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Summary form only given. Networks of intelligent sensors that are distributed through the physical world will revolutionize practices in the life sciences, civil engineering, manufacturing, security, agriculture, ubiquitous computing, and many other areas. They also present an opportunity and a need to explore distributed algorithms that are wedded to the noisy, localized, time varying physical world...
Reprogramming of sensor networks is an important and challenging problem as it is often necessary to reprogram the sensors in place. In this paper, we propose a multihop reprogramming service designed for Mica-2/XSM motes. One of the problems in reprogramming is the issue of message collision. To reduce the problem of collision and hidden terminal problem, we propose a sender selection algorithm that...
Networking protocols for multi-hop wireless sensor networks (WSNs) are required to simultaneously minimize resource usage as well as optimize performance metrics such as latency and reliability. This paper explores the energy-latency-reliability trade-off for broadcast in multi-hop WSNs, by presenting a new protocol called PBBF (probability-based broadcast forwarding). PBBF works at the MAC layer...
Sensor networks have emerged as a promising technology with various applications, and power consumption is one of the key issues. Since each full function device can act as a coordinator or a device in IEEE 802.15.4 standard, 802.15.4-based sensor networks have various possible network topologies. In this paper, we try to construct network topologies with small number of coordinators while still maintaining...
We prove two theorems saying that no distributed system in which processes coordinate using reliable registers and f-resilient services can solve the consensus problem in the presence of f + 1 undetectable process stopping failures. (A service is f-resilient if it is guaranteed to operate as long as no more than f of the processes connected to it fail.) Our first theorem assumes that the given services...
Cooperation in distributed settings often involves activities that must be performed at least once by the participating processors. When processor failures or delays occur, it becomes unavoidable that some tasks are done redundantly. To make efficient use of the available processors, several distributed algorithms schedule the activities of the processors in terms of permutations of tasks that need...
Since the design of lock-free data structures often poses a formidable intellectual challenge, researchers are constantly in search of abstractions and primitives that simplify this design. The multiword LL/SC object is such a primitive: many existing algorithms are based on this primitive, including the nonblocking and wait-free universal constructions (Anderson et. al., 1995), the closed objects...
We consider a simple model for reputation systems such as the one used by eBay. In the model there are n players, some of which may exhibit arbitrarily malicious (Byzantine) behavior, and there are m objects, some of which are bad. The goal of the honest players is to find a good object. To facilitate collaboration, the system maintains a shared billboard. A basic step of a player consists of consulting...
We study how a server may disseminate a large volume of data to a set of clients in the shortest possible time. Cooperative scenarios where clients are willing to upload data to each other and, under a simple bandwidth model, derive an optimal solution involving communication on a hypercube-like overlay network were first considered. The authors also studied different randomized algorithms, and show...
Large-scale competitive P2P networks are threatened by the non-cooperation problem, where peers do not forward queries to potential competitors. Non-cooperation will be a growing problem in such applications as pay-per-transaction file-sharing, P2P auctions, and P2P service discovery networks, where peers are in competition with each other to provide services. Here, the authors showed how non-cooperation...
The allocation of IP addresses in hybrid wireless networks is one of the most critical issues in all-IP converged wireless networks. The reason is that centralized IP address allocation mechanisms may not be available in networks comprised of heterogeneous mobile wireless devices. In this paper, the authors proposed zero-maintenance address allocation (ZAL), a fully distributed address allocation...
Position-based ad hoc routing algorithms have proved to have decent performance in delivery ratio and end-to-end delay. Position service is essential for such algorithms. In this paper, a distributed position service system, named VDPS, is proposed and evaluated. In the system, each node has a virtual home region (VHR), which is a geographic area. Nodes residing in a node's VHR will act as its position...
In a typical wireless mobile ad hoc network (MANET) using a shared communication medium, every node receives or overhears every data transmission occurring in its vicinity. However, this technique is not applicable when a power saving mechanism (PSM) such as the one specified in IEEE 802.11 is employed, where a packet advertisement period is separated from the actual data transmission period. When...
Database queries, in particular, event-driven continuous queries, are useful for many pervasive computing applications, such as video surveillance. In order to enable these applications, we have developed a pervasive query processing framework called Aorta. Unlike traditional database systems, a pervasive query processor requires systems support for managing a large number of networked, heterogeneous...
Advances in distributed service-oriented computing and global communications have formed a strong technology push for large-scale data integration among organizations and enterprises. However, concerns about data privacy become increasingly important for large-scale mission-critical data integration applications. Ideally, given a database query spanning multiple private databases, the authors wished...
More and more applications require peer-to-peer (P2P) systems to support complex queries over multi-dimensional data. For example, a P2P auction network for real estate frequently needs to answer queries such as "select five available buildings closest to the airport". Such queries are not efficiently supported in current P2P systems. Towards an efficient and scalable P2P system capable...
Communication-induced checkpointing protocols that ensure rollback-dependency trackability (RDT) guarantee important properties to the recovery system without explicit coordination. However, there was no garbage collection algorithm for them which did not use some type of process synchronization, like time assumptions or reliable control message exchanges. This paper addresses the problem of garbage...
Distributed checkpointing is an important concept in providing fault tolerance in distributed systems. In today's applications, e.g., grid and massively parallel applications, the imposed overhead of taking a distributed checkpoint using the known approaches can often outweigh its benefits due to coordination and other overhead from the processes. This paper presents an innovative approach for distributed...
Data reliability of distributed brick storage systems critically depends on the replica placement policy, and the two governing forces are repair speed and sensitivity to multiple concurrent failures. In this paper, the authors provided an analytical framework to reason and quantify the impact of replica placement policy to system reliability. The novelty of the framework is its consideration of the...
The lack of a flexible consistency management solution hinders P2P implementation of applications involving updates, such as read-write file sharing, directory services, online auctions and wide area collaboration. Managing mutable shared data in a P2P setting requires a consistency solution that can operate efficiently over variable-quality failure-prone networks, support pervasive replication for...
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