Wireless sensor networks come of age and start moving out of the laboratory into the field. As the number of deployments is increasing the need for an efficient and reliable code update mechanism becomes pressing. Rea...
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ISBN:
(数字)9783540691709
ISBN:
(纸本)9783540691693
Wireless sensor networks come of age and start moving out of the laboratory into the field. As the number of deployments is increasing the need for an efficient and reliable code update mechanism becomes pressing. Reasons for updates are manifold ranging from fixing software bugs to retasking the whole sensor network. The scale of deployments and the potential physical inaccessibility of individual nodes asks for a wireless software management scheme. In this paper we present an efficient code update strategy which utilizes the knowledge of former program versions to distribute mere incremental changes. Using a small set of instructions, a delta of minimal size is generated. This delta is then disseminated throughout the network allowing nodes to rebuild the new application based on their currently running code. The asymmetry of computational power available during the process of encoding (PC) and decoding (sensor node) necessitates a careful balancing of the decoder complexity to respect the limitations of today's sensor network hardware. We provide a seamless integration of our work into Deluge, the standard TinyOS code dissemination protocol. The efficiency of our approach is evaluated by means of testbed experiments showing a significant reduction in message complexity and thus faster updates.
This paper proposes a distributed coordinate-free non-triangulated hole recovery algorithm for sensor networks called 3MeSH-DR (Triangular Mesh distributed hole Recovery), which recovers coverage holes with the minimu...
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Visual coverage is an essential issue in the research on visual sensor networks. However, because of the presence of visual occlusions, the statistics of visual coverage blend the statistics of nodes and targets and a...
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ISBN:
(数字)9783540691709
ISBN:
(纸本)9783540691693
Visual coverage is an essential issue in the research on visual sensor networks. However, because of the presence of visual occlusions, the statistics of visual coverage blend the statistics of nodes and targets and are extremely difficult to derive. By assuming the deployment of nodes as a stationary Poisson point process and ignoring boundary effects, this paper presents the first attempt to estimate the probability that an arbitrary target in the field is visually k-covered. The major challenge for the estimation is how to formulate the probability (q) that a node captures a target in its visual range. To tackle this challenge, we first assume a visual detection model that takes visual occlusions into account and then derive several significant statistical parameters of q based on this model. According to these parameters, we can finally reconstruct the probability density function of q as a combination of a Binomial function and an impulse function. With the estimated coverage statistics, we further propose an estimate of the minimum node density that suffices to ensure a K-coverage across the field.
In this paper we consider the performance behavior of two protocols: AODV and DSR using TwoRayGround model. We study the routing efficiency of the ad-hoc sensor network and compare the performance of two protocols for...
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We consider a mobile sensor network monitoring a spatio-temporal field. Given limited caches at the sensor nodes, the goal is to develop a distributed cache management algorithm to efficiently answer queries with a kn...
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ISBN:
(数字)9783540691709
ISBN:
(纸本)9783540691693
We consider a mobile sensor network monitoring a spatio-temporal field. Given limited caches at the sensor nodes, the goal is to develop a distributed cache management algorithm to efficiently answer queries with a known probability distribution over the spatial dimension. First, we propose a novel distributed information theoretic approach assuming knowledge of the distribution of the monitored phenomenon. Under this scheme, nodes minimize an entropic utility function that captures the average amount of uncertainty in queries given the probability distribution of query locations. Second, we propose a correlation-based technique, which only requires knowledge of the second-order statistics, relaxing the stringent constraint of a priori knowledge of the query distribution, while significantly reducing the computational overhead. We show that the proposed approaches considerably improve the average field estimation error. Further, we show that the correlation-based technique is robust to model mismatch in case of imperfect knowledge of the underlying generative correlation structure.
We present a protocol for secure data aggregation in wireless sensor networks that offers end-to-end data confidentiality by using homomorphic functions and interleaved encryption. Hop-by-hop aggregation in sensor net...
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Densely distributed wireless real-time system must perform communication scheduling and protocols in addition to task scheduling to achieve schedulability and reliable communication. While many wireless sensor network...
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ISBN:
(纸本)9780769533490
Densely distributed wireless real-time system must perform communication scheduling and protocols in addition to task scheduling to achieve schedulability and reliable communication. While many wireless sensor networks are densely distributed, they assume low duty cycling and trivial data packet rates, and the), cannot handle many real-world applications. To highlight these design issues, this paper presents a case study with EcoDAQ, a wireless data acquisition system with 50 sensor nodes streaming real-time data over the same frequency channel. To achieve reliable communication, we define a pulling protocol that minimizes node complexity while guaranteeing collision freedom on a given frequency channel. Our case study illustrates the impact of communication requirements on the rest of the systems including bus and processing speeds. Experimental results show that our monitoring station can sustain gathering accelerometer data from up to 50 nodes in one square meter area at up to 15,000 samples per second with minimal latency and show very high expandability, flexibility and reliability.
sensors have been increasingly used for many ubiquitous computing applications such as asset location monitoring, visual surveillance, and human motion tracking. In such applications, it is important to place sensors ...
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ISBN:
(数字)9783540691709
ISBN:
(纸本)9783540691693
sensors have been increasingly used for many ubiquitous computing applications such as asset location monitoring, visual surveillance, and human motion tracking. In such applications, it is important to place sensors such that every point of the target area can be sensed by more than one sensor. Especially, many practical applications require 3-coverage for triangulation, 3D hull building, and etc. Also, in order to extract meaningful information from the data sensed by multiple sensors, those sensors need to be placed not too close to each other-minimum separation requirement. To address the 3-coverage problem with the minimum separation requirement, this paper proposes two methods, so called, overlaying method and TRE-based method, which complement each other depending on the minimum separation requirement. For these two methods, we also provide mathematical analysis that can clearly guide us when to use the TRE-based method and when to use the overlaying method and also how many sensors are required. To the best of our knowledge, this is the first work that systematically addresses the 3-coverage problem with the minimum separation requirement.
Data-driven macroprogramming of wireless sensor networks (WSNs) provides an easy to use high-level task graph representation to the application developer. However, determining an energy-efficient initial placement of ...
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ISBN:
(数字)9783540691709
ISBN:
(纸本)9783540691693
Data-driven macroprogramming of wireless sensor networks (WSNs) provides an easy to use high-level task graph representation to the application developer. However, determining an energy-efficient initial placement of these tasks onto the nodes of the target network poses a set of interesting problems. We present a framework to model this task-mapping problem arising in WSN macroprogramming. Our model can capture task placement constraints, and supports easy specification of energy-based optimization goals. Using our framework, we provide mathematical formulations for the task-mapping problem for two different metrics - energy balance and total energy spent. Due to the complex nature of the problems, these formulations are not linear. We provide linearization heuristics for the same, resulting in mixed-integer programming (MIP) formulations. We also provide efficient heuristics for the above. Our experiments show that the our heuristics give the same results as the MIP for real-world sensor network macroprograms, and show a speedup of up to several orders of magnitude.
A novel sensor network configuration is introduced for traffic surveillance in Intelligent Transportation systems. distributedsensor nodes based on passive acoustic transducers are non intrusively/obtrusively deploye...
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ISBN:
(纸本)9780769533308
A novel sensor network configuration is introduced for traffic surveillance in Intelligent Transportation systems. distributedsensor nodes based on passive acoustic transducers are non intrusively/obtrusively deployed at motorway road-side to provide real-time traffic data collection for dynamic queue/jam detection. The system is capable to provide a complete real-time picture of traffic flow at unprecedented time/space scale. The infrastructure is based on a stand-alone, install-and-forget architecture, featuring an energy efficient protocol for sensor networking and providing connectivity to back-end computing environment via TCP/IP over UMTS. Extensive experimental demonstration is given for long term operation on a motorway test site.
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