We consider the problem of estimating vector-valued variables from noisy "relative" measurements. The measurement model can be expressed in terms of a graph, whose nodes correspond to the variables being est...
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Wireless sensor networks (WSNs) typically exploit a single base station for collecting data and coordinating activities. However, decentralized architectures are rapidly emerging, as witnessed by wireless sensor and a...
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sensor replacement is important for sensor networks to provide continuous sensing services. Existing approaches relocate redundant nodes to fill the holes created by failed sensors and require all or most sensor nodes...
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sensors are envisioned to be at the center of distributed collaborative computing services involving time-critical decision support. sensors are small devices with limited communication and computational capabilities ...
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ISBN:
(纸本)9781424404285
sensors are envisioned to be at the center of distributed collaborative computing services involving time-critical decision support. sensors are small devices with limited communication and computational capabilities that collect data on their neighboring physical world and send the data periodically to server machines. sensors form a collaborative network with these servers, where the sensors gather information and the servers perform various operations (e.g. filter, aggregate, join etc) on the information streams in real-time according to predefined queries or rules. sensor data streams are continuous, un-ending and have highly volatile characteristics. As a result, traditional database systems are inappropriate for handling queries for sensor streams, and several stream data management systems have been proposed in the literature. In this paper we focus on a special type of query, namely join queries, which is the most expensive query operator. Here, we address the problem of finding an optimal join tree that maximizes throughput for sliding window based multi-join queries over continuous sensor data streams. We present a polynomial time algorithm Fodp and three variants of Fodp. Our experiments in ARES(1). show that for almost all instances, trees from Fodp and its variants perform close to the optimal trees from our exponential time algorithm OptDP [1], and significantly better than existing XJoin based heuristic algorithms.
Existing network reprogramming protocols target the efficient, reliable, multi-hop dissemination of application updates in sensor networks, but assume correct or fail-stop behavior from participating sensors. Compromi...
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The location estimation is a fundamental and essential issue for wireless sensor networks(WSNs). In this paper, we assume that only a few sensor nodes (named as beacon nodes) get their locations by Global Positioning ...
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ISBN:
(纸本)0769525539
The location estimation is a fundamental and essential issue for wireless sensor networks(WSNs). In this paper, we assume that only a few sensor nodes (named as beacon nodes) get their locations by Global Positioning System (GPS) and the remaining nodes without GPS (named as normal nodes) need to estimate their own locations by gathering the nearby neighboring information. Existing works are either too costly or not accurate enough. To improve previous works, we propose a distributed location estimation algorithm for WSNs. In our algorithm, each node without location information only needs to collect the location information of neighboring nodes and use simple computation to estimate its location. Besides, we improve the accuracy of the normal node's estimative region by discarding the communication area of the beacon node (named as the farther neighboring beacon node), which does not cover the normal node, from the original estimative region. We derive some rules to adjust the estimative region according to the relative location of the normal node and the farther neighboring beacon node. Simulation results show that the proposed algorithm achieves better accuracy of estimative locations.
In peer-to-peer (P2P) environments, trust is a very important issue when transactions/interactions occur between peers. In general, the trust evaluation on transactions/interactions relies on the recommendations from ...
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ISBN:
(纸本)0769525539
In peer-to-peer (P2P) environments, trust is a very important issue when transactions/interactions occur between peers. In general, the trust evaluation on transactions/interactions relies on the recommendations from other peers, which may be inaccurate. This paper presents DynamicTrust, a P2P trust evaluation system. It is based on our peer trust evaluation model, which measures the credibility of peers' recommendations, and thus filters noise in responses and obtains more accurate and objective trust values.
User access control in sensor networks defines a process of granting user the access right to the information and resources. It is essential for the future real sensor network deployment in which sensors may provide u...
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Resource constrained systems often are programmed using an event-based model. Many applications do not lend themselves well to an event-based approach, but preemptive multithreading pre-allocates resources that cannot...
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We present the design and implementation of POS, an in-network service that computes accurate order statistics energy-efficiently. POS returns a stream of periodic samples from any order statistic. It initially comput...
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