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A Path-Connected-Cluster Wireless Sensor Network and Its Formation, Addressing, and Routing Protocols
(2012-06-01)
Tsai, Chia-Hung
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Although wireless sensor networks (WSNs) have been extensively researched, their deployment is still a main concern. We observe that many monitoring applications for WSNs have adopted a path-connected-cluster (PCC) topology, where regions to be monitored are deployed with clusters of sensor nodes. Since these clusters might be physically separated, paths of sensor nodes are used to connect them together. We call such networks PCC-WSNs. PCC-WSNs may be widely applied in real situations, such as bridge-connected islands, street-connected buildings, and pipe-connected ponds. In this paper, we show that the address assignment scheme defined by ZigBee will perform poorly in terms of address utilization. We then propose a systematical solution, which includes network formation, automatic address assignment, and light-weight routing. Simulation results verify the effectiveness of the proposed solution.
Range-Free Mobile Actor Relocation in a Two-Tiered Wireless Sensor and Actor Network
(2016-05)
Wu, Fang-Jing
;
Hsu, Hsiu-Chi
;
Shen, Chien-Chung
;
Tseng, Yu-Chee
;
資訊工程學系
Two-tiered wireless sensor and actor networks (WSANs) have been proposed to enhance network capabilities, where a set of resource-rich mobile nodes (termed actors) form a connected backbone to relay sensing data from static sensors to the sink and sometimes are requested by sensors to perform a particular action. Such a two-tiered WSAN facilitates scalability and can efficiently reduce the energy consumption incurred by conventional hop-by-hop relaying via only sensors. However, relocating actors to achieve both connectivity and load balance is a challenge, especially when there is no location information of the nodes. Connectivity ensures that the actors are connected, whereas load balance ensures that actors collect and originate a similar amount of sensory data from the sensors. In this article, we formulate the Connected and Balanced Mobile Actor Relocation (CBMAR) optimization problem to address both connectivity and load balance and prove that the problem is NP-hard. We thus propose a dual-mode distributed actor relocation protocol that does not rely on any location information of nodes to relocate actors. The idea is to locally form virtual Voronoi cells of actors (termed covering cells) based on the lower-tiered topology, where each actor locally recruits its own sensor members to form its own covering cell. By maintaining the covering cell, each actor locally relocates itself toward a sensor along the lower-tiered topology. Extensive simulation results show that the protocol can achieve both objectives of connectivity and load balance with low moving and communication overheads.
Compression and storage schemes in a sensor network with spatial and temporal coding techniques
(2008)
Wang, You-Chiun
;
Hsieh, Yao-Yu
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Wireless sensor networks provide a convenient manner to monitor the physical environments. How to extend the network lifetime by reducing the amount of message transmissions is a critical issue. In this paper, we propose a multi-resolution compression and storage (MCS) framework to compress and preserve sensing data in a wireless sensor network. Our MCS framework adopts spatial and temporal compression schemes to reduce the amount of message transmissions, so the network lifetime can he prolonged and the network congestion can be alleviated. In addition, we also develop a storage mechanism to maintain sensing data in sensor nodes, so that users can query more detailed data when necessary. Our proposed methods consider the hardware limitations of sensor nodes. We also implement a prototyping system on the MICAz Mote platform.
iPCA: an integration information system for patient controlled analgesia using wireless techniques
(2013)
Yang, Shu-Fen
;
Ku, Tien-Hsiung
;
Jeng, Andy An-Kai
;
Jan, Rong-Hong
;
Tseng, Yu-Chee
Recently, pain management has become an important aspect of medical care. Patient Controlled Analgesia (PCA) is a particularly effective and flexible treatment that allows patients to adjust the dosages of the analgesics that control their pain after surgery. However, PCA requires manual operation for sustained attention, and should be analysed with other pathology information for synergic usage. In this paper, we propose an integrated information system for pain management, called Integrated Patient Controlled Analgesia (iPCA). The system integrates various PCA-related devices by wireless techniques to provide real-time information for medial staffs, and offer more efficient and convenient pain control for both in-hospital and at-home patients. To evaluate our system, we have developed a prototype and conducted a series of field trails at a large private hospital in southern Taiwan. The results show that the iPCA system indeed works well with patients, and can provide better post-operative pain control by efficiently collecting PCA usage information.
A lightweight, self-adaptive lock gate designation scheme for data collection in long-thin wireless sensor networks
(2013-01-01)
Wang, You-Chiun
;
Chuang, Che-Hsi
;
Tseng, Yu-Chee
;
Shen, Chien-Chung
;
資訊工程學系
Constrained by the physical environments, the long-thin topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, a long-thin topology is composed of a number of long branches of sensor nodes, where along a branch each sensor node has only one potential parent node toward the sink node. Although data aggregation may alleviate excessive packet contention, the maximum payload size of a packet and the dynamically changing traffic loads may severely affect the amount of sensor readings that may be collected along a long branch of sensor nodes. In addition, many practical applications of long-thin WSNs demand the exact sensor readings at each location along the deployment areas for monitoring and analysis purposes, so sensor readings may not be aggregated when they are collected. This paper proposes a lightweight, self-adaptive scheme that designates multiple collection nodes, termed lock gates, along a long-thin network to collect sensor readings sent from their respective upstream sensor nodes. The self-adaptive lock gate designation scheme balances between the responsiveness and the congestion of data collection while mitigating the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time-varying sensor reading generation rates of different sensor nodes. A testbed of 100 Jennic sensor nodes is developed to demonstrate the effectiveness of the proposed lock gate designation scheme. Copyright (c) 2011 John Wiley & Sons, Ltd.
A Path-Connected-Cluster Wireless Sensor Network and Its Formation, Addressing, and Routing Protocols
(2012-06-01)
Tsai, Chia-Hung
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Although wireless sensor networks (WSNs) have been extensively researched, their deployment is still a main concern. We observe that many monitoring applications for WSNs have adopted a path- connected- cluster (PCC) topology, where regions to be monitored are deployed with clusters of sensor nodes. Since these clusters might be physically separated, paths of sensor nodes are used to connect them together. We call such networks PCC-WSNs. PCC-WSNs may be widely applied in real situations, such as bridge-connected islands, street-connected buildings, and pipe-connected ponds. In this paper, we show that the address assignment scheme defined by ZigBee will perform poorly in terms of address utilization. We then propose a systematical solution, which includes network formation, automatic address assignment, and light-weight routing. Simulation results verify the effectiveness of the proposed solution.
Mobility management algorithms and applications for mobile sensor networks
(2012-01-01)
Wang, You-Chiun
;
Wu, Fang-Jing
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Wireless sensor networks (WSNs) offer a convenient way to monitor physical environments. In the past, WSNs are all considered static to continuously collect information from the environment. Today, by introducing intentional mobility to WSNs, we can further improve the network capability on many aspects, such as automatic node deployment, flexible topology adjustment, and rapid event reaction. In this paper, we survey recent progress in mobile WSNs and compare works in this field in terms of their models and mobility management methodologies. The discussion includes three aspects. Firstly, we discuss mobility management of mobile sensors for the purposes of forming a better WSN, enhancing network coverage and connectivity, and relocating some sensors. Secondly, we introduce path-planning methods for data ferries to relay data between isolated sensors and to extend a WSN's lifetime. Finally, we review some existing platforms and discuss several interesting applications of mobile WSNs. Copyright (C) 2010 John Wiley & Sons, Ltd.
Data Gathering by Mobile Mules in a Spatially Separated Wireless Sensor Network
(2009)
Wu, Fang-Jing
;
Huang, Chi-Fu
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
While wireless sensor networks (WSNs) are typically targeted at large-scale deployment, due to many practical or inevitable reasons, a WSN may not always remain connected. In this paper we consider the possibility that a WSN may be spatially separated into multiple subnetworks. Data gathering, which is a fundamental mission of WSN, thus may rely on a mobile mule ("mule" for short) to conduct data gathering by visiting each subnetwork. This leads to the problem of minimizing the path length traversed by the mobile mule. We show that minimizing the path length, which may reflect the data gathering latency and the energy consumption of the mule is a generalization of the traveling salesman problem and is NP-complete. Some heuristics based on geometrical properties of node deployment are proposed. Our simulation results show that these heuristics perform very close to optimal solutions in most practical cases.
Distributed deployment schemes for mobile wireless sensor networks to ensure multilevel coverage
(2008-09-01)
Wang, You-Chiun
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
One of the key research issues in wireless sensor networks (WSNs) is how sensors can efficiently be deployed to cover an area. In this paper, we solve the k-coverage sensor deployment problem to achieve multilevel (k) coverage of the area of interest I. We consider two subproblems: the k-coverage placement problem and the distributed dispatch problem. The placement problem asks how the minimum number of sensors required and their locations in I can be determined to guarantee that I is k-covered and the network is connected, while the dispatch problem asks how mobile sensors can be scheduled to move to the designated locations according to the result computed by the placement strategy if they are not in the current positions such that the energy consumption due to movement is minimized. Our solutions to the placement problem consider both the binary and probabilistic sensing models and allow an arbitrary relationship between the communication distance and the sensing distance of sensors, thereby relaxing the limitations of existing results. For the dispatch problem, we propose a competition-based scheme and a pattern-based scheme. The competition-based scheme allows mobile sensors to bid for their closest locations, while the pattern-based scheme allows sensors to derive the target locations on their own. Our proposed schemes are efficient in terms of the number of sensors required and are distributed in nature. Simulation results are presented to verify their effectiveness.
Multiresolution Spatial and Temporal Coding in a Wireless Sensor Network for Long-Term Monitoring Applications
(2009-06-01)
Wang, You-Chiun
;
Hsieh, Yao-Yu
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
In many WSN (wireless sensor network) applications, such as [1], [2], [3], the targets are to provide long-term monitoring of environments. In such applications, energy is a primary concern because sensor nodes have to regularly report data to the sink and need to continuously work for a very long time so that users may periodically request a rough overview of the monitored environment. On the other hand, users may occasionally query more in-depth data of certain areas to analyze abnormal events. These requirements motivate us to propose a multiresolution compression and query (MRCQ) framework to support in-network data compression and data storage in WSNs from both space and time domains. Our MRCQ framework can organize sensor nodes hierarchically and establish multiresolution summaries of sensing data inside the network, through spatial and temporal compressions. In the space domain, only lower resolution summaries are sent to the sink; the other higher resolution summaries are stored in the network and can be obtained via queries. In the time domain, historical data stored in sensor nodes exhibit a finer resolution for more recent data, and a coarser resolution for older data. Our methods consider the hardware limitations of sensor nodes. So, the result is expected to save sensors' energy significantly, and thus, can support long-term monitoring WSN applications. A prototyping system is developed to verify its feasibility. Simulation results also show the efficiency of MRCQ compared to existing work.

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