Ohio State University

Displaying 1-40 of 181 results

  • White Papers // Feb 2014

    On Big Data Benchmarking

    Big data systems address the challenges of capturing, storing, managing, analyzing, and visualizing big data. Within this context, developing benchmarks to evaluate and compare big data systems has become an active topic for both research and industry communities. To date, most of the state-of-the-art big data benchmarks are designed for...

    Provided By Ohio State University

  • White Papers // Mar 2013

    Life-Add: Lifetime Adjustable Design for WiFi Networks With Heterogeneous Energy Supplies

    WiFi usage significantly reduces the battery lifetime of handheld devices such as Smartphones and tablets, due to its high energy consumption. In this paper, the authors propose "Life-Add": a Lifetime Adjustable design for WiFi networks, where the devices are powered by battery, electric power, and/or renewable energy. In Life-Add, a...

    Provided By Ohio State University

  • White Papers // Feb 2013

    Retransmission Delays With Bounded Packets: Power Law Body and Exponential Tail

    Retransmissions serve as the basic building block that communication protocols use to achieve reliable data transfer. Until recently, the number of retransmissions were thought to follow a geometric (light-tailed) distribution. However, recent work shows that when the distribution of the packet sizes have infinite support, retransmission-based protocols may result in...

    Provided By Ohio State University

  • White Papers // Jan 2013

    On Sample-Path Optimal Dynamic Scheduling for Sum-Queue Minimization in Forests

    The authors investigate the problem of minimizing the sum of the queue lengths of all the nodes in a wireless network with a forest topology. Each packet is destined to one of the roots (sinks) of the forest. They consider a time-slotted system, and a primary (or one-hop) interference model....

    Provided By Ohio State University

  • White Papers // Jan 2013

    Network Control Without CSI Using Rateless Codes for Downlink Cellular Systems

    Wireless network scheduling and control techniques (e.g., opportunistic scheduling) rely heavily on access to Channel State Information (CSI). However, obtaining this information is costly in terms of bandwidth, time, and power, and could result in large overhead. Therefore, a critical question is how to optimally manage network resources in the...

    Provided By Ohio State University

  • White Papers // Jan 2013

    LDPC-in-SSD: Making Advanced Error Correction Codes Work Effectively in Solid State Drives

    Conventional Error Correction Codes (ECCs), such as the commonly used BCH code, have become increasingly inadequate for Solid State Drives (SSDs) as the capacity of NAND flash memory continues to increase and its reliability continues to degrade. It is highly desirable to deploy a much more powerful ECC, such as...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Understanding the Robustness of SSDs Under Power Fault

    Modern storage technology (SSDs, No-SQL databases, commoditized RAID hardware, etc.) bring new reliability challenges to the already complicated storage stack. Among other things, the behavior of these new components during power faults - which happen relatively frequently in data centers - is an important yet mostly ignored issue in this...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Exploiting Double Opportunities for Deadline Based Content Propagation in Wireless Networks

    In this paper, the authors focus on mobile wireless networks comprising of a powerful communication center and a multitude of mobile users. They investigate the propagation of deadline-based content in the wireless network characterized by heterogeneous (time-varying and user-dependent) wireless channel conditions, heterogeneous user mobility, and where communication could occur...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Online Packet Scheduling With Hard Deadlines in Multihop Communication Networks

    The problem of online job or packet scheduling with hard deadlines has been studied extensively in the single hop setting, whereas it is notoriously difficult in the multihop setting. This difficulty stems from the fact that packet scheduling decisions at each hop influences and is influenced by decisions on other...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Distributed Cross-Layer Optimization in Wireless Networks: A Second-Order Approach

    Due to the rapidly growing scale and heterogeneity of wireless networks, the design of distributed cross-layer optimization algorithms has received significant interest from the networking research community. So far, the standard distributed cross-layer approach in the literature is based on the first-order Lagrangian dual decomposition and the sub-gradient method, which...

    Provided By Ohio State University

  • White Papers // Jan 2013

    An Economic Analysis of Regulating Security Investments in the Internet

    Regulating the ISPs to adopt more security measures has been proposed as an effective method in mitigating the threats of attacks in the Internet. However, economic incentives of the ISPs and the network effects of security measures can lead to an under-investment in their adoption. The authors study the potential...

    Provided By Ohio State University

  • White Papers // Jan 2013

    A New Analytical Technique for Designing Provably Efficient MapReduce Schedulers

    With the rapid increase in size and number of jobs that are being processed in the MapReduce framework, efficiently scheduling jobs under this framework is becoming increasingly important. The authors consider the problem of minimizing the total flow-time of a sequence of jobs in the MapReduce framework, where the jobs...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Exploring the Inefficiency and Instability of Back-Pressure Algorithms

    In this paper, the authors focus on the issue of stability in multi-hop wireless networks under flow-level dynamics, and explore the inefficiency and instability of the celebrated Back-Pressure algorithms. It has been well-known that the Back-Pressure (or MaxWeight) algorithms achieve queue stability and throughput optimality in a wide variety of...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Maximizing Social Welfare in Operator-Based Cognitive Radio Networks Under Spectrum Uncertainty and Sensing Inaccuracy

    In Cognitive Radio Networks (CRNs), Secondary Users (SUs) are allowed to opportunistically access the unused/under-utilized channels of Primary Users (PUs). To utilize spectrum resources efficiently, an auction scheme is often applied where an operator serves as an auctioneer and accepts spectrum requests from SUs. Most existing works on spectrum auctions...

    Provided By Ohio State University

  • White Papers // Jan 2013

    Providing Probabilistic Guarantees on the Time of Information Spread in Opportunistic Networks

    Spreading patterns of pandemics, computer viruses, and information have been widely studied in various research disciplines including epidemics, biology, physics, sociology, and computer networks. In these disciplines, most studies have been devoted to characterizing spread behaviors toward a network of mobile agents including humans, vehicles, and mobile devices over time....

    Provided By Ohio State University

  • White Papers // Dec 2012

    Performance of Low-Complexity Greedy Scheduling Policies in Multi-Channel Wireless Networks: Optimal Throughput and Near-Optimal Delay

    In this paper, the authors focus on the scheduling problem in multi-channel wireless networks, e.g., the downlink of a single cell in Fourth Generation (4G) OFDM-based cellular networks. Their goal is to design efficient scheduling policies that can achieve provably good performance in terms of both throughput and delay, at...

    Provided By Ohio State University

  • White Papers // Nov 2012

    Maximizing Information in Unreliable Sensor Networks Under Deadline and Energy Constraints

    The authors study the problem of maximizing the information in a wireless sensor network with unreliable links. They consider a sensor network with a tree topology, where the root corresponds to the sink, and the rest of the network detects an event and transmits data to the sink. They formulate...

    Provided By Ohio State University

  • White Papers // Oct 2012

    Performance Analysis of Work-Conserving Schedulers for Minimizing Total Flow-Time With Phase Precedence

    The authors consider the problem of minimizing the total flow-time of multiple jobs in a pool of multiple homogeneous machines, where the jobs arrive over time and have to be served with phase precedence. This is a common occurrence in job scheduling for the increasingly popular data center oriented systems,...

    Provided By Ohio State University

  • White Papers // Oct 2012

    An Extended Reduction Based Parallel Programming Paradigm with Low Overhead Fault-Tolerance Support

    It is widely accepted that the existing MPI-based fault-tolerance solutions will not be applicable in the exascale era, as with growing level of concurrency and relatively lower I/O bandwidths, the time required to complete a check-point can exceed the Mean-Time To Failure (MTTF). In this paper, the authors show that...

    Provided By Ohio State University

  • White Papers // Sep 2012

    A High-Fidelity Temperature Distribution Forecasting System for Data Centers

    Data centers have become a critical computing infrastructure in the era of cloud computing. Temperature monitoring and forecasting are essential for preventing over heating induced server shutdowns and improving a data center's energy efficiency. This paper presents a novel cyber-physical approach for temperature forecasting in data centers, which integrates Computational...

    Provided By Ohio State University

  • White Papers // Sep 2012

    Maximizing System Throughput Using Cooperative Sensing in Multi-Channel Cognitive Radio Networks

    In Cognitive Radio Networks (CRNs), unlicensed users are allowed to access the licensed spectrum when it is not currently being used by Primary Users (PUs). To guarantee a high system throughput in CRNs, the channel state of PUs needs to be accurately detected to reduce conflict. To this end, cooperative...

    Provided By Ohio State University

  • White Papers // Aug 2012

    A Fault-Tolerant Environment for Large-Scale Query Processing

    As datasets are increasing in size, the data management and processing needs are being met with added parallelism, i.e., by involving more nodes and/or cores in the system. This, in turn, is increasing the chances of failures during processing. In this paper, the authors present the design and implementation of...

    Provided By Ohio State University

  • White Papers // Jun 2012

    Low-Complexity Optimal Scheduling Over Correlated Fading Channels With ARQ Feedback

    The authors investigate the downlink scheduling problem under Markovian ON/OFF fading channels, where the instantaneous channel state information is not directly accessible, but is revealed via ARQ-type feedback. The scheduler can exploit the temporal correlation/channel memory inherent in the Markovian channels to improve network performance. However, designing low-complexity and throughput-optimal...

    Provided By Ohio State University

  • White Papers // May 2012

    On Wireless Network Infrastructure Optimization for Cyber-Physical Systems in Future Smart Buildings

    Today, most Cyber-Physical Systems (CPS) in smart buildings require a wireless-based network infrastructure for sensing, communication, and actuation. In such CPSs, the energy expenditure and hence battery lifetime of the wireless network infrastructure depend heavily upon the placement of the Base Stations (BS). However, in indoor environments, BS placement is...

    Provided By Ohio State University

  • White Papers // Apr 2012

    Scheduling Heterogeneous Delay Tolerant Tasks in Smart Grid With Renewable Energy

    The smart grid is the new generation of electricity grid that can efficiently facilitate new distributed sources of energy (e.g., harvested renewable energy), and allow for dynamic electricity price. In this paper, the authors investigate the cost minimization problem for an end-user, such as a home, community, or a business,...

    Provided By Ohio State University

  • White Papers // Apr 2012

    Maximizing a Submodular Utility for Deadline Constrained Data Collection in Sensor Networks

    The authors study the utility maximization problem for data collection in sensor networks subject to a deadline constraint, where the data on a selected subset of nodes are collected through a routing tree rooted at a sink subject to the 1-hop interference model. Their problem can be viewed as a...

    Provided By Ohio State University

  • White Papers // Mar 2012

    Design of a Power Efficient Cloud Computing Environment: Heavy Traffic Limits and QoS

    Cloud computing is fast being deployed by the industry as a means to provide efficient computing resources. A significant fraction of the overall cost of cloud computing operation is the amount of power it consumes, which is related to the number of machines in operation. In order to efficiently manage...

    Provided By Ohio State University

  • White Papers // Mar 2012

    Spammer Behavior Analysis and Detection in User Generated Content on Social Networks

    Spam content is surging with an explosive increase of User Generated Content (UGC) on the Internet. Spammers often insert popular keywords or simply copy and paste recent articles from the Web with spam links inserted, attempting to disable content-based detection. In order to effectively detect spam in user generated content,...

    Provided By Ohio State University

  • White Papers // Feb 2012

    Tracking Conflicting Accesses Efficiently for Software Record and Replay

    Record and replay, which records a multithreaded program's execution in one run and reproduces it deterministically in a second run, is useful for program debugging, fault detection and analysis. The key challenge in multithreaded record and replay is ensuring that conflicting, cross-thread accesses to shared variables are properly detected, recorded...

    Provided By Ohio State University

  • White Papers // Jan 2012

    TurfCast: A Service for Controlling Information Dissemination in Wireless Networks

    Recent years have witnessed mass proliferation of mobile devices with rich wireless communication capabilities as well as emerging mobile device based information dissemination applications that leverage these capabilities. This paper proposes TurfCast, a novel information dissemination service that selectively broadcasts information in particular "Turfs," abstract logical spaces in which receivers...

    Provided By Ohio State University

  • White Papers // Jan 2012

    A Distributed Newton's Method for Joint Multi-Hop Routing and Flow Control: Theory and Algorithm

    The fast growing scale and heterogeneity of current communication networks necessitate the design of distributed cross-layer optimization algorithms. So far, the standard approach of distributed cross-layer design is based on dual decomposition and the sub-gradient algorithm, which is a first-order method that has a slow convergence rate. In this paper,...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Maximizing System Throughput by Cooperative Sensing in Cognitive Radio Networks

    Cognitive Radio Networks allow unlicensed users to opportunistically access the licensed spectrum without causing disruptive interference to the Primary Users (PUs). One of the main challenges in CRNs is the ability to detect PU transmissions. Recent works have suggested the use of Secondary User (SU) cooperation over individual sensing to...

    Provided By Ohio State University

  • White Papers // Jan 2012

    A Pursuer-Evader Game for Sensor Networks

    In this paper, the authors present a self-stabilizing program for solving a pursuer-evader problem in sensor networks. The program can be tuned for tracking speed or energy efficiency. In the program, sensor motes close to the evader dynamically maintain a "Tracking" tree of depth R that is always rooted at...

    Provided By Ohio State University

  • White Papers // Jan 2012

    A Hierarchy-Based Fault-Local Stabilizing Algorithm for Tracking in Sensor Networks

    In this paper, the authors introduce the concept of hierarchy-based fault-local stabilization and a novel self-healing/fault-containment technique and apply them in Stalk. Stalk is an algorithm for tracking in sensor networks that maintains a data structure on top of an underlying hierarchical partitioning of the network. Starting from an arbitrarily...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Design and Analysis of a Fast Local Clustering Service for Wireless Sensor Networks

    The authors present a fast local clustering service, FLOC, that partitions a multi-hop wireless network into non-overlapping and approximately equal-sized clusters. Each cluster has a cluster-head such that all nodes within unit distance of the cluster-head belong to the cluster but no node beyond distance m from the cluster-head belongs...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Understanding the Signicance of Network Performance in End Applications: A Case Study With EtherFabric and InniBand

    Due to the low speeds of earlier generation networks such as Fast Ethernet, network communication was considered to be one of the primary bottlenecks in cluster computing. Accordingly, researchers used a number of techniques to hide the communication overheads in networks. In order to alleviate this problem, several researchers and...

    Provided By Ohio State University

  • White Papers // Jan 2012

    On the Secrecy Capacity of Fading Channels

    The authors consider the secure transmission of information over an ergodic fading channel in the presence of an eavesdropper. They eavesdropper can be viewed as the wireless counterpart of Wyner's wiretapper. The secrecy capacity of such a system is characterized under the assumption of asymptotically long coherence intervals. They first...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Loss-Tolerant Real-Time Content Integrity Validation for P2P Video Streaming

    The use of Peer-To-Peer (P2P) mechanisms for content delivery is attractive to content and service providers alike. P2P data transfers offload the demand on servers and reduce the bandwidth requirements, with corresponding benefits of improved scalability and performance. This, however, poses interesting challenges in ensuring content integrity. Peers may be...

    Provided By Ohio State University

  • White Papers // Dec 2011

    Femtocell Base Station Deployment in Commercial Buildings: A Global Optimization Approach

    While the deployment of femtocell in residential buildings has firmly positioned it as a major performance leap in wireless communications, its deployment in commercial buildings remains under-explored. In commercial building environments, the femtocell Base Station (FBS) placement planning is particularly challenging due to the impact of the building size, layout,...

    Provided By Ohio State University

  • White Papers // Nov 2011

    Expectation-Maximization Bernoulli-Gaussian Approximate Message Passing

    In this paper, the authors navigate the space between these two extremes by modeling the signal as i.i.d Bernoulli-Gaussian (BG) with unknown prior sparsity, mean, and variance, and the noise as zero-mean Gaussian with unknown variance, and they simultaneously reconstruct the signal while learning the prior signal and noise parameters....

    Provided By Ohio State University

  • White Papers // Apr 2011

    Cooperative Encoding for Secrecy in Interference Channels

    This paper investigates the fundamental performance limits of the two-user interference channel in the presence of an external eavesdropper. In this setting, the authors construct an inner bound, to the secrecy capacity region, based on the idea of cooperative encoding in which the two users cooperatively design their randomized codebooks...

    Provided By Ohio State University

  • White Papers // Jan 2011

    Scalable Collective Communication for Next-Generation Multicore Clusters With InfiniBand

    The emergence of multicore systems poses several challenges for the next-generation cluster architecture. Due to the availability of multiple processing cores per node, more number of application processes can be run on each node. In this context, the scalability of the cluster communication middleware like MPI is important for the...

    Provided By Ohio State University

  • White Papers // Apr 2011

    Non-Bayesian Rate-Adaptive Wireless Communication Using ACK/NAK-Feedback

    To combat the detrimental effects of the variability in wireless channels, the authors consider cross-layer rate adaptation based on limited feedback. In particular, based on limited feedback in the form of link-layer ACKnowledgements (ACK) and Negative AcKnowledgements (NAK), they maximize the physical-layer transmission rate subject to an upper bound on...

    Provided By Ohio State University

  • White Papers // Jun 2009

    Improving Explicit Congestion Notification With the Mark-Front Strategy

    Delivering congestion signals is essential to the performance of networks. Current TCP/IP networks use packet losses to signal congestion. Packet losses not only reduces TCP performance, but also adds large delay. Explicit Congestion Notification (ECN) delivers a faster indication of congestion and has better performance. However, current ECN implementations mark...

    Provided By Ohio State University

  • White Papers // Jun 2009

    Optimal Flooding Protocol for Routing in Adhoc Networks

    Location discovery is a fundamental problem in wireless ad hoc networks. Most of the ad hoc routing protocols use some form of flooding to discover the location and route of a mobile node. Despite various optimizations, many messages are propagated unnecessarily. The authors propose the Optimal Flooding Protocol (OFP), based...

    Provided By Ohio State University

  • White Papers // Nov 2010

    Improving QoS-Based Routing by Limiting Interference in Lossy Wireless Sensor Networks

    Many new routing protocols have been proposed for wireless sensor networks to maximize throughput, minimize delay or improve other QoS metrics in order to solve the problems of resource-constrained sensor nodes in large networks. However, many of them are based on flooding or its variants. Many routing messages are propagated...

    Provided By Ohio State University

  • White Papers // May 2011

    Concentrating Renewable Energy in Grid-Tied Datacenters

    Datacenters, the large server farms that host widely used Internet services, account for a larger fraction of worldwide carbon emissions each year. Increasingly, datacenters are reducing their emissions by using clean, renewable energy from rooftop solar panels to partially power their servers. While some customers value renewable-powered servers, many others...

    Provided By Ohio State University

  • White Papers // Sep 2010

    Renewable Energy for Datacenters: Energy Flow in Datacenters

    While envisaging datacenters going green (100% dependent on clean renewable energy sources), there is a need to analyze the required energy consumption in datacenters: The amount of energy flowing at different levels in the datacenter and the type of systems using this energy. The experiment carried out involved doing an...

    Provided By Ohio State University

  • White Papers // Jul 2010

    Design and Analysis of Systems Based on RF Receivers With Multiple Carbon Nanotube Antennas

    In this paper, possible uses of systems composed of multiple CNT-based EM receivers are introduced and their communication-theoretical analysis developed. Four possible example applications that involve multiple CNTs are discussed and their system-level designs are emphasized. Then, a communication-theoretical analysis of the performance of a generic system that involves multiple...

    Provided By Ohio State University

  • White Papers // Jan 2010

    On Secrecy Capacity Scaling in Wireless Networks

    The broadcast nature of the wireless communication makes it susceptible to eavesdropping. This motivates considering secrecy as a Quality of Service (QoS) constraint that must be accounted for in the network design. The scaling laws of wireless networks under the assumption of pre-distributed private keys was studied in. However, it...

    Provided By Ohio State University

  • White Papers // Dec 2009

    Joint Power and Secret Key Queue Management for Delay Limited Secure Communication

    In recent years, the famous wiretap channel has been revisited by many researchers and information theoretic secrecy has become an active area of research in this setting. In this paper, the authors design a wireless communication system that achieves constant bit rate data transmission over a block fading channel, securely...

    Provided By Ohio State University

  • White Papers // Oct 2008

    Detecting Worms Via Mining Dynamic Program Execution

    Worm attacks have been major security threats to the Internet. Detecting worms, especially new, unseen worms, is still a challenging problem. In this paper, the authors propose a new worm detection approach based on mining dynamic program executions. This approach captures dynamic program behavior to provide accurate and efficient detection...

    Provided By Ohio State University

  • White Papers // Jan 2011

    Database Support for Data-Driven Scientific Applications in the Grid

    In this paper the authors describe a services oriented software system to provide basic database support for efficient execution of applications that make use of scientific datasets in the Grid. This system supports two core operations: efficient selection of the data of interest from distributed databases and efficient transfer of...

    Provided By Ohio State University

  • White Papers // Feb 2010

    Parameterized Specification, Configuration and Execution of Data-Intensive Scientific Workflows

    Data analysis processes in scientific applications can be expressed as coarse-grain workflows of complex data processing operations with data flow dependencies between them. Performance optimization of these workflows can be viewed as a search for a set of optimal values in a multidimensional parameter space consisting of input performance parameters...

    Provided By Ohio State University

  • White Papers // Jan 2011

    Combining Distributed Memory and Shared Memory Parallelization for Data Mining Algorithms

    In this paper, the authors focus on using a cluster of SMPs for scalable data mining. They have developed distributed memory and shared memory parallelization techniques that are applicable to a number of common data mining algorithms. These techniques are incorporated in a middleware called FREERIDE (FRamework for Rapid Implementations...

    Provided By Ohio State University

  • White Papers // Jan 2011

    A Systematic Approach for Optimizing Complex Mining Tasks on Multiple Databases

    Many real world applications involve not just a single dataset, but a view of multiple datasets. These datasets may be collected from different sources and/or at different time instances. In such scenarios, comparing patterns or features from different datasets and understanding their relationships can be an extremely important part of...

    Provided By Ohio State University

  • White Papers // Jan 2011

    New Sampling-Based Estimators for OLAP Queries

    One important way in which sampling for approximate query processing in a database environment differs from traditional applications of sampling is that in a database, it is feasible to collect accurate summary statistics from the data in addition to the sample. This paper describes a set of sampling-based estimators for...

    Provided By Ohio State University

  • White Papers // Jan 2011

    An Algorithm for In-Core Frequent Itemset Mining on Streaming Data

    Frequent itemset mining is a core data mining operation and has been extensively studied over the last decade. This paper takes a new approach for this problem and makes two major contributions. First, the authors present a one pass algorithm for frequent itemset mining, which has deterministic bounds on the...

    Provided By Ohio State University

  • White Papers // Jan 2011

    Simultaneous Optimization of Complex Mining Tasks With a Knowledgeable Cache

    With an increasing use of data mining tools and techniques, the authors envision that a Knowledge Discovery and Data Mining System (KDDMS) will have to support and optimize for the following scenarios: Sequence of Queries: a user may analyze one or more datasets by issuing a sequence of related complex...

    Provided By Ohio State University

  • White Papers // Dec 2009

    Communication Over Doubly Selective Channels: Efficient Equalization and Max-Diversity Precoding

    The authors consider the problem of practical communication over a Doubly Selective (DS) channel, i.e., a time and frequency selective channel. The problem is approached in two different ways: coherent communication and non-coherent communication, and for each communication scheme they propose practical and near-optimal equalizers and maximum-diversity precoders. Toward these...

    Provided By Ohio State University

  • White Papers // Apr 2011

    Asymptotically Tight Steady-State Queue Length Bounds Implied by Drift Conditions

    The Foster-Lyapunov theorem and its variants serve as the primary tools for studying the stability of queueing systems. In addition, it is well known that setting the drift of the Lyapunov function equal to zero in steady-state provides bounds on the expected queue lengths. However, such bounds are often very...

    Provided By Ohio State University

  • White Papers // Nov 2011

    Expectation-Maximization Bernoulli-Gaussian Approximate Message Passing

    In this paper, the authors navigate the space between these two extremes by modeling the signal as i.i.d Bernoulli-Gaussian (BG) with unknown prior sparsity, mean, and variance, and the noise as zero-mean Gaussian with unknown variance, and they simultaneously reconstruct the signal while learning the prior signal and noise parameters....

    Provided By Ohio State University

  • White Papers // Nov 2011

    Full-Duplex Bidirectional MIMO: Achievable Rates Under Limited Dynamic Range

    In this paper, the authors consider the problem of full-duplex bidirectional communication between a pair of modems, each with multiple transmit and receive antennas. The principal difficulty in implementing such a system is that, due to the close proximity of each modem's transmit antennas to its receive antennas, each modem's...

    Provided By Ohio State University

  • White Papers // Feb 2011

    Optimal Resource Allocation in OFDMA Downlink Systems With Imperfect CSI

    In this paper, the authors address the problem of joint scheduling and resource allocation in the downlink of an Orthogonal Frequency Division Multiple Access (OFDMA)-based wireless network when the per-user SNR is known only in distribution. In particular, they consider sum-utility maximization over user schedules, powers, and code rates, subject...

    Provided By Ohio State University

  • White Papers // Feb 2011

    A Message-Passing Receiver for BICM-OFDM Over Unknown Clustered-Sparse Channels

    The authors propose a factor-graph-based approach to joint channel-estimation and-decoding of Bit-Interleaved Coded Orthogonal Frequency Division Multiplexing (BICM-OFDM). In contrast to existing designs, ours is capable of exploiting not only sparsity in sampled channel taps but also clustering among the large taps, behaviors which are known to manifest at larger...

    Provided By Ohio State University

  • White Papers // Nov 2009

    OFDMA Downlink Resource Allocation Via ARQ Feedback

    In OFDMA downlink resource allocation, the base station exploits knowledge of the users' channel realizations in order to opportunistically assign users to appropriate subchannels, as well as to optimize the rates and powers across those subchannels. Because reverse-link bandwidth is scarce, the base station's channel knowledge must be obtained via...

    Provided By Ohio State University

  • White Papers // Oct 2008

    A Fluid-Flow Model for Backlog-Based CSMA Policies

    The authors present a fluid flow model to analyze backlog-based CSMA policies. The model is obtained using a CSMA fixed point approximation that has been recently proposed and analyzed. They provide numerical case studies to illustrate the accuracy of the fluid-flow model. Recently, there has been a growing interest in...

    Provided By Ohio State University

  • White Papers // Jun 2009

    Data Layout Transformation for Enhancing Data Locality on NUCA Chip Multiprocessors

    With increasing numbers of cores, future CMPs (Chip Multi-Processors) are likely to have a tiled architecture with a portion of shared L2 cache on each tile and a bank-interleaved distribution of the address space. Although such an organization is effective for avoiding access hot-spots, it can cause a significant number...

    Provided By Ohio State University

  • White Papers // Jul 2010

    Combined Iterative and Model-Driven Optimization in an Automatic Parallelization Framework

    Today's multi-core era places significant demands on an optimizing compiler, which must parallelize programs, exploit memory hierarchy, and leverage the ever-increasing SIMD capabilities of modern processors. Existing model-based heuristics for performance optimization used in compilers are limited in their ability to identify profitable parallelism/locality trade-offs and usually lead to sub-optimal...

    Provided By Ohio State University

  • White Papers // Sep 2009

    Pointcut Rejuvenation: Recovering Pointcut Expressions in Evolving Aspect-Oriented Software

    Pointcut fragility is a well-documented problem in Aspect-Oriented Programming; changes to the base-code can lead to join points incorrectly falling in or out of the scope of pointcuts. The authors present an automated approach that limits fragility problems by providing mechanical assistance in pointcut maintenance. The approach is based on...

    Provided By Ohio State University

  • White Papers // May 2009

    Rejuvenate Pointcut: A Tool for Pointcut Expression Recovery in Evolving Aspect-Oriented Software

    Aspect-Oriented Programming (AOP) strives to localize the scattered and tangled implementations of Cross-Cutting Concerns (CCCs) by allowing developers to declare that certain actions (advice) should be taken at specific points (join points) during the execution of software where a CCC (an aspect) is applicable. However, it is non-trivial to construct...

    Provided By Ohio State University

  • White Papers // Nov 2009

    Specifying Reusable Aspects

    Aspect-Oriented (AO) programming enables designers and developers to manage, in a more modular fashion, implementations of Cross-Cutting Concerns (CCCs) that might be scattered or tangled if AO techniques were not utilized. The authors' interest in this paper is on considering techniques for specifying precise properties of aspects. In particular, they...

    Provided By Ohio State University

  • White Papers // Feb 2012

    Tracking Conflicting Accesses Efficiently for Software Record and Replay

    Record and replay, which records a multithreaded program's execution in one run and reproduces it deterministically in a second run, is useful for program debugging, fault detection and analysis. The key challenge in multithreaded record and replay is ensuring that conflicting, cross-thread accesses to shared variables are properly detected, recorded...

    Provided By Ohio State University

  • White Papers // Jan 2012

    A Pursuer-Evader Game for Sensor Networks

    In this paper, the authors present a self-stabilizing program for solving a pursuer-evader problem in sensor networks. The program can be tuned for tracking speed or energy efficiency. In the program, sensor motes close to the evader dynamically maintain a "Tracking" tree of depth R that is always rooted at...

    Provided By Ohio State University

  • White Papers // Jan 2012

    A Hierarchy-Based Fault-Local Stabilizing Algorithm for Tracking in Sensor Networks

    In this paper, the authors introduce the concept of hierarchy-based fault-local stabilization and a novel self-healing/fault-containment technique and apply them in Stalk. Stalk is an algorithm for tracking in sensor networks that maintains a data structure on top of an underlying hierarchical partitioning of the network. Starting from an arbitrarily...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Design and Analysis of a Fast Local Clustering Service for Wireless Sensor Networks

    The authors present a fast local clustering service, FLOC, that partitions a multi-hop wireless network into non-overlapping and approximately equal-sized clusters. Each cluster has a cluster-head such that all nodes within unit distance of the cluster-head belong to the cluster but no node beyond distance m from the cluster-head belongs...

    Provided By Ohio State University

  • White Papers // Oct 2008

    On Power Control and Frequency Reuse in the Two User Cognitive Channel

    This paper considers the generalized cognitive radio channel where the secondary user is allowed to reuse the frequency during both the idle and active periods of the primary user, as long as the primary rate remains the same. In this setting, the optimal power allocation policy with Single-Input Single-Output (SISO)...

    Provided By Ohio State University

  • White Papers // Jul 2011

    Algorithm Design for Femtocell Base Station Placement in Commercial Building Environments

    Although femtocell deployments in residential buildings have been increasingly prevalent, femtocell deployment in commercial building environments remains in its infancy. One of the main challenges lies in the Femtocell Base Stations (FBS) placement problem, which is complicated by the buildings' size, layout, structure, and floor/wall separations. In this paper, the...

    Provided By Ohio State University

  • White Papers // Jun 2012

    Low-Complexity Optimal Scheduling Over Correlated Fading Channels With ARQ Feedback

    The authors investigate the downlink scheduling problem under Markovian ON/OFF fading channels, where the instantaneous channel state information is not directly accessible, but is revealed via ARQ-type feedback. The scheduler can exploit the temporal correlation/channel memory inherent in the Markovian channels to improve network performance. However, designing low-complexity and throughput-optimal...

    Provided By Ohio State University

  • White Papers // Jan 2012

    Understanding the Signicance of Network Performance in End Applications: A Case Study With EtherFabric and InniBand

    Due to the low speeds of earlier generation networks such as Fast Ethernet, network communication was considered to be one of the primary bottlenecks in cluster computing. Accordingly, researchers used a number of techniques to hide the communication overheads in networks. In order to alleviate this problem, several researchers and...

    Provided By Ohio State University