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58
Chr: a distributed hash table for wireless ad hoc networks
 in The 25th IEEE International Conference on Distributed Computing Systems Workshops (DEBS ’02
, 2005
"... This paper focuses on the problem of implementing a distributed hash table (DHT) in wireless ad hoc networks. Scarceness of resources and node mobility turn routing into a challenging problem and therefore, we claim that building a DHT as an overlay network (like in wired environments) is not the be ..."
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Cited by 15 (3 self)
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This paper focuses on the problem of implementing a distributed hash table (DHT) in wireless ad hoc networks. Scarceness of resources and node mobility turn routing into a challenging problem and therefore, we claim that building a DHT as an overlay network (like in wired environments) is not the best option. Hence, we present a proofofconcept DHT, called Cell Hash Routing (CHR), designed from scratch to cope with problems like limited available energy, communication range or node mobility. CHR overcomes these problems, by using position information to organize a DHT of clusters instead of individual nodes. By using positionbased routing on top of these clusters, CHR is very efficient. Furthermore, its localized routing and its load sharing schemes, make CHR very scalable in respect to network size and density. For these reasons, we believe that CHR is a simple and yet powerful adaptation of the DHT concept for wireless ad hoc environments. ∗ Selected sections of this report were published in the Proceedings of the Fourth International Workshop on Distributed EventBased Systems (DEBS’05), in conjuction with the 25th
D2B: a de Bruijn Based ContentAddressable Network
, 2005
"... We show that the de Bruijn graph is appropriate for maintaining dynamic connections, e.g., between the members of a P2P application who join and leave the system at their convenience. We describe the contentaddressable network D2B, based on an overlay network preserving de Bruijn connections dynami ..."
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Cited by 15 (1 self)
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We show that the de Bruijn graph is appropriate for maintaining dynamic connections, e.g., between the members of a P2P application who join and leave the system at their convenience. We describe the contentaddressable network D2B, based on an overlay network preserving de Bruijn connections dynamically, and on a distributed hash table (DHT) supporting efficient publish and search procedures. The overlay network has constant expected degree, and any publish or search operation in the DHT takes a logarithmic expected number of steps.
GeoPeer: A LocationAware PeerToPeer System
 In The 3rd IEEE International Conference on Network Computing and Applications (NCA ’04
, 2003
"... This paper presents a novel peertopeer system that is particularly well suited to support contextaware computing. The system, called GeoPeer, combines the advantages of general purpose peertopeer systems with the suitability of geographical routing for supporting locationconstrained queries an ..."
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This paper presents a novel peertopeer system that is particularly well suited to support contextaware computing. The system, called GeoPeer, combines the advantages of general purpose peertopeer systems with the suitability of geographical routing for supporting locationconstrained queries and information dissemination. To achieve this goal, GeoPeer incorporates sophisticated mechanisms to establish longrange contacts that permit to achieve a small network diameter. These mechanisms take explicitly into account the unbalanced distribution of nodes in the geographical space.
A Scheme for Load Balancing in Heterogeneous Distributed Hash Tables
, 2005
"... We present a scheme for evenly partitioning the key space in distributed hash tables among the participating nodes. The scheme is based on the multiple random choices paradigm [3, 19], and handles both node joins and leaves. It achieves, with high probability, a ratio of at most 4 between the loads ..."
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Cited by 12 (0 self)
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We present a scheme for evenly partitioning the key space in distributed hash tables among the participating nodes. The scheme is based on the multiple random choices paradigm [3, 19], and handles both node joins and leaves. It achieves, with high probability, a ratio of at most 4 between the loads of the most and least burdened nodes, in the face or arbitrary node arrivals and departures. Each join or leave operation incurs message cost that is, with high probability, O(log 2 n), where n is the number of nodes, and causes the relocation of keys from at most one node (for joins) or three nodes (for leaves). A version of our scheme is suitable for heterogeneous systems, where the capacities of nodes to serve keys can vary widely.
The dynamic andor quorum system
 Proc. of 19th International Symposium on Distributed Computing (DISC’05), volume 3724 of LNCS
, 2005
"... Abstract. We investigate issues related to the probe complexity of the AndOr quorum system and its implementation in a dynamic environment. Our contribution is twofold: We first analyze the algorithmic probe complexity of the AndOr quorum system, and present two optimal algorithms. The first is a ..."
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Abstract. We investigate issues related to the probe complexity of the AndOr quorum system and its implementation in a dynamic environment. Our contribution is twofold: We first analyze the algorithmic probe complexity of the AndOr quorum system, and present two optimal algorithms. The first is a nonadaptive algorithm with O ( √ n log n) probe complexity, which matches a known lower bound. The second is an adaptive algorithm with a probe complexity that is linear in the cardinality of a quorum set (O ( √ n)), and requires at most O(log log n) rounds. To the best of our knowledge, all other adaptive algorithms with same parameters (load and probe complexity) require θ ( √ n) rounds. Our second contribution is presenting the ‘dynamic AndOr ’ quorum system an adaptation of the above quorum system to a dynamic environment, where processors join and leave the network. It is based on a dynamic overlay network that emulates the DeBruijn network and maintains the good properties of the quorum system(e.g.,load and availability). The algorithms suggested for the maintenance of these dynamic data structures are strongly coupled with the dynamic overlay network. This fact enables the use of gossip protocols which saves in message complexity and keeps the protocols simple and local. All these qualities make the ‘dynamic AndOr ’ an excellent candidate for an implementation of dynamic quorums. 1
dbblue: Low diameter and selfrouting bluetooth scatternet
 in Proceedings of DialMPOMC
, 2003
"... This paper addresses the problem of scatternet formation for singlehop Bluetooth based ad hoc networks, with minimal communication overhead. We adopt the wellknown structure de Bruijn graph to form the backbone of Bluetooth scatternet, hereafter called dBBlue, such that every master node has at ..."
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This paper addresses the problem of scatternet formation for singlehop Bluetooth based ad hoc networks, with minimal communication overhead. We adopt the wellknown structure de Bruijn graph to form the backbone of Bluetooth scatternet, hereafter called dBBlue, such that every master node has at most seven slaves, every slave node is in at most two piconets, and no node assumes both master and slave roles. Our structure dBBlue also enjoys a nice routing property: the diameter of the graph is O(log n) and we can find a path with at most O(log n) hops for every pair of nodes without any routing table. Moreover, the congestion of every node is at most O(log n=n), assuming that a unit of total traffic demand is equally distributed among all pair of nodes. We discuss in detail a vigorous method to locally update the structure dBBlue using at most O(log n) communications when a node joins or leaves the network. In most cases, the cost of updating the scatternet is actually O(1) since a node can join or leave without affecting the remaining scatternet. The number of nodes affected when a node joins or leaves the network is always bounded from above by a constant. To facilitate selfrouting and easy updating, we design a scalable MAC assigning mechanism for piconet, which guarantees the packet delivery during scatternet updating. The dBBlue scatternet can be constructed incrementally when the nodes join the network one by one. Previously no method can guarantee all these properties although some methods can achieve some of the properties.
Cayley DHTs  A GroupTheoretic Framework for Analyzing DHTs Based on Cayley Graphs
 In International Symposium on Parallel and Distributed Processing and Applications (ISPA
, 2004
"... Static DHT topologies influence important features of such DHTs such as scalability, communication load balancing, routing efficiency and fault tolerance. Nevertheless, it is commonly recognized that the primary difficulty in designing DHT is not in static DHT topologies, but in the dynamic DHT algo ..."
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Cited by 8 (1 self)
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Static DHT topologies influence important features of such DHTs such as scalability, communication load balancing, routing efficiency and fault tolerance. Nevertheless, it is commonly recognized that the primary difficulty in designing DHT is not in static DHT topologies, but in the dynamic DHT algorithm which adapts various static DHT topologies to a dynamic network at Internet. As a direct consequence, the DHT community has been paying more attention to the dynamic DHT algorithm design, resulting in a variety of DHT systems lacking of a common view for analysis and interoperation.In this paper we reiterate the importance of static DHT topologies in the DHT system design by analyzing and classifying current DHTs in terms of their static topologies based on a grouptheoretic model: Cayley graphs. We show that most of current DHT proposals use Cayley graphs as static DHT topologies, thus taking advantage of several important Cayley graph properties such as vertex/edge symmetry, decomposability, optimal fault tolerance and hamiltonicity. We observe that several nonCayleygraph based DHT proposals such as Koorde /D2B/Distance Halving and Pastry/Tapestry also rely on techniques in their dynamic DHT algorithm design trying to imitate desirable Cayley graph properties. Based on Cayley graphs, we propose the class of Cayley DHTs as a unified grouptheoretic model for investigating DHTs from a graph theoretic perspective. The significance of Cayley DHTs is in their explicit inspiration to a uniform dynamic DHT algorithm design, which can directly leverage algebraic design methods thus is able to generate sets of highperformance DHTs adopting various Cayley graph based static DHT topologies but still sharing the same dynamic DHT algorithm.
LAND: Stretch (1 + ɛ) LocalityAware Networks for DHTs
 PROC. 15TH ANN. ACMSIAM SYMP. ON DISCRETE ALGORITHMS (SODA
, 2004
"... This paper proposes the first peertopeer network and lookup algorithm that for any 0 < ɛ has worst case stretch bounded by 1 + ɛ. The construction uses an expected logarithmic number of links. It is suitable for a very realistic class of metrics in which the only restriction on density is a gro ..."
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Cited by 8 (1 self)
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This paper proposes the first peertopeer network and lookup algorithm that for any 0 < ɛ has worst case stretch bounded by 1 + ɛ. The construction uses an expected logarithmic number of links. It is suitable for a very realistic class of metrics in which the only restriction on density is a growthbound. It is completely decentralized and readily deployable in dynamic networks.
Incentive, Resilience and Load Balancing in Multicasting through Clustered de Bruijn Overlay Network
 IN &QUOT;14TH IEEE INTERNATIONAL CONFERENCE ON NETWORKS (ICON
, 2006
"... In this paper, we consider the problem of multicasting a stream of packets in a large scale peertopeer environment. In that context peers should have incentive to cooperate. We present PrefixStream, an algorithm that addresses this problem by using reciprocity in packet forwarding. Each node thus ..."
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Cited by 7 (3 self)
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In this paper, we consider the problem of multicasting a stream of packets in a large scale peertopeer environment. In that context peers should have incentive to cooperate. We present PrefixStream, an algorithm that addresses this problem by using reciprocity in packet forwarding. Each node thus has incentive to forward since recipients send back other packets of the stream. To achieve this efficiently, PrefixStream strips the content across two sets of clustered trees built upon the symmetric de Bruijn graph. This both allows to banish nodes that do not respect reciprocity of exchanges and gives resilience to node failures. Furthermore, it reduces the forwarding load of every node to the stream bandwidth (every node uploads as much as it downloads) even when the size of its cluster varies. Conversely to previously proposed hierarchical schemes, PrefixStream promotes disjoint clustering. This enables loose maintenance and network latencies optimization. We sketch the design of PrefixStream and analyze its performances.
On de Bruijn routing in distributed hash tables: There and back again
 IN PEERTOPEER COMPUTING
, 2004
"... We show in this paper that de Bruijn networks, despite providing efficient search while using constant routing table size, as well as simplicity of the understanding and implementation of such networks, are unsuitable where key distribution will be uneven, a realistic scenario for most practical app ..."
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Cited by 6 (0 self)
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We show in this paper that de Bruijn networks, despite providing efficient search while using constant routing table size, as well as simplicity of the understanding and implementation of such networks, are unsuitable where key distribution will be uneven, a realistic scenario for most practical applications. In presence of arbitrarily skewed data distribution, it has only recently been shown that some traditional P2P overlay networks with nonconstant (typically logarithmic) instead of constant routing table size can meet conflicting objectives of storage load balancing as well as search efficiency. So this paper, while showing that de Bruijn networks fail to meet these dual objectives, opens up a more general problem for the research community as to whether P2P systems with constant routing table can at all achieve the conflicting objectives of retaining search efficiency as well as storage load balancing, while preserving key ordering (which leads to uneven key distribution).