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Network file storage with graceful performance degradation
 ACM Transactions on Storage
, 2005
"... A file storage scheme is proposed for networks containing heterogeneous clients. In the scheme, the performance measured by fileretrieval delays degrades gracefully under increasingly serious faulty circumstances. The scheme combines coding with storage for better performance. The problem is NPhar ..."
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Cited by 9 (3 self)
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A file storage scheme is proposed for networks containing heterogeneous clients. In the scheme, the performance measured by fileretrieval delays degrades gracefully under increasingly serious faulty circumstances. The scheme combines coding with storage for better performance. The problem is NPhard for general networks; and this paper focuses on tree networks with asymmetric edges between adjacent nodes. A polynomialtime memoryallocation algorithm is presented, which determines how much data to store on each node, with the objective of minimizing the total amount of data stored in the network. Then a polynomialtime datainterleaving algorithm is used to determine which data to store on each node for satisfying the qualityofservice requirements in the scheme. By combining the memoryallocation algorithm with the datainterleaving algorithm, an optimal solution to realize the file storage scheme in tree networks is established.
Multicluster interleaving on paths and cycles
 IEEE TRANSACTIONS ON INFORMATION THEORY
, 2005
"... Interleaving codewords is an important method not only for combatting bursterrors, but also for distributed data retrieval. This paper introduces the concept of MultiCluster Interleaving (MCI), a generalization of traditional interleaving problems. MCI problems for paths and cycles are studied. T ..."
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Cited by 4 (4 self)
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Interleaving codewords is an important method not only for combatting bursterrors, but also for distributed data retrieval. This paper introduces the concept of MultiCluster Interleaving (MCI), a generalization of traditional interleaving problems. MCI problems for paths and cycles are studied. The following problem is solved: how to interleave integers on a path or cycle such that any m (m ≥ 2) nonoverlapping clusters of order 2 in the path or cycle have at least 3 distinct integers. We then present a scheme using a ‘hierarchicalchain structure’ to solve the following more general problem for paths: how to interleave integers on a path such that any m (m ≥ 2) nonoverlapping clusters of order L (L ≥ 2) in the path have at least L + 1 distinct integers. It is shown that the scheme solves the second interleaving problem for paths that are asymptotically as long as the longest path on which an MCI exists, and clearly, for shorter paths as well.
Interleaving schemes on circulant graphs with two offsets
, 2008
"... Interleaving is used for errorcorrecting on a bursty noisy channel. Given a graph G describing the topology of the channel, we label the vertices of G so that each labelset is sufficiently sparse. The interleaving scheme corrects for any error burst of size at most t; it is a labeling where the di ..."
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Cited by 3 (2 self)
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Interleaving is used for errorcorrecting on a bursty noisy channel. Given a graph G describing the topology of the channel, we label the vertices of G so that each labelset is sufficiently sparse. The interleaving scheme corrects for any error burst of size at most t; it is a labeling where the distance between any two vertices in the same labelset is at least t. We consider interleaving schemes on infinite circulant graphs with two offsets 1 and d. In such graph the vertices are integers; edge ij exists if and only if i − j  ∈ {1, d}. Our goal is to minimize the number of labels used. Our constructions are covers of the graph by the minimal number of translates of some labelset S. We focus on minimizing the index of S, which is the inverse of its density rounded up. We establish lower bounds and prove that our constructions are optimal or almost optimal, both for the index of S and for the number of labels.
ON THE OPTIMALITY OF COLORING WITH A LATTICE ∗ YAEL BENHAIM † AND TUVI ETZION ‡
"... Abstract. For z1,z2,z3 ∈ Z 2, the tristance d3(z1,z2,z3) is a generalization of the L1distance on Z 2 to a quality that reflects the relative dispersion of three points rather than two. In this paper we prove that at least 3k 2 colors are required to color the points of Z 2, such that the tristance ..."
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Abstract. For z1,z2,z3 ∈ Z 2, the tristance d3(z1,z2,z3) is a generalization of the L1distance on Z 2 to a quality that reflects the relative dispersion of three points rather than two. In this paper we prove that at least 3k 2 colors are required to color the points of Z 2, such that the tristance between any three distinct points, colored with the same color, is at least 4k. We prove that 3k 2 +3k +1 colors are required if the tristance is at least 4k + 2. For the first case we show an infinite family of colorings with 3k 2 colors and conjecture that these are the only colorings with 3k 2 colors.
1 General field of research Research Statement
"... My research interest is in the general field of information networks. My study and research are in the areas of algorithms, combinatorial and convex optimization, distributed systems and information theory. So far my research has focused on two fields — file storage in networks, and wireless ad hoc ..."
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My research interest is in the general field of information networks. My study and research are in the areas of algorithms, combinatorial and convex optimization, distributed systems and information theory. So far my research has focused on two fields — file storage in networks, and wireless ad hoc communication and sensor networks. I plan to use my research experience and knowledge to explore broader aspects of information networks, including overlay storage/distribution networks, sensor networks and many other forms, all essential for pervasive computing. Two key components shared by different kinds of information networks are data storage/sharing and network structure design/utilization. The first component, data storage/sharing, requires optimized placement of data for efficient access, even when the users of the data are extensively distributed, mobile or have very different communication and computing capabilities. Information theory can be applied to help both the storage and the retrieval of data to achieve an optimal performance/redundancy tradeoff. Examples include the storage of shared files in networks using erasure codes for high availability, rate allocation for nodes collecting data in sensor networks, fractionally cascading of information for fast data detection and locating, multicast based on Network Coding, etc. The second component, network structure design/utilization, is on the design of real or overlaynetwork