University of Texas

Displaying 81-120 of 269 results

  • White Papers // Mar 2011

    HartFi: An Energy-Efficient Localization System

    Location-Based Applications (LBAs) are emerging to be the killer applications on mobile devices. To know the where-abouts of devices, various interfaces (i.e., GPS, Wi-Fi or cellular) can be used to sense their locations. Ideally, localization should be done all the time. However, keeping any of these interfaces running continuously would...

    Provided By University of Texas

  • White Papers // Mar 2011

    Secure Friend Discovery in Mobile Social Networks

    Mobile social networks extend social networks in the cyberspace into the real world by allowing mobile users to discover and interact with existing and potential friends who happen to be in their physical vicinity. Despite their promise to enable many exciting applications, serious security and privacy concerns have hindered wide...

    Provided By University of Texas

  • White Papers // Mar 2011

    Downlink SDMA With Limited Feedback in Interference-Limited Wireless Networks

    The tremendous capacity gains promised by Space Division Multiple Access (SDMA) depend critically on the accuracy of the transmit channel state information. In the broadcast channel, even without any network interference, it is known that such gains collapse due to interstream interference if the feedback is delayed or low rate....

    Provided By University of Texas

  • White Papers // Mar 2011

    A Generic Handover Decision Management Framework for Next Generation Networks

    Next generation networks are defined to be packet based networks that provide telecommunication services to users by utilizing different transport technologies, wired and wireless. In this paper the authors provide a generic framework for handover decision management in next generation networks. They show that any handover decision algorithm can utilize...

    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...

    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 // Feb 2011

    Is That You? Authentication in a Network Without Identities

    Most networks require that their users have "Identities", i.e. have names that are fixed for a relatively long time, unique, and have been approved by a central authority (in order to guarantee their uniqueness). Unfortunately, this requirement, which was introduced to simplify the design of networks, has its own drawbacks....

    Provided By University of Texas

  • White Papers // Feb 2011

    On Secure and Resilient Telesurgery Communications Over Unreliable Networks

    Telesurgical Robot Systems (TRSs) address mission critical operations emerging in extreme fields such as battlefields, underwater, and disaster territories. The lack of wire-lined communication infrastructure in such fields makes the use of wireless technologies including satellite and ad-hoc networks inevitable. TRSs over wireless environments pose unique challenges such as preserving...

    Provided By University of Texas

  • White Papers // Feb 2011

    Synthesizing Concurrent Schedulers for Irregular Algorithms

    Scheduling is the assignment of tasks or activities to processors for execution, and it is an important concern in parallel programming. Most prior work on scheduling has focused either on static scheduling of applications in which the dependence graph is known at compile-time or on dynamic scheduling of independent loop...

    Provided By University of Texas

  • White Papers // Feb 2011

    A Tractable Approach to Coverage and Rate in Cellular Networks

    Cellular networks are usually modeled by placing the base stations on a grid, with mobile users either randomly scattered or placed deterministically. These models have been used extensively but suffer from being both highly idealized and not very tractable, so complex system-level simulations are used to evaluate coverage/outage probability and...

    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 // Feb 2011

    Innovating To Optimize Supply Chain Management

    As an innovator dedicated to collaboration with the network of vendors and customers, Advanced Micro Devices (AMD) considers the supply chain to be a key component to the success and one of the most important competitive assets. How important? Just one change the way the authors handle the supply chain...

    Provided By University of Texas

  • White Papers // Jan 2011

    Corporate Taxes And Investment: The Cash Flow Channel

    Existing literature focuses on how corporate taxation affects firms' investment decisions by altering after-tax returns. This paper instead examines how corporate taxation affects investment by reducing the cash flow a firm has available to invest in the current period. The author uses a sharp nonlinearity in the mapping from pre-tax...

    Provided By University of Texas

  • White Papers // Jan 2011

    Decentralizing Attribute-Based Encryption

    The authors propose a Multi-Authority Attribute-Based Encryption (ABE) system. In the system, any party can become an authority and there is no requirement for any global coordination other than the creation of an initial set of common reference parameters. A party can simply act as an ABE authority by creating...

    Provided By University of Texas

  • White Papers // Jan 2011

    Pseudorandom Financial Derivatives

    Arora, Barak, Brunnermeier, and Ge [ABBG] showed that taking computational complexity into account, a dishonest seller could dramatically increase the lemon costs of a family of financial derivatives. The authors show that if the seller is required to construct derivatives of a certain form, then this phenomenon disappears. In particular,...

    Provided By University of Texas

  • White Papers // Jan 2011

    Programming Many-Core Architectures - A Case Study: Dense Matrix Computations on the Intel SCC Processor

    A message passing, distributed-memory parallel computer on a chip is one possible design for future, many-core architectures. The authors discuss initial experiences with the Intel Single-chip Cloud Computer research processor, which is a prototype architecture that incorporates 48 cores on a single die that can communicate via a small, shared,...

    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 2011

    Lightweight Distributed Selective Re-Execution and Its Implications for Value Speculation

    In this paper, the authors describe a lightweight protocol to support selective re-execution on the TRIPS processor. The protocol permits multiple waves of speculation to be traversing a dataflow graph simultaneously and in any order, with a cleanup "Commit" wave propagating as well to determine completion of a group of...

    Provided By University of Texas

  • White Papers // Jan 2011

    Enhancing Both Network and User Performance for Networks Supporting Best Effort Traffic

    With a view on improving user perceived performance on networks supporting best effort flows, e.g., multimedia/data file transfers, the authors propose a family of bandwidth allocation criteria that depends on the residual work of on-going transfers. Analysis and simulations show that allocating bandwidth in this fashion can significantly improve the...

    Provided By University of Texas

  • White Papers // Jan 2011

    Practical Utilities for Monitoring Multicast Service Availability

    Monitoring has become one of the key issues for the successful deployment of IP multicast in the Internet. During the last decade, several tools and systems have been developed to monitor several different characteristics of IP multicast. In this paper, the authors focus on one specific monitoring task: monitoring end-to-end...

    Provided By University of Texas

  • White Papers // Jan 2011

    Operating System Support for Massive Replication

    The increasing number of devices used by each user to access data and services and the increasing importance of the data and services available electronically both favor "Access-anywhere" network-delivered services. Unfortunately, making such services highly available is difficult. For example, even though end servers or service hosting sites advertise an...

    Provided By University of Texas

  • White Papers // Jan 2011

    Discovering Substructures in the Chemical Toxicity Domain

    The researcher's ability to interpret the data and discover interesting patterns within the data is of great importance as it helps in obtaining relevant SARs [Srinivasan et al.], for the cause of chemical cancers (e.g., Progol identified a primary amine group as a relevant SAR for the cause of chemical...

    Provided By University of Texas

  • White Papers // Jan 2011

    Structure Discovery in Sequentially-Connected Data Streams

    Much of current data mining research is focused on discovering sets of attributes that discriminate data entities into classes, such as shopping trends for a particular demographic group. In contrast, the authors are working to develop data mining techniques to discover patterns consisting of complex relationships between entities. Their research...

    Provided By University of Texas

  • White Papers // Jan 2011

    Using a Graph-Based Data Mining System to Perform Web Search

    The World Wide Web provides an immense source of information. Accessing information of interest presents a challenge to scientists and analysts, particularly if the desired information is structural in nature. The authors' goal is to design a structural search engine that uses the hyperlink structure of the Web, in addition...

    Provided By University of Texas

  • White Papers // Jan 2011

    Qualitative Comparison of Graph-Based and Logicbased Multi-Relational Data Mining: A Case Study

    The goal of this paper is to generate insights about the differences between graph-based and logic-based approaches to multi-relational data mining by performing a case study of graph-based system, Subdue and the inductive logic programming system, CProgol. The authors identify three key factors for comparing graph-based and logic-based multi-relational data...

    Provided By University of Texas

  • White Papers // Jan 2011

    Vertical Specialization, Intermediate Tariffs, And The Pattern Of Trade: Assessing The Role Of Tariff Liberalization To U.S. Bilateral Trade 1989-2001

    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 // Jan 2011

    DRES: Dynamic Range Encoding Scheme for TCAM Coprocessors

    One of the most critical resource management issues in the use of Ternary Content Addressable Memory (TCAM) for packet classification/filtering is how to effectively support filtering rules with ranges, known as range matching. In this paper, a Dynamic Range Encoding Scheme (DRES) is proposed to significantly improve TCAM storage efficiency...

    Provided By University of Texas

  • White Papers // Jan 2011

    Using Valgrind to Detect Undefined Value Errors With Bit-Precision

    The authors present Memcheck, a tool that has been implemented with the dynamic binary instrumentation framework Valgrind. Memcheck detects a wide range of memory errors in programs as they run. This paper focuses on one kind of error that Memcheck detects: undefined value errors. Such errors are common, and often...

    Provided By University of Texas

  • White Papers // Jan 2011

    Toward a Practical Packet Marking Approach for IP Traceback

    IP traceback is an important step in defending against Denial-of-Service (DoS) attacks. Probabilistic Packet Marking (PPM) has been studied as a promising approach to realize IP traceback. In this paper, the authors propose a new PPM approach that improves the current state of the art in two practical directions: it...

    Provided By University of Texas

  • White Papers // Jan 2011

    Toward a More Practical Marking Scheme for IP Traceback

    Probabilistic Packet Marking (PPM) has been studied as a promising approach to realize IP traceback. In this paper, the authors propose a new PPM approach that improves the current state of the art in two practical directions: it improves the efficiency and accuracy of IP traceback and it provides incentives...

    Provided By University of Texas

  • White Papers // Jan 2011

    FONet : A Federated Overlay Network for DoS Defense in the Internet (A Position Paper)

    The authors propose a novel service architecture to provide DoS resistant communication services in the Internet. The architecture consists of a large scale federated overlay network with DoS protected tunnels established between overlay nodes. Individual overlay nodes are deployed and maintained by the domains hosting them. The overlay network as...

    Provided By University of Texas

  • White Papers // Jan 2011

    Variable Power Broadcasting in Ad Hoc Networks

    Network wide broadcast is a frequently used operation in ad hoc networks and consumes significant amount of energy. Reducing the overall power consumption is extremely important in increasing the longevity of ad hoc networks. As a result, developing energy efficient broadcast operations becomes an important issue in ad hoc networks....

    Provided By University of Texas

  • White Papers // Jan 2011

    Intersection Characteristics of End-to-End Internet Paths and Trees

    This paper focuses on understanding the scale and the distribution of "State overhead" (briefly load) that is incurred on the routers by various value-added network services, e.g., IP multicast and IP traceback. This understanding is essential to developing appropriate mechanisms and provisioning resources so that the Internet can support such...

    Provided By University of Texas

  • White Papers // Jan 2011

    The Impact Of Financial Constraints On The Relation Between Shareholder Taxes And The Cost Of Equity Capital

    Using both the Tax Relief Act of 1997 (TRA) and the Jobs and Growth Tax Relief and Reconciliation Act of 2003 (JGTRRA), the authors conduct the first empirical investigation on how the tax cuts on dividends and/or capital gains affect the cost of equity differently for firms facing different degrees...

    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 // Jan 2011

    A Parametric Model for the Distribution of the Angle of Arrival and the Associated Correlation Function and Power Spectrum at the Mobile Station

    One of the main assumptions in the Clarke's classic channel model is isotropic scattering, i.e. uniform distribution for the angle of arrival of multipath components at the mobile station. However, in many mobile radio channels the authors encounter non-isotropic scattering, which strongly affects the correlation function and power spectrum of...

    Provided By University of Texas

  • White Papers // Jan 2011

    Pilot Designs for Consistent Frequency Offset Estimation in OFDM Systems

    This paper presents pilot designs for consistent frequency offset estimation of OFDM systems in frequency-selective fading channels. The authors describe two design approaches, namely consistency in the probabilistic sense and absolute consistency. Existing preambles and pilot designs in the literature do not guarantee the absolute consistency. They derive general criteria...

    Provided By University of Texas

  • White Papers // Jan 2011

    A Fully Pipelined XQuery Processor

    The authors present a high-performance, pull-based streaming processor for XQuery, called XQPull, that can handle many essential features of the language, including general predicates, recursive queries, backward axis steps, and function calls, using a very small amount of caching. Their framework is based on a new type of event streams,...

    Provided By University of Texas

  • White Papers // Dec 2010

    Just-in-Time Analytics on Large File Systems

    As file systems reach the peta-bytes scale, users and administrators are increasingly interested in acquiring high-level analytical information for file management and analysis. Two particularly important tasks are the processing of aggregate and top-k queries which, unfortunately, cannot be quickly answered by hierarchical file systems such as ext3 and NTFS....

    Provided By University of Texas

  • 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 // 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...

    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 // Mar 2010

    Multi-Mode Transmission for the MIMO Broadcast Channel With Imperfect Channel State Information

    This paper proposes an adaptive multi-mode transmission strategy to improve the spectral efficiency achieved in the Multiple-Input Multiple-Output (MIMO) broadcast channel with delayed and quantized channel state information. The adaptive strategy adjusts the number of active users, denoted as the transmission mode, to balance transmit array gain, spatial division multiplexing...

    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 // 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 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 // 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 // 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 // Sep 2009

    Random Access Transport Capacity

    The authors develop a new metric for quantifying end-to-end throughput in multihop wireless networks, which they term random access transport capacity since the interference model presumes uncoordinated transmissions. The metric quantifies the average maximum rate of successful end-to-end transmissions, multiplied by the communication distance, and normalized by the network area....

    Provided By University of Texas

  • White Papers // Mar 2011

    HartFi: An Energy-Efficient Localization System

    Location-Based Applications (LBAs) are emerging to be the killer applications on mobile devices. To know the where-abouts of devices, various interfaces (i.e., GPS, Wi-Fi or cellular) can be used to sense their locations. Ideally, localization should be done all the time. However, keeping any of these interfaces running continuously would...

    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 // 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 // May 2011

    Architecture and Abstractions for Environment and Traffic Aware System-Level Coordination of Wireless Networks

    This paper presents a system level approach to interference management in an infrastructure based wireless network with full frequency reuse. The key idea is to use loose base station coordination that is tailored to the spatial load distribution and the propagation environment to exploit the diversity in a user population's...

    Provided By University of Texas

  • White Papers // May 2011

    Practical Adaptive User Association Policies for 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 be...

    Provided By University of Texas

  • White Papers // Mar 2010

    Lightweight Checkpoint Mechanism and Modeling in GPGPU Environment

    While High Performance Computing (HPC) systems continue to scale in volume of computing elements and overall computing powers, the performance/cost benefit of these systems is subject to their abilities to provide high reliability, availability, and transparency in utilizing the underlying computing resources. This is evidenced by a recent announcement from...

    Provided By University of Texas

  • White Papers // Jan 2011

    A Parametric Model for the Distribution of the Angle of Arrival and the Associated Correlation Function and Power Spectrum at the Mobile Station

    One of the main assumptions in the Clarke's classic channel model is isotropic scattering, i.e. uniform distribution for the angle of arrival of multipath components at the mobile station. However, in many mobile radio channels the authors encounter non-isotropic scattering, which strongly affects the correlation function and power spectrum of...

    Provided By University of Texas

  • White Papers // Sep 2011

    Transmission Capacity of Ad-Hoc Networks With Multiple Antennas Using Transmit Stream Adaptation and Interference Cancelation

    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. Assuming that the transmitter locations are distributed as a Poisson point process, this paper derives upper and lower bounds on...

    Provided By University of Texas

  • White Papers // Jan 2011

    Pilot Designs for Consistent Frequency Offset Estimation in OFDM Systems

    This paper presents pilot designs for consistent frequency offset estimation of OFDM systems in frequency-selective fading channels. The authors describe two design approaches, namely consistency in the probabilistic sense and absolute consistency. Existing preambles and pilot designs in the literature do not guarantee the absolute consistency. They derive general criteria...

    Provided By University of Texas

  • White Papers // May 2010

    Query Processing in Connectivity-Challenged Environments

    This paper presents a discussion of issues that need to be addressed for processing relational queries in distributed environments where the connectivity is unstable and is changing continuously. Query processing over data across nodes that are collecting information is an example of such an environment. Traditional distributed query processing techniques...

    Provided By University of Texas

  • White Papers // Nov 2009

    Opportunistic Routing for Interactive Traffic in Wireless Networks

    To take advantage of the broadcast nature of wireless communication, a number of opportunistic routing techniques have recently been proposed. In order to manage the extra signaling overhead associated with operation of the opportunistic routing, these schemes work in terms of 'Batches' consisting of multiple packets. While these opportunistic techniques...

    Provided By University of Texas

  • White Papers // Mar 2011

    Fuzzy Optimization for Mobile Ad Hoc Networks: A Bottom-up Cross-Layer Approach

    In this paper, the authors introduce a new method for cross-layer design in mobile ad hoc networks. They use Fuzzy Logic System (FLS) to coordinate physical layer, data-link layer and application layer for cross-layer design. Ground speed, average delay and packets successful transmission ratio are selected as antecedents for the...

    Provided By University of Texas

  • White Papers // Apr 2010

    Distributed Rate Allocation for Wireless Networks

    This paper develops a distributed algorithm for rate allocation in wireless networks that achieves the same throughput region as optimal centralized algorithms. This cross-layer algorithm jointly performs Medium Access Control (MAC) and physical-layer rate adaptation. The paper establishes that this algorithm is throughput-optimal for general rate regions. In contrast to...

    Provided By University of Texas

  • White Papers // Jul 2010

    Queue-Architecture and Stability Analysis in Cooperative Relay Networks

    An abstraction of the physical layer coding using bit pipes that are coupled through data-rates is insufficient to capture notions such as node cooperation in cooperative relay networks. Consequently, network-stability analyses based on such abstractions are valid for non-cooperative schemes alone and meaningless for cooperative schemes. Motivated from this, this...

    Provided By University of Texas

  • White Papers // Feb 2010

    On the Impact of Mobility on Multicast Capacity of Wireless Networks

    Analogous to the beneficial impact that mobility has on the throughput of unicast networks, this paper establishes that mobility can provide a similar gain in the order-wise growth-rate of the throughput for multicast networks. This paper considers an all-mobile multicast network, and characterizes its multicast capacity scaling. The scaling result...

    Provided By University of Texas