Karlsruhe Institute of Technology

Displaying 1-40 of 103 results

  • White Papers // Mar 2014

    Comparison of Request Admission Based Performance Isolation Approaches in Multi-Tenant Saas Applications

    In the Software-as-a-Service (SaaS) model one single application instance is usually shared between different tenants to decrease operational costs. However, sharing at this level may lead to undesired influence from one tenant onto the performance observed by the others. Intentionally, the application does not manage hardware resources and the responsible...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Mar 2014

    Resource Usage Control in Multi-Tenant Applications

    Multi-tenancy is an approach to share one application instance among multiple customers by providing each of them a dedicated view. This approach is commonly used by SaaS providers to reduce the costs for service provisioning. Tenants also expect to be isolated in terms of the performance they observe and the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jan 2014

    Scalable Business Process Execution in the Cloud

    Business processes orchestrate service requests in a structured fashion. Process knowledge, however, has rarely been used to predict and decide about cloud infrastructure resource usage. In this paper, the authors present an approach for BPM-aware cloud computing that builds on process knowledge to improve the timeliness and quality of resource...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jan 2014

    The Invasive Network on Chip - A Multi-Objective Many-Core Communication Infrastructure

    Invasive computing is a novel paradigm for massively parallel computing systems. The core objective of invasive computing is to support resource-aware programming through all layers of a system. An invasive application has the ability to explore and dynamically spawn its computation to neighboring processors, taking into account the status of...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jan 2014

    Interacting with Statistical Linked Data via OLAP Operations

    On-Line Analytical Processing (OLAP) promises an interface to analyze Linked Data containing statistics going beyond other interaction paradigms such as follow-your-nose browsers, faceted-search interfaces and query builders. As a new way to interact with statistical Linked Data the authors define common OLAP operations on data cubes modelled in RDF and...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Nov 2013

    Scalable and Live Trace Processing with Kieker Utilizing Cloud Computing

    Knowledge of the internal behavior of applications often gets lost over the years. This paper can arise, for example, from missing documentation. Application-level monitoring, e.g., provided by the researcher, can help with the comprehension of such internal behavior. However, it can have large impact on the performance of the monitored...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2013

    Future Challenges for Linked APIs

    A number of approaches combine the principles and technologies of linked data and RESTful services. Services and APIs are thus enriched by, and contribute to, the web of data. These resource-centric approaches, referred to as linked APIs, focus on flexibility and the integration capabilities of linked data. The authors use...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2013

    Knowledge Discovery meets Linked APIs

    Knowledge Discovery and Data Mining (KDD) is a very well-established research field with useful techniques that explore patterns and regularities in large relational, structured and unstructured datasets. Theoretical and practical development in this field have led to useful and scalable solutions for the tasks of pattern mining, clustering, graph mining,...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2013

    Towards Online Performance Model Extraction in Virtualized Environments

    Virtualization increases the complexity and dynamics of modern software architectures making it a major challenge to manage the end-to-end performance of applications. Architecture-level performance models can help here as they provide the modeling power and analysis flexibility to predict the performance behavior of applications under varying workloads and configurations. However,...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2013

    Model-Based Throughput Prediction in Data Center Networks

    In this paper, the authors address the problem of performance analysis in computer networks. They present a new meta-model designed for the performance modeling of network infrastructures in modern data centers. Instances of their meta-model can be automatically transformed into stochastic simulation models for performance prediction. They evaluate the approach...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2013

    LoGV: Low-overhead GPGPU Virtualization

    Over the last few years, running high performance computing applications in the cloud has become feasible. At the same time, GPGPUs are delivering unprecedented performance for HPC applications. Cloud providers thus face the challenge to integrate GPGPUs into their virtualized platforms, which has proven difficult for current virtualization stacks. In...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2013

    Vectorizing Database Column Scans with Complex Predicates

    The performance of the full table scan is critical for the overall performance of column-store database systems such as the SAP HANA database. Compressing the underlying column data format is both an advantage and a challenge, because it reduces the data volume involved in a scan on one hand and...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2013

    Multi-Tenancy Performance Benchmark for Web Application Platforms

    Cloud environments reduce data center operating costs through resource sharing and economies of scale. Infrastructure-as-a-Service (IaaS) is one example that leverages virtualization to share infrastructure resources. However, virtualization is often insufficient to provide Software-as-a-Service (SaaS) applications due to the need to replicate the operating system, middleware and application components for...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2013

    Elasticity in Cloud Computing: What It Is, and What It Is Not

    Originating from the field of physics and economics, the term elasticity is nowadays heavily used in the context of cloud computing. In this context, elasticity is commonly understood as the ability of a system to automatically provision and deprovision computing resources on demand as workloads change. However, elasticity still lacks...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2013

    A Method for Simulating Cloud Business Models: A Case Study on Platform as a Service

    Cloud computing has changed how software is produced, distributed, consumed, and priced. The cloud paradigm has had a disruptive effect on existing business models and elicited a need for more thoroughly defined business models as well as the tools to represent and compare business models. In this paper, the authors...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Mar 2013

    Conceptual Approach for Performance Isolation in Multi-Tenant Systems

    Multi-Tenant Applications (MTAs) share one application instance among several customers to increase the efficiency. Due to the tight coupling, customers may influence each other with regards to the performance they observe. Existing paper focuses on methods and concrete algorithms to performance-isolate the tenants. In this paper, the authors present conceptual...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Dec 2012

    Towards Truthful Resource Reservation in Cloud Computing

    Prudent capacity planning to meet their clients future computational needs is one of the major issues cloud computing providers face today. By offering resource reservations in advance, providers gain insight into the projected demand of their customers and can act accordingly. However, customers need to be given an incentive, e.g....

    Provided By Karlsruhe Institute of Technology

  • White Papers // Dec 2012

    Decentralized Control Based on Globally Optimal Estimation

    A new method for globally optimal estimation in decentralized sensor-networks is applied to the decentralized control problem. The resulting approach is proven to be optimal when the nodes have access to all information in the network. More precisely, the authors utilize an algorithm for optimal distributed estimation in order to...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Nov 2012

    A Social Content Delivery Network for Scientific Cooperation: Vision, Design, and Architecture

    Data volumes have increased so significantly that the authors need to carefully consider how they interact with, share, and analyze data to avoid bottlenecks. In contexts such as e-Science and scientific computing, a large emphasis is placed on collaboration, resulting in many well-known challenges in ensuring that data is in...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2012

    A Flexible Approach for Compiling Scilab to Reconfigurable Multi-Core Embedded Systems

    The mapping process of high performance embedded applications to today's reconfigurable Multi-Processor System-on-Chip (MPSoC) devices suffers from a complex tool-chain and programming process. Thus, the efficient programming of such architectures in terms of achievable performance and power consumption is limited to experts only. Enabling them to non-experts requires a simplified...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2012

    Network Virtualization for QoS-Aware Resource Management in Cloud Data Centers: A Survey

    The increasing popularity of Cloud Computing is leading to the emergence of large virtualized data centers hosting increasingly complex and dynamic IT systems and services. Over the past decade, the efficient sharing of computational resources through virtualization has been subject to intensive research, while network management in cloud data centers...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Optimal Point Estimates for Multi-Target States Based on Kernel Distances

    Almost all multi-target tracking systems have to generate point estimates for the targets, e.g., for displaying the tracks. The novel idea in this paper is to consider point estimates for multi-target states that are optimal according to a kernel distance measure. Because the kernel distance is a metric on point...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Stochastic Nonlinear Model Predictive Control Based on Progressive Density Simplification

    Increasing demand for nonlinear model predictive control with the ability to handle highly noise-corrupted systems has recently given rise to stochastic control approaches. Besides providing high-quality results within a noisy environment, these approaches have one problem in common, namely a high computational demand and, as a consequence, generally a short...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Sequence-Based Control for Networked Control Systems Based on Virtual Control Inputs

    In this paper, the authors address the problem of controlling a system over an unreliable UDP-like network that is affected by time-varying delays and randomly occurring packet losses. A major challenge of this setup is that the controller just has uncertain information about the control inputs actually applied by the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Optimal Kalman Gains for Combined Stochastic and Set-Membership State Estimation

    In state estimation theory, two directions are mainly followed in order to model disturbances and errors. Either uncertainties are modeled as stochastic quantities or they are characterized by their membership to a set. Both approaches have distinct advantages and disadvantages making each one inherently better suited to model different sources...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2012

    A Conceptual Framework for Simulating Autonomic Cloud Markets

    One of the major challenges facing the Cloud paradigm is the emergence of suitable economic platforms for the trading of Cloud services. Today, many researchers investigate how specific Cloud market platforms can be conceived and in some cases implemented. However, such endeavours consider only specific types of actors, business models,...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2012

    Control Over Unreliable Networks Based on Control Input Densities

    Time delays and data losses arising from an unreliable communication between the components of a control loop decrease the quality of control and thus, have to be incorporated explicitly in the control decision. In this paper, a novel concept, the so-called virtual control inputs, is presented, which extends the well-established...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2012

    Combined Stochastic and Set-Membership Information Filtering in Multisensor Systems

    In state estimation theory, stochastic and set membership approaches are generally considered separately from each other. Both concepts have distinct advantages and disadvantages making each one inherently better suited to model different sources of estimation uncertainty. In order to better utilize the potentials of both concepts, the core element of...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jun 2012

    Tightly Secure Signatures and Public-Key Encryption

    The authors construct the first public-key encryption scheme whose chosen-ciphertext (i.e., INDCCA) security can be proved under a standard assumption and does not degrade in either the number of users or the number of ciphertexts. In particular, their scheme can be safely deployed in unknown settings in which no a-priori...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jun 2012

    Spectral Estimation-Based OFDM Radar Algorithms for IEEE 802.11a Signals

    Recently, OFDM radar has gained attention as new algorithms for range and Doppler estimation specific to OFDM signals have been developed. The major advantage of OFDM is that it is both well-suited for radar processing as well as being suitable for communication. In previous work, the authors have proposed parametrizations...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jun 2012

    Collision-Balancing Frequency Hopping in Single-Hop Mobile Ad Hoc Networks

    The authors consider a single-hop Frequency Hopping (FH) Mobile Ad hoc NETwork (MANET). To increase throughput Orthogonal FH (O-FH) with hop-synchronous hopping can be used, thereby allowing collision-free transmissions under certain circumstances. However, as the MANET grows, hopping sequences must be re-used. As a result, nodes sharing the same sequence...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Hopping Strategies for Adaptive FH-CDMA Ad Hoc Networks Under External Interference

    The authors discuss the performance of an adaptive FHCDMA ad hoc network under the influence of external interference where node positions are modeled by a homogeneous Poisson point process. The optimum channel assignment that balances internal network interference due to spatial reuse and external interference is derived analytically for a...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Increasing the One-Hop Progress of Nearest Neighbor Forwarding

    Wireless networks have recently gained much attraction due to several reasons: research on hardware has achieved considerable advances in the development of small and inexpensive communications devices. A fundamental property of these networks is that communication does not rely on a wired backbone. Hence, nodes additionally have to function as...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Adaptive Frequency Hopping in Ad Hoc Networks With Rayleigh Fading and Imperfect Sensing

    A probabilistic model for Adaptive Frequency Hopping (AFH) based wireless ad hoc networks with Rayleigh fading, where interference is due to self - and to slow-varying external interference, is proposed. Different AFH sensing techniques are studied in terms of Area Spectral Efficiency (ASE) and it is shown that self-interference can...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Tracking 3D Shapes in Noisy Point Clouds With Random Hypersurface Models

    State of the art depth-sensors such as range cameras (time-of-flight, structured light, stereo) or laser rangefinder obtain three-dimensional point cloud data of a given real-world scene. Recently, multi-sensor setups have received increasing attention. Point clouds have become highly relevant for many real world applications, such as surveillance, target tracking, 3D...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Interference and Throughput in Aloha-based Ad Hoc Networks With Isotropic Node Distribution

    The authors study the interference and outage statistics in a slotted Aloha ad hoc network, where the spatial distribution of nodes is non-stationary and isotropic. In such a network, outage probability and local throughput depend on both the particular location in the network and the shape of the spatial distribution....

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Modeling the Target Extent With Multiplicative Noise

    Extended target tracking deals with simultaneously tracking the shape and the kinematic parameters of a target. In this paper, the authors formulate the extended target tracking problem as a state estimation problem with both multiplicative and additive measurement noise. In case of extended targets with known orientation, they show that...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    State Estimation in Networked Control Systems

    The authors consider the problem of state estimation in a Networked Control System, where measurements and control inputs are transmitted via a communication network. The network is subject to time-varying delays and stochastic data losses and does not provide acknowledgments of successfully transmitted data packets. A challenge that arises in...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    A Robust Computational Test for Overlap of Two Arbitrary-Dimensional Ellipsoids in Fault-Detection of Kalman Filters

    On-line fault-detection in uncertain measurement and estimation systems is of particular interest in many applications. In certain systems based on the Kalman filter, this test can be performed by checking whether hyper-ellipsoids overlap. This test can be applied to detecting failure in the system itself or in the sensors used...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Recursive Bayesian Calibration of Depth Sensors With Non-Overlapping Views

    Setting up a network of multiple depth sensors introduces several issues that need to be addressed. For example, the popular Microsoft Kinect TM device acquires depth information using an active measurement system which projects an infrared pattern. This has important consequences in setups with overlapping fields of view, where the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Hopping Strategies for Adaptive FH-CDMA Ad Hoc Networks Under External Interference

    The authors discuss the performance of an adaptive FHCDMA ad hoc network under the influence of external interference where node positions are modeled by a homogeneous Poisson point process. The optimum channel assignment that balances internal network interference due to spatial reuse and external interference is derived analytically for a...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Mar 2012

    ECO/ee: Energy-Aware Collaborative Organic Execution Environment for Wireless Sensor Networks

    This paper presents an energy-aware execution environment, called Energy-aware Collaborative Organic Execution Environment (ECO/ee), for Wireless Sensor Networks (WSN). ECO/ee provides an energy-aware and autonomous data routing scheme. It can dynamically adapt to the user's queries and efficiently determine the energy-abundant delivery paths. The fundamental concepts are inspired by the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Apr 2012

    CloudGenius: Decision Support for Web Server Cloud Migration

    Cloud computing is the latest computing paradigm that delivers hardware and software resources as virtualized services in which users are free from the burden of worrying about the low-level system administration details. Migrating Web applications to Cloud services and integrating Cloud services into existing computing infrastructures is non-trivial. It leads...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Feb 2012

    A Virtualized Usage Control Bus System

    Usage control is an extension of access control that additionally defines what must and must not happen to data after access has been granted. The process of enforcing usage control requirements on data must take into account all the different representations that the data may assume at different levels of...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Stochastic Nonlinear Model Predictive Control Based on Progressive Density Simplification

    Increasing demand for nonlinear model predictive control with the ability to handle highly noise-corrupted systems has recently given rise to stochastic control approaches. Besides providing high-quality results within a noisy environment, these approaches have one problem in common, namely a high computational demand and, as a consequence, generally a short...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Optimal Point Estimates for Multi-Target States Based on Kernel Distances

    Almost all multi-target tracking systems have to generate point estimates for the targets, e.g., for displaying the tracks. The novel idea in this paper is to consider point estimates for multi-target states that are optimal according to a kernel distance measure. Because the kernel distance is a metric on point...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Sequence-Based Control for Networked Control Systems Based on Virtual Control Inputs

    In this paper, the authors address the problem of controlling a system over an unreliable UDP-like network that is affected by time-varying delays and randomly occurring packet losses. A major challenge of this setup is that the controller just has uncertain information about the control inputs actually applied by the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2012

    Optimal Kalman Gains for Combined Stochastic and Set-Membership State Estimation

    In state estimation theory, two directions are mainly followed in order to model disturbances and errors. Either uncertainties are modeled as stochastic quantities or they are characterized by their membership to a set. Both approaches have distinct advantages and disadvantages making each one inherently better suited to model different sources...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Dec 2012

    Decentralized Control Based on Globally Optimal Estimation

    A new method for globally optimal estimation in decentralized sensor-networks is applied to the decentralized control problem. The resulting approach is proven to be optimal when the nodes have access to all information in the network. More precisely, the authors utilize an algorithm for optimal distributed estimation in order to...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Modeling the Target Extent With Multiplicative Noise

    Extended target tracking deals with simultaneously tracking the shape and the kinematic parameters of a target. In this paper, the authors formulate the extended target tracking problem as a state estimation problem with both multiplicative and additive measurement noise. In case of extended targets with known orientation, they show that...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    State Estimation in Networked Control Systems

    The authors consider the problem of state estimation in a Networked Control System, where measurements and control inputs are transmitted via a communication network. The network is subject to time-varying delays and stochastic data losses and does not provide acknowledgments of successfully transmitted data packets. A challenge that arises in...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    A Robust Computational Test for Overlap of Two Arbitrary-Dimensional Ellipsoids in Fault-Detection of Kalman Filters

    On-line fault-detection in uncertain measurement and estimation systems is of particular interest in many applications. In certain systems based on the Kalman filter, this test can be performed by checking whether hyper-ellipsoids overlap. This test can be applied to detecting failure in the system itself or in the sensors used...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2012

    Control Over Unreliable Networks Based on Control Input Densities

    Time delays and data losses arising from an unreliable communication between the components of a control loop decrease the quality of control and thus, have to be incorporated explicitly in the control decision. In this paper, a novel concept, the so-called virtual control inputs, is presented, which extends the well-established...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Apr 2011

    Multiple Access Interference Mitigation Through Multi-Level Locally Orthogonal FH-CDMA

    Multi-Level Locally Orthogonal Frequency Hopping Mode Division Multiple Access (MLLO-FH-CDMA) is introduced as a novel method to reduce self-interference in large scale FHCDMA ad hoc networks. It is analyzed in a stochastic geometry scenario and verified with simulations. The performance gains of multi-level hopping are shown by comparing it to...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jun 2011

    Capacity Regions of Wireless Multi-Channel Ad Hoc Networks

    The authors consider the influence of FDMA on the capacity region of wireless ad hoc networks with a small number of nodes. It is found that FDMA offers an additional degree of freedom that is beneficial in interference-limited networks. Furthermore, simulation results indicate that static FDMA channel assignment over a...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2011

    On the Single-Target Accuracy of OFDM Radar Algorithms

    Two OFDM radar algorithms (the Maximum Likelihood and a MUSIC-based algorithm) are introduced and their fundamental limits concerning accuracy are explained. To simplify the analysis, the authors research the special case of only one target in the radar's detection range, which facilitates the individual effects on the estimation quality. Through...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Mar 2011

    An Over-the-Air Reconfiguration API for Experimental Cognitive Radio Setups

    The authors present a software solution for over-the-air reconfiguration of remote software radio terminals using the free GNU Radio toolkit, facilitating the development of Cognitive Radio applications. The modular architecture allows for separating the cognitive engine from the signal processing algorithms, thus allowing fast implementation, verification and easier testing. Cognitive...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2010

    Narrow- and Broadband Interference Robustness for OOK/BPPM Based Energy Detection

    An analysis of narrow- and broadband interference robustness within an On-Off Keying/Binary Pulse Position Modulation based non-coherent multiband impulse radio ultra-wideband communication system is presented. Using the energy detector's processing gain closed-form expressions of the noise and interference related second order moment statistics at the output of an energy detection...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2011

    Lower Bounds on the Success Probability for Ad Hoc Networks With Local FDMA Scheduling

    This paper studies the performance of ad hoc networks with local FDMA scheduling using stochastic point processes. In such networks, the Poisson assumption is not justified due to interdependencies between points introduced by scheduling. For this reason, an upper bound on the second reduced moment measure is derived. Using this...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Feb 2011

    Resolving the Connectivity-Throughput Trade-Off in Random Networks

    The discrepancy between the upper bound on throughput scaling in wireless networks and the throughput scaling in random networks is due to the connectivity-throughput trade-off. In this paper, nodes know their location and employ power control. The expected throughput-progress is analyzed for a nearest neighbor forwarding strategy, which benefits from...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2012

    Increasing the One-Hop Progress of Nearest Neighbor Forwarding

    Wireless networks have recently gained much attraction due to several reasons: research on hardware has achieved considerable advances in the development of small and inexpensive communications devices. A fundamental property of these networks is that communication does not rely on a wired backbone. Hence, nodes additionally have to function as...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jan 2011

    Lowering Outage Probability in Ad Hoc Networks by Nearest Neighbor FDMA Scheduling

    This paper investigates the performance of a wireless ad hoc network capable of dynamically coordinating a set of orthogonal frequency channels such that every receiver and its nearest interferer operate in different channels. The distribution of the ratio of the interference powers of the second and first interferer is derived...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2010

    Components for Software Radio Wideband Receivers: A Space Segment Survey

    Many interesting scenarios are emerging on the horizon of satellite communication: communication system flexibility is a keyword for revenue enhancement and Software Defined Radio (SDR) is a means for achieving it. However, its development on the satellite side is slowed down by several constraints that the harsh space environment imposes...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2010

    A Note on Local Receive Channel Scheduling versus Transmit Channel Scheduling in Wireless Multi-Channel Ad Hoc Networks

    A wireless ad hoc network consists of a collection of nodes communicating without a-priori known traffic pattern. In contrast to cellular networks, nodes in an ad hoc network must organize network topology and exchange information concerning the network state. The interrelation of many components of ad hoc networks such as...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Apr 2010

    Combination of Centralized & Decentralized Database and Terminal-Based Spectrum Sensing for Secondary Spectrum Access

    Since, the original Cognitive Radio (CR) concept had emerged, the opportunistic usage of selected frequency bands has become one of the most promising application scenarios from the perspective of a near-to mid-term broad market deployment. Driven by the prospect of a hugely increased overall spectral efficiency through the opportunistic exploitation...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Feb 2010

    Incremental Relaying With Imperfect Feedback in Wireless Cooperative Networks

    The authors present the ???-outage capacity in the low Signal-to-Noise Ratio (SNR) regime of an incremental relaying network. The network consists of one source, one destination, and two half-duplex relays. The one-bit feedback from the destination node is considered to be imperfect and is modeled as binary symmetric channel. The...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2010

    On the Frame Design for Joint OFDM Radar and Communications

    The authors discuss how to design OFDM signals which are suitable for both radar and communications using high-bandwidth OFDM signals. A list of constraints which the signal configuration must comply with is defined. They present a solution which satisfies the requirements for radar and allows for reliable communications. In the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jun 2010

    Signal Design and Coding for High-Bandwidth OFDM in Car-to-Car Communication

    The authors analyze mobile propagation channels which occur in the context of car-to-car communications in the 24 GHz ISM band. From the information gathered, they design robust frame designs for combined radar and communication systems using high-bandwidth OFDM signals. Two solutions are proposed: the combination of a spread spectrum technique...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Oct 2009

    Wireless Networks In-the-Loop: Software Radio as the Enabler

    A software architecture to rapidly develop and test radio networks in real and physical environments is proposed. Radio network terminals are developed in software and run on generic hardware to maximize re-configurability. Due to the software nature of the radio terminals, radio networks can be simulated in a virtual environment,...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jan 2010

    Maximum Likelihood Speed and Distance Estimation for OFDM Radar

    A distance and speed estimation algorithm for OFDM based radar is analyzed statistically. The maximum likelihood estimator is derived and compared to previous results. A connection to spectral analysis is drawn, simplifying the analysis of the estimator in question. Finally, a method to evaluate the performance of the algorithm is...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Feb 2010

    Wideband Receiver for a Spaceborne Software Radio Application

    Software Defined Radio (SDR), thanks to the recent technological advancements, has become one of the valuable solutions to achieve flexibility in a regenerative communication payload on board the satellite. However, in order to take advantage of all its potentialities much work needs still to be done to overcome the related...

    Provided By Karlsruhe Institute of Technology

  • White Papers // May 2010

    Wireless Networks In-the-Loop: Emulating an RF Front-End in GNU

    The objective of this paper is to emulate the behavior of the Universal Software Radio Peripheral as an example of an RF front-end hardware for software radios. The model includes digital and analog signal processing. The emulator is implemented in GNU Radio and is intended to be used as part...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Mar 2010

    A Simple Stochastic Channel Simulator for Car-to-Car Communication at 24 GHz

    A channel model, based on stochastics and Ray tracing, is described for a communication system, in which moving participants communicate in the 24 GHz band. A realistic behaviour of propagation effects, both short-term and long-term, is modeled. This allows to simulate and design future vehicle-to-vehicle systems. Due to the increasing...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Nov 2009

    Software Defined Radio in Public and Governmental Security Systems

    Radio communication is crucial for Public and Governmental Security (P&GS) systems. No matter if a police officer waits for a radio message to get to his next scene or a firefighter needs to contact the operator, there will always be the need for a reliable, secure and fast radio communication...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2009

    Outage Regions and Optimal Power Allocation for Wireless Relay Networks

    The authors study outage regions for energy-constrained multi-hop and adaptive multi-route networks with an arbitrary number of relay nodes. Optimal power allocation strategies in the sense that outage probability is minimized are derived depending on the distances between the transmit nodes. They further investigate the rate gain of adaptive multi-route...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2009

    Outage Capacity of Incremental Relaying for Low Signal-to-Noise Ratios

    The authors present the ?-outage capacity of incremental relaying at low Signal-to-Noise Ratios (SNR) in a wireless cooperative network with slow Rayleigh fading channels. The relay performs decode-and-forward and repetition coding is employed in the network, which is optimal in the low SNR regime. They derive an expression on the...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Jul 2009

    A Novel Combining Receiver for a Dual-Diversity Wireless Relay Network

    The authors present a simple combining receiver for a dual-diversity wireless relay network. The main concern of the paper is to face the trade-off between performance and complexity. The receiver focuses on Signal-to-Noise Ratio (SNR) monitoring and selects dynamically between Selection Combining (SC) and Equal Gain Combining (EGC) depending on...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Sep 2009

    On Linearly Precompressed Non-Parametric Spectrum Estimation

    Extending the derivation of a maximum likelihood spectrum estimator by Stoica and Sundin, non-parametric spectrum estimation with linear pre-compression is introduced. For real-time applications, linear pre-compression allows for a scalable trade-off between data rate and accuracy of the estimate. Pre-compression is based on linear projection with a compression matrix formed...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Aug 2009

    Parametrization of Joint OFDM-Based Radar and Communication Systems for Vehicular Applications

    The design process of a joint radar and communication system employing OFDM is analyzed. In particular, the question on how to choose OFDM modulation parameters such as carrier distance, guard interval length, frame length or pilot design is studied. Such systems use the same OFDM frames to transmit data and...

    Provided By Karlsruhe Institute of Technology

  • White Papers // Apr 2009

    Compressed Spectrum Estimation for Cognitive Radios

    Cognitive Radios observe the spectral environment through spectrum estimation. In particular, reconfigurable Software Defined Radio architectures generate large amounts of sample data, which can be computationally expensive to analyze. Compression by time-shifted random pre-integration prior to spectrum estimation reduces the amount of data to be processed. It is simple to...

    Provided By Karlsruhe Institute of Technology