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International Conference on High Performance Computing, Network, Storage and Analysis; 01/2012
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ABSTRACT: Stealthy packet dropping is a suite of four attacks-misrouting, power control, identity delegation, and colluding collision-that can be easily launched against multihop wireless ad hoc networks. Stealthy packet dropping disrupts the packet from reaching the destination through malicious behavior at an intermediate node. However, the malicious node gives the impression to its neighbors that it performs the legitimate forwarding action. Moreover, a legitimate node comes under suspicion. A popular method for detecting attacks in wireless networks is behavior-based detection performed by normal network nodes through overhearing the communication in their neighborhood. This leverages the open broadcast nature of wireless communication. An instantiation of this technology is local monitoring. We show that local monitoring, and the wider class of overhearing-based detection, cannot detect stealthy packet dropping attacks. Additionally, it mistakenly detects and isolates a legitimate node. We present a protocol called Sadec that can detect and isolate stealthy packet dropping attack efficiently. Sadec presents two techniques that can be overlaid on baseline local monitoring: having the neighbors maintain additional information about the routing path, and adding some checking responsibility to each neighbor. Additionally, Sadec provides an innovative mechanism to better utilize local monitoring by considerably increasing the number of nodes in a neighborhood that can do monitoring. We show through analysis and simulation experiments that baseline local monitoring fails to efficiently mitigate most of the presented attacks while SADEC successfully mitigates them.
IEEE Transactions on Mobile Computing 09/2011; · 2.28 Impact Factor
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ABSTRACT: The US Network for Earthquake Engineering Simulation (NEES) operates a shared network of civil engineering experimental facilities aimed at facilitating research on mitigating earthquake damage and loss of life. The NEEShub gateway was created in response to the NEES community's needs, combining data, simulation, and analysis functionality with collaboration tools.
Computing in Science and Engineering 09/2011; · 1.42 Impact Factor
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ABSTRACT: As smart phones grow in popularity, manufacturers are in a race to pack an increasingly rich set of features into these tiny devices. This brings additional complexity in the system software that has to fit within the constraints of the devices (chiefly memory, stable storage, and power consumption) and hence, new bugs are revealed. How this evolution of smartphones impacts their reliability is a question that has been largely unexplored till now. With the release of open source OSes for hand-held devices, such as, Android (open sourced in October 2008) and Symbian (open sourced in February 2010), we are now in a position to explore the above question. In this paper, we analyze the reported cases of failures of Android and Symbian based on bug reports posted by third-party developers and end users and documentation of bug fixes from Android developers. First, based on 628 developer reports, our study looks into the manifestation of failures in different modules of Android and their characteristics, such as, their persistence and dependence on environment. Next, we analyze similar properties of Symbian bugs based on 153 failure reports. Our study indicates that Development Tools, Web Browsers, and Multimedia applications are most error-prone in both these systems. We further analyze 233 bug fixes for Android and categorized the different types of code modifications required for the fixes. The analysis shows that 77% of errors required minor code changes, with the largest share of these coming from modifications to attribute values and conditions. Our final analysis focuses on the relation between customizability, code complexity, and reliability in Android and Symbian. We find that despite high cyclomatic complexity, the bug densities in Android and Symbian are surprisingly low. However, the support for customizability does impact the reliability of mobile OSes and there are cautionary tales for their further development.
Software Reliability Engineering (ISSRE), 2010 IEEE 21st International Symposium on; 12/2010
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ABSTRACT: Because of transient wireless link failures, incremental node deployment, and node mobility, existing information dissemination protocols used in wireless ad-hoc and sensor networks cause nodes to periodically broadcast "advertisement" containing the version of their current data item even in the "steady state" when no dissemination is being done. This is to ensure that all nodes in the network are up-to-date. This causes a continuous energy expenditure during the steady state, which is by far the dominant part of a network's lifetime. In this paper, we present a protocol called Varuna which incurs a constant energy cost, independent of the duration of the steady state. In Varuna, nodes monitor the traffic pattern of the neighboring nodes to decide when an advertisement is necessary. Using testbed experiments and simulations, we show that Varuna achieves several orders of magnitude energy savings compared to Trickle, the existing standard for dissemination in sensor networks, at the expense of a reasonable amount of memory for state maintenance.
Reliable Distributed Systems, 2010 29th IEEE Symposium on; 12/2010
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ABSTRACT: Data aggregation in wireless sensor networks is vulnerable to security attacks and natural failures. A few nodes can drastically alter the result of the aggregation by reporting erroneous data. In this paper we present RDAS, a robust data aggregation protocol that uses a reputation based approach to identify and isolate malicious nodes in a sensor network. RDAS is based on a hierarchical clustering arrangement of nodes, where a cluster head analyzes data from the cluster nodes to determine the location of an event. It uses the redundancy of multiple nodes sensing an event to determine what data should have been reported by each node. Nodes form part of a distributed reputation system, where they share information about other node's performance in reporting accurate data and use the reputation ratings to suppress reports from malicious nodes. RDAS is able to perform accurate data aggregation in the presence of individually malicious and colluding nodes, as well as nodes that try to compromise the integrity of the reputation system by lying about other nodes' behavior. We show that RDAS is more resilient to security attacks with respect to accuracy of event localization than the baseline data aggregation protocol with no security feature.
Sensor Mesh and Ad Hoc Communications and Networks (SECON), 2010 7th Annual IEEE Communications Society Conference on; 07/2010
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ABSTRACT: Ad-hoc wireless networks are being deployed in critical applications that require protection against sophisticated adversaries. However, wireless routing protocols, such as the widely-used AODV, are often designed with the assumption that nodes are benign. Cryptographic extensions such as Secure AODV (SAODV) protect against some attacks but are still vulnerable to easily-performed attacks using colluding adversaries, such as the wormhole attack. In this paper, we make two contributions to securing routing protocols. First, we present a protocol called route verification (RV) that can detect and isolate malicious nodes involved in routing-based attacks with very high likelihood. However, RV is expensive in terms of energy consumption due to its radio communications. To remedy the high energy cost of RV, we make our second contribution. We propose a multigrade monitoring (MGM) approach. The MGM approach employs a previously developed lightweight local monitoring technique to detect any necessary condition for an attack to succeed. However, local monitoring suffers from false positives due to collisions on the wireless channel. When a necessary condition is detected, the heavy-weight RV protocol is triggered. We show through simulation that MGM applied to AODV generally requires little extra energy compared to baseline AODV, under the common case where there is no attack present. It is also more resource-efficient and powerful than SAODV in detecting attacks. Our work, for the first time, lays out the framework of multigrade monitoring, which we believe fundamentally addresses the tension between security and resource consumption in ad-hoc wireless networks.
Mobile Adhoc and Sensor Systems, 2009. MASS '09. IEEE 6th International Conference on; 11/2009
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ABSTRACT: There has been significant recent interest in covert communication using timing channels. In network timing channels, information is leaked by controlling the time between transmissions of consecutive packets. Our work focuses on network timing channels and provides two main contributions. The first is to quantify the threat posed by covert network timing channels. The other is to use timing channels to communicate at a low data rate without being detected. In this paper, we design and implement a covert TCP/IP timing channel. We are able to quantify the achievable data rate (or leak rate) of such a covert channel. Moreover, we show that by sacrificing data rate, the traffic patterns of the covert timing channel can be made computationally indistinguishable from that of normal traffic, which makes detecting such communication virtually impossible. We demonstrate the efficacy of our solution by showing significant performance gains in terms of both data rate and covertness over the state-of-the-art.
INFOCOM 2009, IEEE; 05/2009
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ABSTRACT: Wireless reprogramming of sensor nodes is a requirement for long-lived networks due to changes in the functionality of the software running on the nodes. The amount of information that needs to be wirelessly transmitted during reprogramming should be minimized to reduce reprogramming time and energy. In this paper, we present a multi-hop incremental reprogramming protocol called Hermes that transfers over the network the delta between the old and new software and lets the sensor nodes rebuild the new software using the received delta and the old software. It reduces the delta by using techniques to mitigate the effects of function and global variable shifts caused by the software modifications. Then it compares the binary images at the byte level with a method to create small delta. For a wide range of software change scenarios that we experimented with, we find that Hermes transfers up to 201 times less information than Deluge, the standard reprogramming protocol for TinyOS and 64 times less than an existing incremental reprogramming protocol by Jeong and Culler.
INFOCOM 2009, IEEE; 05/2009
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ABSTRACT: We describe a discrete event simulator developed for daily prediction of WIP position in an operational 300 mm wafer fabrication factory to support tactical decision-making. The simulator is distinctive in that its intended prediction horizon is relatively short, on the order of a few days, while its modeling scope is relatively large. The simulation includes over 90% of the wafers being processed in the fab and all process, measurement and testing tools. The model parameters are automatically updated using statistical analyses performed on the historical event logs generated by the factory. This paper describes the simulation model and the parameter estimation methods. A key requirement to support daily and weekly decision-making is good validation results of the simulation against actual fab performance. Therefore, we also present validation results that compare simulated production metrics against those obtained from the actual fab, for fab-wide, process, tool and product specific metrics.
Simulation Conference, 2008. WSC 2008. Winter; 01/2009
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ABSTRACT: In several computer engineering and computer science courses, it has been observed that active learning activities (ALAs) aid the students in better understanding of the technical material. In this paper, we explore the influence of the type of the ALA and the academic quality of the student on the effectiveness of the technique. We perform the study in two junior level courses-a course on discrete mathematics as applied to computer engineering topics and an ASIC (Application-Specific Integrated Circuit) design course. The first course has no laboratory component and teaches several abstract mathematical concepts. The latter course deals with the design of digital circuits using the VHDL hardware description language and has a laboratory component. We conduct ALAs of three kinds-solving problems in-class with active participation of the students; homework problems which are worked on collaboratively by the students and with solutions provided later; and, practice examinations handed out before the actual examination which the students are encouraged to solve in groups. The effect on the students is measured through examination questions. Looking at the aggregate class performance, the ALAs through in-class questions and homeworks do not appear to have a significant effect, while the practice examination questions do. However, on segmenting the data, we observe that the ldquoArdquo students benefited from the in-class ALAs while both ldquoArdquo and ldquoBrdquo students benefited from the practice examinations. The worst performing students did not benefit significantly from any of the ALAs. This study leads us to investigate further the possibility of tailoring the ALA to the different learning styles and academic calibers of the students.
Frontiers in Education Conference, 2008. FIE 2008. 38th Annual; 11/2008
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ABSTRACT: While the effect of service learning in technology-based curriculum has been documented, it is as yet unknown what benefits or challenges are felt by the students when the technologies being applied in their service learning course lie in the research domain. We investigate these questions through a study carried out in the context of a service learning program called EPICS, in which teams of undergraduates develop real systems to address engineering and computing-based needs for a local community partner. Through a questionnaire, we study the studentspsila perception of the availability of resources and skills for their project, and their perception of the value add of the project to their curriculum. The experimental group consists of teams that use cutting-edge research technologies in their projects. The control group consists of teams that develop prototypes using mature technologies. The study uncovered that neither group of students felt hampered by a lack of resources or skills. However, the control group felt greater ease in dealing with the community partner. It is hoped that this effort will serve to increase the viability of integrating research and service learning activities.
Frontiers in Education Conference, 2008. FIE 2008. 38th Annual; 11/2008
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ABSTRACT: Wireless reprogramming of a sensor network is useful for uploading new code or for changing the functionality of existing code. Through the process, a node should remain receptive to future code updates because reprogramming may be done multiple times during the node's lifetime. Existing reprogramming protocols, such as Deluge, achieve this by bundling the reprogramming protocol and the application as one program image, thereby increasing the overall size of the image which is transferred through the network. This increases both time and energy required for network reprogramming. We present a protocol called Stream that mitigates the problem by significantly reducing the size of the program image. Using the facility of having multiple code images on a node and switching between them, Stream pre-installs the reprogramming protocol as one image and the application program equipped with the ability to listen to new code updates as the second image. For a sample application, Stream reduces the size of the program image by 10 pages (48 packets/page) compared to Deluge. Stream is implemented on the Mica2 nodes and we conduct testbed and simulation experiments to show the reduction in energy and reprogramming time of Stream compared to Deluge.
INFOCOM 2007. 26th IEEE International Conference on Computer Communications. IEEE; 06/2007
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L. Mathew,
M. Sadd,
S. Kalpat,
M. Zavala,
T. Stephens,
R. Mora, S. Bagchi,
C. Parker,
J. Vasek,
D. Sing, [......],
G. Ablen,
Z. Shi,
J. Saenz,
B. Min,
D. Burnett,
B.-Y. Nguyen,
J. Mogab,
M.M. Chowdhury,
W. Zhang,
J.G. Fossum
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ABSTRACT: In this paper we demonstrate for the first time a novel CMOS IT-FET (inverted T channel FET) architecture. We demonstrate well functional ITFET SRAM bit-cells. Vertical devices such as FinFET and planar ultra thin body devices have been shown to exhibit good short channel control and proposed for future device scaling. The ITFET is novel device architecture that takes advantage of both vertical and horizontal thin-body devices. A doped channel IT-FET process has been developed and is the focus of this paper. This technology can be scaled beyond 45nm technologies using undoped channels. An ITFET device comprises of an ultra thin body planar horizontal channels and vertical channels in a single device. The devices have multi-gate control around these channels to improve short channel control. A single device has multiple orientations and hence mobility enhancement of both (110) and (100) planes can be used optimally. The devices presented have 15nm planar horizontal thin body and 40nm vertical channels of 100nm height, 17Aring gate dielectric and 50nm gate length. These devices are especially useful in circuits that need ratioing such as in SRAM cells and a well functional SRAM cell is demonstrated
Electron Devices Meeting, 2005. IEDM Technical Digest. IEEE International; 01/2006
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ABSTRACT: In this paper, we investigate the use of multiple directional antennas on sensor motes for location determination and mobile node monitoring. One key aspect that distinguishes wireless sensor networks is inexpensive transmitters and receivers that still maintain acceptable connectivity. Therefore, complex RF solutions are often not applicable. We propose and demonstrate a location estimation algorithm on a single sensor node equipped with inexpensive directional antennas by measuring the received signal strength of the transmission peers. This algorithm is further applied to the dynamic tracking of a wandering mote. The location tracking error can be reduced from 30% to 16% by using moving average schemes and merging estimates from different sets of antennas. The mean error of tracking estimates can be obtained to provide the certainty of location tracking. Therefore, only a single mote with angular diverse multiple antennas is needed to determine the location of a mote without triangulation.
Microwave Symposium Digest, 2005 IEEE MTT-S International; 07/2005
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D. Zhang,
B.Y. Nguyen,
T. White,
B. Goolsby,
T. Nguyen,
V. Dhandapani,
J. Hildreth,
M. Foisy,
V. Adams,
Y. Shiho, [......],
C. Werkhoven,
H. Kirby,
C.H. Chang,
C.T. Lin,
H.C. Tuan,
Y.C. See,
S. Venkatesan,
V. Kolagunta,
N. Cave,
J. Mogab
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ABSTRACT: We report for the first time PMOS drive current enhancement with in-situ boron doped SiGe incorporation in recessed S/D regions for devices built on thin body SOI substrate. For P-channel PD-SOI devices with 450 A silicon on insulator and 38nm gate length, 35% linear drain current enhancement and 20% saturation drain current improvement have been achieved with this approach. Device integration and performance improvement are discussed below.
VLSI Technology, 2005. Digest of Technical Papers. 2005 Symposium on; 07/2005
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ABSTRACT: We describe an IBM strategic consulting offering involving a methodology and an analytic tool. The methodology, the Risk and Opportunity Assessment, provides a systematic approach for diagnosing problems in the value chain of the enterprise, and for selecting and prioritizing e-business initiatives. Applying this methodology involves the use of an analytic tool, the Value Chain Modeling Tool, that uses management science and operations research techniques, as well as techniques from the domains of finance and supply chain management, to model the end-to-end value chain of the enterprise. This approach has been successfully used to improve the financial and operating performance of several enterprises.
Ibm Systems Journal 02/2003; · 1.29 Impact Factor
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S.B. Samavedam,
H.H. Tseng,
P.J. Tobin,
J. Mogab,
S. Dakshina-Murthy,
L.B. La,
J. Smith,
J. Schaeffer,
M. Zavala,
R. Martin, [......],
M. Moosa,
D.C. Gilmer,
C. Hobbs,
W.J. Taylor,
J.M. Grant,
R. Hegde, S. Bagchi,
E. Luckowski,
V. Arunachalam,
M. Azrak
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ABSTRACT: We report for the first time electrical characterization of HfO<sub>2</sub> p- and n-MOSFETs with CVD TiN and PVD TaSiN gates respectively fabricated using conventional CMOS integration. Their performance is compared to PVD TiN-gated HfO<sub>2</sub> and SiO<sub>2</sub> n- and p-MOSFETs. To understand the issues with metal gates on high K gate dielectrics, PVD TiN MOSFETs were extensively characterized. At 10 nA/μm leakage, 0.345 mA/μm drive current was obtained from PVD TiN/HfO<sub>2</sub> p-MOSFETs. HfO<sub>2</sub> n-MOSFETs with metal gates show about 10<sup>4</sup> times reduction in gate leakage compared to poly/SiO<sub>2</sub> devices.
VLSI Technology, 2002. Digest of Technical Papers. 2002 Symposium on; 02/2002
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C. Hobbs,
L. Dip,
K. Reid,
D. Gilmer,
R. Hegde,
T. Ma,
B. Taylor,
B. Cheng,
S. Samavedam,
H. Tseng, [......],
M. Rendon,
L. Prabhu,
R. Rai, S. Bagchi,
J. Conner,
S. Backer,
F. Dumbuya,
J. Locke,
D. Workman,
P. Tobin
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ABSTRACT: MOSFETs with a zirconium dioxide (ZrO<sub>2</sub>) gate dielectric
and poly-silicon gate were fabricated using a low temperature CMOS
process. Well-behaved transistor characteristics were obtained for
devices with sizes of 14 μm×1.4 μm or smaller. Devices 14
μm×14 μm or larger were found to be nonfunctional due to the
formation of Zr-silicide at the polySi-gate/Zr0<sub>2</sub> interface.
In this paper, we present results on the electrical and physical
characterization
VLSI Technology, Systems, and Applications, 2001. Proceedings of Technical Papers. 2001 International Symposium on; 02/2001
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C. Hobbs,
H. Tseng,
K. Reid,
B. Taylor,
L. Dip,
L. Hebert,
R. Garcia,
R. Hegde,
J. Grant,
D. Gilmer, [......],
V. Dhandapani,
M. Azrak,
L. Prabhu,
R. Rai, S. Bagchi,
J. Conner,
S. Backer,
F. Dumbuya,
B. Nguyen,
P. Tobin
[show abstract]
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ABSTRACT: We report here for the first time the formation of an amorphous
oxide layer between the polysilicon gate and hafnium oxide (HfO<sub>2
</sub>) gate dielectric due to a lateral oxidation mechanism at the gate
edge. Using a polySi reoxidation-free CMOS process, well behaved 80 nm
MOSFETs were fabricated with no evidence of lateral oxidation. A CETinv
of 25 Å with a leakage current 1000× lower than SiO<sub>2
</sub> was obtained for a 30 Å HfO<sub>2</sub>/12 Å
interfacial oxide stack. In this paper, we present results on the
physical and electrical characterization
Electron Devices Meeting, 2001. IEDM Technical Digest. International; 02/2001
