McGill University

Displaying 1-40 of 123 results

  • White Papers // Feb 2014

    Associative Memories Based on Multiple-Valued Sparse Clustered Networks

    Associative memories are structures that store data patterns and retrieve them given partial inputs. Sparse Clustered Networks (SCNs) are recently-introduced binary-weighted associative memories that significantly improve the storage and retrieval capabilities over the prior state-of-the art. However, deleting or updating the data patterns result in a significant increase in the...

    Provided By McGill University

  • White Papers // Oct 2013

    Improving Sparse Associative Memories by Escaping from Bogus Fixed Points

    Associative memories are different from conventional memory systems in that they do not require explicit addresses to the information the authors are interested in. They store paired patterns. When an associative memory is given an input pattern as the probe, the content of the input itself addresses the paired output...

    Provided By McGill University

  • White Papers // Oct 2013

    A Massively Parallel Associative Memory Based on Sparse Neural Networks

    Associative memories store content in such a way that the content can be later retrieved by presenting the memory with a small portion of the content, rather than presenting the memory with an address as in more traditional memories. Associative memories are used as building blocks for algorithms within database...

    Provided By McGill University

  • White Papers // Oct 2012

    Bayesian Quantized Network Coding Via Belief Propagation

    In this paper, the authors propose an alternative for routing based packet forwarding, which uses network coding to increase transmission efficiency, in terms of both compression and error resilience. This non-adaptive encoding is called quantized network coding, which involves random linear mapping in the real field, followed by quantization to...

    Provided By McGill University

  • White Papers // Aug 2012

    Classical Codes for Quantum Broadcast Channels

    The authors discuss two techniques for transmitting classical information over quantum broadcast channels. The first technique is a quantum generalization of the superposition coding scheme for the classical broadcast channel. They use a quantum simultaneous non-unique decoder and obtain a simpler proof of the rate region recently published by Yard...

    Provided By McGill University

  • White Papers // Aug 2012

    Joint Utility Maximization in Two-Tier Networks by Distributed Pareto-Optimal Power Control

    This paper addresses the critical problem of interference management in two-tier networks, where the newly-deployed Femtocell UsErs (FUEs) operate in the licensed spectrum owned by the existing macrocell. A Pareto-optimal power-control algorithm is devised that jointly maximizes the utilities of both macrocell and femtocell networks while robustly guaranteeing the macrocell's...

    Provided By McGill University

  • White Papers // Jun 2012

    An Analysis of ZVP-Attack on ECC Cryptosystems

    Elliptic Curve Cryptography (ECC) is an efficient public cryptosystem with a short key size. For this reason it is suitable for implementing on memory-constraint devices such as smart cards, mobile devices, etc. However, these devices leak information about their private key through side channels (power consumption, electromagnetic radiation and timing,...

    Provided By McGill University

  • White Papers // May 2012

    On the Benefits of Non-Uniform Signaling in Chip-Asynchronous CDMA

    This paper explores chip-asynchronous CDMA transmission when single-user demodulation and decoding are used at the receiver. First, a chip-level channel model is presented to account for chip-asynchronism between different users. Using the model, the symmetric capacity of chip-asynchronous CDMA is investigated. Numerical results indicate that a sum rate of 2...

    Provided By McGill University

  • White Papers // May 2012

    Cascaded Doubly-Selective Channel Estimation in Multi-Relay AF OFDM Transmissions

    This paper studies the problem of channel estimation in Amplify-and-Forward (AF) multi-relay transmissions over time- and frequency-selective (doubly selective) channels. To avoid two separate channel estimation processes of source-to-relay and relay-to-destination links, a cascaded doubly selective channel model is formulated to characterize the Source-to-Relay-to-Destination (SRD) channel. Time-varying SRD channel gains...

    Provided By McGill University

  • White Papers // May 2012

    Impulse Noise Detection Techniques for Retransmission to Reduce Delay in DSL Systems

    To protect Digital Subscriber Loop (DSL) systems against Impulse Noise (IN), interleaving combined with Reed-Solomon (RS) coding has been used. Nevertheless, interleaving introduces a long delay. This paper considers retransmission instead of interleaving to reduce such delay and proposes an approach using the available RS decoding failure status to trigger...

    Provided By McGill University

  • White Papers // May 2012

    Efficient Erasure Marking Technique for Interleaving Delay Reduction in DSL Systems Impaired by Impulse Noise

    Reed-Solomon (RS) coding and interleaving are usually combined to protect Digital Subscriber Line (DSL) systems against Impulse Noise (IN) but introducing a long delay. It is proved that interleaving delay can be significantly reduced by Error and Erasure Decoding (EED). This paper proposes an erasure marking technique to enhance the...

    Provided By McGill University

  • White Papers // May 2012

    On Optimal Input Distribution and Capacity Limit of Bernoulli-Gaussian Impulsive Noise Channels

    In this paper, the authors rigorously analyze the optimal input distribution and capacity of an additive Bernoulli-Gaussian (BG) Impulsive Noise (IN) channel in high and low input power regimes. First, they obtain an input distribution for which the channel output is Gaussian distributed. This distribution, if valid, shall result in...

    Provided By McGill University

  • White Papers // May 2012

    Joint Estimation of Time of Arrival and Channel Power Delay Profile for Pulse-Based UWB Systems

    Sub-Nyquist Maximum Likelihood (ML)-based Time Of Arrival (TOA) estimation methods for Ultra-WideBand (UWB) signals normally assume a priori knowledge of the UWB channel in the form of the Average Power Delay Profile (APDP). In practice however, and despite its importance, the APDP is not always available. To address this issue,...

    Provided By McGill University

  • White Papers // May 2012

    Optimal Power Adaption for NAF Relaying With Channel Side Information

    In this paper, the authors develop optimal power adaptation schemes by means of power amplification coefficients at the relay for the half-duplex single-relay Non-orthogonal Amplify-and-Forward (NAF) system with Channel Side Information (CSI) available at the relay. In particular, assuming that the relay has full knowledge of the channel gains, optimal...

    Provided By McGill University

  • White Papers // May 2012

    EM-Based Joint Estimation and Detection for Multiple Antenna Cognitive Radios

    In this paper, the authors present an iterative spectrum sensing scheme for multiantenna assisted Cognitive Radio (CR) using the Expectation-Maximization (EM) algorithm. Considering a wideband frequency spectrum, the Secondary User (SU) performs an EM-based Joint Estimation and Detection (JED), where the channel coefficients and noise variance are estimated jointly with...

    Provided By McGill University

  • White Papers // May 2012

    Capacity Limit of Static Single-Relay Amplify-and-Forward Channels

    In this paper, the authors establish in closed-form the capacity and characterize the optimal input covariance matrix at the source and the optimal power allocation scheme between source and relay for a half-duplex single-relay Amplify-and-Forward (AF) system with static channel gains. Different from Multiple-Input Multiple-Output (MIMO) systems, the channel matrix...

    Provided By McGill University

  • White Papers // May 2012

    Optimal Distributed Coding Schemes for Energy Efficiency in the Fading Relay Channel

    The authors propose three energy-optimal distributed schemes for the half-duplex relay channel with block fading to maintain a desired source rate. They consider both network energy consumption and consumption of the relay alone, assuming only local channel knowledge. Then, they combine both into a generalized distributed energy-efficient scheme. In these...

    Provided By McGill University

  • White Papers // May 2012

    Partial Decode-Forward Coding Schemes for the Gaussian Two-Way Relay Channel

    The authors design novel Partial Decode-Forward (PDF) schemes for the Gaussian two-way relay channel with direct link. Different from pure decode-forward, each user divides its message into two parts and the relay decodes only one part of each. The relay then generates its codeword as a function of the two...

    Provided By McGill University

  • White Papers // May 2012

    Heterogeneous Space Switches for Power-Efficient Optical Interconnection Networks

    Space switches are the fundamental elements in single plane and multi-plane optical interconnection networks. This paper proposes a heterogeneous implementation of optical space switches based on two gating elements, amplifiers such as Semiconductor Optical Amplifier (SOA) and modulators such as Mach-Zehnder modulators. The heterogeneous implementation has the advantage of being...

    Provided By McGill University

  • White Papers // May 2012

    Topology-Aware VM Migration in Bandwidth Oversubscribed Datacenter Networks

    Virtualization can deliver significant benefits for cloud computing by enabling VM migration to improve utilization, balance load and alleviate hotspots. While several mechanisms exist to migrate VMs, few efforts have focused on optimizing migration policies in a multi-rooted tree datacenter network. The general problem has multiple facets, two of which...

    Provided By McGill University

  • White Papers // Apr 2012

    Asking and Answering Questions About Unfamiliar APIs: An Exploratory Study

    The increasing size of APIs and the increase in the number of APIs available imply developers must frequently learn how to use unfamiliar APIs. To identify the types of questions developers want answered when working with unfamiliar APIs and to understand the difficulty they may encounter answering those questions, the...

    Provided By McGill University

  • White Papers // Mar 2012

    Recovering Traceability Links Between an API and Its Learning Resources

    Large frameworks and libraries require extensive developer learning resources, such as documentation and mailing lists, to be useful. Maintaining these learning resources is challenging partly because they are not explicitly linked to the frameworks' API, and changes in the API are not reflected in the learning resources. Automatically recovering traceability...

    Provided By McGill University

  • White Papers // Mar 2012

    Restricted Isometry Property in Quantized Network Coding of Sparse Messages

    Efficient data gathering in sensor networks has been the topic of many research projects where different applications have been considered. One of the concerns in data gathering is to take care of inter-node redundancy during the transmission. When the knowledge of inter-node dependency is known at the encoders (i.e., sensor...

    Provided By McGill University

  • White Papers // Mar 2012

    Learning-Based Opportunistic Spectrum Access With Hopping Transmission Strategy

    This paper considers opportunistic spectrum access for Secondary Users (SUs) from an adaptive learning perspective. A SU dynamically hops over multiple idle frequency-slots of a licensed frequency band, each with an adaptive activity factor. Aiming to determine the optimal activity factors of SUs, an algorithm is developed, in which each...

    Provided By McGill University

  • White Papers // Mar 2012

    Sum-Rate Maximization in the Multicell MIMO Multiple-Access Channel With Interference Coordination

    This paper is concerned with the maximization of the weighted sum-rate in the multicell MIMO Multiple Access Channel (MAC). Considered is the multicell network operating on the same frequency channel with multiple Mobile Stations (MS) per cell. Assuming the interference coordination mode in the multicell network, each Base-Station (BS) only...

    Provided By McGill University

  • White Papers // Mar 2012

    Rate Maximization for Half-Duplex Multiple Access With Cooperating Transmitters

    The authors derive the optimal power allocation of a practical half-duplex scheme for the Multiple Access Channel with Transmitter Co-operation (MAC-TC). The system consists of two users in half-duplex mode communicating with one destination over a complex channel with additive white Gaussian noise. The transmission scheme is performed over 3...

    Provided By McGill University

  • White Papers // Jan 2012

    Temporal Analysis of API Usage Concepts

    Software reuse through Application Programming Interfaces (APIs) is an integral part of software development. The functionality offered by an API is not always accessed uniformly throughout the lifetime of a client program. The authors propose Temporal API Usage Pattern Mining to detect API usage patterns in terms of their time...

    Provided By McGill University

  • White Papers // Jan 2012

    Analyzing Temporal API Usage Patterns

    Software reuse through Application Programming Interfaces (APIs) is an integral part of software development. As developers write client programs, their understanding and usage of APIs change over time. Can the people learn from long-term changes in how developers work with APIs in the lifetime of a client program? The authors...

    Provided By McGill University

  • White Papers // Jan 2012

    Proof Pearl: The Power of Higher-Order Encodings in the Logical Framework LF

    In this proof pearl, the authors demonstrate the power of higher-order encodings in the logical framework Twelf[PS99] by investigating proofs about an algorithmic specification of bounded subtype polymorphism, a problem from the POPLmark challenge [ABF+05]. Their encoding and representation of the problem plays to the strengths of the logical framework...

    Provided By McGill University

  • White Papers // Dec 2011

    Partial Decode-Forward Binning Schemes for the Causal Cognitive Relay Channels

    The causal Cognitive Relay Channel (CRC) has two sender-receiver pairs, in which the second sender obtains information from the first sender causally and assists the transmission of both senders. In this paper, the authors study both the full- and half-duplex modes. In each mode, they propose two new coding schemes...

    Provided By McGill University

  • White Papers // Nov 2011

    Dynamic Control of Electricity Cost With Power Demand Smoothing and Peak Shaving for Distributed Internet Data Centers

    Internet based service providers, such as Amazon, Google, Yahoo, etc, build their Data Centers (IDC) across multiple regions to provide reliable and low latency of services to clients. Ever-increasing service demand, complexity of services and growing client population cause enormous power consumptions by these IDCs incuring a major part of...

    Provided By McGill University

  • White Papers // Nov 2011

    On Compress-Forward Without Wyner-Ziv Binning for Relay Networks

    Noisy network coding is recently proposed for the general multi-source network by Lim, Kim, El Gamal and Chung. This scheme builds on Compress-Forward (CF) relaying but involves three new ideas, namely no Wyner-Ziv binning, relaxed simultaneous decoding and message repetition. In this paper, using the two-way relay channel as the...

    Provided By McGill University

  • White Papers // Oct 2011

    Compress-Forward Without Wyner-Ziv Binning for the One-Way and Two-Way Relay Channels

    The authors consider the role of Wyner-Ziv binning in compress-forward for relay channels. In the one-way relay channel, they analyze a compress-forward scheme without Wyner-Ziv binning but with joint decoding of both the message and compression index. It achieves the same rate as the original compress-forward scheme with binning and...

    Provided By McGill University

  • White Papers // Oct 2011

    Distributed Dual Averaging for Convex Optimization Under Communication Delays

    In this paper, the authors extend and analyze the distributed dual averaging algorithm. They employ the fixed delay model introduced in and show that distributed dual averaging still converges in the presence of finite and fixed communication delays. In addition, using a different bounding technique than, for a fixed network...

    Provided By McGill University

  • White Papers // Sep 2011

    Approximating Signals Supported on Graphs

    In this paper, the authors investigate the notion of smoothness for signals supported on the vertices of a graph. They provide theoretical explanations when and why the Laplacian eigenbasis can be regarded as a meaningful "Fourier" transform of such signals. Moreover, they analyze the desired properties of the underlying graphs...

    Provided By McGill University

  • White Papers // Sep 2011

    Graph Spectral Compressed Sensing for Sensor Networks

    For many Wireless Sensor Network (WSN) applications, the signals measured are likely to be correlated either spatially or temporally; i.e., the authors can find an appropriate transform domain where the signals are compressible. WSNs are characterized by having simple battery-powered wireless nodes with limited energy and communication resources. In order...

    Provided By McGill University

  • White Papers // Sep 2011

    High-Level Design of Integrated Microsystems - Arithmetic Perspective

    Cyber-physical systems are characterized by tighter integration of embedded computer systems and the physical sensing and actuating devices. Integration of physical sensing and actuating interfaces into embedded systems presents a new set of high-level design and synthesis challenges. An important aspect of such integration is the explicit use of numerical...

    Provided By McGill University

  • White Papers // Aug 2011

    A Half-Duplex Relay Coding Scheme Optimized for Energy Efficiency

    The authors explore the issue of the network energy efficiency in relay channels. They first propose a half-duplex decode-forward coding scheme. They, then optimize the power allocation to minimize the total power consumption while maintaining a desired source rate. They show that this scheme significantly outperforms direct and two-hop transmissions....

    Provided By McGill University

  • White Papers // Aug 2011

    Decode-Forward and Compute-Forward Coding Schemes for the Two-Way Relay Channel

    The authors consider the full-duplex two-way relay channel with direct link between two users and propose two coding schemes: a partial decode-forward scheme, and a combined decode-forward and compute-forward scheme. Both schemes use rate-splitting and superposition coding at each user and generate code words for each node independently. When applied...

    Provided By McGill University

  • White Papers // Aug 2011

    Energy Minimization for the Half-Duplex Relay Channel With Decode-Forward Relaying

    The authors analyze coding for energy efficiency in the relay channel for a fixed source rate. They propose a comprehensive half-duplex decode-forward coding scheme and three optimal sets of power allocation, which respectively minimize the network, the relay and the source energy consumption. Analysis shows that minimizing the network energy...

    Provided By McGill University

  • White Papers // May 2012

    On the Benefits of Non-Uniform Signaling in Chip-Asynchronous CDMA

    This paper explores chip-asynchronous CDMA transmission when single-user demodulation and decoding are used at the receiver. First, a chip-level channel model is presented to account for chip-asynchronism between different users. Using the model, the symmetric capacity of chip-asynchronous CDMA is investigated. Numerical results indicate that a sum rate of 2...

    Provided By McGill University

  • White Papers // May 2012

    Cascaded Doubly-Selective Channel Estimation in Multi-Relay AF OFDM Transmissions

    This paper studies the problem of channel estimation in Amplify-and-Forward (AF) multi-relay transmissions over time- and frequency-selective (doubly selective) channels. To avoid two separate channel estimation processes of source-to-relay and relay-to-destination links, a cascaded doubly selective channel model is formulated to characterize the Source-to-Relay-to-Destination (SRD) channel. Time-varying SRD channel gains...

    Provided By McGill University

  • White Papers // May 2012

    Impulse Noise Detection Techniques for Retransmission to Reduce Delay in DSL Systems

    To protect Digital Subscriber Loop (DSL) systems against Impulse Noise (IN), interleaving combined with Reed-Solomon (RS) coding has been used. Nevertheless, interleaving introduces a long delay. This paper considers retransmission instead of interleaving to reduce such delay and proposes an approach using the available RS decoding failure status to trigger...

    Provided By McGill University

  • White Papers // May 2012

    Efficient Erasure Marking Technique for Interleaving Delay Reduction in DSL Systems Impaired by Impulse Noise

    Reed-Solomon (RS) coding and interleaving are usually combined to protect Digital Subscriber Line (DSL) systems against Impulse Noise (IN) but introducing a long delay. It is proved that interleaving delay can be significantly reduced by Error and Erasure Decoding (EED). This paper proposes an erasure marking technique to enhance the...

    Provided By McGill University

  • White Papers // May 2012

    On Optimal Input Distribution and Capacity Limit of Bernoulli-Gaussian Impulsive Noise Channels

    In this paper, the authors rigorously analyze the optimal input distribution and capacity of an additive Bernoulli-Gaussian (BG) Impulsive Noise (IN) channel in high and low input power regimes. First, they obtain an input distribution for which the channel output is Gaussian distributed. This distribution, if valid, shall result in...

    Provided By McGill University

  • White Papers // Mar 2012

    Learning-Based Opportunistic Spectrum Access With Hopping Transmission Strategy

    This paper considers opportunistic spectrum access for Secondary Users (SUs) from an adaptive learning perspective. A SU dynamically hops over multiple idle frequency-slots of a licensed frequency band, each with an adaptive activity factor. Aiming to determine the optimal activity factors of SUs, an algorithm is developed, in which each...

    Provided By McGill University

  • White Papers // Mar 2012

    Sum-Rate Maximization in the Multicell MIMO Multiple-Access Channel With Interference Coordination

    This paper is concerned with the maximization of the weighted sum-rate in the multicell MIMO Multiple Access Channel (MAC). Considered is the multicell network operating on the same frequency channel with multiple Mobile Stations (MS) per cell. Assuming the interference coordination mode in the multicell network, each Base-Station (BS) only...

    Provided By McGill University

  • White Papers // Dec 2008

    Turbo Processing for Joint Channel Estimation, Synchronization, and Decoding in Coded MIMO-OFDM Systems

    This paper proposes a turbo joint channel estimation, synchronization, and decoding scheme for coded Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems. The effects of Carrier Frequency Offset (CFO), Sampling Frequency Offset (SFO), and Channel Impulse Responses (CIRs) on the received samples are analyzed and explored to develop the turbo...

    Provided By McGill University

  • White Papers // Apr 2011

    Efficient Delay-Tolerant Particle Filtering

    This paper proposes a novel framework for delay-tolerant particle filtering that is computationally efficient and has limited memory requirements. Within this framework the informativeness of a delayed (Out-Of-Sequence) Measurement (OOSM) is estimated using a lightweight procedure and uninformative measurements are immediately discarded. The framework requires the identification of a threshold...

    Provided By McGill University

  • White Papers // Oct 2010

    Distributed Auxiliary Particle Filters Using Selective Gossip

    This paper introduces a distributed auxiliary particle filter for target tracking in sensor networks. Nodes maintain a shared particle filter by coming to a consensus about the likelihoods associated with each particle using the selective gossip procedure. Selective gossip provides a mechanism to efficiently identify the particles with largest weights...

    Provided By McGill University

  • White Papers // Oct 2009

    Optimization and Analysis of Distributed Averaging With Memory

    This paper analyzes the rate of convergence of a distributed averaging scheme making use of memory at each node. In conventional distributed averaging, each node computes an update based on its current state and the current states of their neighbours. Previous work observed the trajectories at each node converge smoothly...

    Provided By McGill University

  • White Papers // Sep 2008

    Accelerated Distributed Average Consensus Via Localized Node State Prediction

    This paper proposes an approach to accelerate local, linear iterative network algorithms asymptotically achieving distributed average consensus. The authors focus on the class of algorithms in which each node initializes its "State value" to the local measurement and then at each iteration of the algorithm, updates this state value by...

    Provided By McGill University

  • White Papers // Aug 2009

    Service Overlay Network Design With Reliability Constraints

    The authors studied a class of Service Overlay Network (SON) design problem with reliability constraints. It is assumed that a SON network could enter an inadmissible status for two reasons; first when there is insufficient resource to accommodate new connections, second when some hardware devices malfunction. The design problem is...

    Provided By McGill University

  • White Papers // May 2009

    The Pricing of the Grade of Service Guarantees in the Service Overlay Networks

    The authors studied a class of Service Overlay Network (SON) capacity allocation problem. By analyzing the problem with two different nonlinear optimization formulations, they show that the prices of offering service guarantees are closely related to a set of Lagrange multipliers. Moreover, if the Grade of Service (GoS) constraints are...

    Provided By McGill University

  • White Papers // Apr 2009

    Maximum Profit Vs Minimum Cost in Service Overlay Network Design

    The authors studied a class of Service Overlay Network (SON) capacity allocation problem with Grade of Service (GoS) constraints. The problem can be formulated as either a Maximum Profit (MP) optimization problem or a Minimum Cost (MC) optimization problem. In this paper, the authors investigate the relationship between the MP...

    Provided By McGill University

  • White Papers // Mar 2012

    Recovering Traceability Links Between an API and Its Learning Resources

    Large frameworks and libraries require extensive developer learning resources, such as documentation and mailing lists, to be useful. Maintaining these learning resources is challenging partly because they are not explicitly linked to the frameworks' API, and changes in the API are not reflected in the learning resources. Automatically recovering traceability...

    Provided By McGill University

  • White Papers // Apr 2012

    Asking and Answering Questions About Unfamiliar APIs: An Exploratory Study

    The increasing size of APIs and the increase in the number of APIs available imply developers must frequently learn how to use unfamiliar APIs. To identify the types of questions developers want answered when working with unfamiliar APIs and to understand the difficulty they may encounter answering those questions, the...

    Provided By McGill University

  • White Papers // Jan 2012

    Temporal Analysis of API Usage Concepts

    Software reuse through Application Programming Interfaces (APIs) is an integral part of software development. The functionality offered by an API is not always accessed uniformly throughout the lifetime of a client program. The authors propose Temporal API Usage Pattern Mining to detect API usage patterns in terms of their time...

    Provided By McGill University

  • White Papers // Apr 2011

    Using Structure-Based Recommendations to Facilitate Discoverability in APIs

    Empirical evidence indicates that developers face significant hurdles when the API elements necessary to implement a task are not accessible from the types they are working with. The authors propose an approach that leverages the structural relationships between API elements to make API methods or types not accessible from a...

    Provided By McGill University

  • White Papers // Jan 2012

    Analyzing Temporal API Usage Patterns

    Software reuse through Application Programming Interfaces (APIs) is an integral part of software development. As developers write client programs, their understanding and usage of APIs change over time. Can the people learn from long-term changes in how developers work with APIs in the lifetime of a client program? The authors...

    Provided By McGill University

  • White Papers // Mar 2011

    The Influence of the Task on Programmer Behaviour

    Programmers performing a change task must understand the existing software in addition to performing the actual change. This process is likely to be affected by characteristics of the task. The authors investigated whether the nature of a task has any relationship with when a programmer edits code during a programming...

    Provided By McGill University

  • White Papers // Sep 2009

    Improving API Usage Through Automatic Detection of Redundant Code

    Software projects often rely on third-party libraries made accessible through Application Programming Interfaces (APIs). The authors have observed many cases where APIs are used in ways that are not the most effective. They developed a technique and tool support to automatically detect such patterns of API usage in software projects....

    Provided By McGill University

  • White Papers // Oct 2009

    A Detailed Examination of the Correlation Between Imports and Failure-Proneness of Software Components

    Research has provided evidence that type usage in source files is correlated with the risk of failure of software components. Previous studies that investigated the correlation between type usage and component failure assigned equal blame to all the types imported by a component with a failure history, regardless of whether...

    Provided By McGill University

  • White Papers // Feb 2009

    Detecting Inefficient API Usage

    Large software projects often rely on third-party libraries, made accessible through Application Programming Interfaces (APIs). The authors have observed many cases where APIs are used in ways that are not efficient. They developed a technique to automatically detect inefficient API usage in software projects. The main hypothesis underlying the technique...

    Provided By McGill University

  • White Papers // Jul 2008

    Retrieving Task-Related Clusters From Change History

    During software maintenance tasks, developers often spend an important amount of effort investigating source code. This effort can be reduced if tools are available to help developers navigate the source code effectively. For this purpose, the authors propose to search the change history of a software system to identify clusters...

    Provided By McGill University

  • White Papers // Oct 2011

    Distributed Dual Averaging for Convex Optimization Under Communication Delays

    In this paper, the authors extend and analyze the distributed dual averaging algorithm. They employ the fixed delay model introduced in and show that distributed dual averaging still converges in the presence of finite and fixed communication delays. In addition, using a different bounding technique than, for a fixed network...

    Provided By McGill University

  • White Papers // Aug 2011

    Distributed Consensus and Optimization Under Communication Delays

    The authors study the effects of communication delays in distributed consensus and optimization algorithms. They propose two ways to model delays. First, assuming each edge of a communication network has a fixed delay, they characterize the consensus value exactly as a function of the delays and edge weights and obtain...

    Provided By McGill University

  • White Papers // Feb 2011

    Local Silencing Rules for Randomized Gossip

    Randomized gossip algorithms are attractive for collaborative in-network processing and aggregation because they are fully asynchronous, they require no overhead to establish and form routes, and they do not create any bottleneck or single point of failure. Previous studies have focused on analyzing the worst-case number of transmissions required to...

    Provided By McGill University

  • White Papers // Sep 2011

    Approximating Signals Supported on Graphs

    In this paper, the authors investigate the notion of smoothness for signals supported on the vertices of a graph. They provide theoretical explanations when and why the Laplacian eigenbasis can be regarded as a meaningful "Fourier" transform of such signals. Moreover, they analyze the desired properties of the underlying graphs...

    Provided By McGill University

  • White Papers // Sep 2011

    Graph Spectral Compressed Sensing for Sensor Networks

    For many Wireless Sensor Network (WSN) applications, the signals measured are likely to be correlated either spatially or temporally; i.e., the authors can find an appropriate transform domain where the signals are compressible. WSNs are characterized by having simple battery-powered wireless nodes with limited energy and communication resources. In order...

    Provided By McGill University

  • White Papers // Apr 2010

    Fast Decentralized Averaging Via Multi-Scale Gossip

    Applications in sensor networks often demand that nodes cooperatively accomplish a task without centralized coordination. Autonomy is often equated with robustness and scalability in large-scale networked systems. This is especially true in wireless networks, where fundamental limits on spatial and temporal channel reuse limit the amount of communication possible at...

    Provided By McGill University

  • White Papers // Apr 2009

    Compressed RF Tomography for Wireless Sensor Networks: Centralized and Decentralized Approaches

    Radio Frequency (RF) tomography refers to the process of inferring information about an environment by capturing and analyzing RF signals transmitted between nodes in a wireless sensor network. In the case where few available measurements are available, the inference techniques applied in previous work may not be feasible. Under certain...

    Provided By McGill University

  • White Papers // May 2009

    Multi-Hop Greedy Gossip With Eavesdropping

    Greedy Gossip with Eavesdropping (GGE) is a randomized gossip algorithm that computes the average consensus by exploiting the broadcast nature of wireless communications. Each node eavesdrops on its immediate neighbors to track their values so that when it comes time to gossip, a node can myopically exchange information with the...

    Provided By McGill University

  • White Papers // Sep 2008

    The Speed of Greed: Characterizing Myopic Gossip Through Network Voracity

    This paper analyzes the rate of convergence of Greedy Gossip with Eavesdropping (GGE). In previous work, the authors proposed GGE, a fast gossip algorithm based on exploiting the broadcast nature of wireless communications rather than location information. Assuming all transmissions are wireless broadcasts, nodes can keep track of their neighbors'...

    Provided By McGill University

  • White Papers // Sep 2008

    Rates of Convergence for Greedy Gossip With Eavesdropping

    Greedy Gossip with Eavesdropping (GGE) is a randomized gossip algorithm that exploits the broadcast nature of wireless communications to converge rapidly on grid-like network topologies without requiring that nodes know their geographic locations. When a node decides to gossip, rather than choosing one of its neighbors randomly, it greedily chooses...

    Provided By McGill University

  • White Papers // Aug 2011

    Energy Minimization for the Half-Duplex Relay Channel With Decode-Forward Relaying

    The authors analyze coding for energy efficiency in the relay channel for a fixed source rate. They propose a comprehensive half-duplex decode-forward coding scheme and three optimal sets of power allocation, which respectively minimize the network, the relay and the source energy consumption. Analysis shows that minimizing the network energy...

    Provided By McGill University

  • White Papers // Jul 2011

    Achievable Rates and Outer Bound for the Half-Duplex MAC With Generalized Feedback

    This paper provides comprehensive coding and outer bound for the half-duplex Multiple Access Channel with Generalized Feedback (MAC-GF). Two users communicate with one destination over a discrete memoryless channel using time division. Each transmission block is divided into 3 time slots with variable durations: the destination is always in receive...

    Provided By McGill University

  • White Papers // Oct 2011

    Compress-Forward Without Wyner-Ziv Binning for the One-Way and Two-Way Relay Channels

    The authors consider the role of Wyner-Ziv binning in compress-forward for relay channels. In the one-way relay channel, they analyze a compress-forward scheme without Wyner-Ziv binning but with joint decoding of both the message and compression index. It achieves the same rate as the original compress-forward scheme with binning and...

    Provided By McGill University

  • White Papers // Aug 2011

    Decode-Forward and Compute-Forward Coding Schemes for the Two-Way Relay Channel

    The authors consider the full-duplex two-way relay channel with direct link between two users and propose two coding schemes: a partial decode-forward scheme, and a combined decode-forward and compute-forward scheme. Both schemes use rate-splitting and superposition coding at each user and generate code words for each node independently. When applied...

    Provided By McGill University

  • White Papers // Aug 2011

    A Half-Duplex Relay Coding Scheme Optimized for Energy Efficiency

    The authors explore the issue of the network energy efficiency in relay channels. They first propose a half-duplex decode-forward coding scheme. They, then optimize the power allocation to minimize the total power consumption while maintaining a desired source rate. They show that this scheme significantly outperforms direct and two-hop transmissions....

    Provided By McGill University