ICST

Displaying 121-160 of 255 results

  • White Papers // Jun 2011

    Transmitting-Collision Tradeoff in Cognitive Radio Networks: A Flexible Transmitting Approach

    In cognitive radio networks, in order to avoid collision to Primary User (PU), Cognitive Radio (CR) user ought to sense the spectrum periodically to certify that PU is absent. However, the collision to PU also occurs due to imperfect sensing or PU's returning when CR user is transmitting. In this...

    Provided By ICST

  • White Papers // Jun 2011

    Intelligent Data Rate Control in Cognitive Mobile Heterogeneous Networks

    An adaptive Rate Controller (ARC) based on Adaptive Neural Fuzzy Inference System (ANFIS) is designed to autonomously adjust the data rate of a mobile heterogeneous network to adapt the changing traffic load and the user speed for multimedia call services. Through simulations, it is demonstrated that the ARC is able...

    Provided By ICST

  • White Papers // Jun 2011

    Uncoordinated Beamforming for Cognitive Networks

    In this paper, the authors propose jointly-optimized beamforming algorithms for cognitive networks to maximize the achievable rates assuming single information stream in both primary and secondary links. The primary and cognitive users share the same spectrum and are equipped with multiple antennas. No coordination is required between the primary and...

    Provided By ICST

  • White Papers // Jun 2011

    Achievable Capacity of Cognitive Radio Systems Coexisting With a Macro Cellular System

    A theoretical analysis of achievable capacity by a cognitive radio systems is discussed, when the Cognitive Radio System (CRS) uses spectrum allocated to a macro cellular system. As for the spectrum sharing mechanisms, the authors consider two methods based on listen-before-talk and adaptive transmit power control principles. Moreover, outdoor and...

    Provided By ICST

  • White Papers // Jun 2011

    Modeling and Simulation of Time-Correlation Properties of Spectrum Use in Cognitive Radio

    The development of the cognitive radio technology can enormously benefit from the availability of realistic and accurate spectrum occupancy models. Time-dimension models of spectrum use proposed in the literature so far are able to capture and reproduce essential temporal characteristics such as the mean occupancy level (duty cycle) and the...

    Provided By ICST

  • White Papers // Jun 2011

    Low Complexity Cyclostationary Feature Detection Method to Compenstate Cyclostationarity-Degradation by Guard Interval Insertion

    In cognitive radio system, it is necessary for spectrum sensing technology to search for vacant channel. Cyclostationary feature detection method has superior noise-immune and recognition. However, since the mismatch between the detected signal and detection duration by Guard Interval (GI) insertion occurs, the cyclostationarity is degraded. In this paper, the...

    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 // 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 // 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

    Large-Deviations Analysis for Energy-Saving Mechanisms in Wireless Networks

    In wireless telecommunication networks, there is a strong interest in energy efficiency. Sleep-mode mechanisms, which temporarily switch off mobile devices or base stations, are popular means to attain this goal. The authors look at the performance of different sleep-mode mechanisms with large-deviations tools. These allow one to look at a...

    Provided By ICST

  • White Papers // May 2011

    More About Base Station Location Games

    This paper addresses the problem of locating base stations in a certain area which is highly populated by mobile stations; each mobile station is assumed to select the closest base station. Base stations are modeled by players who choose their best location for maximizing their uplink throughput. The approach of...

    Provided By ICST

  • White Papers // May 2011

    HS-Measure : A Hybrid Clustering Validity Measure to Interpret Road Traffic Data

    Clustering validity measures aim to evaluate the goodness of clustering results in order to find the best partition. Results are obtained by varying the input parameters values. However, sometimes, the values generated by these measures are very close and the choice of the optimal value associated to the best partition...

    Provided By ICST

  • White Papers // May 2011

    Throughput and QoS Pricing in Wireless Communication

    In this paper, the authors investigate a bi-level economic model of wireless communications. They take into account the user's demand and also the QoS offered by the network. They determine with their model when a provider can make more pro t by investing into new technology. They consider a Stackelberg...

    Provided By ICST

  • White Papers // May 2011

    Uplink Power Control and Subcarrier Assignment for an OFDMA Multicellular Network Based on Game Theory

    This paper proposes an energy-efficient game-theoretic approach to the issue of resource allocation for the uplink of a multi-cellular OFDMA network. The problem is decoupled into subcarrier assignment and power control, assuming the data rates to be fixed for all subcarriers and all terminals in the network. To capture the...

    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

    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