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Data collection in wireless sensor networks with mobile elements: A survey
- ACM Trans. Sensor Networks
"... Wireless sensor networks (WSNs) have emerged as an effective solution for a wide range of applications. Most of the traditional WSN architectures consist of static nodes which are densely deployed over a sensing area. Recently, several WSN architectures based on mobile elements (MEs) have been propo ..."
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Cited by 34 (4 self)
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Wireless sensor networks (WSNs) have emerged as an effective solution for a wide range of applications. Most of the traditional WSN architectures consist of static nodes which are densely deployed over a sensing area. Recently, several WSN architectures based on mobile elements (MEs) have been proposed. Most of them exploit mobility to address the problem of data collection in WSNs. In this paper we first define WSNs with MEs and provide a comprehensive taxonomy of their architectures, based on the role of the MEs. Then, we present an overview of the data collection process in such scenario, and identify the corresponding issues and challenges. On the basis of these issues, we provide an extensive survey of the related literature. Finally, we compare the underlying approaches and solutions, with hints to open problems and future research directions.
Exploiting rush hours for energy-efficient contact probing in opportunistic data collection
- In IEEE ICDCS Workshops
, 2011
"... Abstract—In many potential wireless sensor network applications, the cost of the base station infrastructure can be prohibitive. Instead, we consider the use of mobile devices carried by people in their daily life to collect sensor data opportunistically. As the movement of these mobile nodes is, by ..."
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Cited by 6 (6 self)
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Abstract—In many potential wireless sensor network applications, the cost of the base station infrastructure can be prohibitive. Instead, we consider the use of mobile devices carried by people in their daily life to collect sensor data opportunistically. As the movement of these mobile nodes is, by definition, uncontrolled, contact probing becomes a challenging task, particularly for sensor nodes which need to be aggressively duty-cycled to achieve long life. It has been reported that when the duty-cycle of a sensor node is fixed, SNIP, a sensor node-initiated probing mechanism, performs much better than mobile node-initiated probing mechanisms. Considering that the intended applications are delaytolerant, mobile nodes tend to follow some repeated mobility patterns, and contacts are distributed unevenly in temporal, SNIP-RH is proposed in this paper to further improve the performance of contact probing through exploiting Rush Hours during which contacts arrive more frequently. In SNIP-RH, SNIP is activated only when the time is within Rush Hours and there are enough data to be uploaded in the next probed contact. As for the duty-cycle, it is selected based on the mean of contact length that is learned online. Both analysis and simulation results indicate that under a typical simulated roadside wireless sensor network scenario, SNIP-RH can significantly reduce the energy consumed for probing the contacts, that are necessary for uploading the sensed data, or significantly increase the probed contact capacity under a sensor node’s energy budget for contact probing. I.
Ultra-low power time synchronization using passive radio receivers
- In IPSN
, 2011
"... Considering its central importance to sensor networks, time synchronization has received extensive attention by the research community. Nevertheless, we argue in this paper that existing approaches introduce undesirable trade-offs. For example, while GPS offers excellent accuracy for outdoor deploym ..."
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Cited by 6 (0 self)
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Considering its central importance to sensor networks, time synchronization has received extensive attention by the research community. Nevertheless, we argue in this paper that existing approaches introduce undesirable trade-offs. For example, while GPS offers excellent accuracy for outdoor deployments, the high cost and power consumption of GPS receivers make them prohibitive to many applications. Message-passing protocols, such as FTSP, introduce different sets of compromises and constraints. In this paper, we present an inexpensive and ultra-low power (< 100 µA) mote peripheral, we term the Universal Time Signal Receiver, that leverages the availability of time signals transmitted by dedicated radio stations around the globe to provide access to UTC time with millisecond-level accuracy. We present experimental results measuring signal availability, quality of synchronization across motes, and power consumption. We show that the proposed universal time signal receiver achieves global time synchronization and for applications where millisecond-level precision is sufficient, it consumes up to 1,000 times less energy than GPS or FTSP.
Dual-Beacon Mobile-Node Discovery in Sparse Wireless Sensor Networks
"... Abstract – In sparse wireless sensor networks data collection is typically accomplished through specialized mobile nodes. One of the main challenges to be faced in this kind of networks is the energy-efficient and timely discovery of mobile nodes. In this paper we propose a simple yet effective disc ..."
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Cited by 1 (1 self)
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Abstract – In sparse wireless sensor networks data collection is typically accomplished through specialized mobile nodes. One of the main challenges to be faced in this kind of networks is the energy-efficient and timely discovery of mobile nodes. In this paper we propose a simple yet effective discovery protocol based on two different Beacon messages emitted by the mobile node (i.e., Long-Range Beacons and Short-Range Beacons). Our simulation results show that, although very simple, the proposed scheme can provide a significant energy reduction with respect to the commonly used scheme based on a single Beacon, especially if the discovery phase is long.
Intelligent Systems Centre Nanyang Technological
"... In sparse and intermittently connected Mobile Sensor Networks (MSNs), the base station cannot easily get the data objects acquired by the mobile sensors in the field. When users query the base station for specific data objects, the base station may not have received the necessary data objects to ans ..."
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In sparse and intermittently connected Mobile Sensor Networks (MSNs), the base station cannot easily get the data objects acquired by the mobile sensors in the field. When users query the base station for specific data objects, the base station may not have received the necessary data objects to answer the queries. In this paper, we propose to use a Mobile Data Collector (MDC) to collect the data objects from the mobile sensors that the base station needs for answering queries. To facilitate the MDC’s data collection, we design a location-based data forwarding protocol that exploits the location metadata of data objects and uses caching to improve data availability in the MSNs. Results of performance study show that our solution can reduce query response times on the base station. 1.
SchedulingSensorsfor MonitoringSentientSpacesusinganApproximatePOMDP Policy
"... Abstract—We present a framework for sensor actuation and control in sentient spaces, in which sensors are used to observe a physical phenomena. We focus on sentient spaces that enable pervasive computing applications, such as smart video surveillance and situational awareness in instrumented office ..."
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Abstract—We present a framework for sensor actuation and control in sentient spaces, in which sensors are used to observe a physical phenomena. We focus on sentient spaces that enable pervasive computing applications, such as smart video surveillance and situational awareness in instrumented office environments. Our framework utilizes the spatio-temporal statistical properties of an observed phenomena, with the goal of maximizing an application-specified reward. Specifically, we define an observation of a phenomena by assigning it a discrete value (state) and we model its semantics as the transition between these values (states). This semantic model is used to predict the future states in which the phenomena is likely to be at, based on partially-observed past states. To accomplish real-time agility, we designed an approximate, adaptive-grid solution for Partially Observable Markov Decision Processes (POMDPs) that yields practically good results, and in some cases, guarantees on the quality of the approximation. We use our framework to control and actuate a large-scale camera network so as to maximize the number and type of captured events. To enable real-time control, we implement an action schedule using a table lookup and make use of a factored probability model to capture state semantics. To the best of our knowledge, we are the first to address the problem of actuating a large-scale sensor network based on a real-time POMDP formulation. I.
2011 31st International Conference on Distributed Computing Systems Workshops Exploiting Rush Hours for Energy-Efficient Contact Probing in Opportunistic Data Collection
"... Abstract—In many potential wireless sensor network applications, the cost of the base station infrastructure can be prohibitive. Instead, we consider the use of mobile devices carried by people in their daily life to collect sensor data opportunistically. As the movement of these mobile nodes is, by ..."
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Abstract—In many potential wireless sensor network applications, the cost of the base station infrastructure can be prohibitive. Instead, we consider the use of mobile devices carried by people in their daily life to collect sensor data opportunistically. As the movement of these mobile nodes is, by definition, uncontrolled, contact probing becomes a challenging task, particularly for sensor nodes which need to be aggressively duty-cycled to achieve long life. It has been reported that when the duty-cycle of a sensor node is fixed, SNIP, a sensor node-initiated probing mechanism, performs much better than mobile node-initiated probing mechanisms. Considering that the intended applications are delaytolerant, mobile nodes tend to follow some repeated mobility patterns, and contacts are distributed unevenly in temporal, SNIP-RH is proposed in this paper to further improve the performance of contact probing through exploiting Rush Hours during which contacts arrive more frequently. In SNIP-RH, SNIP is activated only when the time is within Rush Hours and there are enough data to be uploaded in the next probed contact. As for the duty-cycle, it is selected based on the mean of contact length that is learned online. Both analysis and simulation results indicate that under a typical simulated roadside wireless sensor network scenario, SNIP-RH can significantly reduce the energy consumed for probing the contacts, that are necessary for uploading the sensed data, or significantly increase the probed contact capacity under a sensor node’s energy budget for contact probing. I.
A Framework for Resource-Aware Data Accumulation in Sparse Wireless Sensor Networks
"... Wireless sensor networks (WSNs) have become an enabling technology for a wide range of applications. In contrast with traditional scenarios where static sensor nodes are densely deployed, a sparse WSN architecture can also be used in many cases. In a sparse WSN, special mobile data collectors (MDCs) ..."
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Wireless sensor networks (WSNs) have become an enabling technology for a wide range of applications. In contrast with traditional scenarios where static sensor nodes are densely deployed, a sparse WSN architecture can also be used in many cases. In a sparse WSN, special mobile data collectors (MDCs) are used to gather data from ordinary sensor nodes. In general, sensor nodes do not know when they will be in contact with the MDC, hence they need to discover its presence in their communication range. To this end, discovery mechanisms based on periodic listening and a duty-cycle have shown to be effective in reducing the energy consumption of sensor nodes. However, if not properly tuned, such mechanisms can hinder the data collection process. In this paper, we introduce a Resource-Aware Data Accumulation (RADA), a novel and lightweight framework which allows nodes to learn the MDC arrival pattern, and tune the discovery duty-cycle accordingly. Furthermore, RADA is able to adapt to changes in the operating conditions, and is capable of effectively supporting a number of different MDC mobility patterns. Simulation results show that our solution obtains a higher discovery efficiency and a lower energy consumption than comparable schemes.
� Hierarchical Discovery Scheme
"... All sensor nodes have a fixed location What about introducing mobility? ..."
Research on Mobility-Assisted Data Gathering Strategies in WSNs
"... 摘 要: 利用移动数据收集器(mobile data collectors,简称MDCs)进行传感器网络中感知数据的收集,可以有效地 ..."
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