard, David R. Karger, Michelle Effros
We present a novel randomized network coding approach for robust, distributed transmission and compression of information in networks, and demonstrate its advantages over routing-based approaches.
On the representation of codes in Forney graphs (2002)
Abstract We investigate the representation of codes in graphical models. In particular, we use the notion of a trellis formation on a Forney graph to visualize the structure of a code on a given...
Decoding of Reed-Solomon codes for additive cost functions (2002)
The ecient decoding of Reed-Solomon codes beyond the half the minimum distance is an important problem of coding theory. In this vein, we present an algorithm for any given additive
Soft decoding of Reed Solomon codes and optimal weight assignments (2002)
A polynomial-time decoding algorithm for Reed-Solomon codes is developed in the context of interpolation based decoding algorithms. The developed algorithm maximizes the error correction capability...
On the theory of linear trellises (2002)
Trellis linearity, first considered by McEliece in 1996, turns out to be crucial in the study of tail-biting trellises. In this chapter, basic structural properties of linear trellises are...
A VLSI architecture for interpolation in soft-decision list decoding of Reed-Solomon codes (2002)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
The Koetter-Vardy algorithm is an algebraic soft-decision decoder for Reed-Solomon codes which is based on the Guruswami-Sudan list decoder. There are three main steps: 1) multiplicity calculation,...
A VLSI architecture for interpolation in soft-decision list decoding of Reed-Solomon codes (2002)
Warren J. Gross, Frank R. Kschischang, Ralf Koetter, P. Glenn Gulak
The Koetter-Vardy algorithm is an algebraic soft-decision decoder for Reed-Solomon codes which is based on the Guruswami-Sudan list decoder. There are three main steps: 1) multiplicity calculation,...
On the effective weights of pseudocodewords for codes defined on graphs with cycles (2001)
G. David Forney, Ralf Koetter, Frank R. Kschischang
Abstract. The behavior of an iterative decoding algorithm for a code dened on a graph with cycles and a given decoding schedule is characterized by a cycle-free computation tree. The pseudocodewords...
Nemanja Petrovic, Ira Cohen, Brendan J. Frey, Ralf Koetter, Thomas S. Huang
Accurate calculation of the three dimensional shape of an object is one of the classic research areas of computer vision. Many of the existing methods are based on surface normal estimation, and...
Unwrapping Phases By Relaxed Mean Field Inference (2001)
Kannan Achan, Brendan J. Frey, Ralf Koetter, David Munson
Some types of medical and topographic imaging device produce images in which the pixel values are "phase-wrapped", i.e., measured modulus a known scalar. Phase unwrapping can be viewed as...
Unwrapping Phase Images By Propagating Probabilities Across Graphs (2001)
Ralf Koetter, Brendan J. Frey, Et Al.
Phase images are derived from source images by applying a modulus operation to each pixel value. Phase unwrapping is the problem of inferring the original, unwrapped values from the wrapped values,...
Iteratively decodable codes for watermarking applications (2000)
Mustafa Kesal, M. Kıvanç Mıhçak, Ralf Koetter, Pierre Moulin
The problem of information hiding or watermarking is investigated. Based in an information theoretic analysis of the watermarking task we investigate a strategy to employ binary codes to robustly...
Minimum mean squared error (MMSE) equalization using priors," submitted to (2000)
For data transmission over channels with intersymbol interference (ISI) a soft-in soft-out (SISO) equalizer is introduced to correct for the ISI distortion using linear ltering. In addition to the...
Iteratively decodable codes for watermarking applications (2000)
Mustafa Kesal, Ralf Koetter, Pierre Moulin
The problem of information hiding or watermarking is investigated. Based in an information theoretic analysis of the watermarking task we investigate a strategy to employ binary codes to robustly...
Linear iterative turbo-equalization (LITE) for dual channels (1999)
Andrew Singer, Jill Nelson, Ralf Koetter
We examine a point-to-point communications scenario in which two or more separate, but known, channels are available for data transmission. While sending the same data across multiple channels...
A Framework For Joint Source-Channel Coding Using Factor Graphs. (1999)
Igor Kozintsev, Ralf Koetter, Kannan Ramchandran
We propose a novel factor graph framework for joint source-channel coding for communication with a fidelity criterion. We consider a class of source models that are used in current state-of-the-art...
Arshad Ahmed, Naresh R. Shanbhag, Ralf Koetter
We present a systolic algorithm for performing interpolation, a computationally intensive kernel found in algebraic soft-decoding of Reed-Solomon codes. We reformulate the interpolation algorithm,...