University of British Columbia

Displaying 1-40 of 112 results

  • White Papers // Oct 2012

    Profit Maximization Over Social Networks

    Influence maximization is the problem of finding a set of influential users in a social network such that the expected spread of influence under a certain propagation model is maximized. Much of the previous work has neglected the important distinction between social influence and actual product adoption. However, as recognized...

    Provided By University of British Columbia

  • White Papers // Dec 2011

    Evolutionary Search-Based Test Generation for Software Product Line Feature Models

    Product line-based software engineering is a paradigm that models the commonalities and variabilities of different applications of a given domain of interest within a unique framework and enhances rapid and low cost development of new applications based on reuse engineering principles. Despite the numerous advantages of software product lines, it...

    Provided By University of British Columbia

  • White Papers // Nov 2011

    Bounding Interference in Wireless Ad Hoc Networks With Nodes in Random Position

    The interference at a wireless node s can be modelled by the number of wireless nodes whose trans-mission ranges cover s. Given a set of positions for wireless nodes, the interference minimization problem is to assign a transmission radius (equivalently, a power level) to each node such that the resulting...

    Provided By University of British Columbia

  • White Papers // Sep 2011

    Admission Control and Resource Optimization for Multiple-User OFDMA Cognitive Radio Systems

    In Cognitive Radio (CR) systems, the fluctuating nature of the available frequency resource due to Primary Users (PUs) activity necessitates the introduction of admission and eviction measures at the CR system if a guaranteed Quality of Service (QoS) is required by Real Time (RT) Secondary Users (SUs). This problem has...

    Provided By University of British Columbia

  • White Papers // Sep 2011

    Neighborhood-Knowledge Based Routing in PLC

    One of the challenges of employing Power Line Communication (PLC) in power distribution grids is routing messages using multihop transmission or, in other words, by relaying information through decode and forward packets. In this contribution, the authors show a possible compromise between energy consumption and delivery delay that are performance...

    Provided By University of British Columbia

  • White Papers // Sep 2011

    Inferring Power Line Network Topology Using Frequency Domain Reflectometry

    Power Line Communications (PLC) is an attractive means of data communication for a variety of scenarios and applications, including in-home multimedia and utility applications, the latter of which have gained renewed attention under the label of Smart Grid. The analysis and design of PLC systems should rely on sufficiently accurate...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    A Stackelberg Game for Cooperative Transmission and Random Access in Cognitive Radio Networks

    In cognitive radio networks, the Secondary Users (SUs) can be selected as the cooperative relays to assist the transmission of the Primary User (PU). In order to increase the utility, the PU needs to consider whether it is beneficial to use cooperative transmission and which SU should be chosen as...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    Design of Pre-Rake DS-UWB Downlink With Pre-Equalization

    The authors consider the design of Ultra-WideBand (UWB) systems that enable high data rate communications for short-range wireless applications. In particular, they consider the downlink of a Direct Sequence UWB (DS-UWB) system in which the base station is equipped with multiple antennas and employs pre-rake combining, while each user employs...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    Optimal Real-Time Pricing Algorithm Based on Utility Maximization for Smart Grid

    In this paper, the authors consider a smart power infrastructure, where several subscribers share a common energy source. Each subscriber is equipped with an Energy Consumption Controller (ECC) unit as part of its smart meter. Each smart meter is connected to not only the power grid but also a communication...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    A Coalition Formation Game for Energy-Efficient Cooperative Spectrum Sensing in Cognitive Radio Networks With Multiple Channels

    Spectrum sensing is one of the key technologies to realize spectrum reuse and increase the spectrum efficiency in Cognitive Radio Networks (CRNs). In this paper, the authors study energy-efficient cooperative multi-channel spectrum sensing in CRNs. They first propose a Cooperative Spectrum Sensing and Accessing (CSSA) scheme for all the Secondary...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    Downlink Scheduling With Transmission Strategy Selection for Two-Cell MIMO Networks

    Multiple-Input Multiple-Output (MIMO) processing is a promising technique to achieve high speed data service in next generation cellular networks. However, the performance of multi-cell MIMO networks is limited by the cell-edge users who experience significant inter-cell interference. In this paper, the authors propose to use interference alignment to mitigate interference...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    Context-Aware Mobility Management in Heterogeneous Network Environments

    Context-aware mobility management can provide major enhancements for future mobile communication systems. Not only it considers device mobility, but session mobility is also considered. Context-awareness is a key ingredient in any ubiquitous and pervasive system and provides intelligence to the system, allowing computing devices make appropriate and timely decisions on...

    Provided By University of British Columbia

  • White Papers // Jun 2011

    Profiling-as-a-Service: Adaptive Scalable Resource Profiling for the Cloud in the Cloud

    Run-time profiling of Web-based applications and services is an effective method to aid in the provisioning of required resources, for monitoring server-level objectives, and for detecting implementation defects. Unfortunately, it is difficult to obtain accurate profile data on live client workloads due to the high overhead of instrumentation. This paper...

    Provided By University of British Columbia

  • White Papers // Jun 2011

    Strategic Investments, Technological Uncertainty, And Expected Return Externalities

    The authors study the effect of competition in technological innovation on asset prices. Using a model of an innovation race in which firms face both technological and market-wide uncertainty when they exercise innovation options, they show that a firm's investment in innovation imposes an expected return "Externality" on its rivals....

    Provided By University of British Columbia

  • White Papers // May 2011

    Calibration And Filtering For Multi Factor Commodity Models With Seasonality: Incorporating Panel Data From Futures Contracts

    The authors examine a general multi-factor model for commodity spot prices and futures valuation. They extend the multi-factor long-short model in and in two important aspects: firstly, they allow for both the long and short term dynamic factors to be mean reverting incorporating stochastic volatility factors and secondly, they develop...

    Provided By University of British Columbia

  • White Papers // May 2011

    Exposing File System Mappings With MapFS

    The conventional model of a file as a contiguous array of bytes hides information about the physical location of data from users. While this simplifying abstraction can be useful in some cases, it can also lead to suboptimal performance and unnecessary overhead. A growing number of applications - even those...

    Provided By University of British Columbia

  • White Papers // Apr 2011

    Schedule Data, Not Code

    In this paper, the authors argue that the scheduler, as the intermediary between hardware and software, needs to be fully data-aware. The old paradigm of envisioning tasks as amorphous blobs of 'Work' to be assigned to processors is incomplete and needs be expanded. Some techniques and projects have emerged that...

    Provided By University of British Columbia

  • White Papers // Apr 2011

    On Cooperative Coding for Narrowband PLC Networks

    Low-Frequency NarrowBand (LF NB) Power Line Communications (PLC) is an old data-communication concept that has received renewed interest in industry, standardization, and academia for its potential to become an important element of the communication infrastructure supporting Smart Grid applications. In this paper, dedicated to Prof. Johannes Huber on the occasion...

    Provided By University of British Columbia

  • White Papers // Apr 2011

    Second Order Cone Programming for Sensor Network Localization With Anchor Position Uncertainty

    The authors consider the problem of node localization in sensor networks, and they focus on networks in which the ranging measurements are subject to errors and anchor positions are subject to uncertainty. They consider a statistical model for the uncertainty in the anchor positions and formulate the robust localization problem...

    Provided By University of British Columbia

  • White Papers // Mar 2011

    VMFlock: Virtual Machine Co-Migration for the Cloud

    This paper presents VMFlockMS, a migration service optimized for cross-datacenter transfer and instantiation of groups of Virtual Machine (VM) images that comprise an application-level solution (e.g., a three-tier web application). The authors dub these groups of related VM images VMFlocks. VMFlockMS employs two main techniques: first, data deduplication within the...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Optimal Data Transmission and Channel Code Rate Allocation in Multi-Path Wireless Networks

    Wireless links are often unreliable and prone to transmission error due to varying channel conditions. These can degrade the performance in wireless networks, particularly for applications with tight quality-of-service requirements. A common remedy is to use channel coding where the transmitter node adds redundant bits to the transmitted packets in...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Dynamic Optimal Random Access for Vehicle-to-Roadside Communications

    In a drive-thru scenario where vehicles drive by a roadside Access Point (AP) to obtain temporary Internet access, it is important to design efficient resource allocation schemes to fully utilize the limited communication opportunities. In this paper, the authors study the random access problem in drive-thru communications in a dynamic...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Dynamic Decode-and-Forward Relaying Using Raptor Codes

    Dynamic Decode-and-Forward (DDF) is a version of decode-and-forward relaying in which the duration of the listening phase at relays is not fixed. In this paper, the authors investigate half-duplex DDF relaying based on rateless codes. The use of rateless codes allows relays to autonomously switch from listening to the source...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Economics Of Cross-border Travel

    National borders have been shown to segment markets and generate price differences. The resulting arbitrage opportunities vary over time with the exchange rate and cross-sectionally with distance to the border. The authors estimate a structural model of the border crossing decision using a new dataset containing the residence of each...

    Provided By University of British Columbia

  • White Papers // Jan 2011

    Bursty Impulse Noise Detection by Compressed Sensing

    Impulse Noise (IN) is one of the major impairments for data transmission over power lines. For Power Line Communications (PLC) systems with bandwidths in the high kHz to MHz range, IN occurs in bursts. As long as those bursts are sufficiently short compared to a signal-processing (e.g. coding) frame, there...

    Provided By University of British Columbia

  • White Papers // Jan 2011

    Robust Cyclic Space-Frequency Filtering for BICM-OFDM With Outdated CSIT

    In this paper, the authors introduce robust Cyclic Space - Frequency (CSF) filtering for systems combining Bit - Interleaved Coded Modulation (BICM) and Orthogonal Frequency Division Multiplexing (OFDM). The proposed robust CSF filtering scheme exploits outdated Channel State Information at the Transmitter (CSIT) and takes into account the reliability of...

    Provided By University of British Columbia

  • White Papers // Dec 2010

    Capo: Recapitulating Storage for Virtual Desktops

    Fast and reliable data storage is something that organizations are prepared to pay a premium for, both in the capital costs of enterprise storage hardware and the operational costs of ensuring that important data is written to it. Interestingly, the deployment of virtualization has inverted the historical imperative that systems...

    Provided By University of British Columbia

  • White Papers // Dec 2010

    Evaluation of Wireless Body Area Sensor Placement for Mobility Support in Healthcare Monitoring Systems

    The authors present a 2-tier wireless system for healthcare monitoring of convalescing patients in non-critical condition. A network of sensors adhered to the patient's body used for vital signs collection, and a portable coordinator device forms one tier, whereas a point-to-point link between the coordinator and a fixed access point...

    Provided By University of British Columbia

  • White Papers // Oct 2010

    RLAB: A Reinforcement Learning-Based Adaptive Broadcasting for Vehicular Ad-Hoc Networks

    Effective context-aware broadcasting of information to the Areas of Interest (AoI) is a challenging problem in vehicular ad-hoc networks. It is usually assumed that the information about these AoI are a priori known, either by a centralized source of information or by the entire set of vehicles. In this paper,...

    Provided By University of British Columbia

  • White Papers // Sep 2010

    Outage Rate and Outage Duration of Decode-and-Forward Cooperative Diversity Systems

    A complete evaluation of the benefits of cooperative diversity schemes should not only include the outage and error rate performance but also the second-order statistics of the achievable information-theoretic capacity. In a non-ergodic fading channel, the system is said to be in outage when the destination cannot decode the fixed-rate...

    Provided By University of British Columbia

  • White Papers // Sep 2010

    Bit-Interleaved Coded Modulation With Mismatched Decoding Metrics

    Bit-Interleaved Coded Modulation (BICM) has become the de facto coding standard for communication systems. Recently, BICM has been cast as a mismatched decoding scheme due to the assumption of independent bit metrics. In addition to this inherent mismatch, practical demodulators may produce mismatched decoding metrics because of implementation constraints, such...

    Provided By University of British Columbia

  • White Papers // Aug 2010

    Pyramidal Ownership And The Creation Of New Firms

    The authors study the role of pyramidal ownership in the creation of new firms using a comprehensive panel of manufacturing firms in Europe. Pyramidal ownership structures are used to supply inside funds to new firms that are unable to raise enough external financing, namely, those with large investment requirements and...

    Provided By University of British Columbia

  • White Papers // Aug 2010

    Content Caching and Replication Schemes for Peer-to-Peer File Sharing in Wireless Mesh Networks

    Wireless Mesh Networks (WMNs) have emerged as an important technology in building next generation fixed wireless broadband networks that provide low cost Internet access for fixed and mobile users. An orthogonal evolution in computer networking has been the rise of Peer-to-Peer (P2P) applications such as P2P file sharing. It is...

    Provided By University of British Columbia

  • White Papers // Aug 2010

    DoDOM: Leveraging DOM Invariants for Web 2.0 Application Robustness Testing

    Web 2.0 applications are increasing in popularity. However, they are also prone to errors because of their dynamic nature. This paper presents DoDOM, an automated system for testing the robustness of Web 2.0 applications based on their Document Object Models (DOMs). DoDOM repeatedly executes the application under a trace of...

    Provided By University of British Columbia

  • White Papers // Aug 2010

    Technological Progress, Industry Rivalry, And Stock Returns

    In this paper the authors investigate the link between competition in technological innovation and asset prices. They develop a model of an innovation race in which firms are subject to technological as well as market-wide uncertainty and optimally exercise their options to innovate. The model predicts that the race leader...

    Provided By University of British Columbia

  • White Papers // Jun 2010

    Fast and Cautious Evolution of Cloud Storage

    When changing a storage system, the stakes are high. Any modification can undermine stability, causing temporary downtime, a permanent loss of data, and still worse - a loss of user confidence. This results in a cautious conservatism among storage developers. On one hand, the risks do justify taking great care...

    Provided By University of British Columbia

  • White Papers // May 2010

    Achieving Fairness in Distributed Cognitive Radio Networks Using a Timer Mechanism

    The authors consider the issue of fairness in scheduler design for distributed Cognitive Radio Networks (CRN). They first distinguish between intra- and inter-class fairness as a result of hierarchical resource access right in a secondary spectrum allocation regime. Further, they develop a timer mechanism to achieve round-robin, max-min and proportional...

    Provided By University of British Columbia

  • White Papers // Apr 2010

    Evaluating Two Window Manipulation Techniques on a Large Screen Display

    Large screen displays are a common feature of modern meeting rooms, conference halls, and classrooms. The large size and often high resolution of these displays make them inherently suitable for collaborative work, but these attributes cause traditional windowing systems to become difficult to use because the interaction handles become smaller...

    Provided By University of British Columbia

  • White Papers // Apr 2010

    What Determines European Real Exchange Rates?

    The authors study a newly constructed panel data set of relative prices of a large number of consumer goods among 31 European countries. They find that there is a substantial and non-diminishing deviation from PPP at all levels of aggregation, even among euro zone members. However, real exchange rates are...

    Provided By University of British Columbia

  • White Papers // Feb 2010

    A Linear Algebraic Approach for Loss Tomography in Mesh Topologies Using Network Coding

    Loss tomography aims to infer link loss rates using end-to-end measurements. The authors investigate active loss tomography on mesh topologies. When network coding is applied, based on the content of the received probe packet, a receiver should distinguish which paths have successfully transmitted a probe and which paths have not....

    Provided By University of British Columbia

  • White Papers // Jan 2001

    Play It Again, Sam? Optimal Replacement Policies for A Motion Picture Exhibitor

    Every week, motion picture exhibitors must decide whether to keep or replace the movies playing in their theaters in light of the past week's sales data. This decision is complex because of the dynamic decision environment, the uncertainty of demand, the complex revenue sharing terms between the retailer and the...

    Provided By University of British Columbia

  • White Papers // Jun 2008

    Design Guidelines for IT Security Management Tools

    One of the most important factors that impact usability of security systems within an organization are security tools. This paper reports preliminary results of their survey about design guidelines for IT security management tools. The paper gathered guidelines and recommendations related to IT security management tool from available literature as...

    Provided By University of British Columbia

  • White Papers // Jul 2008

    The Challenges of Using an Intrusion Detection System: Is It Worth the Effort?

    An Intrusion Detection System (IDS) can be a key component of security incident response within organizations. Traditionally, intrusion detection research has focused on improving the accuracy of IDSs, but recent work has recognized the need to support the security practitioners who receive the IDS alarms and investigate suspected incidents. To...

    Provided By University of British Columbia

  • White Papers // Sep 2008

    On Domination Game Analysis for Microeconomic Data Mining

    Game theory is a powerful tool for the analysis of the competitions among manufacturers in a market. This paper presents a study on combining game theory and data mining by introducing the concept of domination game analysis. The paper presents a multidimensional market model, where every dimension represents one attribute...

    Provided By University of British Columbia

  • White Papers // Dec 2008

    Optimized Compressed Sensing for Curvelet-Based Seismic Data Reconstruction

    Compressed Sensing (CS) or compressive sampling provides a new sampling theory to reduce data acquisition, which says that compressible signals can be exactly reconstructed from highly incomplete sets of measurements. Very recently, the CS has been applied for seismic exploration and started to compact the traditional data acquisition. This paper...

    Provided By University of British Columbia

  • White Papers // Jul 2009

    Revealing Hidden Context: Improving Mental Models of Personal Firewall Users

    The Windows Vista personal firewall provides its diverse users with a basic interface that hides many operational details. However, concealing the impact of network context on the security state of the firewall may result in users developing an incorrect mental model of the protection provided by the firewall. The paper...

    Provided By University of British Columbia

  • White Papers // Apr 2009

    Visualizing High Dynamic Range Images in a Web Browser

    This paper presents a technique for embedding High Dynamic Range (HDR) images with interactive exposure control in a web browser. Multiple exposures are encoded as a combination of several basis images, which are stacked together and displayed with different opacity values. The combination of such basis images yields the resulting...

    Provided By University of British Columbia

  • White Papers // Jan 2010

    The "Mighty Mouse" Multi-Screen Collaboration Tool

    Many computers provide seamless support for multiple display screens, but there are few cross-platform tools for collaborative use of multiple computers in a shared display environment. Authors describe a novel approach, tailored specifically for face-to-face collaboration, in which multiple heterogeneous computers (usually laptops) are viewed simultaneously (usually via projectors) by...

    Provided By University of British Columbia

  • White Papers // Oct 2008

    Data Gathering in Optical Networks With the TL1 Toolkit

    This paper describes a new tool for gathering (Performance) data from optical network devices. During the last few years many National Research and Education Networks (NRENs) have deployed hybrid networks. These hybrid networks consist of a traditional routed IP part and an innovative optical part. On the optical part lightpath...

    Provided By University of British Columbia

  • White Papers // Oct 2008

    Performance Analysis of Free-Space Optical Systems in Gamma-Gamma Fading

    Atmospheric turbulence induced fading is one of the main impairments affecting Free-Space Optics (FSO). In recent years, Gamma-Gamma fading has become the dominant fading model for FSO links because of its excellent agreement with measurement data for a wide range of turbulence conditions. In this paper, the authors express the...

    Provided By University of British Columbia

  • White Papers // Jul 2008

    Cooperative Protocols Design for Wireless Ad-Hoc Networks With Multi-Hop Routing

    Wireless ad-hoc networks can experience significant performance degradation under fading channels. Diversity through space has been shown to be an effective way of combating wireless fading with the Multiple-Input-Multiple-Output (MIMO) technique by transmitting correlated information through multiple antennas. The virtual MIMO technique, which allows multiple wireless stations with single antenna...

    Provided By University of British Columbia

  • White Papers // Jun 2010

    Fast and Cautious Evolution of Cloud Storage

    When changing a storage system, the stakes are high. Any modification can undermine stability, causing temporary downtime, a permanent loss of data, and still worse - a loss of user confidence. This results in a cautious conservatism among storage developers. On one hand, the risks do justify taking great care...

    Provided By University of British Columbia

  • White Papers // Sep 2010

    Outage Rate and Outage Duration of Decode-and-Forward Cooperative Diversity Systems

    A complete evaluation of the benefits of cooperative diversity schemes should not only include the outage and error rate performance but also the second-order statistics of the achievable information-theoretic capacity. In a non-ergodic fading channel, the system is said to be in outage when the destination cannot decode the fixed-rate...

    Provided By University of British Columbia

  • White Papers // Dec 2010

    Capo: Recapitulating Storage for Virtual Desktops

    Fast and reliable data storage is something that organizations are prepared to pay a premium for, both in the capital costs of enterprise storage hardware and the operational costs of ensuring that important data is written to it. Interestingly, the deployment of virtualization has inverted the historical imperative that systems...

    Provided By University of British Columbia

  • White Papers // Apr 2008

    Selfish Behaviours and Counteractions in CSMA/CA Wireless Protocol

    Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) protocol is a Medium Access Control (MAC) protocol used by IEEE 802.11 stations to arbitrate the access of the shared wireless medium. With the increasing programmability of network adapter, malicious users can modify the wireless interface easily in order to gain some...

    Provided By University of British Columbia

  • White Papers // Sep 2011

    Admission Control and Resource Optimization for Multiple-User OFDMA Cognitive Radio Systems

    In Cognitive Radio (CR) systems, the fluctuating nature of the available frequency resource due to Primary Users (PUs) activity necessitates the introduction of admission and eviction measures at the CR system if a guaranteed Quality of Service (QoS) is required by Real Time (RT) Secondary Users (SUs). This problem has...

    Provided By University of British Columbia

  • White Papers // Oct 2008

    Reliable and Energy-E?cient Routing Protocol in Dense Wireless Sensor Networks

    Delivering sensed data to the sink reliably in sensor networks calls for a scalable, energy-efficient, and error-resilient routing solution. In this paper, a Reliable Energy-Efficient Routing (REER) protocol is proposed to achieve the above goals for dense Wireless Sensor Networks (WSNs). Based on the geographical information, REER's design harnesses the...

    Provided By University of British Columbia

  • White Papers // Feb 2009

    Multi-Hop Mesh Cooperative Structure Based Data Dissemination for Wireless Sensor Networks

    In this paper, the authors investigate the use of cooperative communications for reliable data dissemination in wireless sensor networks. They first identify the disadvantages of some existing cooperative schemes. While the previously proposed "Multi-hop mesh cooperative transmission structure" addresses these disadvantages, it suffers from large end-to-end delays during data disseminations...

    Provided By University of British Columbia

  • White Papers // May 2010

    Achieving Fairness in Distributed Cognitive Radio Networks Using a Timer Mechanism

    The authors consider the issue of fairness in scheduler design for distributed Cognitive Radio Networks (CRN). They first distinguish between intra- and inter-class fairness as a result of hierarchical resource access right in a secondary spectrum allocation regime. Further, they develop a timer mechanism to achieve round-robin, max-min and proportional...

    Provided By University of British Columbia

  • White Papers // Dec 2008

    Flow Starvation Mitigation for Wireless Mesh Networks

    Wireless mesh networks can provide scalable high-speed Internet access at a low cost. Fair channel access among different nodes in the wireless mesh network, however, is an important consideration that needs technological solutions before mesh networks can be widely deployed. Lack of fairness significantly decreases the throughput of nodes that...

    Provided By University of British Columbia

  • White Papers // Aug 2009

    Reliability-Based Rate Allocation in Wireless Inter-Session Network Coding Systems

    Network coding has recently received increasing attention to improve performance and increase capacity in both wired and wireless communication networks. In this paper, the authors focus on inter-session network coding, where multiple unicast sessions jointly participate in network coding. Wireless links are often unreliable because of varying channel conditions. They...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Optimal Data Transmission and Channel Code Rate Allocation in Multi-Path Wireless Networks

    Wireless links are often unreliable and prone to transmission error due to varying channel conditions. These can degrade the performance in wireless networks, particularly for applications with tight quality-of-service requirements. A common remedy is to use channel coding where the transmitter node adds redundant bits to the transmitted packets in...

    Provided By University of British Columbia

  • White Papers // Feb 2011

    Dynamic Optimal Random Access for Vehicle-to-Roadside Communications

    In a drive-thru scenario where vehicles drive by a roadside Access Point (AP) to obtain temporary Internet access, it is important to design efficient resource allocation schemes to fully utilize the limited communication opportunities. In this paper, the authors study the random access problem in drive-thru communications in a dynamic...

    Provided By University of British Columbia

  • White Papers // Feb 2009

    Random Access Protocols for WLANs Based on Mechanism Design

    In Wireless Local Area Networks (WLANs), Quality of Service (QoS) can be provided by mapping applications with different requirements (e.g., delay and throughput) into one of the available Access Categories (ACs), as is done in the IEEE 802.11e standard. With the increasing programmability of network adapters, a malicious user can...

    Provided By University of British Columbia

  • White Papers // Feb 2010

    A Linear Algebraic Approach for Loss Tomography in Mesh Topologies Using Network Coding

    Loss tomography aims to infer link loss rates using end-to-end measurements. The authors investigate active loss tomography on mesh topologies. When network coding is applied, based on the content of the received probe packet, a receiver should distinguish which paths have successfully transmitted a probe and which paths have not....

    Provided By University of British Columbia

  • White Papers // Jul 2011

    A Coalition Formation Game for Energy-Efficient Cooperative Spectrum Sensing in Cognitive Radio Networks With Multiple Channels

    Spectrum sensing is one of the key technologies to realize spectrum reuse and increase the spectrum efficiency in Cognitive Radio Networks (CRNs). In this paper, the authors study energy-efficient cooperative multi-channel spectrum sensing in CRNs. They first propose a Cooperative Spectrum Sensing and Accessing (CSSA) scheme for all the Secondary...

    Provided By University of British Columbia

  • White Papers // Jul 2011

    A Stackelberg Game for Cooperative Transmission and Random Access in Cognitive Radio Networks

    In cognitive radio networks, the Secondary Users (SUs) can be selected as the cooperative relays to assist the transmission of the Primary User (PU). In order to increase the utility, the PU needs to consider whether it is beneficial to use cooperative transmission and which SU should be chosen as...

    Provided By University of British Columbia

  • White Papers // Feb 2010

    Optimal MISO UWB Pre-Equalizer Design With Spectral Mask Constraints

    In this paper, the authors propose a novel optimizationbased Pre-Equalization Filter (PEF) design for Multiple-Input Single-Output (MISO) Direct-Sequence Ultra-WideBand (DS-UWB) systems with pre-Rake combining. The key feature in their design is that they explicitly take into account spectral mask constraints which are usually imposed by telecommunications regulation and standardization bodies....

    Provided By University of British Columbia

  • White Papers // Oct 2008

    Simple, Optimal, and Robust Random Access

    In this paper, the authors propose two distributed contention-based Medium Access Control (MAC) algorithms to solve a Network Utility Maximization (NUM) problem in wireless ad hoc networks. Most of the previous NUM-based random access algorithms have one or more of the following performance bottlenecks: extensive signaling among nodes, synchronous updates...

    Provided By University of British Columbia

  • White Papers // Feb 2009

    A Game-Theoretic Analysis of Inter-Session Network Coding

    A common assumption in the network coding literature is that the users are cooperative and will not pursue their own interests. However, this assumption can be violated in practice. In this paper, the authors analyze inter-session network coding in a wired network, assuming that the users are selfish and act...

    Provided By University of British Columbia

  • White Papers // Dec 2009

    Bargaining and Price-of-Anarchy in Repeated Inter-Session Network Coding Games

    Most of the previous work on network coding has assumed that the users are not selfish and always follow the designed coding schemes. However, recent results have shown that selfish users do not have the incentive to participate in inter-session network coding in a static non-cooperative game setting. As a...

    Provided By University of British Columbia

  • White Papers // Feb 2010

    Pre-Equalization for DS-UWB Systems With Spectral Mask Constraints

    In this paper, the authors propose a novel optimization-based Pre-Equalization Filter (PEF) design for Direct-Sequence Ultra-WideBand (DS-UWB) systems with pre-Rake combining. The key feature in their design is that they explicitly take into account the spectral mask constraints that are usually imposed by the telecommunication regulation bodies. This avoids the...

    Provided By University of British Columbia

  • White Papers // May 2008

    A Unified Formulation of the Multicast Lifetime Optimization Problem in WANETs

    The authors consider the problem of maximizing the lifetime of a given multicast connection in wireless networks that use directional antennas and have limited energy resources. They provide a globally optimal solution to this problem by developing a general MILP formulation that can apply to many configurable antenna models including...

    Provided By University of British Columbia

  • White Papers // Jun 2008

    Reducing Re-Authentication Delays During UMTS-WLAN Vertical Handovers

    Interworking Universal Mobile Telecommunication Systems (UMTS) and IEEE 802.11 Wireless Local Area Networks (WLANs) introduces new challenges in the design of secured and fast Vertical Handover (VH) protocols. VH operations must not compromise the security of the network. In addition, VH delays must be minimized to maintain the quality of...

    Provided By University of British Columbia

  • White Papers // Jan 2009

    A Reliable Robust Fully Ad Hoc Data Dissemination Mechanism for Vehicular Networks

    Many applications in vehicular networks need the data to be disseminated from a source vehicle to a large number of vehicles in the network. Although many solutions to this problem have been previously proposed by the research community, some challenges and failure scenarios still remain unsolved particularly when the forwarding...

    Provided By University of British Columbia

  • White Papers // Dec 2008

    Maximizing The Growth Rate Under Risk Constraints

    The authors investigate the ergodic problem of growth-rate maximization under a class of risk constraints in the context of incomplete, Ito-process models of financial markets with random ergodic coefficients. Including Value-at-Risk (VaR), Tail-Value-at-Risk (TVaR), and Limited Expected Loss (LEL), these constraints can be both wealth-dependent (relative) and wealth-independent (absolute). The...

    Provided By University of British Columbia

  • White Papers // Jan 2011

    Robust Cyclic Space-Frequency Filtering for BICM-OFDM With Outdated CSIT

    In this paper, the authors introduce robust Cyclic Space - Frequency (CSF) filtering for systems combining Bit - Interleaved Coded Modulation (BICM) and Orthogonal Frequency Division Multiplexing (OFDM). The proposed robust CSF filtering scheme exploits outdated Channel State Information at the Transmitter (CSIT) and takes into account the reliability of...

    Provided By University of British Columbia

  • White Papers // May 2008

    Sphere Constrained Block RSSE With Per-Survivor Intra-Block Processing for CCK Transmission

    In the Wireless Local Area Network (WLAN) standard IEEE 802.11b, Complementary Code Keying (CCK) modulation has been adopted for the high data rate transmission mode, which can be considered as a special type of spread spectrum modulation with data-dependent spreading. In this paper, complexity reduction for block Reduced-State Sequence Estimation...

    Provided By University of British Columbia

  • White Papers // Aug 2009

    Efficient Receivers for GSM MUROS Downlink Transmission

    Currently, Multiple Users Reusing One Slot (MUROS) is discussed in 3GPP GERAN as an extension of the GSM standard. In MUROS, two overlaid GMSK signals are transmitted in the same time slot and at the same frequency resource. By this, capacity of existing GSM networks in principle can be doubled...

    Provided By University of British Columbia

  • White Papers // Mar 2009

    Increased Discrimination in Level Set Methods With Embedded Conditional Random Fields

    The authors propose a novel approach for improving level set segmentation methods by embedding the potential functions from a discriminatively trained Conditional Random Field (CRF) into a level set energy function. The CRF terms can be efficiently estimated and lead to both discriminative local potentials and edge regularizes that take...

    Provided By University of British Columbia