In recent years, Wireless Sensor Networks (WSNs) as a new information gathering paradigm have att... more In recent years, Wireless Sensor Networks (WSNs) as a new information gathering paradigm have attracted much research interest because of its broad applications in smart buildings, military surveillance, environmental, medical and ecological monitoring, among many others. The success of wireless sensor network applications is due to WSN's strong capability of pervasive monitoring and wireless communications. However, some key constraints of wireless sensor networks, such as power consumption, sensing ability and communication bandwidth are not likely to be relaxed in the foreseeable future. Therefore, system designers must carefully design protocols and schemes and adjust parameters to balance various aspects of performance under these stringent constraints. Most published work takes best-effort approaches in the design and relies on trial and error real-world testing to find the best combination of parameters. These approaches have proven to be time and resource consuming, and can cause performance degradation due to environmental fluctuations. Therefore, it is of vital importance to quantitatively analyze the effects of system and protocol parameters on various aspects of wireless sensor networks, and to design protocols or select parameters based on the analysis in order to have predictable performance. This dissertation takes the latter approach to explore the possibility of predicting performance based on quantitative analysis and design with guarantees in three key aspects of wireless sensor network performance, and describes how to integrate wireless sensor network analysis into a well known design tool. The first aspect is sensing coverage, which is critical for many applications. Some applications need even higher degree of coverage for reliable monitoring of critical areas. The degree of coverage requirement needs to be balanced with the requirements on the system lifetime and energy Abdelzaher and Dr. Sang H. Son are always extremely supportive and inspiring, and they help me a lot on the dissertation work. I also get a lot of help from Tian He, Lin Gu, Gang Zhou, Jingbin
Many mission-critical wireless sensor network applications must resolve the inherent conflict bet... more Many mission-critical wireless sensor network applications must resolve the inherent conflict between the tight resource constraints on each sensor node, particularly in terms of energy, with the need to achieve desired quality of service such as end-to-end real-time performance. To address this challenge we propose the Real-time Power-Aware Routing (RPAR) protocol. RPAR achieves required communication delays at minimum energy cost by dynamically adapting the transmission power and routing decisions based on packet deadlines. RPAR integrates a geographic forwarding policy cognizant of deadlines, power, and link quality with new algorithms for on-demand power adaptation and efficient neighborhood discovery. Simulations
In healthcare, there is a strong need to collect physiological data and sensor networking; this p... more In healthcare, there is a strong need to collect physiological data and sensor networking; this paper reviews recent studies and points to the need for future research.
IEEE Transactions on Industrial Informatics, May 1, 2012
This paper describes a novel group based programming abstraction called a 'Bundle' for cyber phys... more This paper describes a novel group based programming abstraction called a 'Bundle' for cyber physical systems (CPS). Similar to other programming abstractions, a Bundle creates logical collections of sensing devices. However, previous abstractions were focused on wireless sensor networks (WSN) and did not address key aspects of CPS. Bundles elevate the programming domain from a single WSN to complex systems of systems by allowing the programming of applications involving multiple CPSs that are controlled by different administrative domains and support mobility both within and across CPSs. Bundles can seamlessly group not only sensors, but also actuators which constitute an important part of CPS. Bundles support heterogeneous devices, such as motes, PDAs, laptops and actuators according to the applications' requirements. They allow different applications to simultaneously use the same sensors and actuators. Bundles facilitate feedback control mechanisms by dynamic membership update and requirements reconfiguration based on feedback from the current members. The Bundle abstraction is implemented in Java which ensures ease and conciseness of programming. We present the design and implementation details of Bundles as well as a performance evaluation using 32 applications written with Bundles. This set includes across-network applications that have sophisticated sensing and actuation logic, mobile nodes that are heterogeneous, and feedback control mechanisms. Each of these applications is programmed in less than 60 lines of code.
Monographs in theoretical computer science, Nov 8, 2010
Military surveillance, home health care or assisted living, and environmental science are three m... more Military surveillance, home health care or assisted living, and environmental science are three major application areas for wireless sensor networks. Revolutionary changes are possible in these areas by using wireless sensor networks. To show the breadth and advantages of wireless sensor networks, design and implementation details are presented for three systems, one in each of these three application domains. Key research challenges and the approaches taken to address them are highlighted. Challenges requiring significantly improved solutions are also identified. These systems and others like them provide significant evidence for the utility of wireless sensor networks.
27th International Conference on Distributed Computing Systems (ICDCS '07), 2007
This paper presents the design, implementation, and evaluation of EnviroMic, a novel distributed ... more This paper presents the design, implementation, and evaluation of EnviroMic, a novel distributed acoustic monitoring, storage, and trace retrieval system. Audio represents one of the least exploited modalities in sensor networks to date. The relatively high frequency and large size of audio traces motivate distributed algorithms for coordinating recording tasks, reducing redundancy of data stored by nearby sensors, filtering out silence, and balancing storage utilization in the network. Applications of acoustic monitoring with EnviroMic range from the study of mating rituals and social behavior of animals in the wild to audio surveillance of military targets. EnviroMic is designed for disconnected operation, where the luxury of having a basestation cannot be assumed. We implement the system on a TinyOS-based platform and systematically evaluate its performance through both indoor testbed experiments and a preliminary outdoor deployment. Results demonstrate up to a 4-fold improvement in effective storage capacity of the network compared to uncoordinated recording.
Tracking is one of the major applications of wireless sensor networks. EnviroSuite, as a programm... more Tracking is one of the major applications of wireless sensor networks. EnviroSuite, as a programming paradigm, provides a comprehensive solution for programming tracking applications, wherein moving environmental targets are uniquely and identically mapped to logical objects to raise the level of programming abstraction. Such mapping is done through distributed group management algorithms, which organize nodes in the vicinity of targets into groups, and maintain the uniqueness and identity of target representation such that each target is given a consistent name. Challenged by tracking fast-moving targets, this paper explores, in a systematic way, various group management optimizations including semi-dynamic leader election, piggy-backed heartbeats, and implicit leader election. The resulting tracking protocol, Lightweight Envi-roSuite, is integrated into a surveillance system. Empirical performance evaluation on a network of 200 XSM motes shows that, due to these optimizations, Lightweight EnviroSuite is able to track targets more than 3 times faster than the fastest targets trackable by the original EnviroSuite even when 20% of nodes fail.
2011 IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications, 2011
Breadcrumb systems (BCS) aid first responders by communicating their physiological parameters to ... more Breadcrumb systems (BCS) aid first responders by communicating their physiological parameters to remotely located base stations. However, state-of-the-art research only focuses on deploying breadcrumb systems on the assumption of uncoordinated users, which is inefficient. In this paper, we present the first design, implementation, and evaluation of reliable multiuser breadcrumb systems (MUBCS) which exploits efficient and automatic coordination among system users to achieve better utilization of limited breadcrumbs. We propose UF, a distributed cooperative deployment algorithm, to achieve longer breadcrumb chain length while maintaining fairness and high system reliability via selecting appropriate benefit and cost functions. UF also requires no prior assumptions about users' mobility models, making the design practical for real applications. We deployed and evaluated our system in real buildings with several different first responder mobility patterns. Experimental results indicate that this approach can maintain connectivity for up to 87% longer distances than baseline greedy coordination approach while maintaining 96% packet delivery ratio.
Proceedings of the 3rd international conference on Embedded networked sensor systems, 2005
A wide variety of sensors have been incorporated into a spectrum of wireless sensor network (WSN)... more A wide variety of sensors have been incorporated into a spectrum of wireless sensor network (WSN) platforms, providing flexible sensing capability over a large number of low-power and inexpensive nodes. Traditional signal processing algorithms, however, often prove too complex for energy-and-cost-effective WSN nodes. This study explores how to design efficient sensing and classification algorithms that achieve reliable sensing performance on energy-andcost-effective hardware without special powerful nodes in a continuously changing physical environment. We present the detection and classification system in a cutting-edge surveillance sensor network, which classifies vehicles, persons, and persons carrying ferrous objects, and tracks these targets with a maximum error in velocity of 15%. Considering the demanding requirements and strict resource constraints, we design a hierarchical classification architecture that naturally distributes sensing and computation tasks at different levels of the system. Such a distribution allows multiple sensors to collaborate on a sensor node, and the detection and classification results to be continuously refined at different levels of the WSN. This design enables reliable detection and classification without involving high-complexity computation, reduces network traffic, and emphasizes resilience and adaptation to the realistic environment. We evaluate the system with performance data collected from outdoor experiments and field assessments. Based on the experience acquired and lessons learned when developing this system, we abstract common issues and introduce several guidelines which can direct future development of detection and classification solutions based on WSNs.
2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004
Sensor networks have recently emerged as a new paradigm for distributed sensing and actuation. Th... more Sensor networks have recently emerged as a new paradigm for distributed sensing and actuation. This paper describes fundamental performance trade-offs in sensor networks and the utility of simple feedback control mechanisms for distributed performance optimization. A data communication and aggregation framework is presented that manipulates the degree of data aggregation to maintain specified acceptable latency bounds on data delivery while attempting to minimize energy consumption. An analytic model is constructed to describe the relationships between timeliness, energy, and the degree of aggregation, as well as to quantify constraints that stem from real-time requirements. Feedback control is used to adapt the degree of data aggregation dynamically in response to network load conditions while meeting application deadlines. The results illustrate the usefulness of feedback control in the sensor network domain.
Proceedings of the fourth ACM workshop on Security of ad hoc and sensor networks, 2006
As sensor networks are deployed in adversarial environments and used for critical applications su... more As sensor networks are deployed in adversarial environments and used for critical applications such as battlefield surveillance and medical monitoring, security weaknesses become a big concern. The severe resource constraints of WSNs give rise to the need for resource bound security solutions. In this paper we present SIGF (Secure Implicit Geographic Forwarding), a configurable secure routing protocol family for wireless sensor networks that provides "good enough" security and high performance. By avoiding or limiting shared state, the protocols prevent many common attacks against routing, and contain others to the local neighborhood. SIGF makes explicit the tradeoff between security provided and state which must be stored and maintained. It comprises three protocols, each forming a basis for the next: SIGF-0 keeps no state, but provides probabilistic defenses; SIGF-1 uses local history and reputation to avoid attackers; and SIGF-2 uses neighborhood-shared state to provide stronger security guarantees. Our performance evaluation shows that SIGF achieves high packet delivery ratios with low overhead and endto-end delay. We evaluate the security of SIGF protocols under various security attacks and show that it effectively contains the damage from compromised nodes and defends against black hole, selective forwarding, Sybil, and some denial of service attacks.
Proceedings of the 9th ACM/IEEE International Conference on Information Processing in Sensor Networks, 2010
As wireless sensor networks mature, they are increasingly being used in real-time applications. M... more As wireless sensor networks mature, they are increasingly being used in real-time applications. Many of these applications require reliable transmission within latency bounds. Achieving this goal is very difficult because of link burstiness and interference. Based on significant empirical evidence of 21 days and over 3,600,000 packets transmission per link, we propose a scheduling algorithm that produces latency bounds of the real-time periodic streams and accounts for both link bursts and interference. The solution is achieved through the definition of a new metric Bmax that characterizes links by their maximum burst length, and by choosing a novel least-burst-route that minimizes the sum of worst case burst lengths over all links in the route. A testbed evaluation consisting of 48 nodes spread across a floor of a building shows that we obtain 100% reliable packet delivery within derived latency bounds. We also demonstrate how performance deteriorates and discuss its implications for wireless networks with insufficient high quality links.
Body sensor networks (BSN) are emerging cyberphysical systems that promise to improve quality of ... more Body sensor networks (BSN) are emerging cyberphysical systems that promise to improve quality of life through improved healthcare, augmented sensing and actuation for the disabled, independent living for the elderly, and reduced healthcare costs. However, the physical nature of BSNs introduces new challenges. The human body is a highly dynamic physical environment that creates constantly changing demands on sensing, actuation, and quality of service. Movement between indoor and outdoor environments and physical movements constantly change the wireless channel characteristics. These dynamic application contexts can also have a dramatic impact on data and resource prioritization. Thus, BSNs must simultaneously deal with rapid changes to both top-down application requirements and bottom-up resource availability. This is made all the more challenging by the wearable nature of BSN devices, which necessitates a vanishingly small size and, therefore, extremely limited hardware resources and power budget. Current research is being performed to develop new principles and techniques for adaptive operation in highly dynamic physical environments, using miniaturized, energy-constrained devices. This paper describes a holistic cross-layer approach that addresses all aspects of the system, from low-level hardware design to higher-level communication and data fusion algorithms, to top-level applications.
In healthcare, there is a strong need to collect physiological data and sensor networking; this p... more In healthcare, there is a strong need to collect physiological data and sensor networking; this paper reviews recent studies and points to the need for future research.
This paper describes a novel group based programming abstraction called a 'Bundle' for cyber phys... more This paper describes a novel group based programming abstraction called a 'Bundle' for cyber physical systems (CPS). Similar to other programming abstractions, a Bundle creates logical collections of sensing devices. However, previous abstractions were focused on wireless sensor networks (WSN) and did not address key aspects of CPS. Bundles elevate the programming domain from a single WSN to complex systems of systems by allowing the programming of applications involving multiple CPSs that are controlled by different administrative domains and support mobility both within and across CPSs. Bundles can seamlessly group not only sensors, but also actuators which constitute an important part of CPS. Bundles support heterogeneous devices, such as motes, PDAs, laptops and actuators according to the applications' requirements. They allow different applications to simultaneously use the same sensors and actuators. Bundles facilitate feedback control mechanisms by dynamic membership update and requirements reconfiguration based on feedback from the current members. The Bundle abstraction is implemented in Java which ensures ease and conciseness of programming. We present the design and implementation details of Bundles as well as a performance evaluation using 32 applications written with Bundles. This set includes across-network applications that have sophisticated sensing and actuation logic, mobile nodes that are heterogeneous, and feedback control mechanisms. Each of these applications is programmed in less than 60 lines of code.
Improving the quality of healthcare and the prospects of "aging in place" using wireless sensor t... more Improving the quality of healthcare and the prospects of "aging in place" using wireless sensor technology requires solving difficult problems in scale, energy management, data access, security, and privacy. We present AlarmNet, a novel system for assisted-living and residential monitoring that uses a two-way flow of data and analysis between the front and back-ends to enable context-aware protocols that are tailored to residents' individual patterns of living. AlarmNet integrates environmental, physiological, and activity sensors in a scalable, heterogeneous architecture. The SenQ query protocol provides real-time access to data and lightweight in-network processing. Circadian Activity Rhythm (CAR) analysis learns resident activity patterns and feeds them back into the network to aid context-aware power management and dynamic privacy policies.
ensor networks hold the promise of facilitating large-scale, real-time data processing in complex... more ensor networks hold the promise of facilitating large-scale, real-time data processing in complex environments. Their foreseeable applications will help protect and monitor military, environmental, safety-critical, or domestic infrastructures and resources. In these and other vital or security-sensitive deployments, keeping the network available for its intended use is essential. The stakes are high: Denial-of-service (DoS) attacks against such networks may permit real-world damage to the health and safety of people. Without proper security mechanisms, networks will be confined to limited, controlled environments, negating much of the promise they hold. The limited ability of individual sensor nodes to thwart failure or attack makes ensuring network availability more difficult. To identify DoS vulnerabilities, we analyze two effective sensor network protocols that did not initially consider security. These examples demonstrate that consideration of security at design time is the best way to ensure successful network deployment. Unless their developers take security into account at design time, sensor networks and the protocols they depend on will remain vulnerable to denial-of-service attacks.
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Papers by John Stankovic