University of Minho

Displaying 1-40 of 90 results

  • White Papers // Mar 2014

    On a Duality Between Recoverable Distributed Storage and Index Coding

    Recently, local repair property of error-correcting codes is the center of a lot of research activity. In a distributed storage system, a single server failure is the most common error event, and in that case, the aim is to reconstruct the content of the server from as few other servers...

    Provided By University of Minho

  • White Papers // Jan 2014

    Exploiting User Interest in Data-Driven Cloud-based Mobile Optimization

    In this paper, the authors present their vision for data-driven cloud-based mobile computing. They identify the concept of Region of Interest (RoI) that reflects the profile of the user in how they access information or interact with applications. Such information enables a series of data-driven optimizations: filtering, aggregation, and speculation,...

    Provided By University of Minho

  • White Papers // Jan 2014

    Nebula: Distributed Edge Cloud for Data Intensive Computing

    Centralized cloud infrastructures have become the de-facto platform for data-intensive computing today. However, they suffer from inefficient data mobility due to the centralization of cloud resources, and hence, are highly unsuited for dispersed data-intensive applications, where the data may be spread at multiple geographical locations. In this paper, the authors...

    Provided By University of Minho

  • White Papers // Jan 2014

    Tiera: Towards Flexible Multi-Tiered Cloud Storage Instances

    Many cloud providers offer an array of storage services that represent different points along the performance, reliability, cost, and durability spectrum. However, an application must manage the complexity of different interfaces to these storage services and their diverse policies, if it needs the composite benefits of multiple storage tiers. The...

    Provided By University of Minho

  • White Papers // Jan 2014

    Tracking Long Duration Flows in Network Traffic

    Network administrators need to monitor their network traffic timely and effectively to respond to network anomalies and security problems or help with traffic engineering decisions. Due to the sheer volume of network traffic, they increasingly rely on sophisticated data streaming algorithms to characterize their network traffic or extract a subset...

    Provided By University of Minho

  • White Papers // Oct 2013

    Characterizing Multi-Threaded Applications for Designing Sharing-Aware Last-Level Cache Replacement Policies

    Recent years have seen a large volume of proposals on managing the shared Last-Level Cache (LLC) of Chip Multi-Processors (CMPs). However, most of these proposals primarily focus on reducing the amount of destructive interference between competing independent threads of multi-programmed workloads. While very few of these studies evaluate the proposed...

    Provided By University of Minho

  • White Papers // Jul 2013

    Accelerating Data Race Detection Utilizing On-Chip Data-Parallel Cores

    Programmers are taking advantage of the increasing availability of on-chip parallelism to meet the rising performance demands of diverse applications. Support of tools that can facilitate the detection of incorrect program execution when concurrent threads are involved is critical to this evolution. Many concurrency bugs manifest as some form of...

    Provided By University of Minho

  • White Papers // Jul 2013

    HAccRG: Hardware-Accelerated Data Race Detection in GPUs

    Modern Graphics Processing Units (GPUs) are capable of supporting thousands of concurrent threads. However, they provide relatively little guarantee with respect to the coherence and consistency of the memory system. Thus, GPUs are prone to multitude of concurrency bugs related to inconsistent memory states. Many such bugs manifest as some...

    Provided By University of Minho

  • White Papers // Jul 2013

    Managing Shared Last-Level Cache in a Heterogeneous Multicore Processor

    Heterogeneous multi-core processors that integrate CPU cores and data-parallel accelerators such as GPU cores onto the same die raise several new issues for sharing various on-chip resources. The shared Last-Level Cache (LLC) is one of the most important shared resources due to its impact on performance. Accesses to the shared...

    Provided By University of Minho

  • White Papers // Jun 2013

    On the Fundamental Limits of Recovering Tree Sparse Vectors from Noisy Linear Measurements

    In this paper the authors establish fundamental performance limits for the task of support recovery of tree-sparse signals from noisy measurements, in settings where measurements may be obtained either non-adaptively (using a randomized Gaussian measurement strategy motivated by initial CS investigations) or by any adaptive sensing strategy. Their main results...

    Provided By University of Minho

  • White Papers // May 2013

    An Upper Bound On the Size of Locally Recoverable Codes

    In a locally recoverable or repairable code, any symbol of a codeword can be recovered by reading only a small (constant) number of other symbols. The notion of local recoverability is important in the area of distributed storage where a most frequent error-event is a single storage node failure (erasure)....

    Provided By University of Minho

  • White Papers // May 2013

    On Chebyshev Radius of a Set in Hamming Space and the Closest String Problem

    The Chebyshev radius of a set in a metric space is defined to be the radius of the smallest ball containing the set. This quantity is closely related to the covering radius of the set and, in particular for Hamming set, is extensively studied in computational biology. This paper investigates...

    Provided By University of Minho

  • White Papers // May 2013

    Ghost Talk: Mitigating EMI Signal Injection Attacks Against Analog Sensors

    ElectroMagnetic Interference (EMI) affects circuits by inducing voltages on conductors. Analog sensing of signals on the order of a few millivolts is particularly sensitive to interference. This paper measures the susceptibility of analog sensor systems to signal injection attacks by intentional, low-power emission of chosen electromagnetic waveforms, and proposes defense...

    Provided By University of Minho

  • White Papers // Jan 2013

    Cross-Phase Optimization in MapReduce

    MapReduce has been designed to accommodate large-scale data-intensive workloads running on large single-site homogeneous clusters. Researchers have begun to explore the extent to which the original MapReduce assumptions can be relaxed including skewed workloads, iterative applications, and heterogeneous computing environments. The authors' work continues this exploration by applying MapReduce across...

    Provided By University of Minho

  • White Papers // Jan 2013

    Accelerating Distributed Workflows With Edge Resources

    Distributed data-intensive workflow applications are increasingly relying on and integrating remote resources including community data sources, services, and computational platforms. Increasingly, these are made available as data, SAAS, and IAAS clouds. The execution of distributed data-intensive workflow applications can expose network bottlenecks between clouds that compromise performance. In this paper,...

    Provided By University of Minho

  • White Papers // Jan 2013

    Spatial Cloaking for Anonymous Location-Based Services in Mobile Peer-to-Peer Environments

    In this paper, the authors tackle a privacy breach in current Location-Based Services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. For example, a user who wants to issue a query asking about her nearest gas...

    Provided By University of Minho

  • White Papers // Jan 2013

    Towards Privacy-Aware Location-Based Database Servers

    The wide spread of location-based services results in a strong market for location-detection devices (e.g., GPS-like devices, RFIDs, handheld devices, and cellular phones). Examples of location-based services include location-aware emergency service, location-based advertisement, live traffic reports, and location-based store under. However, location-detection devices pose a major privacy threat on its...

    Provided By University of Minho

  • White Papers // Nov 2012

    A Feature Combination Approach for the Detection of Early Morning Bathroom Activities with Wireless Sensors

    In this paper the authors investigate the use of wearable accelerometers and wireless home sensors for the detection of early morning daily activities. In particular they focus on the detection of brushing, washing face and shaving activities by using a wireless accelerometer sensor attached to the right wrist of subjects...

    Provided By University of Minho

  • White Papers // Nov 2012

    Panda: A Predictive Spatio-Temporal Query Processor

    This paper presents the Panda system for efficient support of a wide variety of predictive spatio-temporal queries that are widely used in several applications including traffic management, location-based advertising, and ride sharing. Unlike previous attempts in supporting predictive queries, Panda targets long-term query prediction as it relies on adapting a...

    Provided By University of Minho

  • White Papers // Nov 2012

    Application of Geomorphological Data Layers to Landslide Susceptibility Mapping with Analytical Hierarchical Process and GIS Techniques (Case Study: Zonouz Plain, East Azerbaijan, Iran)

    Without a doubt, landslide is one of the most disastrous natural hazards. Therefore, landslide susceptibility maps in regional scale are useful guide for future development activities. In this paper, the Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) were used to produce landslide susceptibility map of the Zonouz Plain...

    Provided By University of Minho

  • White Papers // Sep 2012

    Network-Compressive Coding for Wireless Sensors with Correlated Data

    A network-compressive transmission protocol is developed in which correlated sensor observations belonging to a finite alphabet are linearly combined as they traverse the network on their way to a sink node. Statistical dependencies are modeled using factor graphs. The sum-product algorithm is run under different modeling assumptions to estimate the...

    Provided By University of Minho

  • White Papers // Aug 2012

    Joint Back-Pressure Power Control and Interference Cancellation in Wireless Multi-Hop Networks

    Back-pressure routing and power control policies are well-appreciated for maximizing throughput in wireless multi-hop networks, where power control is used to manage interference in a way that ultimately optimizes throughput, a network-layer performance measure. In addition to transmitter power control, interference can be mitigated via selective receiver-side signal cancellation, provided...

    Provided By University of Minho

  • White Papers // Aug 2012

    Advances in Spectrum Sensing and Cross-Layer Design for Cognitive Radio Networks

    Spectrum sensing is the key task for Cognitive Radio (CR) networks with significant challenges that have attracted a flux of research and innovation in recent years. Various signal processing, learning and optimization techniques have been employed to tackle different aspects. In this paper, progresses made in this area are reviewed...

    Provided By University of Minho

  • White Papers // Jun 2012

    Methodically Modeling the Tor Network

    Live Tor network experiments are difficult due to Tor's distributed nature and the privacy requirements of its client base. Alternative experimentation approaches, such as simulation and emulation, must make choices about how to model various aspects of the Internet and Tor that are not possible or not desirable to duplicate...

    Provided By University of Minho

  • White Papers // Jun 2012

    GeoFeed: A Location-Aware News Feed System

    This paper presents the GeoFeed system; a location-aware news feed system that provides a new platform for its users to get spatially related message updates from either their friends or favorite news sources. GeoFeed distinguishes itself from all existing news feed systems in that it enables users to post message...

    Provided By University of Minho

  • White Papers // May 2012

    Precoder Design for Physical Layer Multicasting

    This paper studies the design of linear precoders via instantaneous rate maximization over a K-user multicast channel, wherein multiple antennas are present at the transmitter as well as at all the receivers. The authors first consider the scenario wherein the linear precoder can be any complex valued matrix subject to...

    Provided By University of Minho

  • White Papers // May 2012

    Collaboration in Social Network-Based Information Dissemination

    Connectivity and trust within social networks have been exploited to build applications on top of these networks, including information dissemination, Sybil defenses, and anonymous communication systems. In these networks, and for such applications, connectivity ensures good performance of applications while trust is assumed to always hold, so as collaboration and...

    Provided By University of Minho

  • White Papers // May 2012

    Reduced-Latency SC Polar Decoder Architectures

    Polar codes have become one of the most favorable capacity achieving Error Correction Codes (ECC) along with their simple encoding method. However, among the very few prior Successive Cancellation (SC) polar decoder designs, the required long code length makes the decoding latency high. In this paper, conventional decoding algorithm is...

    Provided By University of Minho

  • White Papers // Dec 2011

    SocialCloud: Using Social Networks for Building Distributed Computing Services

    In this paper, the authors investigate a new computing paradigm, called SocialCloud, in which computing nodes are governed by social ties driven from a bootstrapping trust possessing social graph. They investigate how this paradigm differs from existing computing paradigms, such as grid computing and the conventional cloud computing paradigms. They...

    Provided By University of Minho

  • White Papers // Nov 2011

    Efficient Similarity Search via Sparse Coding

    In this paper, the authors present a new indexing method using sparse coding for fast approximate Nearest Neighbors (NN) on high dimensional image data. To begin with the sparse code the data using a learned basis dictionary and an index of the dictionary's support set is next used to generate...

    Provided By University of Minho

  • White Papers // Nov 2011

    Mobilizing the Cloud: Enabling Multi-User Mobile Outsourcing in the Cloud

    Mobile devices, such as Smartphone's and tablets, are becoming the universal interface to online services and applications. However, such devices have limited computational power and battery life, which limits their ability to execute rich, resource-intensive applications. Mobile computation outsourcing to external resources has been proposed as a technique to alleviate...

    Provided By University of Minho

  • White Papers // Sep 2011

    Hybrid Cooperative Caching in a Mobile Environment

    Caching is a key technique for improving data access performance of mobile clients. The emergence of peer-to-peer communication technologies now brings to reality "Cooperative caching" in which mobile clients help one another in caching. They not only can retrieve data items from mobile support stations, but also from the cache...

    Provided By University of Minho

  • White Papers // Sep 2011

    Probabilistic Verifiers: Evaluating Constrained Nearest-Neighbor Queries Over Uncertain Data

    In applications like location-based services, sensor monitoring and biological databases, the values of the database items are inherently uncertain in nature. An important query for uncertain objects is the Probabilistic Nearest-Neighbor query (PNN), which computes the probability of each object for being the nearest neighbor of a query point. Evaluating...

    Provided By University of Minho

  • White Papers // Sep 2011

    Shadow: Running Tor in a Box for Accurate and Efficient Experimentation

    Tor is a large and popular overlay network providing both anonymity to its users and a platform for anonymous communication research. New design proposals and attacks on the system are challenging to test in the live network because of deployment issues and the risk of invading users' privacy, while alternative...

    Provided By University of Minho

  • White Papers // Aug 2011

    FAST: A Generic Framework for Flash-Aware Spatial Trees

    Spatial tree index structures are crucial components in spatial data management systems, designed with the implicit assumption that the underlying external memory storage is the conventional magnetic hard disk drives. This assumption is going to be invalid soon, as flash memory storage is increasingly adopted as the main storage media...

    Provided By University of Minho

  • White Papers // Jul 2011

    Strategic Interaction In Local Fiscal Policy: Evidence From Portuguese Municipalities

    This paper aims at testing the degree of interaction between Portuguese municipalities' expenditure levels by estimating a dynamic panel model, based on jurisdictional reaction functions. The analysis is performed for all 278 Portuguese mainland municipalities from 1986 to 2006, using alternative ways to measure neighbourhood. Results indicate that local governments'...

    Provided By University of Minho

  • White Papers // Jul 2011

    Wealth, Labour Income, Stock Returns And Government Bond Yields, And Financial Stress In The Euro Area

    The author shows that when the ratio of asset wealth to human wealth falls, investors become more exposed to idiosyncratic shocks and demand higher stock and government bond risk premia. The author finds that the residuals from the cointegrating vector among asset wealth and labour income, wy, predict both future...

    Provided By University of Minho

  • White Papers // Apr 2011

    A Correlation-Aware Data Placement Strategy for Key-Value Stores

    Key-value stores hold the unprecedented bulk of the data produced by applications such as social networks. Their scalability and availability requirements often outweigh sacrificing richer data and processing models, and even elementary data consistency. Moreover, existing key-value stores have only random or order based placement strategies. In this paper, the...

    Provided By University of Minho

  • White Papers // Mar 2011

    Consumption, Wealth, Stock And Government Bond Returns: International Evidence

    In this paper, the authors show, from the consumer's budget constraint, that the residuals of the trend relationship among consumption, aggregate wealth, and labour income should predict both stock returns and government bond yields. They use data for several OECD countries and find that when agents expect future stock returns...

    Provided By University of Minho

  • White Papers // Mar 2011

    PrefJoin: An Efficient Preference-Aware Join Operator

    Preference queries are essential to a wide spectrum of applications including multi-criteria decision-making tools and personalized databases. Unfortunately, most of the evaluation techniques for preference queries assume that the set of preferred attributes are stored in only one relation, waiving on a wide set of queries that include preference computations...

    Provided By University of Minho

  • White Papers // Dec 2010

    Testing as a Certification Approach

    For years, one of the main reasons to buy commercial software instead of adopting open-source applications was the, supposed, guarantee of quality. Unfortunately that was rarely true and, fortunately, open-source projects soon adopted some good practices in their code development that lead to better tested software and therefore higher quality...

    Provided By University of Minho

  • White Papers // Dec 2010

    GUI Inspection From Source Code Analysis

    Graphical User Interfaces (GUIs) are critical components of today's software. Given their increased relevance, correctness and usability of GUIs are becoming essential. This paper describes the latest results in the development of the tool to reverse engineer the GUI layer of interactive computing systems. The authors use static analysis techniques...

    Provided By University of Minho

  • White Papers // Apr 2011

    A Correlation-Aware Data Placement Strategy for Key-Value Stores

    Key-value stores hold the unprecedented bulk of the data produced by applications such as social networks. Their scalability and availability requirements often outweigh sacrificing richer data and processing models, and even elementary data consistency. Moreover, existing key-value stores have only random or order based placement strategies. In this paper, the...

    Provided By University of Minho

  • White Papers // May 2012

    Precoder Design for Physical Layer Multicasting

    This paper studies the design of linear precoders via instantaneous rate maximization over a K-user multicast channel, wherein multiple antennas are present at the transmitter as well as at all the receivers. The authors first consider the scenario wherein the linear precoder can be any complex valued matrix subject to...

    Provided By University of Minho

  • White Papers // May 2012

    Collaboration in Social Network-Based Information Dissemination

    Connectivity and trust within social networks have been exploited to build applications on top of these networks, including information dissemination, Sybil defenses, and anonymous communication systems. In these networks, and for such applications, connectivity ensures good performance of applications while trust is assumed to always hold, so as collaboration and...

    Provided By University of Minho

  • White Papers // May 2012

    Reduced-Latency SC Polar Decoder Architectures

    Polar codes have become one of the most favorable capacity achieving Error Correction Codes (ECC) along with their simple encoding method. However, among the very few prior Successive Cancellation (SC) polar decoder designs, the required long code length makes the decoding latency high. In this paper, conventional decoding algorithm is...

    Provided By University of Minho

  • White Papers // Apr 2010

    Database Security: A Historical Perspective

    The importance of security in database research has greatly increased over the years as most of critical functionality of the business and military enterprises became digitized. Database is an integral part of any information system and they often hold sensitive data. The security of the data depends on physical security,...

    Provided By University of Minho

  • White Papers // Aug 2012

    Joint Back-Pressure Power Control and Interference Cancellation in Wireless Multi-Hop Networks

    Back-pressure routing and power control policies are well-appreciated for maximizing throughput in wireless multi-hop networks, where power control is used to manage interference in a way that ultimately optimizes throughput, a network-layer performance measure. In addition to transmitter power control, interference can be mitigated via selective receiver-side signal cancellation, provided...

    Provided By University of Minho

  • White Papers // Sep 2009

    Motion Segmentation by SCC on the Hopkins 155 Database

    The authors apply the Spectral Curvature Clustering (SCC) algorithm to a benchmark database of 155 motion sequences, and show that it outperforms all other state-of-the-art methods. The average misclassification rate by SCC is 1.41% for sequences having two motions and 4.85% for three motions. Multiframe motion segmentation is a very...

    Provided By University of Minho

  • White Papers // Sep 2012

    Network-Compressive Coding for Wireless Sensors with Correlated Data

    A network-compressive transmission protocol is developed in which correlated sensor observations belonging to a finite alphabet are linearly combined as they traverse the network on their way to a sink node. Statistical dependencies are modeled using factor graphs. The sum-product algorithm is run under different modeling assumptions to estimate the...

    Provided By University of Minho

  • White Papers // Nov 2012

    A Feature Combination Approach for the Detection of Early Morning Bathroom Activities with Wireless Sensors

    In this paper the authors investigate the use of wearable accelerometers and wireless home sensors for the detection of early morning daily activities. In particular they focus on the detection of brushing, washing face and shaving activities by using a wireless accelerometer sensor attached to the right wrist of subjects...

    Provided By University of Minho

  • White Papers // Jun 2012

    Methodically Modeling the Tor Network

    Live Tor network experiments are difficult due to Tor's distributed nature and the privacy requirements of its client base. Alternative experimentation approaches, such as simulation and emulation, must make choices about how to model various aspects of the Internet and Tor that are not possible or not desirable to duplicate...

    Provided By University of Minho

  • White Papers // Jan 2013

    Spatial Cloaking for Anonymous Location-Based Services in Mobile Peer-to-Peer Environments

    In this paper, the authors tackle a privacy breach in current Location-Based Services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. For example, a user who wants to issue a query asking about her nearest gas...

    Provided By University of Minho

  • White Papers // Jun 2012

    GeoFeed: A Location-Aware News Feed System

    This paper presents the GeoFeed system; a location-aware news feed system that provides a new platform for its users to get spatially related message updates from either their friends or favorite news sources. GeoFeed distinguishes itself from all existing news feed systems in that it enables users to post message...

    Provided By University of Minho

  • White Papers // Sep 2009

    Approximate Evaluation of Range Nearest Neighbor Queries with Quality Guarantee

    The range Nearest-Neighbor (NN) query is an important query type in location-based services, as it can be applied to the case that an NN query has a spatial region, instead of a location point, as the query location. Examples of the applications of range NN queries include uncertain locations and...

    Provided By University of Minho

  • White Papers // Sep 2011

    Probabilistic Verifiers: Evaluating Constrained Nearest-Neighbor Queries Over Uncertain Data

    In applications like location-based services, sensor monitoring and biological databases, the values of the database items are inherently uncertain in nature. An important query for uncertain objects is the Probabilistic Nearest-Neighbor query (PNN), which computes the probability of each object for being the nearest neighbor of a query point. Evaluating...

    Provided By University of Minho

  • White Papers // Sep 2011

    Hybrid Cooperative Caching in a Mobile Environment

    Caching is a key technique for improving data access performance of mobile clients. The emergence of peer-to-peer communication technologies now brings to reality "Cooperative caching" in which mobile clients help one another in caching. They not only can retrieve data items from mobile support stations, but also from the cache...

    Provided By University of Minho

  • White Papers // Nov 2012

    Application of Geomorphological Data Layers to Landslide Susceptibility Mapping with Analytical Hierarchical Process and GIS Techniques (Case Study: Zonouz Plain, East Azerbaijan, Iran)

    Without a doubt, landslide is one of the most disastrous natural hazards. Therefore, landslide susceptibility maps in regional scale are useful guide for future development activities. In this paper, the Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) were used to produce landslide susceptibility map of the Zonouz Plain...

    Provided By University of Minho

  • White Papers // Jun 2009

    Asymptotically Optimal Policies for Hard-Deadline Scheduling Over Fading Channels

    A hard-deadline, opportunistic scheduling problem in which B bits must be transmitted within T time-slots over a time-varying channel is studied: the transmitter must decide how many bits to serve in each slot based on knowledge of the current channel but without knowledge of the channel in future slots, with...

    Provided By University of Minho

  • White Papers // Apr 2009

    Optimized Training and Feedback for MIMO Downlink Channels

    The authors consider a MIMO fading broadcast channel where channel state information is acquired at user terminals via downlink training and channel feedback is used to provide transmitter Channel State InformaTion (CSIT) to the base station. The feedback channel (the corresponding uplink) is modeled as an AWGN channel, orthogonal across...

    Provided By University of Minho

  • White Papers // Mar 2009

    Transmission Capacity of Wireless Ad Hoc Networks: Successive Interference Cancellation Vs. Joint Detection

    The performance benefits of two interference cancellation methods, Successive Interference Cancellation (SIC) and Joint Detection (JD), in wireless ad hoc networks are compared within the transmission capacity framework. SIC involves successively decoding and subtracting out strong interfering signals until the desired signal can be decoded, while higher-complexity JD refers to...

    Provided By University of Minho

  • White Papers // Feb 2009

    Delay Constrained Scheduling Over Fading Channels: Optimal Policies for Monomial Energy-Cost Functions

    A point-to-point discrete-time scheduling problem of transmitting B information bits within T hard delay deadline slots is considered assuming that the underlying energy-bit cost function is a convex monomial. The scheduling objective is to minimize the expected energy expenditure while satisfying the deadline constraint based on information about the unserved...

    Provided By University of Minho

  • White Papers // Jul 2009

    De-Hyping Transmit Diversity in Modern MIMO Cellular Systems

    A contemporary perspective on the tradeoff between transmit antenna diversity and spatial multiplexing is provided. It is argued that, in the context of modern cellular systems and for the operating points of interest, transmission techniques that utilize all available spatial degrees of freedom for multiplexing outperform techniques that explicitly sacrifice...

    Provided By University of Minho

  • White Papers // Dec 2009

    Training and Feedback Optimization for Multiuser MIMO Downlink

    The authors consider a MIMO fading broadcast channel where the fading channel coefficients are constant over time-frequency blocks that span a coherent time ? a coherence bandwidth. In closed-loop systems, Channel State Information at Transmitter (CSIT) is acquired by the downlink training sent by the base station and an explicit...

    Provided By University of Minho

  • White Papers // Apr 2009

    What Is the Value of Joint Processing of Pilots and Data in Block-Fading Channels?

    The spectral efficiency achievable with joint processing of pilot and data symbol observations is compared with that achievable through the conventional (separate) approach of first estimating the channel on the basis of the pilot symbols alone, and subsequently detecting the data symbols. Studied on the basis of a mutual information...

    Provided By University of Minho

  • White Papers // Sep 2010

    On Achievable Rates of the Two-User Symmetric Gaussian Interference Channel

    The authors study the Han-Kobayashi (HK) achievable sum rate for the two-user symmetric Gaussian interference channel. They find the optimal power split ratio between the common and private messages (assuming no time-sharing), and derive a closed form expression for the corresponding sum rate. This provides a finer understanding of the...

    Provided By University of Minho

  • White Papers // Oct 2009

    Efficient Cooperative Spectrum Sensing in Cognitive Radio

    In this paper, the authors present a new cooperative spectrum sensing scheme, which allocates two separate short periods for sensing and cooperation to achieve high capability of detecting the Primary User (PU) with low interference. A mathematical model is built to derive a closed formulation of the detection probability of...

    Provided By University of Minho

  • White Papers // Aug 2010

    Identifying Suspicious Activities Through DNS Failure Graph Analysis

    As a key approach to securing large networks, existing anomaly detection techniques focus primarily on network traffic data. However, the sheer volume of such data often renders detailed analysis very expensive and reduces the effectiveness of these tools. In this paper, the authors propose a light-weight anomaly detection approach based...

    Provided By University of Minho

  • White Papers // Aug 2012

    Advances in Spectrum Sensing and Cross-Layer Design for Cognitive Radio Networks

    Spectrum sensing is the key task for Cognitive Radio (CR) networks with significant challenges that have attracted a flux of research and innovation in recent years. Various signal processing, learning and optimization techniques have been employed to tackle different aspects. In this paper, progresses made in this area are reviewed...

    Provided By University of Minho

  • White Papers // Jul 2009

    Capi: Cloud Computing API

    Cloud Computing is an emerging business model to provide access to IT resources in a pay per use fashion. Those resources range from low-level virtual machines, passing by application platforms and ending in ready to use software delivered through the Internet, creating a layered stack of differentiated services. Different cloud...

    Provided By University of Minho

  • White Papers // Mar 2009

    RFID and Wireless Sensing

    Off late, the demand of markets to use active transponders, is reaching a saturation point. The main reason is because these ones get its power from batteries, which must be periodically replaced or recharged. This increases the final costs (maintenance + management), but contrarily to the passive transponders, theirs advantage...

    Provided By University of Minho

  • White Papers // Sep 2009

    Wireless Communications and Mobile Computing

    The main objective of this course is to provide the students with the competences required for understanding and using the communications component of an universal communications environment. Students will be provided, in particular, with the knowledge required to understand emerging communications networks, their computational demands, the classes of distributed services...

    Provided By University of Minho

  • White Papers // Jun 2009

    Discovery-Based Edit Assistance for Spreadsheets

    Spreadsheets can be viewed as a highly flexible end-users programming environment which enjoys wide-spread adoption. But spreadsheets lack many of the structured programming concepts of regular programming paradigms. In particular, the lack of data structures in spreadsheets may lead spreadsheet users to cause redundancy, loss, or corruption of data during...

    Provided By University of Minho

  • White Papers // May 2010

    Processing XML: A Rewriting System Approach

    Nowadays XML processing is performed using one of two approaches: using the SAX (Simple API for XML) or using the DOM (Document Object Model). While these two approaches are adequate for most cases there are situations where other approaches can make the solution easier to write, read and, therefore, to...

    Provided By University of Minho

  • White Papers // Jul 2010

    Exchange Rates, Employment And Labour Market

    There is increasing evidence that the interaction between shocks and labour market institutions is crucial to understanding the dynamics of employment. In this paper, the authors show that the inclusion of labour adjustment costs in a trade model affects the impact of exchange rate movements on employment. They also explore...

    Provided By University of Minho

  • White Papers // Mar 2010

    Odour User Interface for Authentication: Possibility and Acceptance: Case Study

    Historically, some new technologies are faced with rejection or acceptance. So researchers developed TAM (Technology Acceptance Model). TAM depends upon the user perception of the easiness and benefits. Authentication plays an important role in everyone's lives as everyone uses it every day. Odour, as a biometric technique, has some important...

    Provided By University of Minho

  • White Papers // Apr 2010

    Collateralizable Wealth, Asset Returns, And Systemic Risk: International Evidence

    I assess the role of wealth and systemic risk in explaining future asset returns. The author shows that the residuals of the trend relationship among asset wealth and human wealth predict both stock returns and government bond yields. Using data for a set of industrialized countries, the author finds that...

    Provided By University of Minho

  • White Papers // Mar 2011

    Consumption, Wealth, Stock And Government Bond Returns: International Evidence

    In this paper, the authors show, from the consumer's budget constraint, that the residuals of the trend relationship among consumption, aggregate wealth, and labour income should predict both stock returns and government bond yields. They use data for several OECD countries and find that when agents expect future stock returns...

    Provided By University of Minho

  • White Papers // Feb 2009

    Wealth Effects In Emerging Market Economies

    The authors build a panel of 14 emerging economies to estimate the magnitude of housing, stock market, and money wealth effects on consumption. Using modern panel data econometric techniques and quarterly data for the period 1990:1-2008:2, they show that: wealth effects are statistically significant and relatively large in magnitude; housing...

    Provided By University of Minho

  • White Papers // Sep 2010

    Fiscal Policy And Asset Prices

    The authors assess the role played by fiscal policy in explaining the dynamics of asset markets. Using a panel of ten industrialized countries, they show that a positive fiscal shock has a negative impact in both stock and housing prices. However, while stock prices immediately adjust to the shock and...

    Provided By University of Minho