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Digital Communications and Networking

2007

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Articles 1 - 25 of 25

Full-Text Articles in Computer Engineering

Retransmission Strategies For Moving Networks Over Ricean Fading Channels, Alex Ruiz Lee Dec 2007

Retransmission Strategies For Moving Networks Over Ricean Fading Channels, Alex Ruiz Lee

Theses

The problem of designing retransmission protocols based on Hybrid Automatic Repeat reQuest (HARQ) for moving networks over Ricean fading channels has been considered. The scenario of interest consists of one receiver traveling at a given speed while connected to a wireless network based on OFDM (e.g., WiMax) through several base stations located along the path. Five different retransmission protocols that combine HARQ with handover between adjacent base stations are considered. Their performance in terms of number of retransmissions per packet via numerical simulations, considering both frequency selective and nonselective channels are presented. The results obtained show the relevant advantage ...


Proactive Methods For Measurement Of Available Bandwidth And Link Capacity, Khondaker Musfakus Salehin Dec 2007

Proactive Methods For Measurement Of Available Bandwidth And Link Capacity, Khondaker Musfakus Salehin

Theses

With the continuous expansion of network infrastructure and deployment of applications sensitive to Quality-of-Service, network measurement plays a major role in both network planning and management. Accurate measurement of various network parameters, e.g., available bandwidth, link capacity, delay, packet loss and jitter, provides a positive impact for effective traffic engineering, Quality-of-Service (QoS) routing, optimization of end-to-end transport performance, and link capacity planning. For network measurement, there exists several proactive estimation tools based on either probe-gap model or probe-rate model that estimate path related attributes. Most of these tools that have been implemented can measure tight-link capacity (smallest available bandwidth ...


Using Gis To Optimize The Design And Implementation Of The Rtk Reference Network In Abu Dhabi, Mustafa Abdulla Mohammed Almusawa Dec 2007

Using Gis To Optimize The Design And Implementation Of The Rtk Reference Network In Abu Dhabi, Mustafa Abdulla Mohammed Almusawa

Theses

Several challenging applications and construction works demand real-time measurements for positioning at the centimeter-level accuracy. This positioning accuracy can be obtained by using a Global Positioning System (GPS) roving unit and employing a single reference station (base-station) or through utilizing the service of multiple reference stations forming a Real-Time Kinematics (RTK) Reference Network.

The limitation of the single reference approach is that measurement errors are distance dependent and good accuracy can be only obtained when distances are less than 10 kms. In addition, this method requires a nearby Geodetic Control Point (GCP). Recently, RTK reference networks are widely established in ...


Broadband Adoption And Content Consumption, Lorin M. Hitt, Prasanna B Tambe Oct 2007

Broadband Adoption And Content Consumption, Lorin M. Hitt, Prasanna B Tambe

Operations, Information and Decisions Papers

We explore how broadband access drives changes in the quantity and diversity of consumption of online content by using panel data that describes household Internet usage before and after broadband adoption. Our data suggests that on average, broadband adoption increases usage by over 1300 min per month. We also find that information consumption becomes more evenly distributed within the population, driven in part by post-adoption usage gains of almost 1800 min per month among individuals who were in the lowest usage quintile before adopting broadband. After adopting broadband, this pre-adoption lowest-usage quintile consumes content in greater quantities than users in ...


The Effects Of Contention Among Stations On Video Streaming Applications Over Wireless Local Area Networks: An Experimental Approach, Nicola Cranley, Tanmoy Debnath Oct 2007

The Effects Of Contention Among Stations On Video Streaming Applications Over Wireless Local Area Networks: An Experimental Approach, Nicola Cranley, Tanmoy Debnath

Conference papers

Multimedia streaming applications have a large impact on the resource requirements of the WLAN. There are many variables involved in video streaming, such as the video content being streamed, how the video is encoded and how it is sent. This makes the role of radio resource management and the provision of QoS guarantees extremely difficult. For video streaming applications, packet loss and packets dropped due to excessive delay are the primary factors that affect the received video quality. In this paper, we experimentally analyse the effects of contention on the performance of video streaming applications with a given delay constraint ...


Lazy Preservation: Reconstructing Websites From The Web Infrastructure, Frank Mccown Oct 2007

Lazy Preservation: Reconstructing Websites From The Web Infrastructure, Frank Mccown

Computer Science Theses & Dissertations

Backup or preservation of websites is often not considered until after a catastrophic event has occurred. In the face of complete website loss, webmasters or concerned third parties have attempted to recover some of their websites from the Internet Archive. Still others have sought to retrieve missing resources from the caches of commercial search engines. Inspired by these post hoc reconstruction attempts, this dissertation introduces the concept of lazy preservation{ digital preservation performed as a result of the normal operations of the Web Infrastructure (web archives, search engines and caches). First, the Web Infrastructure (WI) is characterized by its preservation ...


Cognitive Radio: Fundamentals And Opportunities, Robert H. Morelos-Zaragoza Aug 2007

Cognitive Radio: Fundamentals And Opportunities, Robert H. Morelos-Zaragoza

Robert Henry Morelos-Zaragoza

This talk is aimed at MSEE students in San Jose State University. It provides an overview of cognitive radio concepts and technologies. A MATLAB Simulink of demonstration of digital channel selection using a low IF radio architecture is presented. Technical challenges that remain to be solved in this area are identified.


What Can Antitrust Contribute To The Network Neutrality Debate?, Christopher S. Yoo Aug 2007

What Can Antitrust Contribute To The Network Neutrality Debate?, Christopher S. Yoo

Faculty Scholarship at Penn Law

Over the course of the last year, policymakers have begun to consider whether antitrust can play a constructive role in the network neutrality debate. A review of both the theory and the practice of antitrust suggests that it does have something to contribute. As an initial matter, antitrust underscores that standardization and interoperability are not always beneficial and provides a framework for determining the optimal level of standardization. In addition, the economic literature and legal doctrine on vertical exclusion reveal how compelling network neutrality could reduce static efficiency and show how mandating network neutrality could impair dynamic efficiency by deterring ...


Maximizing Broadcast And Multicast Traffic Load Through Link-Rate Diversity In Wireless Mesh Networks, Chun Tung Chou, Bao Hua Liu, Archan Misra Jun 2007

Maximizing Broadcast And Multicast Traffic Load Through Link-Rate Diversity In Wireless Mesh Networks, Chun Tung Chou, Bao Hua Liu, Archan Misra

Research Collection School Of Information Systems

This paper studies some of the fundamental challenges and opportunities associated with the network-layer broadcast and multicast in a multihop multirate wireless mesh network (WMN). In particular, we focus on exploiting the ability of nodes to perform link-layer broadcasts at different rates (with correspondingly different coverage areas). We first show how, in the broadcast wireless medium, the available capacity at a mesh node for a multicast transmission is not just a function of the aggregate pre-existing traffic load of other interfering nodes, but intricately coupled to the actual (sender, receiver) set and the link-layer rate of each individual transmission. We ...


Evaluating Software Engineering Processes In Commercial And Community Open Source Projects, Tony Wasserman, Eugenio Capra Apr 2007

Evaluating Software Engineering Processes In Commercial And Community Open Source Projects, Tony Wasserman, Eugenio Capra

Tony Wasserman

We describe a current study for obtaining information about management of commercial and community open source projects. We have interviewed and surveyed leaders of more than 75 open source projects. Questions focused on the styles of leadership and communication, with a technical focus on testing and quality assurance processes. This paper describes the methods used to identify and contact subjects, as well as the questions posed and some results.


Maximizing Communication Concurrency Via Link-Layer Packet Salvaging In Mobile Ad Hoc Networks, Chansu Yu, Kang G. Shin, Lubo Song Apr 2007

Maximizing Communication Concurrency Via Link-Layer Packet Salvaging In Mobile Ad Hoc Networks, Chansu Yu, Kang G. Shin, Lubo Song

Electrical Engineering & Computer Science Faculty Publications

Carrier-sense medium access control (MAC) protocols such as the IEEE 802.11 distributed coordination function (DCF) avoid collisions by holding up pending packet transmission requests when a carrier signal is observed above a certain threshold. However, this often results in unnecessarily conservative communication, thus making it difficult to maximize the utilization of the spatial spectral resource. This paper shows that a higher aggregate throughput can be achieved by allowing more concurrent communications and adjusting the communication distance on the fly, which needs provisions for the following two areas. On the one hand, carrier sense-based MAC protocols do not allow aggressive ...


Detecting Compromised Nodes In Wireless Sensor Networks, Mary Lisa Mathews Apr 2007

Detecting Compromised Nodes In Wireless Sensor Networks, Mary Lisa Mathews

Electrical & Computer Engineering Theses & Disssertations

While wireless sensor networks are proving to be a versatile tool, many of the applications in which they are utilized have sensitive data. Therefore, security is crucial in many of these applications. Once a sensor node has been compromised, the security of the network degrades quickly if measures are not taken to deal with this event. There have been many approaches researched to tackle the issue. In this thesis, an anomaly-based intrusion detection protocol is developed to detect compromised nodes in wireless sensor networks.

The proposed protocol is implemented after the sensors are deployed into the environment in which they ...


A Grid Computing Network Platform For Enhanced Data Management And Visualization, Javier Delgado Mar 2007

A Grid Computing Network Platform For Enhanced Data Management And Visualization, Javier Delgado

FIU Electronic Theses and Dissertations

This thesis presents a novel approach towards providing a collaboration environment by using Grid Computing. The implementation includes the deployment of a cluster attached to a mural display for high performance computing and visualization and a Grid-infrastructure for sharing storage space across a wide area network and easing the remote use of the computing resources. A medical data processing application is implemented on the platform. The outcome is enhanced use of remote storage facilities and quick return time for computationally-intensive problems.

The central issue of this thesis work is thus one that focuses on the development of a secure distributed ...


Public Health For The Internet Φ Towards A New Grand Challenge For Information Management, Joseph M. Hellerstein, Tyson Condie, Minos Garofalakis, Boon Thau Loo, Petros Maniatis, Timothy Roscoe, Nina A. Taft Jan 2007

Public Health For The Internet Φ Towards A New Grand Challenge For Information Management, Joseph M. Hellerstein, Tyson Condie, Minos Garofalakis, Boon Thau Loo, Petros Maniatis, Timothy Roscoe, Nina A. Taft

Departmental Papers (CIS)

Business incentives have brought us within a small factor of achieving the database community's Grand Challenge set out in the Asilomar Report of 1998. This paper makes the case for a new, focused Grand Challenge: Public Health for the Internet. The goal of PHI (or φ) is to enable collectives of hosts on the Internet to jointly monitor and promote network health by sharing information on network conditions in a peer-to-peer fashion. We argue that this will be a positive effort for the research community for a variety of reasons, both in terms of its technical reach and its ...


User Security Behavior On Wireless Networks: An Empirical Study, Tim Chenoweth, Robert Minch, Sharon Tabor Jan 2007

User Security Behavior On Wireless Networks: An Empirical Study, Tim Chenoweth, Robert Minch, Sharon Tabor

IT and Supply Chain Management Faculty Publications and Presentations

Wireless networks are rapidly becoming ubiquitous but are often insecure and leave users responsible for their own security. We empirically study whether users are successfully securing their client computers when using wireless networks. Automated techniques are used that scan users' machines after they associate with a university wireless network. This determines whether a firewall is being used and what TCP ports are open. Results show that over 9% of 3,331 unique computers scanned were not using a properly configured firewall. In addition, almost 9% had at least one TCP port open, with almost 6% having open ports with significant ...


Optimal Layout Of Multicast Groups Using Network Embedded Multicast Security In Ad Hoc Sensor Networks, Richard R. Brooks, Brijesh Pillai, Michele C. Weigle, Matthew Pirretti Jan 2007

Optimal Layout Of Multicast Groups Using Network Embedded Multicast Security In Ad Hoc Sensor Networks, Richard R. Brooks, Brijesh Pillai, Michele C. Weigle, Matthew Pirretti

Computer Science Faculty Publications

This paper considers the security of sensor network applications. Our approach creates multicast regions that use symmetric key cryptography for communications. Each multicast region contains a single keyserver that is used to perform key management and maintain the integrity of a multicast region. Communications between two multicast regions is performed by nodes that belong to both regions. To ease the network management burden, it is desirable for the networks to self-organize into regions and dynamically select their keyservers. This paper shows how to determine the number of keyservers (k) to use and the size in the number of hops (h ...


Applying The Levels Of Conceptual Interoperability Model In Support Of Integratability, Interoperability, And Composability For System-Of-Systems Engineering, Andreas Tolk, Saikou Y. Diallo, Charles D. Turnitsa Jan 2007

Applying The Levels Of Conceptual Interoperability Model In Support Of Integratability, Interoperability, And Composability For System-Of-Systems Engineering, Andreas Tolk, Saikou Y. Diallo, Charles D. Turnitsa

Computational Modeling and Simulation Engineering Faculty Publications

The Levels of Conceptual Interoperability Model (LCIM) was developed to cope with the different layers of interoperation of modeling & simulation applications. It introduced technical, syntactic, semantic, pragmatic, dynamic, and conceptual layers of interoperation and showed how they are related to the ideas of integratability, interoperability, and composability. The model was successfully applied in various domains of systems, cybernetics, and informatics.


Use Of The Wfg Toolkit And Pisa For Comparison Of Moeas, Lucas Bradstreet, Luigi Barone, Lyndon While, Simon Huband, Philip Hingston Jan 2007

Use Of The Wfg Toolkit And Pisa For Comparison Of Moeas, Lucas Bradstreet, Luigi Barone, Lyndon While, Simon Huband, Philip Hingston

ECU Publications Pre. 2011

Understanding the behaviour of different optimisation algorithms is important in order to apply the best algorithm to a particular problem. The WFG toolkit was designed to aid this task for multi-objective evolutionary algorithms (MOEAs), offering an easily modifiable framework that allows practitioners the ability to test different features by "plugging" in different forms of transformations. In doing so, the WFG toolkit provides a set of problems that exhibit a variety of different characteristics. This paper presents a comparison between two state of the art MOEAs (NSGA-II and SPEA2) that exemplifies the unique capabilities of the WFG toolkit. By altering the ...


Passive And Active Optical Bit-Pattern Recognition Structures For Multiwavelength Optical Packet Switching Networks, Muhsen Aljada, Kamal Alameh Jan 2007

Passive And Active Optical Bit-Pattern Recognition Structures For Multiwavelength Optical Packet Switching Networks, Muhsen Aljada, Kamal Alameh

ECU Publications Pre. 2011

Next generation High-Speed optical packet switching networks require components capable of recognising the optical header to enable on-the-fly accurate switching of incoming data packets to their destinations. This paper experimentally demonstrates a comparison between two different optical header recognition structures; A passive structure based on the use of Fiber Bragg Gratings (FBGs), whereas the active structure employs Opto-VLSI processors that synthesise dynamic wavelength profile through digital phase holograms. The structures are experimentally demonstrated at 10Gbps. Performance comparison between the two structures is also discussed. These optical header recognition structures are attractive for multiwavelength optical network and applications.


Investigating Text Message Classification Using Case-Based Reasoning, Matt Healy Jan 2007

Investigating Text Message Classification Using Case-Based Reasoning, Matt Healy

Masters

Text classification is the categorization of text into a predefined set of categories. Text classification is becoming increasingly important given the large volume of text stored electronically e.g. email, digital libraries and the World Wide Web (WWW). These documents represent a massive amount of information that can be accessed easily. To gain benefit from using this information requires organisation. One way of organising it automatically is to use text classification. A number of well known machine learning techniques have been used in text classification including Naïve Bayes, Support Vector Machines and Decision Trees, and the less commonly used are ...


Keeping The Internet Neutral?: Tim Wu And Christopher Yoo Debate, Tim Wu, Christopher S. Yoo Jan 2007

Keeping The Internet Neutral?: Tim Wu And Christopher Yoo Debate, Tim Wu, Christopher S. Yoo

Faculty Scholarship at Penn Law

No abstract provided.


Mandating Access To Telecom And The Internet: The Hidden Side Of Trinko, Daniel F. Spulber, Christopher S. Yoo Jan 2007

Mandating Access To Telecom And The Internet: The Hidden Side Of Trinko, Daniel F. Spulber, Christopher S. Yoo

Faculty Scholarship at Penn Law

No abstract provided.


Using Flossmole Data In Determining Business Readiness Ratings, Tony Wasserman, Ashutosh Das Dec 2006

Using Flossmole Data In Determining Business Readiness Ratings, Tony Wasserman, Ashutosh Das

Tony Wasserman

This paper is a preliminary report on using FLOSSmole data retrieved from open source repositories (forges) to calculate Business Readiness Rating scores.


Methods And Tools For Developing Interactive Information Systems: An Historical Perspective, Tony Wasserman Dec 2006

Methods And Tools For Developing Interactive Information Systems: An Historical Perspective, Tony Wasserman

Tony Wasserman

This paper describes the evolution of hardware and software technology over the past three decades, focusing on approaches for building interactive information systems and web applications. Successive generations of technology have used advances in hardware and software technology, along with increasingly sophisticated development methods and tools, to reduce development times and to produce a better user experience. After describing the key technology characteristics of each generation, this paper also describes the evolution of a specific methodology, User Software Engineering, from its origins in the 1970’s to its applicability to the development of modern applications.


A Busy-Tone Based Mac Scheme For Wireless Ad Hoc Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu Dec 2006

A Busy-Tone Based Mac Scheme For Wireless Ad Hoc Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Applying directional antennas in wireless ad hoc networks offers numerous benefits, such as extended communication range, increased spatial reuse, improved capacity and suppressed interference. However, directional antennas can cause new location-dependent carrier sensing problems, such as new hidden terminal and deafness problems, which can cause severe penalties to the performance. Recently, a few schemes have been proposed to tackle these problems. However, these methods can provide limited solutions on the hidden terminal and deafness problems. We propose a new MAC protocol, termed the busy-tone based directional medium access control (BT-DMAC) protocol. When the transmission is in progress, the sender and ...