Publications by Sung Hoon Lim | EPFL Graph Search

Distributed Lossy Computation with Structured Codes: From Discrete to Continuous Sources

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

This paper considers the problem of distributed lossy compression where the goal is to recover one or more linear combinations of the sources at the decoder, subject to distortion constraints. For certain configurations, it is known that codes with algebra ...

2023

A Unified Discretization Approach to Compute–Forward: From Discrete to Continuous Inputs

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

Compute–forward is a coding technique that enables receiver(s) in a network to directly decode one or more linear combinations of the transmitted codewords. Initial efforts focused on Gaussian channels and derived achievable rate regions via nested lattice ...

Institute of Electrical and Electronics Engineers (IEEE)2023

A Discretization Approach to Compute-Forward

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

We present a novel unified framework of compute- forward achievable rate regions for simultaneous decoding of multiple linear codeword combinations. This framework covers a wide class of discrete and continuous-input channels, and computation over finite f ...

IEEE2021

Compute-Forward for DMCs: Simultaneous Decoding of Multiple Combinations

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

Algebraic network information theory is an emerging facet of network information theory, studying the achievable rates of random code ensembles that have algebraic structure, such as random linear codes. A distinguishing feature is that linear combinations ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2020

Compute–Forward Multiple Access (CFMA): Practical Implementations

Michael Christoph Gastpar, Adriano Pastore, Jingge Zhu, Erixhen Sula, Sung Hoon Lim

We present a practical strategy that aims to attain rate points on the dominant face of the multiple access channel capacity using a standard low complexity decoder. This technique is built upon recent theoretical developments of Zhu and Gastpar on compute ...

2019

Communication Versus Computation: Duality for Multiple-Access Channels and Source Coding

Michael Christoph Gastpar, Jingge Zhu, Sung Hoon Lim

Computation codes in network information theory are designed for scenarios where the decoder is not interested in recovering the information sources themselves, but only a function thereof. Körner and Marton showed for distributed source coding (DSC) that ...

2019

Towards an Algebraic Network Information Theory: Distributed Lossy Computation of Linear Functions

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

Consider the important special case of the K-user distributed source coding problem where the decoder only wishes to recover one or more linear combinations of the sources. The work of Körner and Marton demonstrated that, in some cases, the optimal rate re ...

2019

A Joint Typicality Approach to Compute–Forward

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

This paper presents a joint typicality framework for encoding and decoding nested linear codes in multi-user networks. This framework provides a new perspective on compute–forward within the context of discrete memoryless networks. In particular, it establ ...

2018

On the Duality between Multiple-Access Codes and Computation Codes

Michael Christoph Gastpar, Jingge Zhu, Sung Hoon Lim

For a two-user Gaussian multiple access channel, computation codes are designed for the scenarios where the decoder is not interested in decoding the two codewords, but only the sum of them. It has been observed that good computation codes should possess s ...

2017

Information-Theoretic Caching: The Multi-User Case

Michael Christoph Gastpar, Chien-Yi Wang, Sung Hoon Lim

In this paper, we consider a cache aided network in which each user is assumed to have individual caches, while upon users’ requests, an update message is sent through a common link to all users. First, we formulate a general information theoretic setting ...

Institute of Electrical and Electronics Engineers2017

Towards an algebraic network information theory: Simultaneous joint typicality decoding

Michael Christoph Gastpar, Adriano Pastore, Sung Hoon Lim, Chen Feng

Recent work has employed joint typicality encoding and decoding of nested linear code ensembles to generalize the compute-forward strategy to discrete memoryless multiple-access channels (MACs). An appealing feature of these nested linear code ensembles is ...

2017

Compute-forward multiple access (CFMA) with nested LDPC codes

Michael Christoph Gastpar, Adriano Pastore, Jingge Zhu, Erixhen Sula, Sung Hoon Lim

Inspired by the compute-and-forward scheme from Nazer and Gastpar, a novel multiple-access scheme introduced by Zhu and Gastpar makes use of nested lattice codes and sequential decoding of linear combinations of codewords to recover the individual messages ...

2017

A New Converse Bound for Coded Caching

Michael Christoph Gastpar, Chien-Yi Wang, Sung Hoon Lim

An information-theoretic lower bound is developed for the caching system studied by Maddah-Ali and Niesen. By comparing the proposed lower bound with the decentralized coded caching scheme of Maddah-Ali and Niesen, the optimal memory--rate tradeoff is char ...

2016

Information-Theoretic Caching: Sequential Coding for Computing

Michael Christoph Gastpar, Chien-Yi Wang, Sung Hoon Lim

Under the paradigm of caching, partial data are delivered before the actual requests of users are known. In this paper, this problem is modeled as a canonical distributed source coding problem with side information, where the side information represents th ...

Institute of Electrical and Electronics Engineers2016

Information Theoretic Caching: The Multi-User Case

Michael Christoph Gastpar, Chien-Yi Wang, Sung Hoon Lim

In this paper, we present information theoretic inner and outer bounds on the fundamental tradeoff between cache memory size and update rate in a multi-user cache network. Each user is assumed to have individual caches, while upon users’ requests, an updat ...

Ieee2016

Information-Theoretic Caching

Michael Christoph Gastpar, Chien-Yi Wang, Sung Hoon Lim

Motivated by the caching problem introduced by Maddah-Ali and Niesen, a problem of distributed source coding with side information is formulated, which captures a distinct interesting aspect of caching. For the single-user case, a single-letter characteriz ...

2015

A joint typicality approach to compute-forward

Michael Christoph Gastpar, Sung Hoon Lim, Chen Feng

A general framework for analyzing linear codes with joint typicality encoders and decoders is presented. Using this approach, we provide a new perspective on the compute-forward framework. In particular, an achievable rate region for computing the weighted ...

2015