Decentralized Erasure Codes for Distributed Networked Storage

We consider the problem of constructing an erasure code for storage over a network when the data sources are distributed. Specifically, we assume that there are n storage nodes with limited memory and k<n sources generating the data. We want a data collector, who can appear anywhere in the network, to query any k storage nodes and be able to retrieve the data. We introduce Decentralized Erasure Codes, which are linear codes with a specific randomized structure inspired by network coding on random bipartite graphs. We show that decentralized erasure codes are optimally sparse, and lead to reduced communication, storage and computation cost over random linear coding.Comment: to appear in IEEE Transactions on Information Theory, Special Issue: Networking and Information Theor

From Dumb Wireless Sensors to Smart Networks using Network Coding

The vision of wireless sensor networks is one of a smart collection of tiny, dumb devices. These motes may be individually cheap, unintelligent, imprecise, and unreliable. Yet they are able to derive strength from numbers, rendering the whole to be strong, reliable and robust. Our approach is to adopt a distributed and randomized mindset and rely on in network processing and network coding. Our general abstraction is that nodes should act only locally and independently, and the desired global behavior should arise as a collective property of the network. We summarize our work and present how these ideas can be applied for communication and storage in sensor networks.Comment: To be presented at the Inaugural Workshop of the Center for Information Theory and Its Applications, University of California - San Diego, La Jolla, CA, February 6 - 10, 200

Networked Slepian-Wolf: theory, algorithms, and scaling laws

Consider a set of correlated sources located at the nodes of a network, and a set of sinks that are the destinations for some of the sources. The minimization of cost functions which are the product of a function of the rate and a function of the path weight is considered, for both the data-gathering scenario, which is relevant in sensor networks, and general traffic matrices, relevant for general networks. The minimization is achieved by jointly optimizing a) the transmission structure, which is shown to consist in general of a superposition of trees, and b) the rate allocation across the source nodes, which is done by Slepian-Wolf coding. The overall minimization can be achieved in two concatenated steps. First, the optimal transmission structure is found, which in general amounts to finding a Steiner tree, and second, the optimal rate allocation is obtained by solving an optimization problem with cost weights determined by the given optimal transmission structure, and with linear constraints given by the Slepian-Wolf rate region. For the case of data gathering, the optimal transmission structure is fully characterized and a closed-form solution for the optimal rate allocation is provided. For the general case of an arbitrary traffic matrix, the problem of finding the optimal transmission structure is NP-complete. For large networks, in some simplified scenarios, the total costs associated with Slepian-Wolf coding and explicit communication (conditional encoding based on explicitly communicated side information) are compared. Finally, the design of decentralized algorithms for the optimal rate allocation is analyzed

Founsure 1.0: An erasure code library with efficient repair and update features

Founsure is an open-source software library that implements a multi-dimensional graph-based erasure coding entirely based on fast exclusive OR (XOR) logic. Its implementation utilizes compiler optimizations and multi-threading to generate the right assembly code for the given multi-core CPU architecture with vector processing capabilities. Founsure possesses important features that shall find various applications in modern data storage, communication, and networked computer systems, in which the data needs protection against device, hardware, and node failures. As data size reached unprecedented levels, these systems have become hungry for network bandwidth, computational resources, and average consumed power. To address that, the proposed library provides a three-dimensional design space that trades off the computational complexity, coding overhead, and data/node repair bandwidth to meet different requirements of modern distributed data storage and processing systems. Founsure library enables efficient encoding, decoding, repairs/rebuilds, and updates while all the required data storage and computations are distributed across the network nodes.Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) Grant Number : 115C111 - 119E235WOS:000656825700019Scopus - Affiliation ID: 60105072Science Citation Index ExpandedQ3ArticleUluslararası işbirliği ile yapılmayan - HAYIRJanuary2021YÖK - 2020-2

Academics and Social Networking Sites: Benefits, Problems and Tensions in Professional Engagement with Online Networking

The web has had a profound effect on the ways people interact, with online social networks arguably playing an important role in changing or augmenting how we connect with others. However, uptake of online social networking by the academic community varies, and needs to be understood. This paper presents an independent, novel analysis of a large-scale dataset published by Nature Publishing Group detailing the results of a survey about academics use of online social networking services. An open coding approach was used to analyse 480 previously unused text responses. The analysis revealed a wide range of benefits and also problems associated with engaging with online networking, and tensions within this. The analysis provides further insight into the nuances of uptake, by exploring clusters of co-reported benefits and problems within the qualitative analysis. The findings will help move forward current debates surrounding social media use by academics from being viewed in solely beneficial terms, towards an understanding of the problems and tensions that arise through academic work online

Control Over Noisy Channels

Abstract-Communication is an important component of distributed and networked controls systems. In our companion paper we presented a framework for studying control problems with a digital noiseless communication channel connecting the sensor to the controller [TM1]. Here we generalize that framework by applying traditional information theoretic tools of source coding and channel coding to the problem. We present a general necessary condition for observability and stabilizability for a large class of communication channels. Then we study sufficiency conditions for Internet-like channels that suffer erasures

Internet Utopianism and the Practical Inevitability of Law

Writing at the dawn of the digital era, John Perry Barlow proclaimed cyberspace to be a new domain of pure freedom. Addressing the nations of the world, he cautioned that their laws, which were “based on matter,” simply did not speak to conduct in the new virtual realm. As both Barlow and the cyberlaw scholars who took up his call recognized, that was not so much a statement of fact as it was an exercise in deliberate utopianism. But it has proved prescient in a way that they certainly did not intend. The “laws” that increasingly have no meaning in online environments include not only the mandates of market regulators but also the guarantees that supposedly protect the fundamental rights of internet users, including the expressive and associational freedoms whose supremacy Barlow asserted. More generally, in the networked information era, protections for fundamental human rights — both on- and offline — have begun to fail comprehensively. Cyberlaw scholarship in the Barlowian mold isn’t to blame for the worldwide erosion of protections for fundamental rights, but it also hasn’t helped as much as it might have. In this essay, adapted from a forthcoming book on the evolution of legal institutions in the information era, I identify and briefly examine three intersecting flavors of internet utopianism in cyberlegal thought that are worth reexamining. It has become increasingly apparent that functioning legal institutions have indispensable roles to play in protecting and advancing human freedom. It has also become increasingly apparent, however, that the legal institutions we need are different than the ones we have