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Analysis of EDF Scheduling for Wireless Sensor-Actuator Networks
"... Abstract—Industry is adopting Wireless Sensor-Actuator Net-works (WSANs) as the communication infrastructure for process control applications. To meet the stringent real-time performance requirements of control systems, there is a critical need for fast end-to-end delay analysis for real-time flows ..."
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Abstract—Industry is adopting Wireless Sensor-Actuator Net-works (WSANs) as the communication infrastructure for process control applications. To meet the stringent real-time performance requirements of control systems, there is a critical need for fast end-to-end delay analysis for real-time flows that can be used for online admission control. This paper presents a new end-to-end delay analysis for periodic flows whose transmissions are scheduled based on the Earliest Deadline First (EDF) policy. Our analysis comprises novel techniques to bound the communication delays caused by channel contention and transmission conflicts in a WSAN. Furthermore, we propose a technique to reduce the pessimism in admission control by iteratively tightening the delay bounds for flows with short deadlines. Experiments on a WSAN testbed and simulations demonstrate the effectiveness of our analysis for online admission control of real-time flows. I.
Maximizing network lifetime of wireless sensor-actuator networks under graph routing
- in Technical Report Number: WUCSE2015-004 (2015). All Computer Science and Engineering Research, 2015, http://openscholarship.wustl.edu/cse research/508/. [Online]. Available: http://openscholarship.wustl.edu/cse research/508
"... Process industries are adopting wireless sensor-actuator networks (WSANs) as the communication infrastructure. The dynamics of industrial environments and stringent reliability requirements necessitate high degrees of fault tolerance in routing. WirelessHART is an open industrial standard for WSANs ..."
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Process industries are adopting wireless sensor-actuator networks (WSANs) as the communication infrastructure. The dynamics of industrial environments and stringent reliability requirements necessitate high degrees of fault tolerance in routing. WirelessHART is an open industrial standard for WSANs that have seen world-wide deployments. WirelessHART employs graph routing schemes to achieve network reliability through multiple paths. Since many industrial devices operate on batteries in harsh environments where changing batteries are prohibitively labor-intensive, WSANs need to achieve long network lifetime. To meet industrial demand for long-term reliable communication, this paper studies the problem of maximizing network lifetime for WSANs under graph routing. We formulate the network lifetime maximization problem for WirelessHART networks under graph routing. Then, we propose the optimal algorithm and two more efficient algorithms to prolong the network lifetime of WSANs. Experiments in a physical testbed and simulations show our linear programming relaxation and greedy heuristics can improve the network lifetime by up to 50 % while preserving the reliability benefits of graph routing.... Read complete abstract on page 2.
Incorporating Emergency Alarms in Reliable Wireless Process Control
"... Recent years have witnessed adoption of wireless sensor-actuator networks (WSANs) in process control. Many real-world process control systems must handle various emer-gency alarms under stringent timing constraints in addition to regular control loops. However, despite considerable theo-retical resu ..."
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Recent years have witnessed adoption of wireless sensor-actuator networks (WSANs) in process control. Many real-world process control systems must handle various emer-gency alarms under stringent timing constraints in addition to regular control loops. However, despite considerable theo-retical results on wireless control, the problem of incorporat-ing emergency alarms in wireless control has received little attention. This paper presents, to the best of our knowl-edge, the first systematic approach to incorporate emergency alarms into wireless process control. The challenge in emer-gency communication lies in the fact that emergencies occur occasionally, but must be delivered within their deadlines when they occur. The contributions of this work are three-fold: (1) we propose efficient real-time emergency communi-cation protocols based on slot stealing and event-based com-munication; (2) we build an open-source WirelessHART pro-tocol stack in the Wireless Cyber-Physical Simulator (WCPS) for holistic simulations of wireless control systems; (3) we conduct systematic studies on a coupled water tank sys-tem controlled over a 6-hop 21-node WSAN. Our results demonstrate our real-time emergency communication ap-proach enables timely emergency handling, while allowing regular feedback control loops to effectively share resources in WSANs during normal operations.
Providing End-to-End Delay Guarantees for Multi-hop Wireless Sensor Networks over Unreliable Channels
, 2012
"... Abstract—Wireless sensor networks have been increas-ingly used for real-time surveillance over large areas. In such applications, it is important to support end-to-end delay constraints for packet deliveries even when the correspond-ing flows require multi-hop transmissions. In addition to delay con ..."
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Abstract—Wireless sensor networks have been increas-ingly used for real-time surveillance over large areas. In such applications, it is important to support end-to-end delay constraints for packet deliveries even when the correspond-ing flows require multi-hop transmissions. In addition to delay constraints, each flow of real-time surveillance may require some guarantees on throughput of packets that meet the delay constraints. Further, as wireless sensor networks are usually deployed in challenging environments, it is important to specifically consider the effects of unreliable wireless transmissions. In this paper, we study the problem of providing end-to-end delay guarantees for multi-hop wireless networks. We propose a model that jointly considers the end-to-end delay constraints and throughput requirements of flows, the need for multi-hop transmissions, and the unreliable nature of wireless transmissions. We develop scheduling policies for two types of systems and prove that they are optimal. We also conduct extensive simulations to show that our policies outperform other policies by large margins. I.
low jitter scheduling for industrial wireless sensor and actuator networks
- In Proceedings of the 39th Annual Conference of the IEEE Industrial Electronics Society
, 2013
"... Abstract-Applying Industrial Wireless Sensor and Actuator Networks (IWSANs) in the industrial automation is a growing trend due to flexibility, mobility and low cost. According to the current standards, such as WirelessHART and ISA100.11a, multichannel TDMA transmission is included for reliable and ..."
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Abstract-Applying Industrial Wireless Sensor and Actuator Networks (IWSANs) in the industrial automation is a growing trend due to flexibility, mobility and low cost. According to the current standards, such as WirelessHART and ISA100.11a, multichannel TDMA transmission is included for reliable and deterministic communication. In this paper, we clarify the dependence of TDMA scheduling for sensors and actuators and point out the low correlation between the scheduling delay and the overall quality of control, and focus on reducing jitter in scheduling for improving quality of control and system stability. We propose a scheduling algorithm, aiming for lowing jitter and compare it with two traditional real-time scheduling schemes. Our simulation results exhibit significantly lower jitters by applying our scheduling policy than those two traditional scheduling schemes.
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, 2015
"... To my parents, my wife, and my sister. ii ACKNOWLEDGMENTS I owe a great deal of appreciation to my advisor Dr. Hongwei Zhang. He has an amazing breath of knowledge and depth of vision. His remarkable dedication and determination for deep creative work is admirable, especially in the face of uncertai ..."
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To my parents, my wife, and my sister. ii ACKNOWLEDGMENTS I owe a great deal of appreciation to my advisor Dr. Hongwei Zhang. He has an amazing breath of knowledge and depth of vision. His remarkable dedication and determination for deep creative work is admirable, especially in the face of uncertainties inherent in open-ended research. Perhaps more importantly, he constantly pushes me to go beyond my intellectual limits and accomplish tasks I deem impossible previously, a challenge I am becoming more and more confident to tackle. He also showed that even top-notch researchers have to put their boots on the ground and go through the same hard thinking process as I do. They have no magic shortcut or trick, much to my surprise. This was especially liberating when I was overwhelmed by the fact that I have to compete with established, even world-renowned, professors to publish. My parents put me immensely in their debt for my upbringing. My mother always strives to be the best at her work among her peers, whether it is weaving shoes on a factory floor or attending crops in a field. Her work ethic of perseverance and diligence, even under extremely
WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Wirel. Commun. Mob. Comput. (2012) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/wcm.2238 RESEARCH ARTICLE
"... Multi-regional query scheduling in wireless sensor ..."
