ICST

Displaying 161-200 of 241 results

  • 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...

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  • 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....

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  • 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...

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  • 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...

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  • White Papers // Jun 2011

    A New Spectrum Sensing Scheme Using Overlap FFT Filter-Bank for Dynamic Spectrum Access

    A periodogram scheme, a multi-taper scheme, and a filter-bank scheme are proposed for spectrum sensing for dynamic spectrum access. The filter-bank scheme is advantageous in hardware implementation since the hardware required for communications can be reused for spectrum sensing. However, it is difficult for the conventional filter-bank scheme to change...

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  • White Papers // Jun 2011

    Low Complexity Cooperative Multicast Beamforming in Multiuser Multicell Downlink Networks

    This paper presents a low complexity sub-optimal algorithm for the max-min beamforming problem in multicell multicast transmission. The beam pattern is jointly optimized for all users inside a cell in a multicell scenario such that the Signal to Interference plus Noise Ratio (SINR) of the worst users is maximized subject...

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  • White Papers // Jun 2011

    Joint Coordinated Multicell Processing and MIMO: Selection of Base Stations and Gain

    In this paper, the authors provide the analysis of the downlink Coordinated Multiple Point (CoMP) used in conjunction with the basic MIMO. The CoMP is the joint multi-cell transmission from several BS to mobiles, coupled here to an open-loop MIMO technique that does not require the perfect channel state knowledge....

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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,...

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  • 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,...

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  • 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...

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  • 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...

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  • White Papers // May 2011

    Distributed Stochastic Optimization for Constrained and Unconstrained Optimization

    In this paper, the authors analyze the convergence of a distributed Robbins-Monro algorithm for both constrained and unconstrained optimization in multi-agent systems. The algorithm searches local minima of a (non-convex) objective function which is supposed to coincide with a sum of local utility functions of the agents. The algorithm under...

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  • White Papers // May 2011

    Large-Scale Games in Large-Scale Systems

    Many real-world problems modeled by stochastic games have huge state and/or action spaces, leading to the well-known curse of dimensionality. The complexity of the analysis of large-scale systems is dramatically reduced by exploiting mean field limit and dynamical system viewpoints. Under regularity assumptions and specific time-scaling techniques, the evolution of...

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  • White Papers // May 2011

    HJB Approach for Motion Planning and Reachabilty Analysis

    Because of their importance in many applications, questions of path planning and reachability analysis for nonlinear dynamical systems have been studied extensively in the control theory. Here, the authors focus on the cases when the controlled systems are constrained to evolve in a certain known set (e.g., avoidance of obstacles)....

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  • White Papers // May 2011

    Stability and Asymptotic Optimality of Opportunistic Schedulers in Wireless Systems

    The authors investigate the scheduling of a common resource between several concurrent users when the feasible transmission rate of each user varies randomly over time. Time is slotted and users arrive and depart upon service completion. This may model for example the flow-level behavior of end-users in a narrowband HDR...

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  • White Papers // May 2011

    Continuous Polling With Rerouting and Applications to Ferry Assisted Wireless LANs

    In almost all studied continuous polling systems, the user leaves the system after his service is completed. There are interesting applications, in which the users demand a second service (or more). For example, in a ferry assisted wireless network, for every local data transfer the ferry has to collect the...

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  • White Papers // May 2011

    Deriving Generalised Stochastic Petri Net Performance Models From High-Precision Location Tracking Data

    Stochastic performance models have been widely used to analyze the performance and reliability of systems that involve the flow and processing of customers and/or resources with multiple service centres. However, the quality of performance analysis delivered by a model depends critically on the degree to which the model accurately represents...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • White Papers // May 2011

    Learning to Use the Spectrum in Self-Configuring Heterogenous Networks: A Logit Equilibrium Approach

    In this paper, the authors study the particular scenario where several transmitter-receiver pairs communicate subject to mutual interference due to the usage of the same frequency bands. In particular, they focus on the case of heterogeneous networks, where radio devices have different interests (utility functions), transmit configurations (sets of actions),...

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  • White Papers // May 2011

    Revenue Maximization in Spectrum Auction for Dynamic Spectrum Access

    In this paper, the authors consider the revenue maximization problem in auctions for dynamic spectrum access. They assume a frequency division method of spectrum sharing with a primary spectrum owner that can divide the available spectrum into sub-bands and sell them to secondary users. They assume that a secondary user's...

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  • White Papers // May 2011

    Modeling Network Coded TCP Throughput: A Simple Model and Its Validation

    The authors analyze the performance of TCP and TCP with Network Coding (TCP/NC) in lossy wireless networks. They build upon the simple framework introduced by Padhye et al. and characterize the throughput behavior of classical TCP as well as TCP/NC as a function of erasure rate, roundtrip time, maximum window...

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  • White Papers // May 2011

    A Symbolic Approach to Quantitative Analysis of Preemptive Real-Time Systems With Non-Markovian Temporal Parameters

    The method of stochastic state classes provides a means for quantitative analysis of a rather wide class of non-Markovian models. As a major and structural limitation, the approach cannot be applied to models encompassing a preemptive policy, which in the practice rules out the mechanism of suspension and resume usually...

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  • White Papers // May 2011

    Socially Optimal Pricing of Cloud Computing Resources

    The cloud computing paradigm offers easily accessible computing resources of variable size and capabilities. The authors consider a cloud-computing facility that provides simultaneous service to a heterogeneous, time-varying population of users, each associated with a distinct job. Both the completion time, as well as the user's utility, may depend on...

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  • White Papers // May 2011

    HASL: An Expressive Language for Statistical Verification of Stochastic Models

    The authors introduce the Hybrid Automata Stochastic Logic (HASL), a new temporal logic formalism for the verification of Discrete Event Stochastic Processes (DESP). HASL employs Linear Hybrid Automata (LHA) as machineries to select prefixes of relevant execution paths of a DESP. The advantage with LHA is that rather elaborate information...

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  • White Papers // May 2011

    On Distributed Power Control and Transceiver Optimization in Wireless Networks

    This paper outlines some recent results on the max-min SIR balancing problem in wireless networks in which power control and beamforming are the only mechanisms for resource allocation and interference management. In addition, the authors describe several potential extensions and improvements to existing algorithmic solutions, as well as prove the...

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  • White Papers // May 2011

    A Survey on YouTube Streaming Service

    Established in 2005, YouTube is one of the fastest-growing websites, and has become one of the most accessed sites in the Internet. It has a significant impact on the Internet traffic distribution, but itself is suffering from severe scalability constraints and quality of service. Understanding the features of YouTube is...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • White Papers // Jun 2012

    On Combined Beamforming and OSTBC Over the Cognitive Radio S-Channel With Partial CSI

    A pair of secondary (cognitive, unlicensed) users is communicating in the presence of multiple primary (licensed) user pairs. The cognitive transceiver is implementing beamforming and orthogonal space-time block coding in the presence of external interference, induced by the primary system transmission, that has to be properly handled. Moreover, the cognitive...

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  • White Papers // Jun 2012

    Estimation-Based Noise-Robust Sensing

    It is well known that noise-modeling uncertainties give rise to a fundamental limit on the sensitivity of energy-based detectors (or related moment-based detectors), also known as the "SNR wall". Similar "Walls" appear also when localizing unknown sources for various applications (including cognitive radio), since localization techniques are based on tempo-spatial...

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  • White Papers // Jun 2012

    Spectrum Trading With Interference Rights

    Spectrum, which supports the transmission of sound, data, and video, is critical to the implementation of mobile connected society. Federal Communications Commission (FCC) has been seeking policies that offer more spectrum access opportunities, such as secondary spectrum market and TV white space. In this paper, the authors develop the idea...

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  • White Papers // Jun 2012

    Spectrum Sensing Using Single-Radio Switched-Beam Antenna Systems

    The paper describes spectrum sensing using single-radio switched-beam arrays with reactance-loaded parasitic elements. At a given frequency, the antenna's loading conditions (reactive loads) are optimized for maximum average beamforming gain in the beampattern look direction. Circular permutations of the reactive loads rotate the narrowband beampattern to different angular positions dividing...

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  • White Papers // Jun 2012

    Shadow Chasing : A Resource Allocation Scheme For Heterogeneous Networks

    In this paper, the authors propose a resource allocation scheme for interference mitigation in heterogeneous networks to simultaneously serve both Macrocell User Equipments (MUEs) and Home User Equipments (HUEs). In the proposed Shadow Chasing scheme, a Home eNB (HeNB) uses Downlink Control Information (DCI) together with ACK/NAK feedback to assign...

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  • White Papers // Jun 2012

    Rate Adaptation in Unlicensed Bands Under Smart Jamming Attacks

    Wireless communication protocols for unlicensed frequency bands support Rate Adaptation Algorithms (RAAs) to cope with time-varying channel conditions. RAAs are not designed to operate against adversarial behavior, however. In this paper, the authors analyze the vulnerabilities of two state-of-the-art RAAs, Minstrel and RARF, against a smart jamming model, whereby an...

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  • White Papers // Jun 2012

    On TDD Cross-Tier In-Band Interference Mitigation: A Practical Example

    This paper considers in-band interference that appears in two-tier macro/femto cellular networks when macrocells and femtocells operate on the same frequency band. They focus on the Time Division Duplex (TDD) mode where uplink-downlink interference occurs if time sharing between uplink and downlink are different in the overlaying macrocell and underlying...

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  • White Papers // Jun 2012

    Impact of Deployment Costs and Spectrum Prices on the Business Viability of Mobile Broadband Using TV White Space

    In this paper, the authors analyze the business feasibility of mobile broadband access services using secondary access of spectrum in the TV bands. They use a capacity-cost analysis considering costs for radio equipment, base station sites and radio spectrum. They compare network deployment by a market entrant and an existing...

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  • White Papers // Jun 2012

    GRaTIS: Sensing and Intelligence for Performance in the Presence of Legacy Networks

    Recent work has examined techniques to estimate the "Best" modulation rate for data networks such as OFDM-based 802.11a/g. Each rate is effective in a range of Signal-to-Noise Ratios (SNRs) but the limited number of practical rates often force the transmitter to "Step down" to a lower data rate despite having...

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  • White Papers // Jun 2012

    A Novel Architectural Framework and Configuration Scheme for Spectrum Sensing

    This paper proposes a novel architecture and configuration scheme for single-node spectrum sensing. It is assumed that the sensing node may use more than one sensing algorithms. The proposed sensing architecture allows a dynamic algorithm selection that depends on the sensing configuration parameters, and it includes a regulatory conformance checking....

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  • White Papers // Jun 2012

    Duty Cycle and Channel Occupancy Rate Estimation With MED-FCME LAD ACC

    Duty Cycle (DC) and Channel Occupancy Rate (COR) measurements are important to characterize the availability of white space for cognitive radio systems. To facilitate accurate DC measurements, the authors apply the Localization Algorithm based on Double-thresholding (LAD) with the Adjacent Cluster Combining (ACC). In order to get stable thresholds, the...

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  • White Papers // Jun 2012

    Wideband Frequency Domain Detection Using Teager-Kaiser Energy Operator

    This paper addresses wireless microphone sensing in the TV white space and efficient detection of narrowband FM modulation signals. To this end, a wideband frequency domain analysis is proposed. The required Fast Fourier Transform for this operation may be shared between sensing analysis and modulation functions. A particular decision metric...

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  • White Papers // Jun 2012

    Multiuser Automatic Modulation Classification for Cognitive Radios Using Distributed Sensing in Multipath Fading Channels

    Automatic Modulation Classifier (AMC) is an important component of a Cognitive Radio (CR) architecture that helps in better utilization of the spectrum. The successful implementation and employment of various cognitive radio services are largely dependent on the modulation classification performance of the cognitive radio terminals. AMC in literature is mostly...

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  • White Papers // Jun 2012

    Iterative Receiver Signal Processing for Joint Mitigation of Transmitter and Receiver Phase Noise in OFDM-Based Cognitive Radio Link

    In opportunistic spectrum access and cognitive radio, the device is assumed to be operating over a very wide range of Radio Frequencies (RF). This implies that severe implementation imperfections can take place in the RF modules of the devices. One such imperfection is oscillator phase noise. In this paper, the...

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  • White Papers // Jun 2012

    Server-Uncertain Spectrum Trading in Cognitive Radio Networks: A Queueing-Theoretic Modeling Approach

    Spectrum trading is the promising method to improve spectrum efficiency from the perspective of economics. In this paper, the authors propose a queueing-theory based spectrum trading model, where the primary user plays the server role providing spectrum to the secondary user who acts as the customer. The most significant challenge...

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  • White Papers // Apr 2012

    Minimizing Symbol Error Rate for Cognitive Relaying With Opportunistic Access

    In this paper, the authors present an Optimal Resource Allocation scheme (ORA) for an All-Participate (AP) cognitive relay network that minimizes the Symbol Error Rate (SER). The SER is derived and different constraints are considered on the system. They consider the cases of both individual and global power constraints, individual...

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  • White Papers // Jun 2012

    Long-Range Communications in Licence-Exempt TV White Spaces: An Introduction to Soft-Licence Concept

    Spectrum deregulation in wireless industry along with advancements in Cognitive Radio (CR) technology has opened up opportunities to access under-utilised spectral bands such as TV White Spaces (TVWS). Certain services in TVWS would require access to spectrum which is predictable, measurable and offer a higher degree of certainty currently difficult...

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  • White Papers // Jun 2012

    Jointly Optimal Sensing and Resource Allocation for Multiuser Interweave Cognitive Radios

    Successful deployment of cognitive radios requires efficient sensing of the spectrum and dynamic adaptation of the available resources according to the sensed (imperfect) information. While most works design these two tasks separately, in this paper the sensing and resource allocation schemes are designed jointly. The authors investigate an interweave CR...

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  • White Papers // Jun 2012

    Cognitive Radios With Ergodic Capacity Guarantees for Primary Users

    Cognitive radios implement adaptive resource allocation schemes that exploit knowledge of the channel state information to optimize the performance of the secondary users while limiting the interference to the primary users. The algorithms in this paper are designed to maximize the weighted sum-rate of secondary users which transmit orthogonally and...

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  • White Papers // Jun 2012

    Opportunistic Spectrum Access in Cognitive Radio Based on Channel Switching

    This paper investigates the performance of a cognitive radio transceiver that can monitor multiple channels and opportunistically use any one of them should it be available. In the authors' work, they propose and compare two different opportunistic channel access schemes. The first scheme applies when the Secondary User (SU) has...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • White Papers // Jun 2011

    Stochastic-Geometric Model of Expected Service Area for Cognitive TV White Space Wireless Networks

    The authors address the problem of interference between cognitive wireless networks coexisting in the TV White Space (TVWS). They perform stochastic geometry analysis in order to evaluate the service area secondary cognitive devices can expect under mild to severe interference of neighboring networks. From their analysis, they foresee severe service...

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  • White Papers // May 2011

    Learning to Use the Spectrum in Self-Configuring Heterogenous Networks: A Logit Equilibrium Approach

    In this paper, the authors study the particular scenario where several transmitter-receiver pairs communicate subject to mutual interference due to the usage of the same frequency bands. In particular, they focus on the case of heterogeneous networks, where radio devices have different interests (utility functions), transmit configurations (sets of actions),...

    Provided By ICST

  • White Papers // May 2011

    Revenue Maximization in Spectrum Auction for Dynamic Spectrum Access

    In this paper, the authors consider the revenue maximization problem in auctions for dynamic spectrum access. They assume a frequency division method of spectrum sharing with a primary spectrum owner that can divide the available spectrum into sub-bands and sell them to secondary users. They assume that a secondary user's...

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