University of Arizona

Displaying 1-40 of 60 results

  • White Papers // Apr 2012

    The Link Rank of an Undirected Network

    The authors consider the problem of identifying link metrics in an arbitrary undirected network using measurement nodes and establishing paths/cycles that start and end at these nodes. They assume that the link metrics are unknown constants and combine in an additive manner. They introduce the concept of link rank -...

    Provided By University of Arizona

  • White Papers // Jan 2012

    On the Extraction and Analysis of a Social Network With Partial Organizational Observation

    The behavior of an organization may be inferred based on the behavior of its members, their contacts, and their connectivity. One approach to organizational analysis is the construction and interpretation of a social network graph, where entities of an organization (persons, vehicles, locations, events, etc.) are nodes, and edges represent...

    Provided By University of Arizona

  • White Papers // Jan 2012

    Wavelength Assignment in Optical Networks With Imprecise Network State Information

    Efficient Routing and Wavelength Assignment (RWA) in wavelength-routed all-optical networks is critical for achieving high efficiency over the backbone links. Extensive research has been conducted to find strategies to solve the RWA problem with exact network state available at the time of path selection. The authors consider the problem of...

    Provided By University of Arizona

  • White Papers // Jan 2012

    Deobfuscation Reverse Engineering Obfuscated Code

    In recent years, code obfuscation has attracted attention as a low cost approach to improving software security by making it difficult for attackers to understand the inner workings of proprietary software systems. This paper examines techniques for automatic deobfuscation of obfuscated programs, as a step towards reverse engineering such programs....

    Provided By University of Arizona

  • White Papers // Dec 2011

    Automatic Simplification of Obfuscated JavaScript Code

    Javascript is a scripting language that is commonly used to create sophisticated interactive client-side web applications. It can also be used to carry out browser-based attacks on users. Malicious JavaScript code is usually highly obfuscated, making detection a challenge. This paper describes a simple approach to deobfuscation of JavaScript code...

    Provided By University of Arizona

  • White Papers // Dec 2011

    Spectrum-Aware Beaconless Geographical Routing Protocol for Mobile Cognitive Radio Networks

    A key challenge in routing in Cognitive Radio Networks (CRNs) is how to adaptively and efficiently select a route and assign resources along that route according to the surrounding environment. In this paper, the authors propose a distributed routing protocol for CRNs, in which path selection and resource allocation (e.g....

    Provided By University of Arizona

  • White Papers // Nov 2011

    Multipath Routing and Dual Link Failure Recovery in IP Networks Using Three Link-Independent Trees

    The authors develop an approach for disjoint multipath routing and fast recovery in IP networks that guarantees recovery from arbitrary two link failures. They employ three link-independent trees, referred to as red, blue, and green trees, rooted at every destination. The path from a source to the destination on the...

    Provided By University of Arizona

  • White Papers // Aug 2011

    Spectrum Management and Power Allocation in MIMO Cognitive Networks

    The authors consider the problem of maximizing the throughput of a Multi-Input Multi-Output (MIMO) Cognitive Radio (CR) network. CR users are assumed to be able to share the available spectrum without disturbing existing Primary Radio (PR) transmissions. For each frequency band, a multi-antenna CR node uses MIMO spatial multiplexing to...

    Provided By University of Arizona

  • White Papers // Jul 2011

    Packet-Hiding Methods for Preventing Selective Jamming Attacks

    The open nature of the wireless medium leaves it vulnerable to intentional interference attacks, typically referred to as jamming. This intentional interference with wireless transmissions can be used as a launchpad for mounting Denial-of-Service attacks on wireless networks. Typically, jamming has been addressed under an external threat model. However, adversaries...

    Provided By University of Arizona

  • White Papers // Jun 2011

    Independent Directed Acyclic Graphs for Resilient Multipath Routing

    In order to achieve resilient multipath routing the authors introduce the concept of Independent Directed Acyclic Graphs (IDAGs) in this paper. Link-independent (Node-independent) DAGs satisfy the property that any path from a source to the root on one DAG is link-disjoint (node-disjoint) with any path from the source to the...

    Provided By University of Arizona

  • White Papers // Jun 2011

    Equational Reasoning on X86 Assembly Code

    Analysis of software is essential to addressing problems of correctness, efficiency, and security. Existing source code analysis tools are very useful for such purposes, but there are many instances where high-level source code is not available for software that needs to be analyzed. A need exists for tools that can...

    Provided By University of Arizona

  • White Papers // Mar 2011

    Design and Evaluation of an Efficient Guard-Band-Aware Multi-Channel Spectrum Sharing Mechanism

    Several spectrum access/sharing algorithms for Cognitive Radio Networks (CRNs) have been designed assuming no adjacent-channel interference (i.e., no interference from neighboring CR transmissions operating over adjacent channels). However, in practice, such an assumption may not hold, and guard bands are realistically needed to prevent interference from neighboring CR transmissions operating...

    Provided By University of Arizona

  • White Papers // Feb 2011

    Enhancing Shortest Path Routing for Resilience and Load Balancing

    This paper develops a new resilient multipath routing technique, referred to as SPT-DAG, that has the following characteristics: provides multipath routing over Directed Acyclic Graphs (DAG); the shortest path tree is guaranteed to be part of the DAG; and provides guaranteed recovery from single link failures. The authors develop a...

    Provided By University of Arizona

  • White Papers // Jan 2011

    DEVS Unified Process for Web-Centric Development and Testing of System of Systems

    A critical aspect and differentiator of a System of Systems (SoS) versus a single monolithic system is interoperability among the constituent disparate systems. A major application of Modeling and Simulation (M&S) to SoS Engineering is to facilitate system integration in a manner that helps to cope with such interoperability problems....

    Provided By University of Arizona

  • White Papers // Dec 2010

    A Focused Crawler for Dark Web Forums

    The unprecedented growth of the Internet has propagated the escalation of the Dark Web, the problematic facet of the web associated with cybercrime, hate, and extremism. Despite the need for tools to collect and analyze Dark Web forums, the covert nature of this part of the Internet makes traditional web...

    Provided By University of Arizona

  • White Papers // Nov 2010

    Selective Jamming/Dropping Insider Attacks in Wireless Mesh Networks

    Wireless Mesh Networks (WMNs) promise to extend high-speed wireless connectivity beyond what is possible with the current WiFi-based infrastructure. However, their unique architectural features leave them particularly vulnerable to security threats. In this paper, the authors describe various forms of sophisticated attacks launched from adversaries with internal access to the...

    Provided By University of Arizona

  • White Papers // Nov 2010

    NanoXen: Better Systems Through Rigorous Containment and Active Modeling

    Modern software design has less writing large programs and more orchestrating the actions of prewritten library elements. These elements, generally known as components, are stateful software elements which can operate and interact in unexpected ways. Most errors in large systems result from unanticipated behavior from components, or unexpected interaction between...

    Provided By University of Arizona

  • White Papers // Sep 2010

    A Primary User Authentication System for Mobile Cognitive Radio Networks

    Cognitive Radio Networks (CRNs) exploit the idle portion of the licensed spectrum to establish network communications. Essential to the co-existence of this technology with legacy systems, is the reliable sensing of spectrum opportunities. However, existing spectrum sensing techniques are vulnerable to adversaries that mimic the characteristics of Primary User (PU)...

    Provided By University of Arizona

  • White Papers // Aug 2010

    Reverse Engineering Self-Modifying Code: Unpacker Extraction

    An important application of binary-level reverse engineering is in reconstructing the internal logic of computer malware. Most malware code is distributed in encrypted (or "Packed") form; at runtime, an unpacker routine transforms this to the original executable form of the code, which is then executed. Most of the existing work...

    Provided By University of Arizona

  • White Papers // Jul 2010

    Fast Recovery From Dual Link or Single Node Failures in IP Networks Using Tunneling

    This paper develops novel mechanisms for recovering from failures in IP networks with proactive backup path calculations and IP tunneling. The primary scheme provides resilience for up to two link failures along a path. The highlight of the developed routing approach is that a node re-routes a packet around the...

    Provided By University of Arizona

  • White Papers // Apr 2010

    Performance Analysis of Multi-Channel Wireless Infrastructure Networks

    Wireless infrastructure networks that provide ubiquitous connectivity to mobile nodes in metro areas are becoming increasingly popular. The nodes in such backbone networks are often equipped with multiple transceivers to allow for simultaneous transmissions in multiple non-overlapping channels. This paper develops an analytical model for evaluating the throughput and delay...

    Provided By University of Arizona

  • White Papers // Mar 2010

    Survey of Wireless Multimedia Sensor Networks

    Wireless Sensor Networks (WSNs) have recently been the focus of significant amount of research. The vast majority of these studies apply to conventional WSN applications which need reliable and efficient communication of scalar event features and sensor data such as temperature, pressure, etc. However, the availability of low cost CMOS...

    Provided By University of Arizona

  • White Papers // Mar 2010

    Medical Tourism From US To Border Region Of Mexico: Current Status And Future Prospects

    Medical tourism is an increasingly popular trend that has expanded over the US/Mexican border region. Medical tourism is defined as travel beyond a home country in search of health care that is either less expensive or more accessible. The economic situation in the US has left a large number of...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Scheduling Sensors for Guaranteed Sparse Coverage

    Wireless sensor networks are being increasingly used to due to its vast spectrum of applications including surveillance, security, healthcare, asset tracking and environmental monitoring. Such a network consists of large numbers of nodes which are placed in a region in order to gather and transmit information about activities in that...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Delay-Hiding Energy Management Mechanisms for DRAM

    Current trends in data-intensive applications increase the demand for larger physical memory, resulting in the memory subsystem consuming a significant portion of system's energy. Furthermore, data-intensive applications heavily rely on a large buffer cache that occupies a majority of physical memory. Subsequently, the authors are focusing on the power management...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Detecting Large Route Leaks

    Prefix hijacking, in which an unauthorized network announces IP prefixes of other networks, is a major threat to the Internet routing security. Existing detection systems either generate many false positives, requiring frequent human intervention, or are designed to protect a small number of specific prefixes. Therefore they are not suitable...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Broadcasting in Multi-Channel Wireless Infrastructure Networks Employing Directional Antenna

    Multi-channel wireless networks are increasingly being employed as infrastructure networks in metro areas. In addition, nodes in these networks employ directional antennas to improve spatial throughput. In such networks, they consider the problem of finding a broadcast tree from a given root with channel assignment such that all the links...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Resilient Multipath Routing With Independent Directed Acyclic Graphs

    In this paper, the authors introduce the concept of Independent Directed Acyclic Graphs (IDAGs) to achieve resilient multipath routing. Link-independent (Node-independent) DAGs satisfy the property that any path from a source to the root on one DAG is link-disjoint (node-disjoint) with any path from the source to the root on...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Selective Jamming Attacks in Wireless Networks

    The authors address the problem of selective jamming attacks in wireless networks. In these attacks, the adversary selectively targets specific packets of "High" importance by exploiting his knowledge on the implementation details of network protocols at various layers of the protocol stack. They illustrate the impact of selective jamming on...

    Provided By University of Arizona

  • White Papers // Jan 2010

    Polarization-Multiplexed Rate-Adaptive Nonbinary- Quasi-Cyclic-LDPC-Coded Multilevel Modulation With Coherent Detection for Optical Transport Networks

    In order to achieve high-speed transmission over Optical Transport Networks (OTNs) and maximize its throughput, the authors propose using a rate-adaptive polarization-multiplexed coded multilevel modulation with coherent detection based on component non-binary Quasi-Cyclic (QC) LDPC codes. Compared to prior-art Bit-Interleaved LDPC-Coded Modulation (BILDPC-CM) scheme, the proposed Non-Binary LDPC-Coded Modulation (NB-LDPC-CM)...

    Provided By University of Arizona

  • White Papers // Jan 2010

    A Feasibility Study for Power Management in LAN Switches

    The authors examine the feasibility of introducing power management schemes in network devices in the LAN. Specifically, the authors investigate the possibility of putting various components on LAN switches to sleep during periods of low traffic activity. Traffic collected in the LAN indicates that there are significant periods of inactivity...

    Provided By University of Arizona

  • White Papers // Dec 2009

    On the Aggregatability of Router Forwarding Tables

    The rapid growth of global routing tables has raised concerns among many Internet Service Providers. The most immediate concern regarding routing scalability is the size of the Forwarding Information Base (FIB), which seems to be growing at a faster pace than router hardware can support. This paper focuses on one...

    Provided By University of Arizona

  • White Papers // Dec 2009

    Cooperative Adaptive Spectrum Sharing in Cognitive Radio Networks

    The Cognitive Radio (CR) paradigm calls for open spectrum access according to a predetermined etiquette. Under this paradigm, CR nodes access the spectrum opportunistically by continuously monitoring the operating channels. A key challenge in this domain is how the nodes in a CR Network (CRN) cooperate to access the medium...

    Provided By University of Arizona

  • White Papers // Dec 2009

    Interference Management and Rate Adaptation in OFDM-Based UWB Networks

    Ultra-WideBand (UWB) communications has emerged as a promising technology for high data rate Wireless Personal Area Networks (WPANs). Several proposals for UWB-based WPANs have been made. One widely popular proposal was standardized by ECMA-368, and is based on OFDM. In this paper, the authors address one of the important aspects...

    Provided By University of Arizona

  • White Papers // Nov 2009

    Towards Economically Viable Infrastructure-Based Overlay Multicast Networks

    Internet-scale dissemination of streaming contents (e.g., Live sports games) can be achieved by infrastructure-based overlay multicast networks, where multicast service providers deliver the contents via dedicated servers strategically placed over the Internet. Given the huge amount of data traffic, one of the major operation costs is the ISP cost for...

    Provided By University of Arizona

  • White Papers // Oct 2009

    A Data Parallel Algorithm for XML DOM Parsing

    The extensible markup language XML has become the de facto standard for information representation and interchange on the Internet. XML parsing is a core operation performed on an XML document for it to be accessed and manipulated. This operation is known to cause performance bottlenecks in applications and systems that...

    Provided By University of Arizona

  • White Papers // Sep 2009

    Web Based Distributed Network Analyzer Using SES Over Service Oriented Architecture

    As the network uses, and especially the number of internet users, increases rapidly, an efficient system for managing large network traffic datasets becomes an important issue. Although there are several network traffic analysis tools such as tcpdump, Ethereal, and other applications, these tools have weaknesses: limited size of files, command...

    Provided By University of Arizona

  • White Papers // Sep 2009

    Cyber Security in the National Market System

    A secure financial market system is critical to the national economy. Yet, the authors show that over the past thirty years, financial market regulations have actually increased the vulnerability of U.S. financial trading systems to cyber terrorism by mandating a "National market system" in which otherwise separate trading centers are...

    Provided By University of Arizona

  • White Papers // Sep 2009

    The Fair Value Of Cash Flow Hedges, Future Profitability And Stock Returns

    The author examine the information content of unrealized cash flow hedge gains/losses for future profitability and stock returns. An unrealized gain on a cash flow hedge suggests that the price of the underlying hedged item (i.e. commodity price, foreign currency exchange rate or interest rate) moved in a direction that...

    Provided By University of Arizona

  • White Papers // Aug 2009

    SSWAP - Simple Semantic Web Architecture and Protocol

    Biology is rapidly becoming an information science. Scientific advances require wet lab and field investigations - indeed, that is the sine qua non of science. But informatics is rapidly becoming a necessary, but not sufficient, component of the biological scientific endeavor. Given this, the authors still find ourselves expending thousands...

    Provided By University of Arizona

  • White Papers // Oct 2008

    Energy-Efficient Protocols for Wireless Networks With Adaptive MIMO Capabilities

    Transmission power control has been used in wireless networks to improve the channel reuse and/or reduce energy consumption. It has been mainly applied to Single-Input Single-Output (SISO) systems, where each node is equipped with a single antenna. This paper proposes a power-controlled channel access protocol for MIMO-capable wireless LANs with...

    Provided By University of Arizona

  • White Papers // Jan 2011

    DEVS Unified Process for Web-Centric Development and Testing of System of Systems

    A critical aspect and differentiator of a System of Systems (SoS) versus a single monolithic system is interoperability among the constituent disparate systems. A major application of Modeling and Simulation (M&S) to SoS Engineering is to facilitate system integration in a manner that helps to cope with such interoperability problems....

    Provided By University of Arizona

  • White Papers // Jun 2009

    DEVS Namespace for Interoperable DEVS/SOA

    Interoperable DEVS modeling and simulation is desirable to enhance model composability and reusability with DEVS models and non-DEVS models in different languages and platforms. The barrier to such interoperability is that DEVS simulators implement the DEVS modeling formalism in diverse programming environments. Although the DEVS formalism specifies the same abstract...

    Provided By University of Arizona

  • White Papers // Mar 2009

    Interoperability Between DEVS Simulators Using Service Oriented Architecture and DEVS Namespace

    DEVS Modeling and Simulation (M&S) has various implementations with various computer languages such as JAVA, C++, and C#. To enhance model reusability with different implementation, the authors need interoperable systems such as CORBA, HLA, and SOA, and an interoperable mechanism for simulation of heterogeneous DEVS models. As an infrastructure of...

    Provided By University of Arizona

  • White Papers // Sep 2009

    Web Based Distributed Network Analyzer Using SES Over Service Oriented Architecture

    As the network uses, and especially the number of internet users, increases rapidly, an efficient system for managing large network traffic datasets becomes an important issue. Although there are several network traffic analysis tools such as tcpdump, Ethereal, and other applications, these tools have weaknesses: limited size of files, command...

    Provided By University of Arizona

  • White Papers // Aug 2009

    Multi-Commodity Flow Traffic Engineering With Hybrid MPLS/OSPF Routing

    The common objective of network traffic engineering is to minimize the maximal link utilization in a network in order to accommodate more traffic and reduce the chance of congestion. Traditionally this is done by either optimizing OSPF link weights or using MPLS tunnels to direct traffic. However, they both have...

    Provided By University of Arizona

  • White Papers // Nov 2009

    Towards Economically Viable Infrastructure-Based Overlay Multicast Networks

    Internet-scale dissemination of streaming contents (e.g., Live sports games) can be achieved by infrastructure-based overlay multicast networks, where multicast service providers deliver the contents via dedicated servers strategically placed over the Internet. Given the huge amount of data traffic, one of the major operation costs is the ISP cost for...

    Provided By University of Arizona

  • White Papers // Dec 2009

    On the Aggregatability of Router Forwarding Tables

    The rapid growth of global routing tables has raised concerns among many Internet Service Providers. The most immediate concern regarding routing scalability is the size of the Forwarding Information Base (FIB), which seems to be growing at a faster pace than router hardware can support. This paper focuses on one...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Detecting Large Route Leaks

    Prefix hijacking, in which an unauthorized network announces IP prefixes of other networks, is a major threat to the Internet routing security. Existing detection systems either generate many false positives, requiring frequent human intervention, or are designed to protect a small number of specific prefixes. Therefore they are not suitable...

    Provided By University of Arizona

  • White Papers // Sep 2009

    Cyber Security in the National Market System

    A secure financial market system is critical to the national economy. Yet, the authors show that over the past thirty years, financial market regulations have actually increased the vulnerability of U.S. financial trading systems to cyber terrorism by mandating a "National market system" in which otherwise separate trading centers are...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Broadcasting in Multi-Channel Wireless Infrastructure Networks Employing Directional Antenna

    Multi-channel wireless networks are increasingly being employed as infrastructure networks in metro areas. In addition, nodes in these networks employ directional antennas to improve spatial throughput. In such networks, they consider the problem of finding a broadcast tree from a given root with channel assignment such that all the links...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Delay-Hiding Energy Management Mechanisms for DRAM

    Current trends in data-intensive applications increase the demand for larger physical memory, resulting in the memory subsystem consuming a significant portion of system's energy. Furthermore, data-intensive applications heavily rely on a large buffer cache that occupies a majority of physical memory. Subsequently, the authors are focusing on the power management...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Scheduling Sensors for Guaranteed Sparse Coverage

    Wireless sensor networks are being increasingly used to due to its vast spectrum of applications including surveillance, security, healthcare, asset tracking and environmental monitoring. Such a network consists of large numbers of nodes which are placed in a region in order to gather and transmit information about activities in that...

    Provided By University of Arizona

  • White Papers // Jul 2010

    Fast Recovery From Dual Link or Single Node Failures in IP Networks Using Tunneling

    This paper develops novel mechanisms for recovering from failures in IP networks with proactive backup path calculations and IP tunneling. The primary scheme provides resilience for up to two link failures along a path. The highlight of the developed routing approach is that a node re-routes a packet around the...

    Provided By University of Arizona

  • White Papers // Dec 2010

    A Focused Crawler for Dark Web Forums

    The unprecedented growth of the Internet has propagated the escalation of the Dark Web, the problematic facet of the web associated with cybercrime, hate, and extremism. Despite the need for tools to collect and analyze Dark Web forums, the covert nature of this part of the Internet makes traditional web...

    Provided By University of Arizona

  • White Papers // Feb 2009

    Measuring the Benefits to Sniping on eBay: Evidence From a Field Experiment

    Bidders on eBay frequently engage in sniping: that is, submitting a bid seconds before an auction closes. Using a field experiment, the authors attempt to measure the size of the benefit of sniping (if any). To do this they selected pairs of auctions that were as identical as possible (same...

    Provided By University of Arizona

  • White Papers // May 2009

    Spectrum Opportunity-Based Control Channel Assignment in Cognitive Radio Networks

    The authors address the problem of dynamic assignment of coordination (control) channels in Cognitive Radio Networks (CRNs) by exploiting time - and space-varying spectrum opportunities. Motivated by the inherent grouping of Cognitive Radio (CR) users according to channel availability, they propose a cluster-based architecture for control-channel assignment in a CRN....

    Provided By University of Arizona

  • White Papers // Nov 2010

    Selective Jamming/Dropping Insider Attacks in Wireless Mesh Networks

    Wireless Mesh Networks (WMNs) promise to extend high-speed wireless connectivity beyond what is possible with the current WiFi-based infrastructure. However, their unique architectural features leave them particularly vulnerable to security threats. In this paper, the authors describe various forms of sophisticated attacks launched from adversaries with internal access to the...

    Provided By University of Arizona

  • White Papers // Sep 2010

    A Primary User Authentication System for Mobile Cognitive Radio Networks

    Cognitive Radio Networks (CRNs) exploit the idle portion of the licensed spectrum to establish network communications. Essential to the co-existence of this technology with legacy systems, is the reliable sensing of spectrum opportunities. However, existing spectrum sensing techniques are vulnerable to adversaries that mimic the characteristics of Primary User (PU)...

    Provided By University of Arizona

  • White Papers // Jul 2009

    Dealing With Liars: Misbehavior Identification Via Renyi-Ulam Games

    The authors address the problem of identifying misbehaving nodes that refuse to forward packets in wireless multi-hop networks. They map the process of locating the misbehaving nodes to the classic Renyi-Ulam game of 20 questions. Compared to previous methods, the mapping allows the evaluation of node behavior on a per-packet...

    Provided By University of Arizona

  • White Papers // Feb 2010

    Selective Jamming Attacks in Wireless Networks

    The authors address the problem of selective jamming attacks in wireless networks. In these attacks, the adversary selectively targets specific packets of "High" importance by exploiting his knowledge on the implementation details of network protocols at various layers of the protocol stack. They illustrate the impact of selective jamming on...

    Provided By University of Arizona

  • White Papers // Mar 2010

    Medical Tourism From US To Border Region Of Mexico: Current Status And Future Prospects

    Medical tourism is an increasingly popular trend that has expanded over the US/Mexican border region. Medical tourism is defined as travel beyond a home country in search of health care that is either less expensive or more accessible. The economic situation in the US has left a large number of...

    Provided By University of Arizona

  • White Papers // Dec 2009

    Interference Management and Rate Adaptation in OFDM-Based UWB Networks

    Ultra-WideBand (UWB) communications has emerged as a promising technology for high data rate Wireless Personal Area Networks (WPANs). Several proposals for UWB-based WPANs have been made. One widely popular proposal was standardized by ECMA-368, and is based on OFDM. In this paper, the authors address one of the important aspects...

    Provided By University of Arizona

  • White Papers // Dec 2009

    Cooperative Adaptive Spectrum Sharing in Cognitive Radio Networks

    The Cognitive Radio (CR) paradigm calls for open spectrum access according to a predetermined etiquette. Under this paradigm, CR nodes access the spectrum opportunistically by continuously monitoring the operating channels. A key challenge in this domain is how the nodes in a CR Network (CRN) cooperate to access the medium...

    Provided By University of Arizona

  • White Papers // May 2009

    Coverage-Time Optimization for Clustered Wireless Sensor Networks: A Power-Balancing Approach

    In this paper, the authors investigate the maximization of the coverage time for a clustered Wireless Sensor Network (WSN) by optimal balancing of power consumption among Cluster Heads (CHs). Clustering significantly reduces the energy consumption of individual sensors, but it also increases the communication burden on CHs. To investigate this...

    Provided By University of Arizona

  • White Papers // Dec 2008

    MAC Protocol for Opportunistic Cognitive Radio Networks With Soft Guarantees

    Cognitive Radio (CR) is the key enabling technology for an efficient dynamic spectrum access. It aims at exploiting an underutilized licensed spectrum by enabling opportunistic communications for unlicensed users. In this paper, the authors first develop a distributed COgnitive radio MAC (COMAC) protocol that enables unlicensed users to dynamically utilize...

    Provided By University of Arizona

  • White Papers // Mar 2009

    Coexistence Problem in IEEE 802.22 Wireless Regional Area Networks

    IEEE 802.22 Wireless Regional Area Network (WRAN) is an emerging cognitive radio-based system. One of the major challenges for WRANs is how to efficiently schedule both channel sensing and data transmission for multiple adjacent WRAN cells. This challenge is known as coexistence problem. In this paper, the authors propose four...

    Provided By University of Arizona

  • White Papers // Aug 2011

    Spectrum Management and Power Allocation in MIMO Cognitive Networks

    The authors consider the problem of maximizing the throughput of a Multi-Input Multi-Output (MIMO) Cognitive Radio (CR) network. CR users are assumed to be able to share the available spectrum without disturbing existing Primary Radio (PR) transmissions. For each frequency band, a multi-antenna CR node uses MIMO spatial multiplexing to...

    Provided By University of Arizona

  • White Papers // Jul 2009

    Spectrum Sharing With Adaptive Power Management for Throughput Enhancement in Dynamic Access Networks

    Cognitive Radios (CRs) are emerging as a promising technology to enhance spectrum utilization through opportunistic on-demand access. Many spectrum access/sharing algorithms for CR Networks (CRNs) have been designed assuming multiple transceivers per CR user. However, in practice, such an assumption may not hold due to hardware cost. In this paper,...

    Provided By University of Arizona

  • White Papers // Mar 2011

    Design and Evaluation of an Efficient Guard-Band-Aware Multi-Channel Spectrum Sharing Mechanism

    Several spectrum access/sharing algorithms for Cognitive Radio Networks (CRNs) have been designed assuming no adjacent-channel interference (i.e., no interference from neighboring CR transmissions operating over adjacent channels). However, in practice, such an assumption may not hold, and guard bands are realistically needed to prevent interference from neighboring CR transmissions operating...

    Provided By University of Arizona

  • White Papers // Jul 2009

    Truthful Least-Priced-Path Routing in Opportunistic Spectrum Access Networks

    The authors study the problem of finding the Least-Priced Path (LPP) between a source and a destination in Opportunistic Spectrum Access (OSA) networks. This problem is motivated by economic considerations, whereby spectrum opportunities are sold/leased to Secondary Radios (SRs). This incurs a cost for the communication services, e.g., for traffic...

    Provided By University of Arizona

  • White Papers // Jul 2011

    Packet-Hiding Methods for Preventing Selective Jamming Attacks

    The open nature of the wireless medium leaves it vulnerable to intentional interference attacks, typically referred to as jamming. This intentional interference with wireless transmissions can be used as a launchpad for mounting Denial-of-Service attacks on wireless networks. Typically, jamming has been addressed under an external threat model. However, adversaries...

    Provided By University of Arizona

  • White Papers // Jun 2011

    Independent Directed Acyclic Graphs for Resilient Multipath Routing

    In order to achieve resilient multipath routing the authors introduce the concept of Independent Directed Acyclic Graphs (IDAGs) in this paper. Link-independent (Node-independent) DAGs satisfy the property that any path from a source to the root on one DAG is link-disjoint (node-disjoint) with any path from the source to the...

    Provided By University of Arizona

  • White Papers // Feb 2011

    Enhancing Shortest Path Routing for Resilience and Load Balancing

    This paper develops a new resilient multipath routing technique, referred to as SPT-DAG, that has the following characteristics: provides multipath routing over Directed Acyclic Graphs (DAG); the shortest path tree is guaranteed to be part of the DAG; and provides guaranteed recovery from single link failures. The authors develop a...

    Provided By University of Arizona

  • White Papers // Jan 2010

    Polarization-Multiplexed Rate-Adaptive Nonbinary- Quasi-Cyclic-LDPC-Coded Multilevel Modulation With Coherent Detection for Optical Transport Networks

    In order to achieve high-speed transmission over Optical Transport Networks (OTNs) and maximize its throughput, the authors propose using a rate-adaptive polarization-multiplexed coded multilevel modulation with coherent detection based on component non-binary Quasi-Cyclic (QC) LDPC codes. Compared to prior-art Bit-Interleaved LDPC-Coded Modulation (BILDPC-CM) scheme, the proposed Non-Binary LDPC-Coded Modulation (NB-LDPC-CM)...

    Provided By University of Arizona

  • White Papers // Dec 2011

    Spectrum-Aware Beaconless Geographical Routing Protocol for Mobile Cognitive Radio Networks

    A key challenge in routing in Cognitive Radio Networks (CRNs) is how to adaptively and efficiently select a route and assign resources along that route according to the surrounding environment. In this paper, the authors propose a distributed routing protocol for CRNs, in which path selection and resource allocation (e.g....

    Provided By University of Arizona

  • White Papers // Jan 2012

    Wavelength Assignment in Optical Networks With Imprecise Network State Information

    Efficient Routing and Wavelength Assignment (RWA) in wavelength-routed all-optical networks is critical for achieving high efficiency over the backbone links. Extensive research has been conducted to find strategies to solve the RWA problem with exact network state available at the time of path selection. The authors consider the problem of...

    Provided By University of Arizona

  • White Papers // Mar 2009

    Analyzing Seller Practices in a Brazilian Marketplace

    E-commerce is growing at an exponential rate. In the last decade, there has been an explosion of online commercial activity enabled by World Wide Web (WWW). These days, many consumers are less attracted to online auctions, preferring to buy merchandise quickly using fixed-price negotiations. Sales at Amazon.com, the leader in...

    Provided By University of Arizona

  • White Papers // Dec 2011

    Automatic Simplification of Obfuscated JavaScript Code

    Javascript is a scripting language that is commonly used to create sophisticated interactive client-side web applications. It can also be used to carry out browser-based attacks on users. Malicious JavaScript code is usually highly obfuscated, making detection a challenge. This paper describes a simple approach to deobfuscation of JavaScript code...

    Provided By University of Arizona

  • White Papers // Jun 2011

    Equational Reasoning on X86 Assembly Code

    Analysis of software is essential to addressing problems of correctness, efficiency, and security. Existing source code analysis tools are very useful for such purposes, but there are many instances where high-level source code is not available for software that needs to be analyzed. A need exists for tools that can...

    Provided By University of Arizona