University of California

Displaying 1-40 of 846 results

  • White Papers // Aug 2012

    A Benes Packet Network

    Benes networks are constructed with simple switch modules and have many advantages, including small latency and requiring only an almost linear number of switch modules. As circuit-switches, Benes networks are re-arrangeably non-blocking, which implies that they are full-throughput as packet switches, with suitable routing. Routing in Benes networks can be...

    Provided By University of California

  • White Papers // Jun 2012

    Cooperative Localization Using Angle of Arrival Measurements: Sequential Algorithms and Non-Line-of-Sight Suppression

    The authors investigate localization of a source based on Angle of Arrival (AoA) measurements made at a geographically dispersed network of cooperating receivers. The goal is to efficiently compute accurate estimates despite outliers in the AoA measurements due to multipath reflections in Non-Line-Of-Sight (NLOS) environments. Maximal Likelihood (ML) location estimation...

    Provided By University of California

  • White Papers // Jun 2012

    Collaborative High Accuracy Localization in Mobile Multipath Environments

    The authors study the problem of high accuracy localization of mobile nodes in a multipath-rich environment where sub-meter accuracies are required. They employ a peer-to-peer framework where the vehicles/nodes can get pair-wise multipath-degraded ranging estimates in local neighborhoods together with a fixed number of anchor nodes. The challenge is to...

    Provided By University of California

  • White Papers // Jun 2012

    Hybrid Cloud Support for Large Scale Analytics and Web Processing

    Platform-as-a-service (PaaS) systems, such as Google App Engine (GAE), simplify web application development and cloud deployment by providing developers with complete software stacks: runtime systems and scalable services accessible from well-defined APIs. Extant PaaS offerings are designed and specialized to support large numbers of concurrently executing web applications (multi-tier programs...

    Provided By University of California

  • White Papers // May 2012

    Analysis of Ecrime in Crowd-Sourced Labor Markets: Mechanical Turk Vs. Freelancer

    Research in the economics of security has contributed more than a decade of empirical findings to the understanding of the microeconomics of (in) security, privacy, and ecrime. Here, the authors build on insights from previous macro-level research on crime, and microeconomic analyses of ecrime to develop a set of hypotheses...

    Provided By University of California

  • White Papers // May 2012

    Provenance Management in Databases Under Schema Evolution

    Since, changes caused by database updates combine with the internal changes caused by database schema evolution, an integrated provenance management for data and metadata represents a key requirement for modern information systems. In this paper, the authors introduce the Archived Metadata and Provenance Manager (AM&PM) system which addresses this requirement...

    Provided By University of California

  • White Papers // May 2012

    Discretized Streams: An Efficient and Fault-Tolerant Model for Stream Processing on Large Clusters

    Many important "Big data" applications need to process data arriving in real time. However, current programming models for distributed stream processing are relatively low-level, often leaving the user to worry about consistency of state across the system and fault recovery. Furthermore, the models that provide fault recovery do so in...

    Provided By University of California

  • White Papers // May 2012

    Tackling Intracell Variability in TLC Flash Through Tensor Product Codes

    Flash memory is a promising new storage technology. To fully utilize future multi-level cell Flash memories, it is necessary to develop error correction coding schemes attuned to the underlying physical characteristics of Flash. Based on a careful inspection of fine-grained, experimentally-collected error patterns of TLC (three bits per cell) Flash,...

    Provided By University of California

  • White Papers // May 2012

    A Case for Performance-Centric Network Allocation

    The authors consider the problem of allocating network resources across applications in a private cluster running data-parallel frameworks. Their primary observation is that these applications have different communication requirements and thus require different support from the network to effectively parallelize. They argue that network resources should be shared in a...

    Provided By University of California

  • White Papers // May 2012

    Sweet Storage SLOs With Frosting

    Modern datacenters support a large number of applications with diverse performance requirements. These performance requirements are expressed at the application layer as high-level Service-Level Objectives (SLOs). However, large-scale distributed storage systems are unaware of these high-level SLOs. This lack of awareness results in poor performance when workloads from multiple applications...

    Provided By University of California

  • White Papers // May 2012

    North by Northwest: Infrastructure Agnostic and Datastore Agnostic Live Migration of Private Cloud Platforms

    Cloud technology is evolving at a rapid pace with innovation occurring throughout the software stack. While updates to Software-as-a-Service (SaaS) products require a simple push of code to the production servers or platform, updates to the Infrastructure-as-a-Service (IaaS) or Platform-as-a-Service (PaaS) layers require more intricate procedures to prevent disruption to...

    Provided By University of California

  • White Papers // Apr 2012

    On the Performance of Certain Private Set Intersection Protocols

    Private Set Intersection (PSI) is a useful cryptographic primitive that allows two parties (client and server) to interact based on their respective (private) input sets, in such a way that client obtains nothing other than the set intersection, while server learns nothing beyond client set size. This paper considers one...

    Provided By University of California

  • White Papers // Apr 2012

    Intrusion Detection in Resource-Constrained Cyber Networks: A Restless Multi-Armed Bandit Approach

    The authors consider a large-scale cyber network with N components. Each component is either in a healthy state (0) or an abnormal state (1). Due to intrusions, the state of each component transits from 0 to 1 over time according to an arbitrary stochastic process. The objective is to design...

    Provided By University of California

  • White Papers // Apr 2012

    Automated MAC Protocol Generation With Multiple Neighborhoods and Acknowledgments Based on Symbolic Monte Carlo Simulation

    The authors present a framework for automated Medium Access Control (MAC) protocol generation based on a model that incorporates multiple MAC neighborhoods as well as acknowledgments. Both the advertisement and acknowledgment packets are automatically generated by an optimization program that is built based on symbolic Monte Carlo simulation. The design...

    Provided By University of California

  • White Papers // Mar 2012

    Static Detection of Loop-Invariant Data Structures

    As a culture, object-orientation encourages programmers to create objects, both short- and long-lived, without concern for cost. Excessive object creation and initialization can cause severe runtime bloat, which degrades significantly application performance and scalability. A frequently-occurring coding pattern that may lead to large volumes of (temporary) objects is the creation...

    Provided By University of California

  • White Papers // Mar 2012

    Efficient and Optimally Secure Key-Length Extension for Block Ciphers Via Randomized Cascading

    The authors consider the question of efficiently extending the key length of block ciphers. To date, the approach providing highest security is triple encryption (used e.g., in Triple-DES), which was proved to have roughly k + minfn=2; k=2g bits of security when instantiated with ideal block ciphers with key length...

    Provided By University of California

  • White Papers // Mar 2012

    Achieving Congestion Diversity in Multi-Hop Wireless Mesh Networks

    This paper reports on the first systematic study of congestion-aware routing algorithms for wireless mesh networks to achieve an improved end-end delay performance. In particular, the authors compare 802.11 compatible implementations of a set of congestion-aware routing protocols against their implementation of state of the art shortest path routing protocol...

    Provided By University of California

  • White Papers // Mar 2012

    Context-Aware Sensor Data Dissemination for Mobile Users in Remote Areas

    Many mobile sensing applications consider users reporting and accessing sensing data through the Internet. However, WiFi and 3G connectivities are not always available in remote areas. Existing data dissemination schemes for opportunistic networks are not sufficient for sensing applications as sensing context has not been explored. In this paper, the...

    Provided By University of California

  • White Papers // Mar 2012

    Defining CPS Challenges in a Sustainable Electricity Grid

    Cyber-Physical Systems (CPS) is characterized as complex distributed systems exhibiting substantial uncertainty due to interactions with the physical world. Today's electric grids are often described as CPS because a portfolio of distributed supplies must be dispatched in real-time to match uncontrolled, uncertain demand while adhering to constraints imposed by the...

    Provided By University of California

  • White Papers // Mar 2012

    OnController Initialization in Multivariable Switching Systems

    The authors consider a class of switched systems which consists of a linear MIMO and possibly unstable process in feedback interconnection with a multi-controller whose dynamics switch. It is shown how one can achieve significantly better transient performance by selecting the initial condition for every controller when it is inserted...

    Provided By University of California

  • White Papers // Mar 2012

    Primary User Traffic Estimation for Dynamic Spectrum Access

    Accurate estimation of licensed channel Primary User's (PU) temporal statistics is important for Dynamic Spectrum Access (DSA) systems. With accurate estimation of the mean duty cycle, u, and the mean off- and on-times of PUs, DSA systems can more efficiently assign PU resources to its subscribers, thus, increasing channel utilization....

    Provided By University of California

  • White Papers // Mar 2012

    Broadcast-Efficient Secure Multiparty Computation

    Secure MultiParty Computation (MPC) is perhaps the most popular paradigm in the area of cryptographic protocols. It allows several mutually untrustworthy parties to jointly compute a function of their private inputs, without revealing to each other information about those inputs. In the case of unconditional (information-theoretic) security, protocols are known...

    Provided By University of California

  • White Papers // Mar 2012

    Elements of Cellular Blind Interference Alignment - Aligned Frequency Reuse, Wireless Index Coding and Interference Diversity

    The authors explore Degrees of Freedom (DoF) characterizations of partially connected wireless networks, especially cellular networks, with no channel state information at the transmitters. Specifically, they introduce three fundamental elements - aligned frequency reuse, wireless index coding and interference diversity - through a series of examples, focusing first on infinite...

    Provided By University of California

  • White Papers // Mar 2012

    Opportunistic Routing With Congestion Diversity in Wireless Ad-Hoc Networks

    The authors consider the problem of routing packets across a multi-hop network consisting of multiple sources of traffic and wireless links while ensuring bounded expected delay. Each packet transmission can be overheard by a random subset of receiver nodes among which the next relay is selected opportunistically. The main challenge...

    Provided By University of California

  • White Papers // Feb 2012

    Uncovering Performance Problems in Java Applications With Reference Propagation Profiling

    Many applications suffer from run-time bloat: excessive memory usage and work to accomplish simple tasks. Bloat significantly affects scalability and performance, and exposing it requires good diagnostic tools. The authors present a novel analysis that profiles the run-time execution to help programmers uncover potential performance problems. The key idea of...

    Provided By University of California

  • White Papers // Feb 2012

    A Flexible In-Network IP Anonymization Service

    User privacy on the Internet has been an increasing concern in recent years. With the proliferation and sophistication of information services, data mining, and search engines, a simple network address may be used to reveal a great deal of information about a user, including location, identity, and behavior. Existing approaches...

    Provided By University of California

  • White Papers // Feb 2012

    Multiflow Transmission in Delay Constrained Cooperative Wireless Networks

    This paper considers the problem of energy-efficient transmission in multi-flow multi-hop cooperative wireless networks. Although the performance gains of cooperative approaches are well known, the combinatorial nature of these schemes makes it difficult to design efficient polynomial-time algorithms for joint routing, scheduling and power control. This becomes more so when...

    Provided By University of California

  • White Papers // Feb 2012

    Controlling Applications by Managing Network Characteristics

    Edge network operators have limited tools to control activities on their networks. This paper examines network dissuasion, a new approach to edge network control, based on controlling the fundamental parameters of the network, such as loss rate, delay, and jitter, with the intention of making particular uses of a network...

    Provided By University of California

  • White Papers // Feb 2012

    Sparse Online Low-Rank Projection and Outlier Rejection (SOLO) for 3-D Rigid-Body Motion Registration

    Motivated by an emerging theory of robust low-rank matrix representation, in this paper, the authors introduce a novel solution for online rigid-body motion registration. The goal is to develop algorithmic techniques that enable a robust, real-time motion registration solution suitable for low-cost, portable 3-D camera devices. Assuming 3-D image features...

    Provided By University of California

  • White Papers // Feb 2012

    The Bleak Future of NAND Flash Memory

    In recent years, flash-based SSDs have grown enormously both in capacity and popularity. In highperformance enterprise storage applications, accelerating adoption of SSDs is predicated on the ability of manufacturers to deliver performance that far exceeds disks while closing the gap in cost per gigabyte. However, while flash density continues to...

    Provided By University of California

  • White Papers // Feb 2012

    Mitigate Funnel Effect in Sensor Networks With Multi-Interface Relay Nodes

    Overlay network architectures that use orthogonal channels have been known to provide effective additional resources to underlying networks in high demand. Overlays are composed of relay nodes provided with rich computational resources and multiple wireless interfaces that make them capable of establishing several non-interfering networks. These networks can be used...

    Provided By University of California

  • White Papers // Jan 2012

    Enhancing LRU Replacement Via Phantom Associativity

    In this paper, the authors propose a novel cache design, Phantom Associative Cache (PAC), that alleviates cache thrashing in L2 caches by keeping the in-cache data blocks for a longer time period. To realize PAC, they introduce the concept of phantom lines. A phantom line works like a real cache...

    Provided By University of California

  • White Papers // Jan 2012

    BlueSky: A Cloud-Backed File System for the Enterprise

    The authors present BlueSky, a network file system backed by cloud storage. BlueSky stores data persistently in a cloud storage provider such as Amazon S3 or Windows Azure, allowing users to take advantage of the reliability and large storage capacity of cloud providers and avoid the need for dedicated server...

    Provided By University of California

  • White Papers // Jan 2012

    Weighted Fair Queuing With Differential Dropping

    Weighted Fair Queuing (WFQ) allows Internet operators to define traffic classes and then assign different bandwidth proportions to these classes. Unfortunately, the complexity of efficiently allocating the buffer space to each traffic class turns out to be overwhelming, leading most operators to vastly overprovision buffering - resulting in a large...

    Provided By University of California

  • White Papers // Jan 2012

    PLASMA: A New Routing Paradigm for Wireless Multihop Networks

    In this paper, the authors present a new routing paradigm for wireless multi-hop networks. In plasma routing, each packet is delivered over the best available path to one of the gateways. The choice of the path and gateway for each packet is not made beforehand by the source node, but...

    Provided By University of California

  • White Papers // Jan 2012

    On Detecting Pollution Attacks in Inter-Session Network Coding

    Network coding involves packets being combined at intermediate nodes inside the network. Depending on whether packets from the same or different sessions are combined, network coding is classified as intra-session or inter-session, respectively. Inter-session coding, that is the focus of this paper, has been implemented in practice, such as in...

    Provided By University of California

  • White Papers // Jan 2012

    Distributed Measurement-Aware Routing: Striking a Balance Between Measurement and Traffic Engineering

    Network-wide traffic measurement is important for various network management tasks, ranging from traffic accounting, traffic engineering, and network troubleshooting to security. Existing techniques for traffic measurement tend to be sub-optimal due to poor choice of monitor deployment location or due to constantly evolving monitoring objectives and traffic characteristics. It is...

    Provided By University of California

  • White Papers // Jan 2012

    A Methodology for Clustering XML Documents by Structure

    The processing and management of XML data are popular research issues. However, operations based on the structure of XML data have not received strong attention. These operations involve, among others, the grouping of structurally similar XML documents. Such grouping results from the application of clustering methods with distances that estimate...

    Provided By University of California

  • White Papers // Jan 2012

    Probabilistic Data Management for Pervasive Computing: The Data Furnace Project

    The wide deployment of wireless sensor and RFID (Radio Frequency IDentification) devices is one of the key enablers for next-generation pervasive computing applications, including large-scale environmental monitoring and control, context-aware computing, and "Smart digital homes". Sensory readings are inherently unreliable and typically exhibit strong temporal and spatial correlations (within and...

    Provided By University of California

  • White Papers // Jan 2012

    In-Network PCA and Anomaly Detection

    The authors consider the problem of network anomaly detection in large distributed systems. In this setting, Principal Component Analysis (PCA) has been proposed as a method for discovering anomalies by continuously tracking the projection of the data onto a residual subspace. This method was shown to work well empirically in...

    Provided By University of California

  • White Papers // May 2008

    Seamless Sequence of Software Defined Radio Designs through Hardware Reconfigurability of FPGAs

    Software Defined Radio (SDR) base stations can compensate for failures in disaster scenarios by assimilating different communication technologies. FPGAs play an important role in the platform of an SDR base station because of flexibility and DSP processing power that they deliver. The flexibility of FPGAs comes at the high cost...

    Provided By University of California

  • White Papers // May 2008

    Generic Operations and Capabilities in the JR Concurrent Programming Language

    The JR concurrent programming language extends Java with additional concurrency mechanisms, which are built upon JR's operations and capabilities. JR operations generalize methods in how they can be invoked and serviced. JR capabilities act as reference to operations. Recent changes to the Java language and implementation, especially generics, necessitated corresponding...

    Provided By University of California

  • White Papers // Jan 2011

    Toward a Definition of and Linguistic Support for Partial Quiescence

    The global quiescence of a distributed computation (or distributed termination detection) is an important problem. Some concurrent programming languages and systems provide global quiescence detection as a built-in feature so that programmers do not need to write special synchronization code to detect quiescence. This paper introduces Partial Quiescence (PQ), which...

    Provided By University of California

  • White Papers // Jun 2008

    Distributed Resource Management in Multi-Hop Cognitive Radio Networks for Delay Sensitive Transmission

    In this paper, the authors investigate the problem of multi-user resource management in multi-hop cognitive radio networks for delay-sensitive applications. Since the tolerable delay does not allow propagating global information back and forth throughout the multi-hop network to a centralized decision maker, the source nodes and relays need to adapt...

    Provided By University of California

  • White Papers // May 2010

    Spark: Cluster Computing With Working Sets

    MapReduce and its variants have been highly successful in implementing large-scale data-intensive applications on commodity clusters. However, most of these systems are built around an acyclic data flow model that is not suitable for other popular applications. This paper focuses on one such class of applications: those that reuse a...

    Provided By University of California

  • White Papers // Nov 2011

    Recomputing Materialized Instances After Changes to Mappings and Data

    A major challenge faced by today's information systems is that of evolution as data usage evolves or new data resources become available. Modern organizations sometimes exchange data with one another via declarative mappings among their databases, as in data exchange and collaborative data sharing systems. Such mappings are frequently revised...

    Provided By University of California

  • White Papers // Apr 2009

    Gaming the Jammer: Is Frequency Hopping Effective ?

    Frequency hopping has been the most popularly considered approach for alleviating the effects of jamming attacks. In this paper, the authors provide a novel, measurement-driven, game theoretic framework that captures the interactions between a communication link and an adversarial jammer, possibly with multiple jamming devices, in a wireless network employing...

    Provided By University of California

  • White Papers // Sep 2008

    Model Engineering Using Multimodeling

    The authors study the simultaneous use of multiple modeling techniques in the design of embedded systems. They begin with a pre-existing Statecharts model of a simple case study, a traffic light for a pedestrian crossing, using it to illustrate the need for multi-modeling and the pitfalls. The original model combines...

    Provided By University of California

  • White Papers // May 2008

    PTIDES: A Programming Model for Distributed Real-Time Embedded Systems

    The authors describe a programming model called PTIDES (Programming Temporally Integrated Distributed Embedded Systems), that extends the discrete-event model of computation with a carefully chosen relationship between real time and model time. PTIDES provides a framework for exploring a family of execution strategies for distributed embedded systems. Their objective in...

    Provided By University of California

  • White Papers // Sep 2009

    Verifying Ptolemy II Discrete-Event Models Using Real-Time Maude

    This paper shows how Ptolemy II Discrete-Event (DE) models can be formally analyzed using Real-Time Maude. The authors formalize in Real-Time Maude the semantics of a subset of hierarchical Ptolemy II DE models, and explain how the code generation infrastructure of Ptolemy II has been used to automatically synthesize a...

    Provided By University of California

  • White Papers // Jul 2008

    Scalable Models Using Model Transformation

    Higher-order model composition can be employed as a mechanism for scalable model construction. By creating a description that manipulates model fragments as first-class objects, designers' work of model creation and maintenance can be greatly simplified. In this paper, the authors present their approach to higher-order model composition based on model...

    Provided By University of California

  • White Papers // Dec 2011

    Template-Based Program Veri Cation and Program Synthesis

    Program verification is the task of automatically generating proofs for a program's compliance with a given specification. Program synthesis is the task of automatically generating a program that meets a given specification. Both program verification and program synthesis can be viewed as search problems, for proofs and programs, respectively. For...

    Provided By University of California

  • White Papers // Jan 2009

    SingleTrack: A Dynamic Determinism Checker for Multithreaded Programs

    Multi-threaded programs are prone to errors caused by un-intended interference between concurrent threads. This paper focuses on verifying that deterministically-parallel code is free of such thread interference errors. Deterministically-parallel code may create and use new threads, via fork and join, and coordinate their behavior with synchronization primitives, such as barriers...

    Provided By University of California

  • White Papers // Oct 2011

    Types for Precise Thread Interference

    The potential for unexpected interference between threads makes multi-threaded programming notoriously difficult. Programmers use a variety of synchronization idioms such as locks and barriers to restrict where interference may actually occur. Unfortunately, the resulting actual interference points are typically never documented and must be manually reconstructed as the first step...

    Provided By University of California

  • White Papers // Sep 2010

    Tweakable Block Ciphers

    A common trend in applications of block ciphers over the past decades has been to employ block ciphers as one piece of a "Mode of operation" - possibly, a way to make a secure symmetric-key cryptosystem, but more generally, any cryptographic application. Most of the time, these modes of operation...

    Provided By University of California

  • White Papers // May 2011

    Exploring the Relationship BetweenWeb Application Development Tools and Security

    How should software engineers choose which tools to use to develop secure web applications? Different developers have different opinions regarding which language, framework, or vulnerability-finding tool tends to yield more secure software than another; some believe that there is no difference at all between such tools. This paper adds quantitative...

    Provided By University of California

  • White Papers // May 2011

    Phishing on Mobile Devices

    The authors assess the risk of phishing on mobile platforms. Mobile operating systems and browsers lack secure application iden-tity indicators, so the user cannot always identify whether a link has taken her to the expected application. They conduct a systematic analysis of ways in which mobile applications and web sites...

    Provided By University of California

  • White Papers // Mar 2011

    Defeating UCI: Building Stealthy and Malicious Hardware

    In previous work Hicks et al. proposed a method called Unused Circuit Identification (UCI) for detecting malicious backdoors hidden in circuits at design time. The UCI algorithm essentially looks for portions of the circuit that go unused during design-time testing and flags them as potentially malicious. In this paper, the...

    Provided By University of California

  • White Papers // May 2008

    The Murky Issue of Changing Process Identity: Revising "Setuid Demystified"

    Dropping unneeded process privileges promotes security, but is notoriously error-prone due to confusing set id system calls with unclear semantics and subtle portability issues. To make things worse, existing recipes to accomplish the task are lacking, related manuals can be misleading, and the associated kernel subsystem might contain bugs. The...

    Provided By University of California

  • White Papers // Apr 2010

    Lazy Annotation for Program Testing and Verification

    The authors describe an interpolant-based approach to test generation and model checking for sequential programs. The method generates Floyd/Hoare style annotations of the program on demand, as a result of failure to achieve goals, in a manner analogous to conflict clause learning in a DPLL style SAT solver. The DPLL...

    Provided By University of California

  • White Papers // Jan 2011

    A Self-Healing and Optimizing Routing Technique for Ad Hoc Networks

    On demand routing protocols provide scalable and cost-effective solutions for packet routing in wireless ad hoc networks. The paths generated by these protocols may deviate far from the optimal because of the lack of knowledge about the global topology and the mobility of nodes. Routing optimality affects network performance, especially...

    Provided By University of California

  • White Papers // May 2010

    Beyond Multi-Hop: Optimal Cooperation in Large Wireless Networks

    Multi-hop is the communication architecture of current wireless networks such as mesh or ad hoc networks. Packets are sent from each source to its destination via multiple point-to-point transmissions between relaying nodes. The origins of this approach are rooted in the practice of traditional wire-line networks. Today, the increasing need...

    Provided By University of California

  • White Papers // Feb 2010

    Linear Capacity Scaling in Wireless Networks: Beyond Physical Limits?

    Multi-hop is the communication architecture of current wireless networks such as mesh or ad hoc networks. Packets are sent from each source to its destination via multiple relay nodes. Each relay decodes the packets sent from the previous relay and forwards them to the next relay. Can more sophisticated cooperation...

    Provided By University of California

  • White Papers // Apr 2009

    Reliable Relaying With Uncertain Knowledge

    The motivation for this paper is to analyze the effect of information uncertainty on the design and performance of protocols. The paper considers two types of situations. The first is when different nodes in the network have bounded knowledge about what other nodes know. The second, called common knowledge about...

    Provided By University of California

  • White Papers // Aug 2009

    Utility-Maximizing Scheduling for Stochastic Processing Networks

    Stochastic Processing Networks (SPNs) model manufacturing, communication, or service systems. In such a network, service activities require parts and resources to produce other parts. Because service activities compete for resources, the scheduling in a SPN requires deciding which of a set of conflicting activities should be performed at any given...

    Provided By University of California

  • White Papers // Aug 2009

    Convergence and Stability of a Distributed CSMA Algorithm for Maximal Network Throughput

    Designing efficient scheduling algorithms is an important problem in a general class of networks with resource-sharing constraints, such as wireless networks and stochastic processing networks. The authors proposed a distributed scheduling algorithm that can achieve the maximal throughput in such networks under certain conditions. This algorithm was inspired by CSMA...

    Provided By University of California

  • White Papers // Nov 2009

    Stable and Utility-Maximizing Scheduling for Stochastic Processing Networks

    Stochastic Processing Networks (SPNs) are models of service, processing, communication, or manufacturing systems. In such a network, service activities require parts and resources to produce new parts. Thus, parts flow through a network of buffers served by activities that consume parts and produce new ones. Typically, service activities compete for...

    Provided By University of California

  • White Papers // Jun 2008

    Approximate Characterization of Capacity in Gaussian Relay Networks

    The authors present an achievable rate for general Gaussian relay networks. They show that the achievable rate is within a constant number of bits from the information-theoretic cut-set upper bound on the capacity of these networks. This constant depends on the topology of the network, but not the values of...

    Provided By University of California

  • White Papers // Nov 2009

    Optimal Tradeoff Between Exposed and Hidden Nodes in Large Wireless Networks

    Wireless networks equipped with the CSMA protocol are subject to collisions due to interference. For a given interference range the authors investigate the trade-off between collisions (hidden nodes) and unused capacity (exposed nodes). They determine the optimal sensing range that maximizes throughput and critically depends on the activation rate of...

    Provided By University of California

  • White Papers // Feb 2010

    Performance Bounds of Distributed CSMA Scheduling

    CSMA-based scheduling is a recently proposed distributed scheduling algorithm that is shown to achieve the maximal throughput. Central to this algorithm is a Markov chain that produces samples from a desired distribution. In this paper, the authors discuss the relationships of the achievable throughput, queueing delay and the mixing time...

    Provided By University of California

  • White Papers // Jan 2011

    PoX: Protecting Users From Malicious Facebook Applications

    Online social networks such as Facebook, MySpace, and Orkut store large amounts of sensitive user data. While a user can legitimately assume that a social network provider adheres to strict privacy standards, the authors argue that it is unwise to trust third-party applications on these platforms in the same way....

    Provided By University of California

  • White Papers // Aug 2010

    The Design of a Reliable Reputation System

    Next generation Web 2.0 communities and distributed P2P systems rely on the cooperation of diverse user populations spread across numerous administrative and security domains. Zero accountability via anonymous online identities and divergent interests result in selfish behavior that can disrupt or manipulate networks for personal gain. While "Reputation systems" are...

    Provided By University of California

  • White Papers // Jan 2011

    Routing and Multicast in Multihop, Mobile Wireless Networks

    In this paper, the authors present a multicast protocol which builds upon a cluster based wireless network infrastructure. First, they introduce the network infrastructure which includes several innovative features such as: minimum change cluster formation; dynamic priority token access protocol, and; distributed hierarchical routing. Then, for this infrastructure they propose...

    Provided By University of California

  • White Papers // May 2011

    Maximum Damage Battery Depletion Attack in Mobile Sensor Networks

    Developing reliable security measures against outbreaks of malware will facilitate the proliferation of wireless sensing technologies. The first step toward this goal is to investigate potential attack strategies and the extent of damage they can incur. The malware at each infective node may seek to contact more susceptible nodes by...

    Provided By University of California

  • White Papers // Oct 2011

    Multi-Channel Opportunistic Spectrum Access in Unslotted Primary Systems With Unknown Models

    Multi-channel opportunistic spectrum access in unslotted primary systems is considered. The primary occupancy of each channel is modeled as a general on-off renewal process. The distributions of the busy and idle times and the utilization factors of all channels are unknown to the secondary user. The objective of the secondary...

    Provided By University of California

  • White Papers // Jul 2011

    Multi-Armed Bandit Problems With Heavy Tail Reward Distributions

    In the Multi-Armed Bandit (MAB) problem, there are a given set of arms with unknown reward models. At each time, a player selects one arm to play, aiming to maximize the total expected reward over a horizon of length T. The essence of the problem is the tradeoff between exploration...

    Provided By University of California

  • White Papers // Jan 2011

    Asymptotically Efficient Multi-Channel Estimation for Opportunistic Spectrum Access

    The problem of estimating the parameters of multiple independent continuous-time Markov on-off processes is considered. The objective is to minimize the total Mean Square Error (MSE) under a constraint on the total sensing time. The Fisher information matrix for the primary traffic model and the maximum likelihood estimator are obtained...

    Provided By University of California

  • White Papers // Jan 2011

    Spectrum Opportunity Detection: How Good Is Listen-Before-Talk?

    The authors consider spectrum opportunity detection in cognitive radio networks for spectrum overlay. They highlight the differences between detecting primary signals and detecting spectrum opportunities. They show that besides noise and fading, the geographic distribution and traffic pattern of primary users have significant impact on the performance of spectrum opportunity...

    Provided By University of California

  • White Papers // Mar 2011

    Technology Choices and Pricing Policies in Wireless Networks

    This paper studies the provision of a wireless network by a monopolistic provider who may be either benevolent (seeking to maximize social welfare) or selfish (seeking to maximize provider profit). The paper addresses the following questions: Under what circumstances is it feasible for a provider, either benevolent or selfish, to...

    Provided By University of California

  • White Papers // Aug 2011

    MACE: Model-Inference-Assisted Concolic Exploration for Protocol and Vulnerability Discovery

    Program state-space exploration is central to software security, testing, and verification. In this paper, the authors propose a novel technique for state-space exploration of software that maintains an ongoing interaction with its environment. Their technique uses a combination of symbolic and concrete execution to build an abstract model of the...

    Provided By University of California