摘要 :
In large-scale wireless sensor networks, faulty link detection plays a critical role in network diagnosis and management. Most potential network bottlenecks such as network partition and routing errors can be detected by link scan...
展开
In large-scale wireless sensor networks, faulty link detection plays a critical role in network diagnosis and management. Most potential network bottlenecks such as network partition and routing errors can be detected by link scan. Since sequentially checking all potential links incurs high transmission and storage cost, we propose a passive scheme Link Scanner (LS) for monitoring wireless links. As we know, to maintain a sensor network running in a normal condition, many applications in flooding manner are necessary, such as time synchronization, reprogramming, protocol update, etc. During such regular flooding processes that for other purposes originally, LS passively collects hop counts of received probe messages at sensor nodes. Based on the observation that faulty links can result in mismatch between received hop counts and network topology, LS deduces all links' status with a probabilistic model. We evaluate our scheme by carrying out experiments on a testbed with 60 TelosB motes and conducting extensive simulation tests. A real outdoor system is also deployed to verify that LS can be reliably applied to surveillance networks.
收起
摘要 :
IPTV is increasingly being deployed and offered as a commercial service to residential broadband customers. Compared with traditional ISP networks, an IPTV distribution network (ⅰ) typically adopts a hierarchical instead of mesh-...
展开
IPTV is increasingly being deployed and offered as a commercial service to residential broadband customers. Compared with traditional ISP networks, an IPTV distribution network (ⅰ) typically adopts a hierarchical instead of mesh-like structure, (ⅱ) imposes more stringent requirements on both reliability and performance, (ⅲ) has different distribution protocols (which make heavy use of IP multicast) and traffic patterns, and (ⅳ) faces more serious scalability challenges in managing millions of network elements. These unique characteristics impose tremendous challenges in the effective management of IPTV network and service.
In this paper, we focus on characterizing and troubleshooting performance issues in one of the largest IPTV networks in North America. We collect a large amount of measurement data from a wide range of sources, including device usage and error logs, user activity logs, video quality alarms, and customer trouble tickets. We develop a novel diagnosis tool called Giza that is specifically tailored to the enormous scale and hierarchical structure of the IPTV network. Giza applies multi-resolution data analysis to quickly detect and localize regions in the IPTV distribution hierarchy that are experiencing serious performance problems. Giza then uses several statistical data mining techniques to troubleshoot the identified problems and diagnose their root causes. Validation against operational experiences demonstrates the effectiveness of Giza in detecting important performance issues and identifying interesting dependencies. The methodology and algorithms in Giza promise to be of great use in IPTV network operations.
收起
摘要 :
In wireless sensor networks (WSNs), diagnosis is a crucial and challenging task due to the distributed nature and stringent resources. Most previous approaches are supervised, relying on a-priori knowledge of network faults. Our e...
展开
In wireless sensor networks (WSNs), diagnosis is a crucial and challenging task due to the distributed nature and stringent resources. Most previous approaches are supervised, relying on a-priori knowledge of network faults. Our experience with GreenOrbs, a long-term large-scale WSN system, reveals the need of diagnosis in an agnostic manner. Specifically, in addition to predefined faults (i.e., with known types and symptoms), silent failures that are unknown beforehand, account for a large fraction of network performance degradation. Currently, there is no effective solution for silent failures because they are often diverse and highly system-related. In this paper, we propose Agnostic Diagnosis (AD), an online lightweight failure detection approach. AD is motivated by the fact that the system metrics (e.g., radio-on time, number of packets transmitted) of sensor nodes usually exhibit certain correlation patterns. Violations of such patterns indicate potential silent failures. We implement AD on a working WSN consisting of 330 nodes. Our experimental results demonstrate the advantages of AD to discover silent failures, effectively expanding the capacity and scope of WSN diagnosis.
收起
摘要 :
In this paper we consider the problem of identifying faulty (crashed) nodes in a wireless sensor network. This problem is of fundamental importance in those applicative scenarios of wireless sensor networks in which battery replac...
展开
In this paper we consider the problem of identifying faulty (crashed) nodes in a wireless sensor network. This problem is of fundamental importance in those applicative scenarios of wireless sensor networks in which battery replacement is feasible. The diagnostic information gathered by operational sensors can be used by an external operator for the sake of network reconfiguration and/or repair; thus extending network lifetime. A fault diagnosis protocol specifically designed for wireless sensor networks is introduced and analyzed. The protocol is proved to be optimal and energy efficient under certain assumptions.
收起
摘要 :
Effective network troubleshooting is critical for maintaining efficient and reliable network operation. Troubleshooting is especially challenging in multihop wireless networks because the behavior of such networks depends on compl...
展开
Effective network troubleshooting is critical for maintaining efficient and reliable network operation. Troubleshooting is especially challenging in multihop wireless networks because the behavior of such networks depends on complicated interactions between many unpredictable factors such as RF noise, signal propagation, node interference, and traffic flows. In this paper we propose a new direction for research on fault diagnosis in wireless networks. Specifically, we present a diagnostic system that employs trace-driven simulations to detect faults and perform root cause analysis. We apply this approach to diagnose performance problems caused by packet dropping, link congestion, external noise, and MAC misbehavior. In a 25 node multihop wireless network, we are able to diagnose over 10 simultaneous faults of multiple types with more than 80% coverage. Our framework is general enough for a wide variety of wireless and wired networks.
收起
摘要 :
Safety and optimality are crucial requirements in every industrial process.The success of any fault diagnosis technique depends critically on the sensors measuring the important process variables.Choosing an appropriate sensor net...
展开
Safety and optimality are crucial requirements in every industrial process.The success of any fault diagnosis technique depends critically on the sensors measuring the important process variables.Choosing an appropriate sensor network is a combinato-rially difficult problem,especially when the number of potential measurements is large.There has been considerable amount of work that has been done on developing algorithms for sensor network design for fault diagnosis based on quantitative and qualitative models.Various objectives,such as cost,reliability and fault resolution have been used in the sensor network design.While these design algorithms can provide the best design locations for a given cost,the value of the sensor network for fault diagnosis or benefit accrued is usually not quantified in a manner that is transparent to the user.This is an important aspect that needs to be addressed if these algorithms have to be assimilated into industrial practice.An approach for characterizing the value of a sensor network from a fault diagnosis perspective is proposed.This notion of value can be used directly in sensor network design algorithms.The proposed concepts are explained through a simple example and numerical simulations of a CSTR.
收起
摘要 :
Network diagnosis, an essential research topic for traditional networking systems, has not received much attention for wireless sensor networks (WSNs). Existing sensor debugging tools like sympathy or EmStar rely heavily on an add...
展开
Network diagnosis, an essential research topic for traditional networking systems, has not received much attention for wireless sensor networks (WSNs). Existing sensor debugging tools like sympathy or EmStar rely heavily on an add-in protocol that generates and reports a large amount of status information from individual sensor nodes, introducing network overhead to the resource constrained and usually traffic-sensitive sensor network. We report our initial attempt at providing a lightweight network diagnosis mechanism for sensor networks. We further propose PAD, a probabilistic diagnosis approach for inferring the root causes of abnormal phenomena. PAD employs a packet marking scheme for efficiently constructing and dynamically maintaining the inference model. Our approach does not incur additional traffic overhead for collecting desired information. Instead, we introduce a probabilistic inference model that encodes internal dependencies among different network elements for online diagnosis of an operational sensor network system. Such a model is capable of additively reasoning root causes based on passively observed symptoms. We implement the PAD prototype in our sea monitoring sensor network test-bed. We also examine the efficiency and scalability of this design through extensive trace-driven simulations.
收起
摘要 :
This paper aims to propose a Session Initiation Protocol (SIP) automatic debugger tool. It is a software instrument that will be used to verify the compliance of Voice over Internet Protocol (VoIP) devices, such as soft phones an...
展开
This paper aims to propose a Session Initiation Protocol (SIP) automatic debugger tool. It is a software instrument that will be used to verify the compliance of Voice over Internet Protocol (VoIP) devices, such as soft phones and VoIP gateways to the SIP specifications, and to test the interoperability of VoIP equipment produced by different manufacturers. Different tools are available on the market to conduct a compliance and interoperability validation phase. However, they often have features limited to packet capturing and decoding, or they are simulation tools that often require a complex developing phase to define the behavior of each test. The proposed tool, instead, can be inserted into an SIP network and is capable of observing and analyzing, in an automatic way, the communication steps. It operates by executing three subsequent phases. In the first phase, the SIP messages flowing in the network are captured. Then, a second phase is in charge of grouping SIP messages into transactions and dialog. Finally, a third phase operates by comparing the message flow with a set of predefined rules. Rules have been classified in two groups. Rules belonging to the first group, called static rules, have been obtained by the direct analysis of SIP specifications. Rules belonging to the second group, called dynamic rules, have been obtained by experience with SIP compliance and interoperability testing (with the support of SIP testing experts). When verification of some rules fails, an output is reported by indicating the rule that failed and a list of possible fault causes. The tool has been validated in a laboratory network in different scenarios. Some sample test cases, which have been extracted by these scenarios and show the capability of the SIP automatic debugger tool in finding compliance and interoperability faults, are also presented in this paper.
收起
摘要 :
In this investigation, a new design based on a PANDA ring resonator as an optical trapping tool for tangle protein, molecular motor storage, and delivery is proposed. The optical vortices are generated and the trapping mechanism i...
展开
In this investigation, a new design based on a PANDA ring resonator as an optical trapping tool for tangle protein, molecular motor storage, and delivery is proposed. The optical vortices are generated and the trapping mechanism is controlled in the same way as the conventional optical tweezers. The trapping force is produced by a combination of the gradient field and scattering photons. The required molecular volume is trapped and moved dynamically within the molecular network. The tangle protein and molecular motor can be transported and delivered to the required destinations for Alzheimer's diagnosis by molecular buffer and bus network.
收起
摘要 :
Alzheimer's disease is the third most expensive disease, only after cancer and cardiopathy. It is also the fourth leading cause of death in the elderly after cardiopathy, cancer, and cerebral palsy. The disease lacks specific diag...
展开
Alzheimer's disease is the third most expensive disease, only after cancer and cardiopathy. It is also the fourth leading cause of death in the elderly after cardiopathy, cancer, and cerebral palsy. The disease lacks specific diagnostic criteria. At present, there is still no definitive and effective means for preclinical diagnosis and treatment. It is the only disease that cannot be prevented and cured among the world's top ten fatal diseases. It has now been proposed as a global issue. Computer-aided diagnosis of Alzheimer's disease (AD) is mostly based on images at this stage. This project uses multi-modality imaging MRI/PET combining with clinical scales and uses deep learning-based computer-aided diagnosis to treat AD, improves the comprehensiveness and accuracy of diagnosis. The project uses Bayesian model and convolutional neural network to train experimental data. The experiment uses the improved existing network model, LeNet-5, to design and build a 10-layer convolutional neural network. The network uses a back-propagation algorithm based on a gradient descent strategy to achieve good diagnostic results. Through the calculation of sensitivity, specificity and accuracy, the test results were evaluated, good test results were obtained.
收起
原文获取