bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards highly optimized real-time middleware for software product-line architectures
Authors: Krishna Arvind S. , Gokhale Aniruddha , Schmidt Douglas C. , Ranganath Venkatesh Prasad , Hatcliff John
Published: September 2007

This paper provides the following contributions to the study of middleware optimization techniques for product line architectures in real-time systems. First, we identify different dimensions of generality in standards based middleware implementations. Second, we describe how specialization approaches used in other domains including OS, compiler and programming languages can be applied to address middleware generality challenges. Third, we present preliminary results from the application of our specialization techniques. Our results illustrate that specialization techniques represent a promising approach for minimizing time/space overheads in middleware.
Stream combination
Authors: Liu Bin , Rangaswami Raju , Dimitrijevic Zoran
Published: September 2007

Cycle-based IO schedulers use statically configured time-cycle durations. As a result, they are unable to avoid the formation of virtual bottlenecks. We term a bottleneck as virtual when it occurs within a single resource subsystem, and it is possible to use a secondary under-utilized resource to thwart the bottleneck. The primary reason for virtual bottlenecks in streaming servers is static allocation of memory and disk-bandwidth resources using fixed time-cycle durations. As a result, shifting request workload can cause a virtual bottleneck either in the memory or disk subsystem. We present stream combination, an adaptive IO scheduling technique that addresses this problem in a comprehensive fashion. Stream combination predicts the formation of virtual bottlenecks and proactively alters the IO schedule to avoid them. A simulation study suggests significant performance gains compared to the current state-of-the-art fixed time-cycle IO scheduler.
Towards security and QoS optimization in real-time embedded systems
Authors: Kang Kyoung-Don , Son Sang H.
Published: September 2007

A number of real-time embedded systems (RTESs) are used to manage critical infrastructure such as electric grids or C
4
I systems. In these systems, it is essential to meet deadlines, for example, to avoid a power outage or loss of a life. The importance of security support is also increasing, because more RTESs are being networked. To securely transmit sensitive data, e.g., a battle field status, across the network, RTESs need to protect the data via cryptographic techniques. However, security support may cause deadline misses or unacceptable QoS degradation. As an initial effort to address this problem, we formulate the security support in RTESs as a QoS optimization problem. Also, we propose a novel adaptive approach for security support in which a RTES initially uses a relatively short cryptographic key to maximize the QoS, while increasing the key length when the security risk level is raised. In this way, we can make a possible cryptanalysis several orders of magnitude harder by requiring the attacker to search a larger key space, while meeting all deadlines by degrading the QoS in a controlled manner. To minimize the overhead, we derive the appropriate QoS levels for several key lengths via an offine polynomial time algorithm. When the risk level is raised online, a real-time task can use a longer key and adapt to the corresponding QoS level (derived offine) in O(1) time.
Predictive thermal management for hard real-time tasks
Authors: Cheng Albert Mo Kim , Feng Chen
Published: September 2007

Dynamic thermal management (DTM) techniques help a system to operate within a safe range of temperature by reducing the performance of the CPU dynamically when the system is too hot. Dynamic voltage scaling (DVS) and localized toggling are both DTM techniques. DVS is easier to use for real-time systems since the performance degradation can be controlled accurately so that tasks are still meeting their deadlines. Localized toggling changes architectural configurations of a CPU to a less optimized setting. Its performance degradation is harder to measure and to control accurately. In this paper, we propose a method which applies various localized toggling techniques to real-time systems while still able to meet task deadlines. Our method activates DTM when the temperature over the execution of a job is predicted to be too high at the start time. When DTM is activated, our method measures the performance degradation of different toggling techniques during the slack time to select the most effective technique and still be able to meet deadline. We use instructions per cycle (IPC) as the performance measure. Our method is evaluated on the SimpleScalar CPU simulator with Wattch, the energy simulator, and HotSpot, the thermal model.
Computing Gröbner bases of ideals of few points in high dimensions
Authors: Just Winfried , Stigler Brandilyn
Published: September 2007

A contemporary and exciting application of Gröbner bases is their use in computational biology, particularly in the reverse engineering of gene regulatory networks from experimental data. In this setting, the data are typically limited to tens of points, while the number of genes or variables is potentially in the thousands. As such data sets vastly underdetermine the biological network, many models may fit the same data and reverse engineering programs often require the use of methods for choosing parsimonious models. Gröbner bases have recently been employed as a selection tool for polynomial dynamical systems that are characterized by maps in a vector space over a finite field.

While there are numerous existing algorithms to compute Gröbner bases, to date none has been specifically designed to cope with large numbers of variables and few distinct data points. In this paper, we present an algorithm for computing Gröbner bases of zero-dimensional ideals that is optimized for the case when the numbermof points is much smaller than the numbernof indeterminates. The algorithm identifies those variables that areessential, that is, in the support of the standard monomials associated to a polynomial ideal, and computes the relations in the Gröbner basis in terms of these variables. Whennis much larger thanm, the complexity is dominated bynm3. The algorithm has been implemented and tested in the computer algebra systemMacaulay 2. We provide a comparison of its performance to the Buchberger-Möller algorithm, as built into the system.
"Approximate Commutative Algebra"
Authors: Stetter Hans J.
Published: September 2007

Classical algebra has always considered itself as a discipline in
Discrete Mathematics
, even when it dealt with objects over the real or complex numbers (
R
or
C
), where the inherent topology of the number fields would have invited the use of analytic tools. A first change occurred only when the models of applied mathematics required the treatment of larger and larger systems of linear equations and the emerging electronic computers permitted the implementation of algorithms with huge data sets. In the rapidly growing "Numerical Linear Algebra", norms and distances, contractive iterations etc. were used as standard tools: Classical linear algebra over
R
and
C
became embedded into Analysis. (As a consequence, in the 2000 Mathematics Subject Classification of the AMS, "Numerical Linear Algebra" is not listed as a subdiscipline of Algebra but of Numerical Analysis.)
OSCAS
Authors: Joyner David
Published: September 2007

At the kind invitation of ACM SIGSAM Chair Emil Volcheck, this will start a series of regular columns on open source computer algebra systems. I will consider this series a success if it encourages one of you to contribute in even a small way (submit a bug report or just an encouraging email to the developers!) to one of the systems listed below.
A Fortran binding for the GNU scientific library
Authors: Bader Reinhold
Published: September 2007

The GNU scientific library is a collection of numerical routines for scientific computing. This article discusses some aspects of the design of a fully standard-conforming Fortran binding for GSL via incremental usage of Fortran 2003 features, in particular C interoperation. Suggestions are made on how to deal with function dummy arguments and polymorphic C objects of type void*.
Introduction to NAG Fortran builder
Authors: Chivers Ian D , Sleightholme Jane
Published: September 2007

This article is an introduction to the NAG Fortran Builder product. Fortran Builder is an Integrated Development Environment or IDE for Fortran. The product runs under Windows and was developed in Japan. The version tested included release 5.1 of the NAGWare Fortran compiler. The compiler can also be used from a command prompt if required. As of going to press NAG have not formally released Fortran Builder. If you would like more information could you please contact John Holden at NAG. His email address is: John.Holden@nag.co.uk
Stereoscopic 3D film and animation
Authors: Wittlief Kenneth
Published: September 2007

A new format for stereoscopic 3D movies has recently been introduced to theaters, raising the image and color quality to higher levels. Unlike the old red / blue anaglyph format, the new technology uses polarized lenses, a metalized screen and polarized glasses to allow the viewer to see sharp, full color, separate images with their left and right eyes. In addition a new type of personal video display has been introduced to the DVD and computer market in the last few years. Video Eyewear use two tiny LCDs to provide separate images for each eye, and are worn like a pair of glasses.
VisFiles
Authors: Ma Kwan-Liu
Published: September 2007

It has been twenty years since the surge of visualization research following the publication of the report on Visualization in Scientific Computing by the U.S. National Science Foundation (NSF) in 1987. Visualization has become a mature discipline, and also an indispensable tool for understanding and communicating vast amounts of information in many fields of study. Now we are seeing a second surge of visualization research. One stimulus is the widespread, day-to-day reliance of the Web, while the other is the continuing advances of scientific supercomputing.
Ordering of events in two-process concurrent system
Authors: Banerjee Jayasri , Bandyopadhyay Anup Kumar , Mandal Ajit Kumar
Published: September 2007

Dijkstra's weakest precondition calculus is extended to capture temporal ordering in concurrent systems. This is done by defining temporal ordering predicates that is used to describe necessary conditions. A new logical connective, viz., "implies in the past" is also defined to describe the cause and effect relationships. Ordering mechanism used in Peterson's two process mutual exclusion algorithm is explained by proving a theorem.
Research directions in verification & validation process improvement
Authors: Farooq Ayaz , Dumke Reiner R.
Published: September 2007

Software process establishment, evaluation and improvement are key research areas in the software engineering field today. Extensive research has been carried out and many different kinds of approaches exist to improve the software process and even more efforts are underway. Verification & validation process, which is part of the broader software process activities, plays a vital role in quality and profitability of the developed product but is believed to consume major portion of the development expenses and resources. Probably, research towards improving the verification & validation process has not been as actively directed as compared to software process improvement research. This paper identifies several potential future research directions towards improving verification and validation process.
SEC+
Authors: Khemakhem Sofien , Drira Khalil , Jmaiel Mohamed
Published: September 2007

This paper presents an ontology to describe functional and non-functional properties of software components, associated with a portable implementation for enhanced discovering. Without leaving the development environment, the developer loads SEC+, a persistent component that acts as an intelligent search engine. It generates a query from developer specification. It handles generated queries and automatically locates and presents a list of compliant components that could be used in the current development situation.
Code quality tools
Authors: Krishnan R , Krishna S Murali , Bharill Nishil
Published: September 2007

In this paper we share some of our experiences relating to tools used in coding phase. We primarily focus our discussion on two topics, namely UT (Unit Testing) and Memory related errors.

Unit Testing (UT) [1] is a critical early-phase verification activity that ensures the quality of the product soon after the code is ready. Newer paradigms of software development like Extreme Programming [7] have a strong focus on UT. However, UT is very effort-intensive as it involves test harness development and repetitive execution. In Motorola software Group, we evaluated a set of commercial tools and selected a tool for use in our projects. In this paper, we will share the evaluation criteria, which was identified for the tool selection and the various technical challenges encountered in adopting a UT tool solution in a heterogeneous environment along with the associated learning. One of the major challenges encountered, was arriving to a consensus on definition of term 'Unit'. The other issues included handling of complex data structures, event driven code, integration with development environment etc.

One of the major categories of errors introduced and found in coding phase relates to memory. As these errors may have security implications, leaving them undetected might be a big risk. For trapping memory related errors, a framework to categorize these errors was created along with the associated code samples. In this paper, two types of memory related errors will be discussed, namely memory leak and buffer overflow. This memory related errors can be exploited to compromise the security of the system. This paper also discusses the causes, types and impact of buffer overflows, as well as the precautions to be taken to prevent buffer overflows.
Designing software components to tolerances
Authors: Riehle Richard
Published: September 2007

Many traditional engineering designs, other than software, depend on the physical properties of components. Those properties enable the engineer to specify precise tolerances between those components. Software components are abstractions with no inherent physical properties. The absence of physical properties makes it more difficult, but not impossible, to design to tolerances. This paper describes some design metrics for designing software components to tolerances. It uses some already established design metrics, and expands on the role of other software practices already available. This paper also restricts the discussion to software components, rather than to the algorithms contained within those components.
The Grand Theory of Everything
Authors: Schaefer Robert
Published: September 2007

The Grand Theory of Everything (tGToE) is a powerful, elegant and unique Model which may be used towards the Understanding and Development of Man-Made Systems. This Model may be used to Identify, Explore, and Predict Faults of Systems-Making, and Faults in Systems and Faults in Systems-Use. Although the tGToE Model provides an Understanding of Systems and Choices, it may not necessarily identify Best Choices or Practical Solutions as that requires Judgment. As all Models are Abstractions, the Possibility of oversimplification that applies to Models applies equally to tGToE. Refinement of this Model has led the Author to several Curious Observations on Paradoxes in Systems and Observations on the Use of Power in Organizations. Depending on the Ethics of the Reader, the application of tGToE may be used to solve Great Problems or to cause Great Mischief and Harm.
An improved component model for component based software engineering
Authors: Senthil R. , Kushwaha D. S. , Misra A. K.
Published: September 2007

This paper focuses on Component Based Software Engineering (CBSE) and generic connectors for the software components. An attempt has been made to describe n-tier architecture; in particular, data access architecture in a component based application. It attempts to express how data access objects interact with business-tier and data-tier in achieving reusable, robust and scalable component based architecture by implementing Data Adapter interface. It has been able to establish that code efficiency increases when data access object implements the data adapter interface by performing unit test on the code. It has also been able to show that there exists a loose coupling in the component based architecture.
A step towards software preventive maintenance
Authors: Singh Yogesh , Goel Bindu
Published: September 2007

In a world interwoven economically, increasing dependence on critical software applications either in transaction processing (banking, Government services etc) or manufacturing automation (automobiles, pharmaceuticals, chemicals) has accentuated the economic impact aging software can have. Software with increased usage operating in unforeseen conditions at throughput much higher then initial expectations can degrade fast leading to higher altered form and dramatic drop in performance indicators. In the current paper we have tried to analyse the issues governing software maintenance and how preventive maintenance which is still considered a very evolving field in the context of software engineering can help the software product age usefully. We have also attempted to address the above in the essence of how it is done for hardware preventive maintenance which is a better understood and commercially accepted concept. Finally we suggest model for the preventive maintenance integrated within software life cycle.
On checking the consistency of Object-Z classes
Authors: Taibi Fathi , Daniel Jacob K. , Abbou Fouad Mohammed
Published: September 2007

Requirements elicitation involves gathering requirements from different stakeholders. Different stakeholders often hold different views of how a system should behave, resulting in inconsistencies between their descriptions. Rigorous consistency checking methods can be effectively applied if the different views are formally specified. This is possible because of the unambiguous and precise nature of formal specification languages. However, ensuring that each formal view is self-consistent is critical before checking that the different views are inter-consistent. In this paper, an algorithm is proposed to check the self-consistency of the classes of an Object-Z specification. The proposed approach combines specification testing, model abstraction, and model checking to perform the verification.
ACM TOSEM
Authors: Notkin David
Published: September 2007

As the eagle-eyed among you may have noticed, ACM TOSEM has a new editorial charter. Approved by both the TOSEM editorial board and the ACM Publications Board, it is now posted to the TOSEM website.
Aspects in Architectural Description
Authors: Clements Paul , Emery David , Hilliard Rich , Kruchten Philippe
Published: September 2007

The First Workshop on Aspects in Architectural Description was held in Vancouver, British Columbia as a part of Aspect-Oriented Software Development (AOSD) 2007. This workshop report presents a summary of the topics addressed, contributions and issues raised, and workshop conclusions.
4
th
Intl. ICSE workshop on Software Engineering for Automotive Systems
Authors: Pretschner Alexander , Salzmann Christian , Schätz Bernhard , Stauner Thomas
Published: September 2007

This paper summarizes the fourth International Workshop on Software Engineering for Automotive Systems, held in conjunction with ICSE 2007.
Architectural knowledge and rationale
Authors: Avgeriou Paris , Kruchten Philippe , Lago Patricia , Grisham Paul , Perry Dewayne
Published: September 2007

The second workshop on Sharing and Reusing Architectural Knowledge (SHARK) and Architecture rationale and Design intent (ADI) was held jointly with ICSE 2007 in Minneapolis. This report presents the themes of the workshop, summarizes the results of the discussions held, and suggests some topics for future research.
Working conference on requirements engineering
Authors: Sawyer Pete , Paech Barbara , Heymans Patrick
Published: September 2007

REFSQ'07 took place over the 11
th
and 12
th
June 2007 in the beautiful Norwegian city of Trondheim. It was attended by 47 people from 14 countries, who came to present and/or discuss 27 papers, the insights they offered and the issues they raised. During the course of the two days, a number of recurrent and important themes emerged. These were co-design of requirements and architecture, analyst-stakeholder-developer communication, requirements dependencies, the role of value in requirements engineering (RE) and the role and the progress made by research in RE.
Letters
Authors: Stanik John
Published: September 2007

Great Curmudgeon column (“Alloneword”) by Stan Kelly-Bootle in the May/June 2007 issue of Queue. I relish satire. I distrust all announced principles of anything.
Gettin’ Your Head Straight
Authors: Neville-Neil George V.
Published: September 2007

Dear KV, One of the biggest problems I have is memory. Not the RAM in my computer, but the wet squishy stuff in my head. It seems that no matter how many signs I put up around my cube, nor how often I turn off all the annoying instant messaging clients I need to use for work, I can’t get through more than 15 minutes of work without someone interrupting me, and then I lose my train of thought. If this happens when I’m reading e-mail, that’s not a problem, but when working on code, in particular when debugging a difficult problem in code, this makes my life very difficult. What tricks are there to being able to maintain a train of thought without moving up the side of a mountain?
A Conversation with Joel Spolsky
Authors: Stanik John
Published: September 2007

Joel Spolsky has never been one to hide his opinions. Since 2000, he has developed a loyal following for his insightful, tell-it-like-it-is essays on software development and management on his popular Weblog “Joel on Software”. The prolific essayist has also published four books and started a successful software company, Fog Creek, in New York City, a place he feels is sorely lacking in product-oriented software development houses. Spolsky started Fog Creek not with a specific product in mind, but rather to create a kind of software developers’ utopia, where “programmers and software developers are the stars and everything else serves only to make them productive and happy.” So far, he has succeeded. The company has maintained a 100 percent employee retention rate while shipping several profitable software products. Its latest release, Fogbugz, is a comprehensive, Web-based project-management system that uses a technique called EBS to help software developers better predict their release dates.
Phishing Forbidden
Authors: Agarwal Naveen , Renfro Scott , Bejar Arturo
Published: September 2007

Phishing is a significant risk facing Internet users today. Through e-mails or instant messages, users are led to counterfeit Web sites designed to trick them into divulging usernames, passwords, account numbers, and personal information. It is up to the user to ensure the authenticity of the Web site. Browsers provide some tools, but these are limited by at least three issues.
Usablity Testing for the Web
Authors: Ingleshwar Vikram V.
Published: September 2007

Today’s Internet user has more choices than ever before, with many competing sites offering similar services. This proliferation of options provides ample opportunity for users to explore different sites and find out which one best suits their needs for any particular service. Users are further served by the latest generation of Web technologies and services, commonly dubbed Web 2.0, which enables a better, more personalized user experience and encourages user-generated content. Although there is considerable debate over the definition of Web 2.0, the term is useful in distinguishing key innovations, such as weblogs, social bookmarking, tagging, wikis, RSS feeds, Ajax, Web APIs, and online Web services, that have significantly altered the Web user experience since the 1990s.
Voyage in the Agile Memeplex
Authors: Kruchten Philippe
Published: September 2007

Agile processes are not a technology, not a science, not a product. They constitute a space somewhat hard to define. Agile methods, or more precisely agile software development methods or processes, are a family of approaches and practices for developing software systems. Any attempt to define them runs into egos and marketing posturing. For our purposes here, we can define this space in two ways: By enumeration. Pointing to recognizable members of the set: XP, scrum, lean development, DSDM, Crystal, FDD, Agile RUP or OpenUP, etc.
Review of "Enterprise Service-Oriented Architectures: Concepts, Challenges, Recommendations by James McGovern, Oliver Sims, Ashish Jain, and Mark Little," Springer-Verlag, 2006, $59.95, ISBN: 140203704X
Authors: Bhattacharya Shantanu
Published: September 2007

Review of "Enterprise Service-Oriented Architectures: Concepts, Challenges, Recommendations by James McGovern, Oliver Sims, Ashish Jain, and Mark Little," Springer-Verlag, 2006, $59.95, ISBN: 140203704X
Review of "Hitchhiker’s Guide to Visual Studio and SQL Server: Best Practice Architectures and Examples, 7th edition (Microsoft Windows Server System Series) by William Vaugh and Peter Blackburn," Addison-Wesley Professional, 2006, $59.99, ISBN: 0321243625
Authors: Paramithiotti Andrea
Published: September 2007

Review of "Hitchhiker’s Guide to Visual Studio and SQL Server: Best Practice Architectures and Examples, 7th edition (Microsoft Windows Server System Series) by William Vaugh and Peter Blackburn," Addison-Wesley Professional, 2006, $59.99, ISBN: 0321243625
Calendar
Authors: Stanik John
Published: September 2007

SIGGRAPH
STEM
Authors: Ansari Furquan , Sathyanath Ajay
Published: September 2007

In the current TCP/IP inter-networking architecture, a transport layer connection or session is uniquely identified by the underlying 5-tuple information, viz. {Src IP, Src Port, Dest IP, Dest Port, Protocol}. This strong coupling between the session and the end-point attributes implies that any change to one or more of the elements in this 5-tuple invariably leads to session failure. We present an architecture (STEM) that decouples this strong association to enable seamless migration of active transport sessions across IP addresses and interfaces. We achieve this migration by directly communicating between the peers and dynamically updating the 5-tuple elements associated with the session. The migration is done in a transparent, simple and secure way.

Our architecture enables new and exciting applications such as fault-tolerant transport sessions (e.g. in BGP) and end-host mobility in the absence of mobile IP infrastructure. Although STEM can be used as an alternative to mobile IP, the two may co-exist as well, if desired. The novelty of this architecture is that it does not require any modifications to standard protocols or applications. In other words, no changes are needed to the finite state machine or protocol messages. We present an implementation of the STEM architecture and validate it by means of experimental results.
Simultaneous adaptive localization of a wireless sensor network
Authors: Sreenath Koushil , Lewis Frank L. , Popa Dan O.
Published: September 2007

A range-free approach for adaptive localization of un-localized sensor nodes employing a mobile robot with GPS is detailed. A mobile robot navigates through the sensor deployment area broadcasting its positional estimate and the uncertainty in its estimate. Distributed computationally-inexpensive, discrete-time Kalman Filters, implemented on each static sensor node, fuse information obtained over time from the robot to decrease the uncertainty in each node's location estimate. On the other hand, due to dead reckoning and other systematic errors, the robot loses positional accuracy over time. Updates from GPS and from the localized sensor nodes serve in improving the localization uncertainty of the robot. A Continuous-Discrete Extended Kalman Filter (CD EKF) running on the mobile robot fuses information from multiple distinct sources (GPS, various sensors nodes) for robot navigation. This two-part procedure achieves simultaneous localization of the sensor nodes and the mobile robot. Also presented is an adaptive localization strategy to navigate the mobile robot to the area of least localized sensor nodes. This ensures that the robot maneuvers to an area where the sensor nodes possess the largest uncertainty in location, so that it can maximize the usefulness of its positional information in best localizing the overall network.
Obfuscating temporal context of sensor data by coalescing at source
Authors: RayChaudhuri Abhishek , Chinthala Ujwal K. , Bhattacharya Amiya
Published: September 2007

Contextual privacy threat arises from divulging the location and time of the triggering events to adversaries. Since, the context of the triggering events serve as useful information to the eavesdropper, data encryption alone renders inadequate for protecting total privacy of a sensing task. Obfuscation of the contextual information is a natural solution to the contextual privacy problem. Since both location and time of a sensed event constitute its context, obfuscation can be performed both spatially and temporally. In [1], the authors employ spatial obfuscation techniques (controlled flooding, probabilistic flooding and fake messaging) by focusing mainly on the location component of the contextual information. Nevertheless, increased message transmissions place an additional burden on the power constrained sensor nodes.
Traffic-aware channel assignment in wireless LANs
Authors: Rozner Eric , Mehta Yogita , Akella Aditya , Qiu Lili
Published: September 2007

Campus and enterprise wireless networks are increasingly characterized by ubiquitous coverage and high traffic demands. An efficient channel assignment of access points (APs) in these networks has the potential to greatly improve wireless LAN performance. Therefore, previous studies have investigated methods for determining effective channel assignments. Existing approaches, however, do not adapt to prevailing traffic conditions in the network. An analysis of wireless traces (e.g. [2]) shows that traffic volume in a wireless LAN can vary significantly across APs. Motivated by this observation, we investigate whether the quality of a channel assignment can be improved by incorporating observed traffic demands at APs and clients in wireless networks. Our results show that being traffic-aware can substantially improve the effectiveness of a channel assignment: in some cases it nearly doubles performance. We further apply traffic demand prediction algorithms to make traffic-aware assignment practical.
Asymmetric sensing by decoupling scheduling from switching
Authors: Gu Yu , He Tian
Published: September 2007

As a key approach to achieve energy efficiency in sensor networks, sensing coverage has been studied extensively. Researchers have designed many coverage protocols to provide various kinds of service guarantees within the network. While the state-of-the-art is encouraging, we believe there are some aspects that need further investigation. First, currently different sensing coverage algorithms focus on different service guarantees. Any single design is not general enough to meet a wide range of sensing requirements under different operating scenarios. Second, lifetime extension in most algorithms is essentially achieved through coordination among neighboring nodes. The local node density, therefore, imposes a theoretical upper bound on the system lifetime.
Managing delay and jitter in mesh networks through path-aware distributed transmission scheduling
Authors: Yackoski Justin , Shen Chien-Chung
Published: September 2007

While usable in single-hop applications, current wireless medium access control (MAC) protocols are often sub-optimal and result in significant per-hop and per-packet delay and/or jitter. As a result, multi-hop wireless networks are a harsh environment for realtime, streaming applications such as VoIP and IPTV. We present a new MAC paradigm where nodes first use simple local coordination mechanisms to agree upon a low-delay schedule for their transmissions, and then continuously re-use the schedule (making slight adjustments when needed) to minimize jitter. We focus on the context of wireless mesh networks carrying delay-sensitive streaming data over multi-hop paths, and on the goal of improving the end-to-end delay and jitter experienced by
most
packets. We compare our approach with IEEE 802.11 DCF via simulation. We show that our approach results in most packets experiencing negligible jitter and comparable or lower end-to-end delay.
Leveraging a power save protocol to improve performance in ad hoc networks
Authors: Feeney Laura Marie , Rohner Christian , Ahlgren Bengt
Published: September 2007

Power save protocols reduce energy consumption in ad hoc and sensor networks by allowing nodes to put their network interface into a low power consumption sleep state. The power save protocol must allow neighboring nodes to establish intervals during which they are mutually awake and available to exchange traffic. Many such protocols are based on a coordinated election of a covering set that is responsible for buffering traffic for sleeping nodes, but uncoordinated (i.e. asynchronous) protocols have also proven an attractive option.
Geographic forwarding and adaptive load balancing in wireless sensor networks
Authors: Casari Paolo , Nati Michele , Petrioli Chiara , Zorzi Michele
Published: September 2007

In the future sensor nodes will either have GPS capabilities, or be able to run localization protocols in order to get an accurate estimation of their position. These features would make geographic convergecasting a feasible and promising solution for WSNs. Key for the actual implementation of WSNs is the design of cross-layer solutions which consider explicitly the resource constraints of sensor nodes, especially in terms of available energy, limited memory and processing capabilities. We present a new protocol, named ALBA (
Adaptive-Load Balanced Algorithm)
, which uses a cross-layer approach, pursuing the following goals:
i
) ALBA minimizes the number of hops required to reach the sink through a geographic forwarding scheme;
ii
) traffic is distributed evenly in the network, favoring nodes that are experiencing low congestion, while avoiding overloaded regions;
iii
) channel access efficiency is optimized through an adaptive back-to-back transmission of "bursts of packets" once a relay is selected, and
iv
) nodes are progressively made aware of routes to redirect the packets to the sink even when a connectivity hole occurs, i.e., when some nodes are not able to deliver packets to the sink because of lack of next-hop relay nodes closer to the sink.
Secure multicast routing in wireless networks
Authors: Curtmola Reza , Nita-Rotaru Cristina
Published: September 2007

We consider the problem of secure content distribution in multihop mobile ad hoc networks (MANETs), where a source disseminates data to a group of receivers. To ensure an efficient utilization of the network resources, multicast routing is the natural choice to be used at the network level. Although several multicast routing protocols have been proposed [1, 2], their security has only been explored under outsider attacks [3, 4] or under limited insider attacks [5]. Due to the lack of physical security and the susceptibility of devices to theft, it is necessary to design protocols resilient to both outsider and insider attacks.
Energy-efficient frame dropping policies for multimedia
Authors: Snader Robin , Harris Albert F. , Kravets Robin
Published: September 2007

Traditionally, multimedia applications have been primarily constrained by a lack of bandwidth. In mobile systems, however, energy constraints must be considered as well. While these constraints are related, they differ in one key way: bandwidth is renewable, but energy is not. This implies that techniques for managing bandwidth, typically performed at the transport layer, must be reconsidered in terms of their energy efficiency as well. Traditionally, these transport layers are evaluated in terms of
application good-put
, or the amount of useful data received by the application. We propose that they should also be evaluated in terms of the total amount of data sent per useful data unit received at the application, which we term
data expansion
.
Mitigating the gateway bottleneck via transparent cooperative caching in wireless mesh networks
Authors: Das Saumitra M. , Pucha Himabindu , Hu Y. Charlie
Published: September 2007

Wireless mesh networks (WMNs) are characterized by mesh routers connected by wireless links to each other and to a few gateway nodes. The most significant application of such networks is to provide broadband Internet access to static or mobile hosts in areas where wired infrastructure is difficult or economically infeasible to deploy. Since most WMN traffic flows through a few gateway nodes, this can cause significant congestion around the gateway.
TRAC
Authors: Rayanchu Shravan , Agarwal Sulabh , Mishra Arunesh , Banerjee Suman , Ganguly Samrat
Published: September 2007

Traffic congestion is a major cause of concern in many cities. A real-time information dissemination system announcing current traffic conditions to travelers is increasingly becoming a necessity in this context. The recent DSRC research initiative[1] envisions a deployment of DSRC access points (APs) along the road side to enable Vehicle to Roadside Communication (VRC) for this purpose. However, even if such an infrastructure is deployed on the roadside, it is not trivial to design a system that distributes on-demand traffic information. Existing solutions employ a centrialized design where the traffic information is stored at a central database and the vehicles then query the database for information of their interest. Such solutions are simply not scalable due to the huge volume of queries the central database would have to handle. Moreover, such a communication architecture does not take into account the fact that traffic related queries are
location sensitive
and that the sources for a particular query also tend to be
localized
.
On the (in)feasibility of fine grained power control
Authors: Shrivastava Vivek , Agrawal Dheeraj , Mishra Arunesh , Banerjee Suman , Nadeem Tamer
Published: September 2007

Spectral efficiency has been a major focus of research in wireless networks. Recent theoretical work has shown that ideal medium access protocol using optimal power control can improve channel utilization by up to a factor of √ρ, where ρ is the density of nodes in the region [1]. Although power control mechanisms have been extensively studied in theory and simulations, their practical evaluation has not been done throughly. Most of the power control mechanisms proposed in literature [3, 4, 5] assume a very fine grained handle on transmit power of wireless nodes and exercise this control to provide sophisticated mechanisms of sharing wireless medium among competing flows. In this work, we investigate the (in)feasibility of fine-grained power control in wireless networks using real testbed experiments. We perform detailed experiments to highlight fundamental issues with power control mechanisms, that cannot be captured by using a network simulator. Our experiments indicate that fine grained power control may not be a viable solution for indoor wireless networks and most power control mechanisms may need to be adapted to be suitable for practical settings.
A scalable public key management scheme in wireless ad hoc networks
Authors: He Wenbo , Huang Ying , Nahrstedt Klara , Lee Whay C.
Published: September 2007

There are emerging needs of secure communications in mission-critical applications over wireless ad hoc networks, including battlefield communications, emergency rescue operations, and disaster recoveries. In these applications, it is important to support secure communications in "anywhere", "anytime" and "anyhow" manner with following attributes:
data integrity, authentication, confidentiality, non-repudiation
, and
service availability
[1]. Being good candidates to address these attributes, Public-Key Cryptography (PKC) schemes have advantages over the symmetric systems. However, characteristics of missioncritical ad hoc networks pose the following new challenges for the design: (1) Vulnerability to the
Sybil
Attack [2]: When the
Sybil
attack happens, an attacker can claim multiple identities and the fake identities can easily defeat reputation and threshold protocols, where a legitimate node must rely on majority of nodes to reach decisions. (2) Unreliable Communications and Network Dynamics: Due to shared-medium nature of wireless links, flows may frequently interfere with each other. Moreover, a network may be partitioned frequently due to node mobility and poor channel condition. (3) Large Scale: The number of ad hoc wireless devices deployed at an incident scene depends on specific nature of the incident. In general, the network size can be very large. In addition, an ad hoc network should be able to accommodate more mobile devices if necessary. (4) Resource Constraints: The wireless devices usually have limited bandwidth, memory and processing power. Among these constrains, communication bandwidth consumption and memory are two big concerns for key management schemes.
Towards highly reliable enterprise network services via inference of multi-level dependencies
Authors: Bahl Paramvir , Chandra Ranveer , Greenberg Albert , Kandula Srikanth , Maltz David A. , Zhang Ming
Published: September 2007

Localizing the sources of performance problems in large enterprise networks is extremely challenging. Dependencies are numerous, complex and inherently
multi-level
, spanning hardware and software components across the network and the computing infrastructure. To exploit these dependencies for fast, accurate problem localization, we introduce an Inference Graph model, which is well-adapted to user-perceptible problems rooted in conditions giving rise to both partial service degradation and hard faults. Further, we introduce the Sherlock system to discover Inference Graphs in the operational enterprise, infer critical attributes, and then leverage the result to automatically detect and localize problems. To illuminate strengths and limitations of the approach, we provide results from a prototype deployment in a large enterprise network, as well as from testbed emulations and simulations. In particular, we find that taking into account multi-level structure leads to a 30% improvement in fault localization, as compared to two-level approaches.
Bubblestorm
Authors: Terpstra Wesley W. , Kangasharju Jussi , Leng Christof , Buchmann Alejandro P.
Published: September 2007

Peer-to-peer systems promise inexpensive scalability, adaptability, and robustness. Thus, they are an attractive platform for file sharing, distributed wikis, and search engines. These applications often store weakly structured data, requiring sophisticated search algorithms. To simplify the search problem, most scalable algorithms introduce structure to the network. However, churn or violent disruption may break this structure, compromising search guarantees.

This paper proposes a simple probabilistic search system, BubbleStorm, built on random multigraphs. Our primary contribution is a flexible and reliable strategy for performing exhaustive search. BubbleStorm also exploits the heterogeneous bandwidth of peers. However, we sacrifice some of this bandwidth for high parallelism and low latency. The provided search guarantees are tunable, with success probability adjustable well into the realm of reliable systems.

For validation, we simulate a network with one million low-end peers and show BubbleStorm handles up to 90% simultaneous peer departure and 50% simultaneous crash.
Securing internet coordinate embedding systems
Authors: Kaafar Mohamed Ali , Mathy Laurent , Barakat Chadi , Salamatian Kave , Turletti Thierry , Dabbous Walid
Published: September 2007

This paper addresses the issue of the security of Internet Coordinate Systems,by proposing a general method for malicious behavior detection during coordinate computations. We first show that the dynamics of a node, in a coordinate system without abnormal or malicious behavior, can be modeled by a Linear State Space model and tracked by a Kalman filter. Then we show, that the obtained model can be generalized in the sense that the parameters of a filtercalibrated at a node can be used effectively to model and predict the dynamic behavior at another node, as long as the two nodes are not too far apart in the network. This leads to the proposal of a Surveyor infrastructure: Surveyor nodes are trusted, honest nodes that use each other exclusively to position themselves in the coordinate space, and are therefore immune to malicious behavior in the system.During their own coordinate embedding, other nodes can thenuse the filter parameters of a nearby Surveyor as a representation of normal, clean system behavior to detect and filter out abnormal or malicious activity. A combination of simulations and PlanetLab experiments are used to demonstrate the validity, generality, and effectiveness of the proposed approach for two representative coordinate embedding systems, namely Vivaldi and NPS.
ProgME
Authors: Yuan Lihua , Chuah Chen-Nee , Mohapatra Prasant
Published: September 2007

Traffic measurements provide critical input for a wide range of network management applications, including traffic engineering, accounting, and security analysis. Existing measurement tools collect traffic statistics based on some pre-determined, inflexible concept of "flows". They do not have sufficient built-in intelligence to understand the application requirements or adapt to the traffic conditions. Consequently, they have limited scalability with respect to the number of flows and the heterogeneity of monitoring applications.

We present ProgME, a
Prog
rammable
ME
asurement architecture based on a novel concept of
flowset
- arbitrary set of flows defined according to application requirements and/or traffic conditions. Through a simple flowset composition language, ProgME can incorporate application requirements, adapt itself to circumvent the challenges on scalability posed by the large number of flows, and achieve a better application-perceived accuracy. ProgME can analyze and adapt to traffic statistics in real-time. Using sequential hypothesis test, ProgME can achieve fast and scalable heavy hitter identification.