University of Texas

Displaying 121-160 of 258 results

  • White Papers // Dec 2010

    Hybrid Partial Evaluation

    The authors present Hybrid Partial Evaluation (HPE), a pragmatic approach to partial evaluation that borrows ideas from both online and offline partial evaluation. HPE performs offline-style specialization using an online approach without static binding time analysis. The goal of HPE is to provide a practical and predictable level of optimization...

    Provided By University of Texas

  • White Papers // Dec 2010

    A Customizable Two-Step Framework for General Equipment Provisioning in Optical Transport Networks

    Optical Transport Network (OTN) is a standard approach to offering transport support to a variety of existing service technologies, e.g., ESCON, HDTV, GE, etc. Multiple service technologies can be concurrently multiplexed onto one common transport network, which offers hierarchical transmission rate wrappers physically supported by Wavelength Division Multiplexing (WDM) lambda...

    Provided By University of Texas

  • White Papers // Dec 2010

    It's on Me! the Benefit of Altruism in BAR Environments

    Cooperation, a necessity for any Peer-To-Peer (P2P) cooperative service, is often achieved by rewarding good behavior now with the promise of future benefits. However, in most cases, interactions with a particular peer or the service itself eventually end, resulting in some last exchange in which departing participants have no incentive...

    Provided By University of Texas

  • White Papers // Dec 2010

    Design of the FutureGrid Experiment Management Framework

    FutureGrid provides novel computing capabilities that enable reproducible experiments while simultaneously supporting dynamic provisioning. This paper describes the Future-Grid experiment management framework to create and execute large scale scientific experiments for researchers around the globe. The experiments executed are performed by the various users of FutureGrid ranging from administrators, software...

    Provided By University of Texas

  • White Papers // Dec 2010

    Parallel Graph Partitioning on Multicore Architectures

    Graph partitioning is a common and frequent preprocessing step in many high-performance parallel applications on distributed and shared-memory architectures. It is used to distribute graphs across memory and to improve spatial locality. There are several parallel implementations of graph partitioning for distributed-memory architectures. In this paper, the authors present a...

    Provided By University of Texas

  • White Papers // Dec 2010

    ASSERT: A Wireless Networking Testbed

    As wireless networking is becoming more pervasive, there has been a greater desire to develop communication hardware and protocol stacks that have a number of desirable properties like increased throughput, reduced latency, reduced energy consumption, quality of service, security, etc. Consequently, several academic and industrial research groups are actively working...

    Provided By University of Texas

  • White Papers // Dec 2010

    Vertical Specialization, Intermediate Tariffs, And The Pattern Of Trade: Assessing The Role Of Tariff Liberalization To U.S.

    How important are intermediate tariffs in determining trade patterns? Empirical work measuring the impact of tariff liberalization most commonly focuses on the effects of barriers imposed by importers, but exporter trade policy should also matter when exports are produced with imported intermediates. Guided by extensions of the Eaton and Kortum...

    Provided By University of Texas

  • White Papers // Nov 2010

    Corporate Leverage, Debt Maturity And Credit Default Swaps: The Role Of Credit Supply

    Does the ability of suppliers of debt to hedge risk through Credit Default Swap (CDS) contracts impact firms' capital structures? This paper uses CDS markets as a proxy for a relaxation of firms' credit supply constraints and tests whether supply frictions impact capital structure and debt maturity. The authors find...

    Provided By University of Texas

  • White Papers // Nov 2010

    Transmission Capacity of Carrier Sensing Ad Hoc Networks With Multiple Antennas

    Multiple antennas have become a common component of wireless networks, improving range, throughput, and spatial reuse, both at the link and network levels. At the same time, carrier sensing is a widely used method of improving spatial reuse in distributed wireless networks, especially when there is limited coordination among non-communicating...

    Provided By University of Texas

  • White Papers // Nov 2010

    The Impact Of Bank Health On The Investment Of Its Corporate Borrowers

    This paper investigates the impact of changes in a bank's health on the investment behavior of its current borrowers for a panel of U.S. firms. The author finds that, after controlling for aggregate credit availability and the condition of outside banks, firms reduce their investment when the health of their...

    Provided By University of Texas

  • White Papers // Nov 2010

    How to Leak on Key Updates

    In the continual memory leakage model, security against attackers who can repeatedly obtain leakage is achieved by periodically updating the secret key. This is an appealing model which captures a wide class of side-channel attacks, but all previous constructions in this model provide only a very minimal amount of leakage...

    Provided By University of Texas

  • White Papers // Nov 2010

    Cooperative Spectral Covariance Sensing Under Correlated Shadowing

    This paper investigates the theoretical limits of white space sensing in a Cognitive Radio (CR) network limited by channel correlation. In a log-normal shadowing channel, the received signal power is correlated based on the distance between the sensors and this makes sensing the presence of a signal difficult, even with...

    Provided By University of Texas

  • White Papers // Oct 2010

    User Admission in MIMO Interference Alignment Networks

    In this paper, the authors consider an interference channel where a set of primary active users are cooperating through interference alignment over a constant multiple-input-multiple-output channel while a set of secondary users desire access to the channel. They present the conditions under which a secondary user can be admitted to...

    Provided By University of Texas

  • White Papers // Sep 2010

    Depot: Cloud Storage With Minimal Trust

    The paper describes the design, implementation, and evaluation of Depot, a cloud storage system that minimizes trust assumptions. Depot tolerates buggy or malicious behavior by any number of clients or servers, yet it provides safety and liveness guarantees to correct clients. Depot provides these guarantees using a two-layer architecture. First,...

    Provided By University of Texas

  • White Papers // Sep 2010

    Identity-Based Encryption Secure Against Selective Opening Attack

    The authors present the first Identity-Based Encryption (IBE) schemes that are proven secure against Selective Opening Attack (SOA). This means that if an adversary, given a vector of ciphertexts, adaptively corrupts some fraction of the senders, exposing not only their messages but also their coins, the privacy of the unopened...

    Provided By University of Texas

  • White Papers // Sep 2010

    Challenges and Future Directions of Software Technology: Secure Software Development

    Developing large scale software systems has major security challenges. This paper describes the issues involved and then addresses two topics: formal methods for emerging secure systems and secure services modeling. Large scale software development is one of the biggest challenges faced by corporations. Incorporating security into the software development process...

    Provided By University of Texas

  • White Papers // Sep 2010

    A Virtual Network Approach for Testing Wireless Mesh in Industrial Process Control

    Unlike wired networks, the configuration and the behavior of wireless networks are heavily dependent on many environmental factors. While this makes it more difficult to build a wireless network testbed whose behavior is controllable, it also makes the availability of such a testbed all the more desirable. Indeed, the difficulties...

    Provided By University of Texas

  • White Papers // Sep 2010

    The Click Convergence Layer: Putting a Modular Router Under DTN2

    The Bundle Protocol shows great promise as a general purpose application-layer protocol for Delay-Tolerant Networks (DTNs) and has found many adopters within the research community. As an application layer protocol, a convergence layer (UDP/TCP sockets or some other domain-specific transport mechanism) is required to deliver bundles between nodes. The authors...

    Provided By University of Texas

  • White Papers // Sep 2010

    On the Accuracy of the Wyner Model in Downlink Cellular Networks

    Compared to real cellular systems where users are spatially distributed and interference levels vary by several orders of magnitude over a cell, in the Wyner model user locations are fixed and the interference intensity is characterized by a single fixed parameter. Although it is a fairly extreme simplification, the Wyner...

    Provided By University of Texas

  • White Papers // Sep 2010

    The Effect of Interference Cancellation on Spectrum-Sharing Transmission Capacity

    The efficiency of spectrum sharing can be improved by interference suppression and/or cancellation. This paper analyzes the performance of spectrum sharing networks with Interference Cancellation (IC) based on the Spectrum-sharing Transmission Capacity (S-TC), defined as the number of successful transmissions per unit area while guaranteeing all target outage probabilities of...

    Provided By University of Texas

  • White Papers // Sep 2010

    Comparison of Fractional Frequency Reuse Approaches in the OFDMA Cellular Downlink

    Fractional Frequency Reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This paper focuses on evaluating the two main types of FFR deployments: strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed,...

    Provided By University of Texas

  • White Papers // Sep 2010

    Two-Way Transmission Capacity of Wireless Ad-Hoc Networks

    The transmission capacity of an ad-hoc network is the maximum density of active transmitters per unit area, given an outage constraint at each receiver for a fixed rate of transmission. Most prior work on finding the transmission capacity of ad-hoc networks has focused only on one-way communication where a source...

    Provided By University of Texas

  • White Papers // Sep 2010

    A New Tractable Model for Cellular Coverage

    Cellular networks are usually modeled by placing the base stations according to a regular geometry such as a grid, with the mobile users scattered around the network either as a Poisson point process (i.e. uniform distribution) or deterministically. These models have been used extensively for cellular design and analysis but...

    Provided By University of Texas

  • White Papers // Aug 2010

    POET: A Scripting Language for Applying Parameterized Source-to-Source Program Transformations

    The authors present POET, a scripting language designed for applying advanced program transformations to code in arbitrary programming languages as well as building ad-hoc translators between these languages. The authors have used POET to support a large number of compiler optimizations, including loop interchange, parallelization, blocking, fusion/ fission, strength reduction,...

    Provided By University of Texas

  • White Papers // Aug 2010

    CDMA Uplink Capacity in Both Open and Closed Access Two-Tier Femtocell Networks

    Femtocells are assuming an increasingly important role in cellular coverage. Femtocells can be configured to be either open access or closed access. Seemingly, the network operator would prefer an open access deployment since this provides an inexpensive way to expand their network capabilities, whereas the femtocell owner would prefer closed...

    Provided By University of Texas

  • White Papers // Aug 2010

    The Case for End-User Programming of Ubiquitous Computing Environments

    Gone are the days that computers will be used by select users sitting at a desk with a mouse and keyboard. The next wave of computing, ubiquitous computing, is upon one. With smart phones, tablet computers, and embedded sensors/ actuators ourishing, users are already interacting with dozens of computers per...

    Provided By University of Texas

  • White Papers // Aug 2010

    Reducing Configurations to Monitor in a Software Product Line

    A software product line is a family of programs where each program is defined by a unique combination of features. Product lines, like conventional programs, can be checked for safety properties through execution monitoring. However, because a product line induces a number of programs that is potentially exponential in the...

    Provided By University of Texas

  • White Papers // Aug 2010

    Minimum-Delay Service Provisioning in Opportunistic Networks

    Opportunistic networks are created dynamically by exploiting contacts between pairs of mobile devices that come within communication range. While forwarding in opportunistic networking has been explored, investigations into asynchronous service provisioning on top of opportunistic networks are unique contributions of this paper. Mobile devices are typically heterogeneous, possess disparate physical...

    Provided By University of Texas

  • White Papers // Aug 2010

    Template-Based Reconstruction of Complex Refactorings

    Knowing which types of refactoring occurred between two program versions can help programmers better understand code changes. The authors' survey of refactoring identification techniques found that existing techniques cannot easily identify complex refactorings, such as an replace conditional with polymorphism refactoring, which consist of a set of atomic refactorings. This...

    Provided By University of Texas

  • White Papers // Aug 2010

    Objective Risk Evaluation for Automated Security Management

    Network security depends on a number of factors. And a common characteristic of these factors is that they are dynamic in nature. Such factors include new vulnerabilities and threats, the network policy structure and traffic. These factors can be divided into two broad categories. Network risk and service risk. As...

    Provided By University of Texas

  • White Papers // Aug 2010

    Greedy Distance Vector Routing

    Greedy Distance Vector (GDV) is the first geographic routing protocol designed to optimize end-to-end path costs using any additive routing metric, such as: hop count, latency, ETX, ETT, etc. GDV requires no node location information. Instead, GDV uses estimated routing costs to destinations which are locally computed from node positions...

    Provided By University of Texas

  • White Papers // Aug 2010

    A Super-Logarithmic Lower Bound for Shuffle-Unshuffle Sorting Networks

    A variety of different classes of sorting networks have been described in the literature. Of particular interest here are the so-called AKS network discovered by Ajtai, Komlos, and Szemeredi, and the sorting networks proposed by Batcher. While the AKS network is the only known sorting network with O (lgn) depth,...

    Provided By University of Texas

  • White Papers // Aug 2010

    Global Scheduling Based Reliability-Aware Power Management for Multiprocessor Real-Time Systems

    Reliability-Aware Power Management (RAPM) has been a recent research focus due the negative effects of the popular power management technique Dynamic Voltage and Frequency Scaling (DVFS) on system reliability. As a result, several RAPM schemes have been proposed for uniprocessor real-time systems. In this paper, for a set of frame-based...

    Provided By University of Texas

  • White Papers // Aug 2010

    Characterizing Link and Path Reliability in Large-Scale Wireless Sensor Networks

    Reliable Data Transfer (RDT) is one of the key issues in Wireless Sensor Networks (WSNs) and can be achieved by using link-level re-transmissions and multipath routing. Another key issue is the scalability of WSNs. In this paper, the authors try to better understand and characterize/quantify the relationships between reliability and...

    Provided By University of Texas

  • White Papers // Aug 2010

    Identifying Unnecessary Bounds Checks Through Block-Qualified Variable Elimination

    Java's memory-safety relies on the Java Virtual Machine checking that each access to an array does not exceed the bounds of that array. When static analysis can determine that some array access instruction will never use an out of bounds index, the cost of dynamically checking the index each time...

    Provided By University of Texas

  • White Papers // Aug 2010

    Functional Specification and Verification of Object-Oriented Programs

    One weakness of Hoare-style verification techniques based on first-order predicate logic is that reasoning is backward from post-conditions to preconditions. A natural, forward reasoning is possible by viewing a program as a mathematical function that maps one program state to another. This functional program verification technique requires a minimal mathematical...

    Provided By University of Texas

  • White Papers // Jul 2010

    Source Capture Time Analysis of Privacy Communication Protocols for Wireless Sensor Networks

    Communication privacy techniques that protect the locations of source sensor nodes and sink nodes from either global or local adversaries have received significant attention recently. The improvement in capture time, which is the time it takes for an adversary to identify the location of the source, is often estimated using...

    Provided By University of Texas

  • White Papers // Jul 2010

    Fast Neighbor Discovery With Lightweight Termination Detection in Heterogeneous Cognitive Radio Networks

    An important step in the initialization of a wireless ad hoc network is neighbor discovery in which every node attempts to determine the set of nodes it can communicate with in one wireless hop. In recent years, cognitive radio technology has gained attention as an attractive approach to alleviate the...

    Provided By University of Texas

  • White Papers // Jul 2010

    Femtocell Access Control in the TDMA/OFDMA Uplink

    This paper investigates open vs. closed access in the uplink of femtocell networks, for the particular case of orthogonal multiple access protocols like TDMA or OFDMA. Open access reduces near-far interference and provides an inexpensive way to expand the capacity of the operator's network. Additionally, with a cap on the...

    Provided By University of Texas

  • White Papers // Jul 2010

    On the Insecurity of Parallel Repetition for Leakage Resilience

    A fundamental question in leakage-resilient cryptography is: Can leakage resilience always be amplified by parallel repetition? It is natural to expect that if people have leakage-resilient primitive tolerating nl bits of leakage, they can take n copies of it to form a system tolerating nl bits of leakage. In this...

    Provided By University of Texas

  • White Papers // Mar 2010

    Analog Equalization for Low Power 60 GHz Receivers in Realistic Multipath Channels

    Multi-gigabit per second wireless network devices are emerging for Personal Area Networks (PAN) in the 60 GHz band. Such devices are typically power hungry, largely due to the requisite high speed Analog to Digital Converters (ADCs) that can consume hundreds of milliwatts of power. This paper studies the use of...

    Provided By University of Texas

  • White Papers // Jan 2011

    Correlation of Link Outages in Low-Mobility Spatial Wireless Networks

    In this paper, the authors consider a network where the nodes' locations are modeled by a realization of a Poisson point process and remain fixed or change very slowly over time. Most of the literature focuses on the spatial average of the link outage probabilities. But each link in the...

    Provided By University of Texas

  • White Papers // Jan 2010

    A Simple SINR Characterization for Linear Interference Alignment Over Uncertain MIMO Channels

    This paper provides a simple closed-form SINR expression for interference alignment over MIMO channels with channel uncertainty. Assuming linear processing (specifically, zero-forcing) at the transmitters and receivers and a complex Gaussian interference channel, the authors show that random matrix theory can be successfully applied to find the SINR distribution of...

    Provided By University of Texas

  • White Papers // Sep 2010

    A New Tractable Model for Cellular Coverage

    Cellular networks are usually modeled by placing the base stations according to a regular geometry such as a grid, with the mobile users scattered around the network either as a Poisson point process (i.e. uniform distribution) or deterministically. These models have been used extensively for cellular design and analysis but...

    Provided By University of Texas

  • White Papers // Dec 2009

    Capacity Scaling of MIMO Broadcast Channels With Random User Distribution

    A novel capacity scaling law for Multiple-Input Multiple-Output (MIMO) broadcast channels is derived considering a random user distribution. The random locations cause unequal average SNRs amongst the users, whereas prior work typically assumes that all users have the same average SNR. Most centralized wireless networks, e.g. cellular systems, are more...

    Provided By University of Texas

  • White Papers // Jan 2010

    A New Method for Computing the Transmission Capacity of Non-Poisson Wireless Networks

    The relative locations of concurrent transmitting nodes play an important role in the performance of wireless networks because it largely determines their mutual interference. In most prior work the set of interfering transmitters has been modeled by a homogeneous Poisson distribution, which assumes independence in the transmitting node positions, and...

    Provided By University of Texas

  • White Papers // Dec 2009

    Multicast Capacity Scaling of Wireless Networks With Multicast Outage

    Multicast transmission has several distinctive traits as opposed to more commonly studied unicast networks. Specially, these include - identical packets must be delivered successfully to several nodes, outage could simultaneously happen at different receivers, and the multicast rate is dominated by the receiver with the weakest link in order to...

    Provided By University of Texas

  • White Papers // Jan 2010

    Spectral Covariance for Spectrum Sensing, With Application to IEEE 802.22

    Despite the shortage of available frequency spectrum, recent studies have shown that the actual usage of the allocated spectrum is scarce. The IEEE is developing the 802.22 standard for spectral reuse in TV bands that uses Cognitive Radio (CR) technology. One of the essential and challenging features of CR is...

    Provided By University of Texas

  • White Papers // Jul 2009

    Block Diagonalization in the MIMO Broadcast Channel With Delayed CSIT

    This paper investigates the impact of delayed Channel State Information at the Transmitter (CSIT) on the MIMO broadcast channel with Block Diagonalization (BD) pre-coding. First, an upper bound for the achievable throughput is provided, which shows that BD is more robust to imperfect CSIT than zero-forcing pre-coding as it has...

    Provided By University of Texas

  • White Papers // Jul 2011

    Distributed SIR-Aware Scheduling in Large-Scale Wireless Networks

    Opportunistic scheduling and routing can in principle greatly increase the throughput of decentralized wireless networks, but to be practical such algorithms must do so with small amounts of timely side information. In this paper, the authors propose three related techniques for low-overhead Distributed Opportunistic Scheduling (DOS) and precisely determine their...

    Provided By University of Texas

  • White Papers // May 2011

    Broadcast Channels With Delayed Finite-Rate Feedback: Predict or Observe?

    Most multiuser pre-coding techniques require accurate Transmitter Channel State Information (CSIT) to maintain orthogonality between the users. Such techniques have proven quite fragile in time-varying channels because the CSIT is inherently imperfect due to estimation and feedback delay, as well quantization noise. An alternative approach recently proposed by Maddah-Ali and...

    Provided By University of Texas

  • White Papers // May 2011

    Characterizing Decentralized Wireless Networks With Temporal Correlation in the Low Outage Regime

    Communication in decentralized wireless networks is limited by interference. Because transmissions typically last for more than a single contention time slot, interference often exhibits strong statistical dependence over time that results in temporally correlated communication performance. The temporal dependence in interference increases as user mobility decreases and/or the total transmission...

    Provided By University of Texas

  • White Papers // Mar 2011

    Ergodic Transmission Capacity of Wireless Ad Hoc Networks With Interference Management

    Most work on wireless network throughput ignores the temporal correlation inherent to wireless channels because it degrades tractability. To better model and quantify the temporal variations of wireless network throughput, this paper introduces a metric termed Ergodic Transmission Capacity (ETC), which includes spatial and temporal ergodicity. All transmitters in the...

    Provided By University of Texas

  • White Papers // Nov 2010

    Cooperative Spectral Covariance Sensing Under Correlated Shadowing

    This paper investigates the theoretical limits of white space sensing in a Cognitive Radio (CR) network limited by channel correlation. In a log-normal shadowing channel, the received signal power is correlated based on the distance between the sensors and this makes sensing the presence of a signal difficult, even with...

    Provided By University of Texas

  • White Papers // Apr 2010

    An Upper Bound on Multi-Hop Transmission Capacity With Dynamic Multipath Routing

    This paper develops upper bounds on the end-to-end transmission capacity of multi-hop wireless networks. Potential source-destination paths are dynamically selected from a pool of randomly located relays, from which a closed-form lower bound on the outage probability is derived in terms of the expected number of potential paths. This is...

    Provided By University of Texas

  • White Papers // Jul 2011

    Capacity Bounds on Multiuser MIMO Transmission in Random Wireless Networks

    The authors consider a large wireless ad hoc network in which each multi-antenna transmitting node sends multiple independent streams to different receivers in a Poisson field of interferers. They provide exact expressions and simplified approximations on the outage probability, contention density, and transmission capacity for dirty paper coding with perfect...

    Provided By University of Texas

  • White Papers // Mar 2011

    Outage Probability for Heterogeneous Cellular Networks With Biased Cell Association

    In this paper, the authors develop a tractable framework for SINR analysis in downlink Heterogeneous Cellular Networks (HCNs) with flexible cell association policies. The HCN is modeled as a multi-tier cellular network where each tier's BSs are randomly located and have a unique transmit power, path loss exponent, spatial density,...

    Provided By University of Texas

  • White Papers // Jun 2011

    Coverage in Two-Tier Cellular Networks With Fractional Frequency Reuse

    Fractional Frequency Reuse (FFR) is an interference management technique well-suited to OFDMA-based cellular networks wherein the cells are partitioned into spatial regions with different frequency reuse factors. These techniques are of further relevance when considered in the context of heterogeneous networks whose performance is often limited by intercell and inter-tier...

    Provided By University of Texas

  • White Papers // Feb 2011

    A New Model for Coverage With Fractional Frequency Reuse in OFDMA Cellular Networks

    Fractional Frequency Reuse (FFR) is an interference management technique well-suited to OFDMA-based cellular networks wherein the cells are partitioned into spatial regions with different frequency reuse factors. To date, FFR techniques have been typically been evaluated through system-level simulations using a hexagonal grid for the base station locations. This paper...

    Provided By University of Texas

  • White Papers // Jul 2011

    Multiuser Zero-Forcing Beamforming With Limited Feedback in Wireless Ad Hoc Networks

    The effect of limited feedback on point-to-multipoint communication is investigated in multi-antennas wireless ad hoc networks. The authors consider zero-forcing beamforming with quantized channel direction information and derive new closed-form expressions for the outage probability, throughput, transmission capacity, and average user rate. Expressions for the performance degradation due to finite...

    Provided By University of Texas

  • White Papers // Jul 2011

    Downlink Femtocell Networks: Open or Closed?

    A fundamental choice in femtocell deployments is the set of users which are allowed to access each femtocell. Closed access restricts the set to specifically registered users, while open access allows any mobile subscriber to use any femtocell. The main results of the paper are lemmas which provide expressions for...

    Provided By University of Texas

  • White Papers // Mar 2011

    A New Way of Computing Rate in Cellular Networks

    It is common practice to model the Base Station (BS) locations in a cellular system by a grid, such as a hexagonal or square lattice. This model is usually analytically intractable as well as quite idealized. Therefore, system designers resort to complex simulations to evaluate network performance. In this paper,...

    Provided By University of Texas

  • White Papers // Sep 2010

    On the Accuracy of the Wyner Model in Downlink Cellular Networks

    Compared to real cellular systems where users are spatially distributed and interference levels vary by several orders of magnitude over a cell, in the Wyner model user locations are fixed and the interference intensity is characterized by a single fixed parameter. Although it is a fairly extreme simplification, the Wyner...

    Provided By University of Texas

  • White Papers // Sep 2010

    The Effect of Interference Cancellation on Spectrum-Sharing Transmission Capacity

    The efficiency of spectrum sharing can be improved by interference suppression and/or cancellation. This paper analyzes the performance of spectrum sharing networks with Interference Cancellation (IC) based on the Spectrum-sharing Transmission Capacity (S-TC), defined as the number of successful transmissions per unit area while guaranteeing all target outage probabilities of...

    Provided By University of Texas

  • White Papers // Feb 2011

    Ergodic Spatial Throughput of Wireless Ad Hoc Networks With Markovian Fading Channels

    Most work on wireless network throughput ignores the temporal correlation inherent to wireless channels, due to trouble with tractability. In order to better capture the temporal variations of wireless network throughput, this paper introduces the metric of Ergodic Spatial Throughput (EST), which includes spatial and temporal ergodicity. All transmitters in...

    Provided By University of Texas

  • White Papers // Jun 2011

    A Tractable Framework for Coverage and Outage in Heterogeneous Cellular Networks

    The authors develop a tractable, flexible, and accurate model for downlink heterogeneous cellular networks. It consists of K tiers of randomly-located Base Stations (BSs), where each tier may differ in terms of the average transmit power, the supported data rate and the BS density. This allows elements spanning traditional, micro,...

    Provided By University of Texas

  • White Papers // Mar 2010

    A Graphical Model Approach to Downlink Cooperative MIMO Systems

    The authors propose a new method for computing transmit beamforming vectors for downlink multi-cell Multiple-Input Multiple-Output (MIMO) networks. The key novelty of the work is the application of graphical model theory to the intercell interference problem. An index restriction beamforming strategy is adopted to mitigate intercell interference, and is implemented...

    Provided By University of Texas

  • White Papers // Jul 2010

    Femtocell Access Control in the TDMA/OFDMA Uplink

    This paper investigates open vs. closed access in the uplink of femtocell networks, for the particular case of orthogonal multiple access protocols like TDMA or OFDMA. Open access reduces near-far interference and provides an inexpensive way to expand the capacity of the operator's network. Additionally, with a cap on the...

    Provided By University of Texas

  • White Papers // Aug 2010

    CDMA Uplink Capacity in Both Open and Closed Access Two-Tier Femtocell Networks

    Femtocells are assuming an increasingly important role in cellular coverage. Femtocells can be configured to be either open access or closed access. Seemingly, the network operator would prefer an open access deployment since this provides an inexpensive way to expand their network capabilities, whereas the femtocell owner would prefer closed...

    Provided By University of Texas

  • White Papers // Nov 2009

    A Simple Upper Bound on Random Access Transport Capacity

    The authors attempt to quantify end-to-end throughput in multi-hop wireless networks using a metric that measures the maximum density of source-destination pairs that can successfully communicate over a specified distance at certain data rate. They term this metric the random access transport capacity, since it is similar to transport capacity...

    Provided By University of Texas

  • White Papers // Mar 2010

    An Overview of the Transmission Capacity of Wireless Networks

    This paper surveys and unifies a number of recent contributions that have collectively developed a metric for decentralized wireless network analysis known as transmission capacity. Although it is notoriously difficult to derive general end-to-end capacity results for multi-terminal or ad hoc networks, the Transmission Capacity (TC) framework allows for quantification...

    Provided By University of Texas

  • White Papers // Apr 2011

    Combating Channel Impairments and Impulsive Noise in Local Utility Powerline Communications

    A smart grid intelligently monitors and controls energy flow in order to improve the efficiency and reliability of power delivery. This monitoring and control requires low-delay, real-time, highly reliable communications between customers, local utilities and regional utilities. This paper focuses on PowerLine Communications (PLC) from the customer power meters to...

    Provided By University of Texas

  • White Papers // Aug 2009

    User Association to Optimize Flow Level Performance In Wireless Systems With Dynamic Interference

    The authors study the impact of user association policies on flow-level performance in interference limited wireless networks. Most research in this area has used static interference models (neighboring base stations are always active) and resorted to intuitive objectives such as load balancing. In this paper, they show that this can...

    Provided By University of Texas

  • White Papers // May 2011

    EVE: Verifying Correct Execution of Cloud-Hosted Web Applications

    The authors present a new approach to verifying that a completely untrusted, Platform-as-a-Service cloud is correctly executing an outsourced web application. Web applications such as blogs, wikis, and online social networks are increasingly hosted on third-party, "Platform-as-a-Service" (PaaS) clouds. The owner outsources the execution of his application to a cloud...

    Provided By University of Texas

  • White Papers // Nov 2010

    The Impact Of Bank Health On The Investment Of Its Corporate Borrowers

    This paper investigates the impact of changes in a bank's health on the investment behavior of its current borrowers for a panel of U.S. firms. The author finds that, after controlling for aggregate credit availability and the condition of outside banks, firms reduce their investment when the health of their...

    Provided By University of Texas

  • White Papers // May 2011

    Secure Data Processing in a Hybrid Cloud

    Cloud computing has made it possible for a user to be able to select a computing service precisely when needed. However, certain factors such as security of data and regulatory issues will impact a user's choice of using such a service. A solution to these problems is the use of...

    Provided By University of Texas

  • White Papers // Mar 2010

    Dynamic Connectivity in ALOHA Ad Hoc Networks

    In a wireless network the set of transmitting nodes changes frequently because of the MAC scheduler and the traffic load. Previously, connectivity in wireless networks was analyzed using static geometric graphs, and as the authors show leads to an overly constrained design criterion. The dynamic nature of the transmitting set...

    Provided By University of Texas

  • White Papers // Jan 2011

    Energy Efficient Schemes for Wireless Sensor Networks With Multiple Mobile Base Stations

    One of the main design issues for a sensor network is conservation of the energy available at each sensor node. The authors propose to deploy multiple, mobile base stations to prolong the lifetime of the sensor network. They split the lifetime of the sensor network into equal periods of time...

    Provided By University of Texas

  • White Papers // Jun 2011

    Average Rate Achievable in K-Tier Downlink Heterogeneous Cellular Networks

    Cellular networks are becoming increasingly heterogeneous due to the co-deployment of many disparate infrastructure elements, including micro, pico and femtocells, and distributed antennas. This introduces new challenges in the modeling, analysis, and design of these networks. While grid-based models have been quite popular in modeling classical macrocell networks, they are...

    Provided By University of Texas

  • White Papers // Mar 2011

    Cooperative Spectral Covariance Sensing: Properties and Analysis

    This paper investigates the theoretical limits of white space sensing in a Cognitive Radio (CR) network limited by channel correlation. In a log-normal shadowing channel, the received signal power is correlated based on the distance among the sensors and this makes sensing the presence of a signal difficult, even with...

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