ICST

Displaying 81-120 of 237 results

  • White Papers // Oct 2011

    Overhearing Conversations in Global Software Engineering - Requirements and an Implementation

    Conversations between colleagues in collaborative software engineering are important for coordinating work, sharing knowledge and creating knowledge. Overhearing conversations of others is useful as well since this: provides access to the information discussed in the conversations, offers the possibility of joining the conversations and provides insight in the communication structure...

    Provided By ICST

  • White Papers // Oct 2011

    The ABA Problem in Multicore Data Structures With Collaborating Operations

    An increasing number of modern real-time systems and the nowadays ubiquitous multicore architectures demand the application of programming techniques for reliable and efficient concurrent synchronization. Some recently developed Compare-And-Swap (CAS) based non-blocking techniques hold the promise of delivering practical and safer concurrency. The ABA2 problem is a fundamental problem to...

    Provided By ICST

  • White Papers // Oct 2011

    OTPM: Failure Handling in Data-Intensive Analytical Processing

    Parallel processing is the key to speedup performance and to achieve high throughput in processing large scale data analytical workloads. However, failures of nodes involved in the analytical query can interrupt the whole process, resulting in the complete restart of the query if the system does not have query fault-tolerance....

    Provided By ICST

  • White Papers // Oct 2011

    CONFLuEnCE: Implementation and Application Design

    Data streams have become pervasive and data production rates are increasing exponentially, driven by advances in technology, for example the proliferation of sensors, smart phones, and their applications. This fact effectuates an unprecedented opportunity to build real-time monitoring and analytics applications, which when used collaboratively and interactively, will provide insights...

    Provided By ICST

  • White Papers // Oct 2011

    DCDIDP: A Distributed, Collaborative, and Data-Driven Intrusion Detection and Prevention Framework for Cloud Computing Environments

    With the growing popularity of cloud computing, the exploitation of possible vulnerabilities grows at the same pace; the distributed nature of the cloud makes it an attractive target for potential intruders. Despite security issues delaying its adoption, cloud computing has already become an unstoppable force; thus, security mechanisms to ensure...

    Provided By ICST

  • White Papers // Oct 2011

    On Data Provenance in Group-Centric Secure Collaboration

    In this paper, the authors explore data provenance in a group-centric secure collaboration environment. In collaborations, participating organizations are likely to want certain trustworthiness on the data that are shared from other organizations and some assurance on how the shared data are used by users regardless of their organizations. By...

    Provided By ICST

  • White Papers // Oct 2011

    REUSES: Questionnaire-Driven Design for the Automatic Generation of Web-Based Collaborative Applications

    In this paper, the authors present a questionnaire-driven collaborative design methodology for the automatic generation of collaborative applications. The methodology is based on a repository of collaborative components and a knowledge base of its application and use modes. The repository includes components built by the team, as well as third-party...

    Provided By ICST

  • White Papers // Oct 2011

    Featuring Automatic Adaptivity Through Workflow Enactment and Planning

    Process Management Systems (PMSs, a.k.a. Workflow Management Systems - WfMSs) are currently more and more used as a supporting tool to coordinate the enactment of processes. In real world scenarios, the environment may change in unexpected ways so as to prevent a process from being successfully carried out. In order...

    Provided By ICST

  • White Papers // Oct 2011

    Mobile XMPP and Cloud Service Collaboration: An Alliance for Flexible Disaster Management

    Recent crises like the Fukushima incident in Japan show that there is a demand for flexible and easy-to-use communication and sensor systems to support post-disaster management (i.e., the organization of actions in the follow-up of disasters), especially when critical infrastructure is affected. This paper introduces a system design that combines...

    Provided By ICST

  • White Papers // Oct 2011

    A Distributed Web Browser as a Platform for Running Collaborative Applications

    Most existing collaborative applications on the Web require centralized servers for storing shared data and relaying communication messages among browsers. This means that users of these applications must fully trust centralized servers that hold and relay potentially sensitive and important data. Furthermore, users can lose access to their data if...

    Provided By ICST

  • White Papers // Oct 2011

    A Trust-Based Approach to Mitigate Rerouting Attacks

    One of the ways a malicious router can launch a Denial of Service (DoS) attack is by rerouting IP-packets of other destinations to the victim node. In this paper, based on the observed traffic anomalies, the authors propose using a Markov chain model to calculate trustworthiness of routers in order...

    Provided By ICST

  • White Papers // Oct 2011

    A Test-Bed for the Evaluation of Business Process Prediction Techniques

    Business process prediction technologies are being increasingly used by organisations to provide timely feedback to their customers and improve their overall productivity. In order to provide valuable information to both customers and system managers, the timings of business processes need to be forecast with high accuracy and efficiency. In particular,...

    Provided By ICST

  • White Papers // Oct 2011

    Towards a Personalized Trust Architecture

    Advances in next generations distributed cyberspace technologies are expected to evolve a global cyberspace marketplace for resource and services. In marketplaces, particularly with the autonomy of users, trading parties differ in many respects, for example their declared agendas, honesty, owned or outsourced resources, and their products. Given these differences and...

    Provided By ICST

  • White Papers // Oct 2011

    Memory-Enabled Autonomic Resilient Networking

    It is becoming increasingly challenging for the contemporary Internet to satisfy the explosion in networking services and applications with their widely diverse and dynamic QoS requirements and resource demands. For smarter networking management and operations, they hypothesize that next generation networks should be endowed with "Memory"-like (i.e., functionally similar to...

    Provided By ICST

  • White Papers // Oct 2011

    Provenance for Collaboration: Detecting Suspicious Behaviors and Assessing Trust in Information

    Data collaborations allow users to draw upon diverse resources to solve complex problems. While collaborations enable a greater ability to manipulate data and services, they also create new security vulnerabilities. Collaboration participants need methods to detect suspicious behaviors (potentially caused by malicious insiders) and assess trust in information when it...

    Provided By ICST

  • White Papers // Oct 2011

    A Content-Aware Collaborative Accessing Model in Ad Hoc Networks

    Reducing the transmission cost is one of the most important issues in multi-hop ad-hoc networks. Considerable research has been done on efficient routing and data accessing algorithms. However, most previous research on routing schemes focus on topological structures, and not much attention has been made to data content distributions in...

    Provided By ICST

  • White Papers // Oct 2011

    An Exploratory Study on Open Conversation Spaces in Software Engineering

    Software engineering is by nature a highly collaborative activity and being able to collaborate effectively is a key factor for project success. However, collaborating effectively in Global Software Engineering, in which team members are geographically, temporally and socio-culturally separated from each other, is an important challenge. In a traditional co-located...

    Provided By ICST

  • White Papers // Oct 2011

    Data Management Support Via Spectrum Perturbation-Based Subspace Classification in Collaborative Environments

    Data management support to enable effective and efficient information sharing in collaborative environments is critical, especially in semantics based search and retrieval. In this paper, a novel spectrum perturbation-based subspace classification is proposed to mine semantics and other useful information from a large-scale dataset by utilizing a lower-dimensional subspace to...

    Provided By ICST

  • White Papers // Oct 2011

    Collaborative Authoring of Adaptive Learning Resources: Opportunities and Challenges

    One issue regarding adaptive learning systems is the provision of learning resources that consist of domain knowledge, pedagogical knowledge with adaptation rules, and learning content. Challenges emerge concerning the lack of usability, interoperability, efficiency and collaboration. This paper critically discusses an enhanced collaborative authoring approach to developing adaptive learning resources....

    Provided By ICST

  • White Papers // Oct 2011

    Protocol for Mitigating the Risk of Hijacking Social Networking Sites

    The proliferation of social and collaborative media has been accompanied by an increased level of cyber attacks on social networking and collaboration sites. One serious type of attack is session hijacking attacks which enable the attacker to impersonate the victim and take over his/her networking session(s). In this paper, the...

    Provided By ICST

  • White Papers // Oct 2011

    Mitigating the Cognitive Overload of Contemporary Argumentation-Based Collaboration Settings

    Current advances in computing and Internet technologies, together with the advent of the Web 2.0 era, have resulted in the development of a plethora of online, publicly available environments such as blogs, discussion forums, wikis, and social networking applications. These offer people an unprecedented level of flexibility and convenience to...

    Provided By ICST

  • White Papers // Oct 2011

    Consistent Replication in Distributed Multi-Tier Architectures

    Replication is commonly used to address the scalability and availability requirements of collaborative web applications in domains such as computer supported cooperative work, social networking, e-commerce and e-banking. While providing substantial benefits, replication also introduces the overhead of maintaining data consistent among the replicated servers. In this paper, the authors...

    Provided By ICST

  • White Papers // Sep 2011

    Spectrum Sharing With Interference Coordination Under Outage Probability Constraint

    In this paper, the authors consider a Cognitive Radio (CR) communication system based on spectrum sharing schemes, where they have a Secondary User (SU) link with multiple transmitting antennas and a single receiving antenna, coexisting with a Primary User (PU) link with a single receiving antenna. At the SU Transmitter...

    Provided By ICST

  • White Papers // Sep 2011

    Joint Switched Transmit Diversity and Adaptive Modulation in Spectrum Sharing Systems

    Under the scenario of an underlay cognitive radio network, the authors propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed Switching...

    Provided By ICST

  • White Papers // Sep 2011

    A Tree Based Recovery Algorithm for Block Sparse Signals

    The structure of block sparsity in multi-band signals is prevalent. Performance of recovery algorithms that taking advantage of the block sparsity structure is promising in the compressed sensing framework. In this paper, the authors propose a binary tree based recovery algorithm for block-sparse signals, where they exploit the fact that...

    Provided By ICST

  • White Papers // Sep 2011

    Sensing Order Dispersion for Autonomous Cognitive Radios

    When autonomous Cognitive Radios (CRs) have to search multiple potential channels for spectrum opportunities, they face competition from one another to access the channel. The end result of this competition is reduced CR throughput due to collisions among CRs that transmit in the same channel. In this context, the channel...

    Provided By ICST

  • White Papers // Sep 2011

    Sparse Signal Sensing With Non-Uniform Undersampling and Frequency Excision

    The authors propose a novel compressive sensing algorithm for cognitive radio networks, based on non-uniform under-sampling. It is known that the spectrum of uniformly under-sampled signals exhibit frequency aliasing, whereby the frequency location is impossible. To alleviate aliasing, non-uniform sampling can be used. This, however, generates a high level of...

    Provided By ICST

  • White Papers // Sep 2011

    An Algorithm for Fast REM Construction

    The Radio Environment Map (REM) stores radio environmental information that can be used to enhance cognitive radio resource management in wireless networks. In this paper, the authors propose an iterative REM building process based on Kriging interpolation technique that builds the REM using geo-located measurements performed by mobile terminals. As...

    Provided By ICST

  • White Papers // Sep 2011

    A Low-Interference Relay Selection for Decode-and-Forward Cooperative Network in Underlay Cognitive Radio

    In the underlay Decode-and-Forward (DaF) cooperative Cognitive Radio (CR) network, an optimal relay can be selected by the conventional max-min selection on the condition of not violating the Interference Temperature (IT) limit. However, the max-min selection may cause some extra amount of interference to the Primary System (PS) such that...

    Provided By ICST

  • White Papers // Sep 2011

    Self-Enforcement Strategy for Energy-Efficient Relaying in Wireless Ad-Hoc Networks

    In this paper, the authors propose and examine 802.11b-based MAC protocol for wireless ad-hoc relay networks. The objective of the proposed protocol is to incorporate self-enforcing strategy to achieve energy efficiency in function of joules required for providing data transmission between end users. Regarding energy requirements for transmitting and receiving...

    Provided By ICST

  • White Papers // Sep 2011

    Exploiting Spatial Dimension in Cognitive Radios and Networks

    This paper studies the maximum number of users that can be allocated in the same frequency band in case of using beamforming in a transmitter and a receiver by simulations. With the use of smart antennas the spectrum can be used efficiently, and at the same time the Quality of...

    Provided By ICST

  • White Papers // Sep 2011

    The Capacity of Cognitive Ad-Hoc Networks With Carrier Sensing Errors

    The authors analyze the capacity of cognitive ad-hoc networks under the effects of sensing errors: false alarm and missed detection. They present an ad-hoc network model overlaid on a primary system from which a cognitive node exploits spectrum holes for retransmissions. They derive per-link capacity, the indicator of the network's...

    Provided By ICST

  • White Papers // Sep 2011

    The Sum Capacity of Underlay Cognitive Broadcast Channel

    The authors study the sum capacity of the underlay cognitive BroadCast (BC) channel with M Primary Receivers (PRs) and K Secondary Receivers (SRs). In particular, the sum capacity is investigated under an average Transmit Power Constraint (TPC) on the SRs and multiple average or peak Interference Power Constraints (IPCs) on...

    Provided By ICST

  • White Papers // Sep 2011

    Network Scale Control for Distributed Networks by BER Analysis

    Node-to-node interference in the distributed networks comes to be one of the major challenges in recent wireless communication studies. The general methods make great improvement on such problem but influence the performances in other layer. It is because the models they based on, like SINR, barely consider the parameters across...

    Provided By ICST

  • White Papers // Sep 2011

    Supporting Mood Awareness in Collaborative Settings

    Affective aspects during collaboration can be exploited as triggers for reflection, yet current tools usually ignore these aspects. In this paper, the authors present a set of design choices to inform the design of systems towards enabling mood awareness in collaborative work settings like meetings or conferences. Design choices have...

    Provided By ICST

  • White Papers // Jun 2011

    An Efficient Routing Protocol on a Dynamic Cluster-Based Sensor Network

    This paper presents an efficient routing protocol on a Dynamic Cluster-based Wireless Sensor Network (WSN). The cluster-based architecture presented here is constructed dynamically. Unlike some previous routing protocol that finds the route on cluster-based architecture which is a spanning tree of graph G, the authors' proposed protocol finds route on...

    Provided By ICST

  • White Papers // Jun 2011

    Distributed Channel Assignment Algorithm Based on Simulated Annealing for Uncoordinated OSA-Enabled WLANs

    A promising approach to alleviate ISM band congestion problems in highly dense WLAN scenarios consists of exploiting Opportunistic Spectrum Access (OSA) to underutilized bands under a primary-secondary model. This paper develops a distributed channel assignment algorithm valid for uncoordinated WLAN deployments where access points do not follow any specific planning...

    Provided By ICST

  • White Papers // Jun 2011

    Impact of Antenna Selection on Cognitive Radio System Capacity

    The authors examine the effect of transmit antenna selection on the Secondary User (SU) and Primary User (PU) capacity in a multiple-input single-output cognitive radio system. They consider antenna selection with the aim of improving SU and PU capacity and mitigating the effects of incomplete channel knowledge by the SU....

    Provided By ICST

  • White Papers // Jun 2011

    Contribution Based Cooperative Spectrum Sensing Against Malfunction Nodes in Cognitive Radio Networks

    In cognitive radio networks, secondary users can cooperate based on their own sensing observations so as to detect the primary user more accurately. However, since of location disadvantage, multipath fading or shadowing, sensing contribution of some secondary users may be untrustworthy, which are termed malfunction nodes in this paper. To...

    Provided By ICST

  • White Papers // Jun 2011

    Signal Separation and Reconstruction Method for Simultaneously Received Multi-System Signals in a Unified Wireless System

    These days, a wide variety of wireless systems are used and new wireless systems appear one after another on the market. In this paper, the authors proposed a unified wireless system that they call "Flexible wireless system". Comprising flexible access points and a flexible signal processing unit, it collectively receives...

    Provided By ICST

  • White Papers // May 2011

    A Positioning of Cooperative Differential Games

    In this paper, the authors embed the theory of cooperative differential games within the theory of dynamic games and discuss a number of results of them. Dynamic game theory brings together four features that are key to many situations in economy, ecology, and elsewhere: optimizing behavior, presence of multiple agents/players,...

    Provided By ICST

  • White Papers // May 2011

    A Self-Optimization Method for Coverage-Capacity Optimization in OFDMA Networks With MIMO

    Self-Organizing Networks (SON) is currently seen as a key lever to improve network performance and simplify its management. This paper considers ?-fair schedulers in an Orthogonal Frequency-Division-Multiple Access (OFDMA) network. The convergence of the ?-fair scheduler is analyzed. Closed-form formulas are given for certain cases to calculate the scheduling gain,...

    Provided By ICST

  • White Papers // May 2011

    K-Means and Adaptive K-Means Algorithms for Clustering DNS Traffic

    Internet Service Providers' DNS traffic can be up to 120000 queries per second and increases around 8% every month. DNSSEC is expected to replace DNS and brings new challenge to naming resolution with heavy signature check. This paper provides an architecture, where incoming DNS traffic is split according to the...

    Provided By ICST

  • White Papers // May 2011

    Worst-Case Delay Bounds With Fixed Priorities Using Network Calculus

    Worst-case delay bounds are an important issue for applications with hard-time constraints. Network calculus is a useful theory to study worst-case performance bounds in networks. In this paper, the authors focus on networks with a fixed priority service policy and provide methods to analyze systems where the traffic and the...

    Provided By ICST

  • White Papers // May 2011

    Power Allocation in Team Jamming Games in Wireless Ad Hoc Networks

    In this paper, the authors study the problem of power allocation in teams. Each team consists of two agents who try to split their available power between the tasks of communication and jamming the nodes of the other team. The agents have constraints on their total energy and instantaneous power...

    Provided By ICST

  • White Papers // May 2011

    Low Complexity Resource Allocation for OFDMA Based on Coalitional Game Theory

    This paper investigates a fair adaptive resource management criterion (in terms of transmit powers and sub-channel assignment) for the uplink of an Orthogonal Frequency Division Multiple Access (OFDMA) network, populated by mobile users with constraints in terms of target data rates. The inherent optimization problem is tackled with the analytical...

    Provided By ICST

  • White Papers // May 2011

    Universal Linear Pricing for Multiple Access and Broadcast Channels Under QoS Requirements

    In this paper, the authors address the problem of power allocation in Multiple Access Channels (MAC) and Broadcast Channels (BC) with linear pricing framework to ensure that each user in the interference network can achieve its utility requirement. In the framework the system optimizer maximizes the system utility with the...

    Provided By ICST

  • White Papers // May 2011

    Adversarial Behavior in Network Mechanism Design

    This paper studies the effects of and countermeasures against adversarial behavior in network resource allocation mechanisms such as pricing and auctions. It models the heterogeneous behavior of users, which ranges from altruistic to selfish and even to malicious, using game theory. The paper adopts a mechanism design approach to quantify...

    Provided By ICST

  • White Papers // May 2011

    Automatic Protocol Signature Generation Framework for Deep Packet Inspection

    The authors present an automatic application protocol signature generating framework for Deep Packet Inspection (DPI) techniques with performance evaluation. They propose to utilize algorithms from the field of bioinformatics. They also present preprocessing methods to accelerate their system. Moreover, they developed several post-processing techniques to refine the accuracy of the...

    Provided By ICST

  • White Papers // Oct 2011

    Collaborative Authoring of Adaptive Learning Resources: Opportunities and Challenges

    One issue regarding adaptive learning systems is the provision of learning resources that consist of domain knowledge, pedagogical knowledge with adaptation rules, and learning content. Challenges emerge concerning the lack of usability, interoperability, efficiency and collaboration. This paper critically discusses an enhanced collaborative authoring approach to developing adaptive learning resources....

    Provided By ICST

  • White Papers // Sep 2011

    Supporting Mood Awareness in Collaborative Settings

    Affective aspects during collaboration can be exploited as triggers for reflection, yet current tools usually ignore these aspects. In this paper, the authors present a set of design choices to inform the design of systems towards enabling mood awareness in collaborative work settings like meetings or conferences. Design choices have...

    Provided By ICST

  • White Papers // Oct 2011

    Protocol for Mitigating the Risk of Hijacking Social Networking Sites

    The proliferation of social and collaborative media has been accompanied by an increased level of cyber attacks on social networking and collaboration sites. One serious type of attack is session hijacking attacks which enable the attacker to impersonate the victim and take over his/her networking session(s). In this paper, the...

    Provided By ICST

  • White Papers // Oct 2011

    Mitigating the Cognitive Overload of Contemporary Argumentation-Based Collaboration Settings

    Current advances in computing and Internet technologies, together with the advent of the Web 2.0 era, have resulted in the development of a plethora of online, publicly available environments such as blogs, discussion forums, wikis, and social networking applications. These offer people an unprecedented level of flexibility and convenience to...

    Provided By ICST

  • White Papers // Oct 2011

    Consistent Replication in Distributed Multi-Tier Architectures

    Replication is commonly used to address the scalability and availability requirements of collaborative web applications in domains such as computer supported cooperative work, social networking, e-commerce and e-banking. While providing substantial benefits, replication also introduces the overhead of maintaining data consistent among the replicated servers. In this paper, the authors...

    Provided By ICST

  • White Papers // Jun 2011

    Game Theoretic Modelling for Dynamic Spectrum Access in TV Whitespace

    In order to assess TV whitespace access scenarios, three oligopoly game models are considered and reformulated in terms of radio access: Cournot, Stackelberg, and Bertrand. Besides revisiting the relevance of Nash and Pareto equilibria, a new equilibrium concept - the joint Nash-Pareto equilibrium is considered. An evolutionary game equilibria detection...

    Provided By ICST

  • White Papers // May 2012

    An Investigation Into the Spectrum Occupancy in Japan in the Context of TV White Space Systems

    This paper presents the results of spectrum occupancy measurements carried out in three locations of Kanto area in Japan. Moreover, the collected data corresponding to DTV broadcasting service is analyzed to evaluate the possibilities of secondary systems operating in TV White Spaces (TVWS) in the framework of FCC regulations and...

    Provided By ICST

  • White Papers // Jun 2011

    An Efficient Routing Protocol on a Dynamic Cluster-Based Sensor Network

    This paper presents an efficient routing protocol on a Dynamic Cluster-based Wireless Sensor Network (WSN). The cluster-based architecture presented here is constructed dynamically. Unlike some previous routing protocol that finds the route on cluster-based architecture which is a spanning tree of graph G, the authors' proposed protocol finds route on...

    Provided By ICST

  • White Papers // Jun 2011

    Trade-Offs in Primary Detection Using a Mobile Phone as a Sensing Device

    Cognitive Radio built on top of spectrum sensing is promised to provide more capacity for users wherever and whenever needed and improve radio spectrum utilization in clever and fair manner. However, practical spectrum sensors have to be implemented and they should provide sufficient protection to legacy users of radio spectrum....

    Provided By ICST

  • White Papers // Jun 2011

    Design and Performance Trade-Offs in Parallelized RF SDR Architecture

    Multi-radio platforms are an interesting design concept. Executing multiple radios on a shared platform presents opportunities not only for component re-use but also for better data throughputs, as non-active radios may dynamically yield resources for active ones. This enhances the conventional SDR approach in the RF domain and provides means...

    Provided By ICST

  • White Papers // Jun 2011

    Fast and Reliable Sensing Using a Background Process for Noise Estimation

    This paper presents an efficient way to ensure a good detection performance by implementing algorithms running in background a reliable noise estimation process. The proposed solution operates at two different time scales: a slow time scale to determine in adjacent sub-bands the supposed slowly varying noise level, and a faster...

    Provided By ICST

  • White Papers // Jun 2011

    Development of a TV White Space Cognitive Radio Prototype and Its Spectrum Sensing Performance

    In this paper, the authors describe a recently developed TeleVision White Space (TVWS) hardware prototype. The prototype includes the following components: a Cognitive Management Entity (CME), a sensing module, a geo-location device, a TV band database, a transmitter and a receiver. The prototype is developed in compliance with recent Singapore...

    Provided By ICST

  • White Papers // Jun 2011

    Multi-Mode, Multi-Band Spectrum Sensor for Cognitive Radios Embedded to a Mobile Phone

    Localized spectrum sensing is an alternate for database centric approaches to solve secondary use of spectrum in cognitive radios. This can be carried out by using collaborative spectrum sensing where larger amount of small devices is utilized for local spectrum sensing. This paper describes a mobile device scale implementation of...

    Provided By ICST

  • White Papers // Jun 2011

    Automatic Modulation Classification in Wireless Disaster Area Emergency Network (W-DAEN)

    Post-disaster situation requires quick and effective rescue efforts by the first responders. Generally the rescue teams use wireless radios for intra-agency communications. Lack of collaboration among different rescue agencies may create interference among the emergency radios. Identification of some physical parameters of these active radios is necessary for collaboration. Carrier...

    Provided By ICST

  • White Papers // Sep 2011

    Spectrum Sharing With Interference Coordination Under Outage Probability Constraint

    In this paper, the authors consider a Cognitive Radio (CR) communication system based on spectrum sharing schemes, where they have a Secondary User (SU) link with multiple transmitting antennas and a single receiving antenna, coexisting with a Primary User (PU) link with a single receiving antenna. At the SU Transmitter...

    Provided By ICST

  • White Papers // Sep 2011

    Joint Switched Transmit Diversity and Adaptive Modulation in Spectrum Sharing Systems

    Under the scenario of an underlay cognitive radio network, the authors propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed Switching...

    Provided By ICST

  • White Papers // Sep 2011

    A Tree Based Recovery Algorithm for Block Sparse Signals

    The structure of block sparsity in multi-band signals is prevalent. Performance of recovery algorithms that taking advantage of the block sparsity structure is promising in the compressed sensing framework. In this paper, the authors propose a binary tree based recovery algorithm for block-sparse signals, where they exploit the fact that...

    Provided By ICST

  • White Papers // Sep 2011

    Sensing Order Dispersion for Autonomous Cognitive Radios

    When autonomous Cognitive Radios (CRs) have to search multiple potential channels for spectrum opportunities, they face competition from one another to access the channel. The end result of this competition is reduced CR throughput due to collisions among CRs that transmit in the same channel. In this context, the channel...

    Provided By ICST

  • White Papers // May 2011

    Analytic Performance Evaluation of Oopportunistic Spectrum Access With Detection Errors

    This paper aims at giving some results on the performances of opportunistic spectrum access when taking into account sensing errors: non detection, which is the cause of collisions with a transmitting user, and false alarm, which is a cause of missed opportunity to access the channel. In a growing number...

    Provided By ICST

  • White Papers // May 2011

    Efficient Calculation of Rare Event Probabilities in Markovian Queueing Networks

    The authors address the computation of rare event probabilities in Markovian queueing networks with huge or possibly even infinite state spaces. For this purpose, they incorporate ideas from importance sampling simulations into a non-simulative numerical method that approximates transient probabilities based on a dynamical truncation of the state space. A...

    Provided By ICST

  • White Papers // May 2011

    Simulating Flow Level Bandwidth Sharing With Pareto Distributed File Sizes

    The authors' goal is to achieve deeper understanding of the limitation of queueing models, on one hand, and of common simulation practice, on the other hand, as tools for predicting performance of bandwidth sharing between competing TCP flows. In particular, they present an overview of simulation problems that are expected...

    Provided By ICST

  • White Papers // May 2012

    Dynamic Power Allocation Games in Parallel Multiple Access Channels

    The authors analyze the distributed power allocation problem in parallel Multiple Access Channels (MAC) by studying an associated non-cooperative game which admits an exact potential function. Even though games of this type have been the subject of considerable study in the literature, they find that the sufficient conditions which ensure...

    Provided By ICST

  • White Papers // May 2011

    Joint Network/Channel Decoding for Heterogeneous Multi-Source/Multi-Relay Cooperative Networks

    In this paper, the authors study joint network/channel decoding for multi-source multi-relay heterogeneous wireless networks. When convolutional and network codes are used at the physical and network layers, respectively, they show that error correction and diversity properties of the whole network can be characterized by an equivalent and distributed convolutional...

    Provided By ICST

  • White Papers // May 2011

    Network Coding Schemes for the Multiple-Access Relay Channel

    The authors examine and compare four different Joint-Network-Channel-Codes (JNCC) and three reference systems for the Multiple-Access Relay Channel (MARC) with block Rayleigh fading channels for symmetric and asymmetric setups. Two of the JNCC's were presented previously in the literature and the other two are novel approaches. The JNCC's outperform the...

    Provided By ICST

  • White Papers // May 2011

    A Framework for Optimization Under Limited Information

    In many real world problems, optimization decisions have to be made often with limited information. The decision maker may have no a priori data about the (non-convex) objective function except from on a limited number of points that are obtained over time through costly observations. This paper presents an optimization...

    Provided By ICST

  • White Papers // May 2012

    QBD Sensitivity Analysis Tool Using Discrete-Event Simulation and Extension of SMCSolver

    The authors propose a tool that provides both analytical and simulation based performance analysis of both homogeneous and inhomogeneous Quasi-Birth-and-Death (QBD) processes. They extend SMCSolvers in order to study inhomogeneous case and to analyze first passage times. Simulations are performed on a discrete-event based approach. They also provide a rich...

    Provided By ICST

  • White Papers // May 2011

    Modeling Quantitative Requirements in SLAs With Network Calculus

    When planning Service-Oriented Architectures requirements declared in Service Level Agreements (SLAs) have to be considered. SLAs cover functional as well as quantitative requirements like load levels, services rates and delay times. As external factors can influence distributed systems, SLAs have to include tolerances for quantitative requirements. Early design phases of...

    Provided By ICST

  • White Papers // May 2011

    Centrality Maps and the Analysis of City Street Networks

    Firstly introduced in social science, the notion of centrality has spread to the whole complex network science. A centrality is a measure that quantifies whether an element of a network is well served or not, easy to reach, necessary to cross. This paper focuses on cities' street network (seen as...

    Provided By ICST

  • White Papers // May 2011

    Optimal Base Station Placement: A Stochastic Method Using Interference Gradient in Downlink Case

    In this paper, the authors study the optimal placement and optimal number of base stations added to an existing wireless data network through the interference gradient method. This proposed method considers a sub-region of the existing wireless data network, hereafter called region of interest. In this region, the provider wants...

    Provided By ICST

  • White Papers // May 2011

    Mean Field Stochastic Games for SINR-Based Medium Access Control

    In this paper, the authors study medium access control with interference management. They formulate a SINR-based dynamic channel access as a stochastic game in which the players adapt their retransmission scheme based on their own backoff state. They analyze the asymptotics of the system using mean field dynamics. Both stable...

    Provided By ICST

  • White Papers // May 2011

    Graph-Based Coalitional Games - An Analysis Via Characteristics

    In this paper, the authors motivate a new approach to analyze the computational complexity of solution concepts and player-based properties, as well as other properties of coalitional games. This approach is based on the idea to abstract away from detailed game representations to analyze games via standard complexity proofs, towards...

    Provided By ICST