| 1. |
- She, Huimin, et al.
(författare)
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A Network-based System Architecture for Remote Medical Applications
- 2007
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Ingår i: Proceedings of the Asia-Pacific Advanced Network Meeting.
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Konferensbidrag (refereegranskat)abstract
- Nowadays, the evolution of wireless communication and networktechnologies enables remote medical services to be availableeverywhere in the world. In this paper, a network-based systemarchitecture adopting wireless personal area network (WPAN)protocol IEEE 802.15.4/Zigbee standard and 3G communicationnetworks for remote medical applications is proposed. In theproposed system, the number and type of medical sensors arescalable depending on individual needs. This feature allows thesystem to be flexibly applied in several medical applications.Furthermore, a differentiated service using priority scheduling anddata compression is introduced. This scheme can not only reducetransmission delay for critical physiological signals and enhancebandwidth utilization at the same time, but also decrease powerconsumption of the hand-held personal server which uses batteryas the energy source.
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| 2. |
- She, Huimin, et al.
(författare)
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Analysis of Traffic Splitting Mechanisms for 2D Mesh Sensor Networks
- 2008
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Ingår i: International Journal of Software Engineering and Its Applications. - 1738-9984. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- For many applications of sensor networks, it is essential to ensure that messages aretransmitted to their destinations within delay bounds and the buffer size of each sensor nodeis as small as possible. In this paper, we firstly introduce the system model of a mesh sensornetwork. Based on this system model, the expressions for deriving the delay bound and bufferrequirement bound are presented using network calculus theory. In order to balance trafficload and improve resource utilization, three traffic splitting mechanisms are proposed. Andthe two bounds are derived in these traffic splitting mechanisms. To show how our methodapplies to real applications, we conduct a case study on a fresh food tracking application,which monitors the food freshness status in real-time during transportation. The numericalresults show that the delay bound and buffer requirement bound are reduced while applyingtraffic splitting mechanisms. Thus the performance of the whole sensor network is improvedwith less cost.
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| 3. |
- She, Huimin, et al.
(författare)
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Analytical Evaluation of Retransmission Schemes in Wireless Sensor Networks
- 2009
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Ingår i: 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE. - 9781424425167 ; , s. 38-42
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Konferensbidrag (refereegranskat)abstract
- Retransmission has been adopted as one of the most popular schemes for improving transmission reliability in wireless sensor networks. Many previous works have been done on reliable transmission issues in experimental ways, however, there still lack of analytical techniques to evaluate these solutions. Based on the traffic model, service model and energy model, we propose an analytical method to analyze the delay and energy metrics of two categories of retransmission schemes: hop-by-hop retransmission (HBH) and end-to-end retransmission (ETE). With the experiment results, the maximum packet transfer delay and energy efficiency of these two scheme are compared in several scenarios. Moreover, the analytical results of transfer delay are validated through simulations. Our experiments demonstrate that HBH has less energy consumption at the cost of lager transfer delay compared with ETE. With the same target success probability, ETE is superior on the delay metric for low bit-error-rate (BER) cases, while HBH is superior for high BER cases.
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| 4. |
- She, Huimin, et al.
(författare)
-
Deterministic Worst-case Performance Analysis for Wireless Sensor Networks
- 2008
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Ingår i: Proceedings of the International Wireless Communications and Mobile Computing Conference. - 9781424422029 ; , s. 1081-1086
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Konferensbidrag (refereegranskat)abstract
- Dimensioning wireless sensor networks requires formal methods to guarantee network performance and cost in any conditions. Based on network calculus, this paper presents a deterministic analysis method for evaluating the worst-case performance and buffer cost of sensor networks. To this end, we introduce three general traffic flow operators and derive their delay and buffer bounds. These operators are general because they can be used in combination to model any complex traffic flowing scenarios in sensor networks. Furthermore, our method integrates variable duty cycle to allow the sensor nodes to operate at lower rates thus saving power. Moreover, it incorporates traffic splitting mechanisms in order to balance network workload and nodes' buffers. To show how our method applies to real applications, we conduct a case study on a fresh food tracking application, which monitors the food freshness in realtime. The experimental results demonstrate that our method can be either used to perform network planning before deployment, or to conduct network reconfiguration after deployment.
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| 5. |
- She, Huimin, et al.
(författare)
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Modeling and Analysis of Rayleigh Fading Channels using Stochastic Network Calculus
- 2011
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Konferensbidrag (refereegranskat)abstract
- Deterministic network calculus (DNC) is not suitable for deriving performance guarantees for wireless networks due to their inherently random behaviors. In this paper, we develop a method for Quality of Service (QoS) analysis of wireless channels subject to Rayleigh fading based on stochastic network calculus. We provide closed-form stochastic service curve for the Rayleigh fading channel. With this service curve, we derive stochastic delay and backlog bounds. Simulation results verify that the bounds are reasonably tight. Moreover, through numerical experiments, we show the method is not only capable of deriving stochastic performance bounds, but also can provide guidelines for designing transmission strategies in wireless networks.
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| 6. |
- She, Huimin, 1982-
(författare)
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Performance Analysis and Deployment Techniques forWireless Sensor Networks
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recently, wireless sensor network (WSN) has become a promising technology with a wide range of applications such as supply chain monitoring and environment surveillance. It is typically composed of multiple tiny devices equipped with limited sensing, computing and wireless communication capabilities. Design of such networks presents several technique challenges while dealing with various requirements and diverse constraints. Performance analysis and deployment techniquesare required to provide insight on design parameters and system behaviors.Based on network calculus, a deterministic analysis method is presented for evaluating the worst-case delay and buffer cost of sensor networks. To this end,traffic splitting and multiplexing models are proposed and their delay and buffer bounds are derived. These models can be used in combination to characterize complex traffic flowing scenarios. Furthermore, the method integrates a variable duty cycle to allow the sensor nodes to operate at low rates thus saving power. In an attempt to balance traffic load and improve resource utilization and performance,traffic splitting mechanisms are introduced for sensor networks with general topologies. To provide reliable data delivery in sensor networks, retransmission has been one of the most popular schemes. We propose an analytical method to evaluate the maximum data transmission delay and energy consumption of two types of retransmission schemes: hop-by-hop retransmission and end-to-end retransmission.In order to validate the tightness of the bounds obtained by the analysis method, the simulation results and analytical results are compared with various input traffic loads. The results show that the analytic bounds are correct and tight.Stochastic network calculus has been developed as a useful tool for Qualityof Service (QoS) analysis of wireless networks. We propose a stochastic servicecurve model for the Rayleigh fading channel and then provide formulas to derive the probabilistic delay and backlog bounds in the cases of deterministic and stochastic arrival curves. The simulation results verify that the tightness of the bounds are good. Moreover, a detailed mechanism for bandwidth estimation of random wireless channels is developed. The bandwidth is derived from the measurement of statistical backlogs based on probe packet trains. It is expressed by statistical service curves that are allowed to violate a service guarantee with a certain probability. The theoretic foundation and the detailed step-by-step procedure of the estimation method are presented.One fundamental application of WSNs is event detection in a Field of Interest(FoI), where a set of sensors are deployed to monitor any ongoing events. To satisfy a certain level of detection quality in such applications, it is desirable that events in the region can be detected by a required number of sensors. Hence, an important problem is how to conduct sensor deployment for achieving certain coverage requirements. In this thesis, a probabilistic event coverage analysis methodis proposed for evaluating the coverage performance of heterogeneous sensor networks with randomly deployed sensors and stochastic event occurrences. Moreover,we present a framework for analyzing node deployment schemes in terms of three performance metrics: coverage, lifetime, and cost. The method can be used to evaluate the benefits and trade-offs of different deployment schemes and thus provide guidelines for network designers.
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| 7. |
- She, Huimin, et al.
(författare)
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Performance Analysis of Flow-Based Traffic Splitting Strategy on Cluster-Mesh Sensor Networks
- 2012
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Ingår i: International Journal of Distributed Sensor Networks. - : Hindawi Publishing Corporation. - 1550-1329 .- 1550-1477. ; , s. 232937-
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Tidskriftsartikel (refereegranskat)abstract
- Performance analysis is crucial for designing predictable and cost-efficient sensor networks. Based on the network calculus theory, we propose a flow-based traffic splitting strategy and its analytical method for worst-case performance analysis on cluster-mesh sensor networks. The traffic splitting strategy can be used to alleviate the problem of uneven network traffic load. The analytical method is able to derive close-form formulas for the worst-case performance in terms of the end-to-end least upper delay bounds for individual flows, the least upper backlog bounds, and power consumptions for individual nodes. Numerical results and simulations are conducted to show benefits of the splitting strategy as well as validate the analytical method. The numerical results show that the splitting strategy enables much better balance on network traffic load and power consumption. Moreover, the simulation results verify that the theoretic bounds are fairly tight.
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| 8. |
- She, Huimin, et al.
(författare)
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Stochastic Coverage in Event-Driven Sensor Networks
- 2011
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Ingår i: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC). - New York : IEEE. - 9781457713484 ; , s. 915-919
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Konferensbidrag (refereegranskat)abstract
- One of the primary tasks of sensor networks is to detect events in a field of interest (FoI). To quantify how well events are detected in such networks, coverage of events is a fundamental problem to be studied. However, traditional studies mostly focus on analyzing the coverage of the FoI, which is usually called are a coverage. In this paper, we propose an analytic method to evaluate the performance of event coverage in sensor networks with randomly deployed sensor nodes and stochastic event occurrences. We provide formulas to calculate the probabilities of event coverage and event missing. The numerical results show how these two probabilities change with the sensor and event densities. Moreover, simulations are conducted to validate the analytic method. This method can provide guidelines for determining the amount of sensor nodes to achieve a certain level of coverage in event-driven sensor networks.
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| 9. |
- She, Huimin, et al.
(författare)
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System-level evaluation of sensor networks deployment strategies : Coverage, lifetime and cost
- 2012
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Ingår i: 2012 8th International Wireless Communications And Mobile Computing Conference (IWCMC). - : IEEE. - 9781457713798 ; , s. 549-554
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Konferensbidrag (refereegranskat)abstract
- In wireless sensor networks, sensor nodes can be organized either randomly or deterministically according to regular deployment patterns. Due to the trade-offs between performance and cost, evaluating the advantages and disadvantages of node deployment strategies are fundamental issues to be solved. In this paper, we present a framework for analyzing node deployment schemes in terms of three performance metrics: coverage, lifetime, and cost. Based on the proposed coverage analysis model, energy model and cost model, we compare the performance of two node deployment schemes: rectangle mesh and uniformly random. The results show that the rectangle mesh scheme is generally better than the uniformly random scheme in terms of coverage and network lifetime. Our method can be used to evaluate the benefits of different deployment schemes and thus provide guidelines for network designers.
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| 10. |
- She, Huimin, et al.
(författare)
-
Traffic splitting with network calculus for mesh sensor networks
- 2007
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Ingår i: Proceedings of Future Generation Communication and Networking, FGCN 2007. - : IEEE Computer Society. - 9780769530482 ; , s. 371-376
-
Konferensbidrag (refereegranskat)abstract
- In many applications of sensor networks, it is essential to ensure that messages are transmitted to their destinations as early as possible and the buffer size of each sensor node is as small as possible. In this paper, we firstly propose a mesh sensor network system model. Based on this system model, the expressions for deriving the delay bound and buffer requirement bound are presented using network calculus. In order to balance traffic load and improve resource utilization, three traffic splitting mechanisms are proposed The numerical results show that the delay bound and buffer requirement bound are lowered while applying those traffic splitting mechanisms. And thus the performance of the whole sensor network is improved.
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