RWSoftware

Displaying 1-40 of 137 results

  • White Papers // Oct 2014

    Privacy-Preserving Indoor Localization

    Upcoming Wi-Fi-based localization systems for indoor environments face a conflict of privacy interests: server-side localization violates location privacy of the users, while localization on the user's device forces the localization provider to disclose the details of the system, e.g., sophisticated classification models. The authors show how secure two-party computation can...

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  • White Papers // Oct 2013

    Detecting Correlation Violations and Data Races by Inferring Non-Deterministic Reads

    With the introduction of multicore systems and parallel programs concurrency bugs have become more common. A notorious class of these bugs is data races that violate correlations between variables. This happens, for example, when the programmer does not update correlated variables atomically, which is needed to maintain their semantic relationship....

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  • White Papers // Oct 2013

    Predicting Parallelization of Sequential Programs Using Supervised Learning

    The authors investigate an automatic method for classifying which regions of sequential programs could be parallelized, using dynamic features of the code collected at runtime. They train a supervised learning algorithm on versions of the NAS Parallel Benchmark (NPB) code hand-annotated with OpenMP parallelization directives in order to approximate the...

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  • White Papers // Oct 2013

    Efficient Offloading of Parallel Kernels Using MPI Comm Spawn

    The integration of accelerators into cluster systems is currently one of the architectural trends in high performance computing. Usually, those accelerators are manycore compute devices which are directly connected to individual cluster nodes via PCI Express. Recent advances of accelerators, however, do not require a host CPU anymore and now...

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  • White Papers // Sep 2013

    Efficient Rough Set Theory Merging

    Theory exploration is a term describing the development of a formal (i.e. with the help of an automated proof-assistant) approach to selected topic, usually within mathematics or computer science. This activity however usually doesn't reflect the view of science considered as a whole, not as separated islands of knowledge. Merging...

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  • White Papers // Sep 2013

    A Multi-Agent Approach to Unstructured Data Analysis Based on Domain-Specific Onthology

    At present most organizations deal with large quantity of documents, licenses, manuals, emails, business letters, financial and technical reports etc. It is already impossible to process all these documents by hand, without automatic assistance. Ontological knowledge bases are a good solution for storing information from these documents, and automatically completing...

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  • White Papers // Sep 2013

    Discovery of Cancellation Regions within Process Mining Techniques

    Process mining is a relatively new field of computer science which deals with process discovery and analysis based on event logs. In this paper, the authors consider the problem of discovering work flow nets with cancellation regions from event logs. Cancellations occur in the majority of real-life event logs. In...

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  • White Papers // Sep 2013

    Analysis of Multilayer Neural Networks with Direct and Cross-Forward Connection

    Artificial neural networks are of much interest for many practical reasons. As of today, they are widely implemented. Of many possible ANNs, the most widely used ANN is the back-propagation model with direct connection. In this model the input layer is fed with input data and each subsequent layers are...

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  • White Papers // Aug 2013

    A Dynamic Resource Management System for Network-Attached Accelerator Clusters

    Over the years, cluster systems have become increasingly heterogeneous by equipping cluster nodes with one or more accelerators such as Graphic Processing Units (GPU). These devices are typically attached to a compute node via PCI Express. As a consequence, batch systems such as TORQUE/Maui and SLURM have been extended to...

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  • White Papers // Jul 2013

    Discovery of Potential Parallelism in Sequential Programs

    Although multicore CPUs are dominating the market of desktops and servers, writing programs that utilize the available hardware parallelism on these architectures still remains a challenge. In this paper, the authors present a dynamic approach for automatically identifying potential parallelism in sequential programs. Their method is based on the notion...

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  • White Papers // Apr 2013

    The Cloud Needs Cross-Layer Data Handling Annotations

    Now-a-days, an ever-increasing number of service providers take advantage of the cloud computing paradigm in order to efficiently offer services to private users, businesses, and governments. However, while cloud computing allows to transparently scale back-end functionality such as computing and storage, the implied distributed sharing of resources has severe implications...

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  • White Papers // Mar 2013

    Automatic Generation of Parallel Unit Tests

    Multithreaded software is subject to data races. Currently available data race detectors report such errors to the developer, but consume large amounts of time and memory; many approaches are not applicable for large software projects. Unit tests containing fractions of the program lead to better results. The authors propose AutoRT,...

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  • White Papers // Jan 2013

    MR-DSJ: Distance-Based Self-Join for Large-Scale Vector Data Analysis with MapReduce

    Data analytics gets faced with huge and tremendously increasing amounts of data for which MapReduce provides a very convenient and effective distributed programming model. Various algorithms already support massive data analysis on computer clusters but, in particular, distance-based similarity self-joins lack efficient solutions for large vector data sets though they...

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  • White Papers // Jan 2013

    On the Outage Probability and Effective Capacity of Multiple Decode-and-Forward Relay System

    This paper investigates the quality-of-service performance of multiple decode-and-forward relay system. In particular, the authors study the outage probability and effective capacity performance of the system based on average channel gain. First, a closed-form expression of outage probability is derived which is more concise than the previous work. Second, they...

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  • White Papers // Dec 2012

    SMC-MuSe: A Framework for Secure Multi-Party Computation on MultiSets

    Secure Multi-Party Computation (SMC) offers a theoretically well-founded way to enable applications that preserve their users' privacy. However, the practical use of SMC has often been questioned in the past. This is partly due to the fact that the system assumptions made in theory are hard to meet in practice...

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  • White Papers // Oct 2012

    A Dynamic Accelerator-Cluster Architecture

    Accelerators such as Graphics Processing Units (GPUs) provide an inexpensive way of improving the performance of cluster systems. In such an arrangement, the individual nodes of the cluster are directly connected to one or more accelerator devices via PCI Express. This results in a static mapping of accelerators onto compute...

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  • White Papers // Oct 2012

    First Survey Results of Quantified User Behavior in User-in-the-Loop Scenarios for Sustainable Wireless Networks

    Traffic in mobile radio networks is expected to continue to increase by 100% per year. This imposes a big challenge for future generations (4G and 5G) of access technologies which were previously dimensioned for over-provisioning especially in the busy hours. Recent forecasts hint that this assumption and approach will not...

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  • White Papers // Oct 2012

    Quantified User Behavior in User-in-the-Loop Spatially and Demand Controlled Cellular Systems

    User-centric services are a growing concern. While the digital society definitely needs better Quality-of-Experience (QoE) for the user, the applications on smart mobile devices will continue to raise traffic in mobile radio networks by almost 100% per annum. Future generations of access technologies are challenged by this and the conventional...

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  • White Papers // Oct 2012

    The Outage Performance of Realtime Transmission in Multiple Asynchronous Relays Enhanced OFDM System

    This paper considers the outage performance of multiple relays transmission in Orthogonal Frequency Division Multiplexing (OFDM) systems. Relaying has been suggested in general to improve the reliability of wireless systems significantly and is therefore a candidate for wireless industrial communication systems that need to meet tough latency and outage requirements....

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  • White Papers // Oct 2012

    Performance Analysis Techniques for Task-Based OpenMP Applications

    To harness the available performance of today's multi-core systems, applications need to make efficient use of the available parallelism. Cores sitting idle, for example in communication calls waiting for data to arrive or in synchronization operations due to load imbalance, waste resources and reduce the overall performance of the application....

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  • White Papers // Oct 2012

    Rate Selection Analysis Under Semi-Persistent Scheduling in LTE Networks

    Upcoming LTE networks have basically two different modes for scheduling data in the down-link by the base station. Dynamic scheduling brings the advantage of exploiting instantaneous channel state information while it puts on the other hand a significant burden on the system in terms of overhead and computation requirements. Especially...

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  • White Papers // Sep 2012

    Energy Efficiency of Network-Based Acoustic Echo Control in Mobile Radio

    In this paper, the authors investigate the energy efficiency of network-based Acoustic Echo Control (AEC). Usually, AEC is implemented in the mobile terminal. Due to the limited resources of the mobile terminal in terms of the battery, computational capacity and memory, the complexity of the AEC algorithm has to be...

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  • White Papers // Sep 2012

    Pattern-Independent Detection of Manual Collectives in MPI Programs

    In parallel applications, a significant amount of communication occurs in a collective fashion to perform, for example, broadcasts, reductions, or complete exchanges. Although the MPI standard defines many convenience functions for this purpose, which not only improve code readability and maintenance but are usually also highly efficient, many application programmers...

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  • White Papers // Aug 2012

    Distributed TV Spectrum Allocation for Cognitive Cellular Network Under Game Theoretical Framework

    This paper proposes efficient schemes for wireless cellular base stations to utilize TV white spectrum (such base stations referred to as white base stations - WBS), so that WBSes can provide good services to their end terminals without violating the incumbent TV services. In particular, the authors consider two complementary...

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  • White Papers // Jul 2012

    Impact of Measurement Configurations on the Accuracy of Propagation Model Estimation With Applications to Dynamic Spectrum Access

    In this paper, the authors investigate the possibility of using measurement-based propagation models in the framework of Dynamic Spectrum Access (DSA), where secondary users can opportunistically access the licensed spectrum of a primary system. In principle this will provide a precise representation of the radio environment since it takes into...

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  • White Papers // Jul 2012

    Reachability of the Capacity in Parallel Quantised Channels

    Based upon profound knowledge about wireless communication systems that was gathered during the past decades, modelling biological systems analogously has become more and more popular. Although the assumptions about the latter are sometimes less reliable than those about technical systems, some models have proven useful in explaining the behaviour of...

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  • White Papers // Jun 2012

    Interference Management in Heterogeneous Wireless Networks Based on Context Information

    Femtocells and WiFi have been considered as viable concepts in cellular networks to increase overall system capacity. Critical functionalities for the successful integration of such technologies in macro-cellular topologies are related to radio resource allocation and interference management techniques that must ensure seamless intra-cell and inter-cell interoperation among macro- and...

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  • White Papers // Jun 2012

    Performance Evaluation of Channel Access Protocols in Overlapping ECMA-368 Wireless Personal Area Networks

    Medium Access Control (MAC) protocols for Wireless Local Area Networks (WLANs) as well as Wireless Personal Area Networks (WPANs) like Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) are known to provide stable distributed channel access for multiple users. The wide acceptance of wireless systems operating in licensed-exempt frequencies demands...

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  • White Papers // Jun 2012

    Cell Spectral Efficiency Optimization in Relay Enhanced Cells

    The broad acceptance of Smartphones results in increasing capacity demands for mobile radio networks. Decode-and-Forward (DF)-Relay Stations (RSs) are promising to improve Cell Spectral Efficiency (CSE) and to better meet the capacity demands. In this paper, the authors investigate the potential of DF-RSs combined with a pico Base Station (BS)...

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  • White Papers // Jun 2012

    Detecting Irregularities in Blog Comment Language Affecting POS Tagging Accuracy

    Studying technology acceptance requires the survey and analysis of user opinions to identify acceptance-relevant factors. In addition to surveys, Web 2.0 poses a huge collection of user comments regarding different technologies. Extracting acceptance-relevant factors and user opinions from such comments requires the application of Natural Language Processing (NLP) methods, particularly...

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  • White Papers // Jun 2012

    How a Layered REM Architecture Brings Cognition to Today's Mobile Networks

    In this paper, the authors present a layered Radio Environment Map (REM) architecture along with its applications to the Self-Organizing Network (SON) functionalities of heterogeneous LTE radio-access networks comprising macrocells and femtocells. In this architecture, the functional blocks re-appear with different spatial and temporal granularity at different architectural layers. Although,...

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  • White Papers // May 2012

    Distributed Compressed Sensing for the MIMO MAC With Correlated Sources

    In this paper, the authors consider the transmission of jointly sparse signals over a MIMO MAC composed of two transmitters and one receiver. Distributed compression is performed at the transmitters using a liner transformation and joint reconstruction at the receiver is enabled using the theory of distributed compressed sensing. The...

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  • White Papers // May 2012

    Dynamic Cell Association for Downlink Sum Rate Maximization in Multi-Cell Heterogeneous Networks

    In this paper, the authors consider a heterogeneous network consisting in several macro nodes and pico nodes. The goal is to associate users, belonging to this network, to one of the nodes, while maximizing the sum rate of all users. They also want to analyze the load balancing achieved by...

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  • White Papers // May 2012

    Mesh-DHT: A Locality-Based Distributed Look-Up Structure for Wireless Mesh Networks

    Distributed Hash Tables (DHTs) offer an elegant and fully distributed solution for reliably storing and retrieving data. Wireless Mesh Networks (WMNs) envision a fully decentralized fashion, and as such require efficient decentralized mechanisms for service discovery, mobility support and data storage and retrieval. Hence, DHTs and WMNs seem to complement...

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  • White Papers // May 2012

    On the Performance of Cellular Network Deployments in TV Whitespaces

    In this paper, the authors analyze the prospects of deploying a cellular network in the TV whitespaces. They study the challenges of planning for a large-scale transmitter network that is constrained by an interference-to-primary regulation. For this purpose they derive a novel methodology to maximize the downlink capacity at the...

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  • White Papers // May 2012

    Wi-Fi, But Not on Steroids: Performance Analysis of a Wi-Fi-Like Network Operating in TVWS Under Realistic Conditions

    The recent decisions by regulators in the USA and UK to open up unused portions of UHF spectrum for secondary use have been met with keen interest in using these TV White Spaces (TVWS) for providing broadband services through Wi-Fi-like connectivity. Amid the ensuing media hype about "Wi-Fi on steroids",...

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  • White Papers // May 2012

    Shadow Fading Correlations With Compressive Sensing: Prediction Accuracy

    The cross-correlation between shadowing components in wireless communications has important implications for wireless systems. The new cooperative and cognitive communications methods can exploit these correlations, if the statistical properties of shadowing correlations were known in particular radio environment under the consideration. The statistical large scale models have higher uncertainty compared...

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  • White Papers // May 2012

    Modeling and Performance Evaluation for Mobile Ricean MIMO Channels

    The authors propose a general channel model for mobile Ricean Multiple-Input Multiple-Output (MIMO) channels, which is characterized by parameters that are readily obtainable from measurements. To this end, a moment-based channel decomposition is derived. For the case of statistical Channel State Information (CSI) at the Transmitter (TX) and instantaneous CSI...

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  • White Papers // Apr 2012

    Intelligibility Assessment of a System for Artifical Bandwidth Extension of Telephone Speech

    For the present study, the extension from the 0.3 - 3.4 kHz range towards higher audio frequencies was considered. The employed ABWE algorithm follows the source-filter model of speech production. Techniques for Artificial BandWidth Extension (ABWE) aim to extend the limited audio bandwidth of current narrowband telephone systems (0.3 -...

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  • White Papers // Apr 2012

    Wireless Mesh Network Security: State of Affairs

    Wireless Mesh Networks (WMNs) surely are one of the most prominent trends for Next Generation Networks. Their future success, however, depends on their security features. In this paper, the authors step back to classify and characterize Wireless Mesh Networks as a whole. This high-level vantage point helps one to define...

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  • White Papers // Feb 2010

    Performance Analysis of Reuse Partitioning Techniques in OFDMA Based Cellular Radio Networks

    Reuse partitioning is a useful method for mitigating Co-Channel Interference (CCI) in Orthogonal Frequency Division Multiple Access (OFDMA) based cellular environments. In this paper, theoretical analysis of a series of reuse partitioning approaches is carried out, which contains the well-known Soft Frequency Reuse (SFR) scheme, the novel Enhanced Fractional Frequency...

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  • White Papers // Feb 2010

    A Closed Loop Control Model Separating Resource and Packet Scheduling in Multihop Cellular Networks

    4G cellular systems and the IMT Advanced candidates will provide broadband wireless access with QoS. Especially in multihop configurations of these systems the base station controls resources centrally while relays can take over a part of the responsibility on the second hop. To make this work on layer two, scheduling...

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  • White Papers // Oct 2009

    Frequency Reuse Techniques for Attaining Both Coverage and High Spectral Efficiency in OFDMA Cellular Systems

    Inter-Cell Interference (ICI) is always a big obstacle to attain wide area coverage and high spectral efficiency in cellular systems. In this paper, the authors make a study of two well-known frequency reuse approaches, namely the Soft Frequency Reuse (SFR) scheme and the Incremental Frequency Reuse (IFR) scheme. Both of...

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  • White Papers // Dec 2010

    Prototypical Implementation of a Service Oriented Wireless Sensor Networks Application

    The Wireless Sensor Networks (WSN) environments are increasingly becoming intelligent with the rapid boost in the capabilities of sensor nodes. The Sun Small Programmable Object Technology (SPOT) platform offers a high-end sensing device in terms of processing, memory and battery configurations compared to the other existing in the community. Within...

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  • White Papers // Jun 2010

    Spectrum Load Smoothing in IEEE 802.16 Systems

    Today's framework for radio spectrum regulation and spectrum usage is undergoing fundamental changes. In the face of scarce radio resources, regulators, industry, and the research community are initiating promising approaches towards a more flexible spectrum usage, as for example cognitive radios for dynamic spectrum assignment. In this paper an intelligent...

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  • White Papers // Nov 2009

    Mobile Web Services in Health Care and Sensor Networks

    The Wireless Sensor Networks (WSN) environments are increasingly becoming intelligent with the rapid boost in the capabilities of sensor nodes. The sun Small Programmable Object Technology (SPOT) platform offers a high-end sensing device in terms of processing, memory and battery configurations compared to other existing in the community. Within the...

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  • White Papers // Oct 2009

    Enhanced Fractional Frequency Reuse to Increase Capacity of OFDMA Systems

    Inter-Cell Interference (ICI) mitigation is always a big challenge issue in cellular systems. In this paper, the authors propose an Enhanced Fractional Frequency Reuse (EFFR) scheme combined with power allocation and an interference-aware reuse mechanism to achieve not only ICI limitation at cell edge but also enhancement of overall cell...

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  • White Papers // Sep 2009

    Model-Based Radio and Channel Assignment in IEEE 802.11 Wireless Mesh Networks

    Local area wireless networks based on IEEE 802.11 have a cellular topology: stations associate to one of several access points, which are connected using a wired backbone. As connectivity is only possible close to the access points, a dense infrastructure is needed, resulting in high costs. A Wireless Mesh Network...

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  • White Papers // Jul 2009

    4G Cross-Layer Closed Loop Control Scheduling

    Packet and resource scheduling are two distinct tasks inside the medium access control layer of a wireless system of the fourth generation. Packet scheduling is the determination of the ordering of packets among competing connections or users, where the server itself is not specified. Resource Scheduling (RS) is the determination...

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  • White Papers // May 2009

    Adaptive Power Control for 4G OFDMA Systems on Frequency Selective Fading Channels

    Future cellular radio systems aim at maximizing the spectral efficiency. OFDMA radio resources are the scarce good with their dimensions bandwidth, time and space. Due to frequency selective fading the effective path-loss varies in all dimensions. Adaptive algorithms are available which allocate the best modulation and coding scheme depending on...

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  • White Papers // May 2009

    On Flow Management for Future Multi-Hop Mobile Radio Networks

    Next generation mobile radio networks of IMT-Advanced systems family will offer ubiquitous broadband high area coverage, at up to 1GBit/s in cities and 100MBit/s in rural areas and QoS support in terms of throughput and low delay. Candidate technologies like 3GPP-LTE, WiMAX, as well as the WINNER system design are...

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  • White Papers // Jun 2009

    Enabling High Performance Mobile Web Services Provisioning

    The TeleCommunication (TelCo) and Information Technology (IT) domains are converging at their intersection to provide vast variety of efficiently accessible services to the consumers. Especially in mobile communication domain, a vital factor that can affect the performance of any mobile application is the resource constraint nature of mobile devices with...

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  • White Papers // Jul 2009

    Analysis of a TDMA Coexistence Approach for IEEE 802.16 Systems

    Today's radio frequency regulation is undergoing fundamental changes. There is a high demand for radio frequency spectrum for data communication but no blank spots in the frequency assignments plan. Under the approach of coexistence and cognitive radio multiple systems can share spectrum in unlicensed bands. Additionally non-exclusive licensing allowing secondary...

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  • White Papers // Aug 2009

    Capacity Analysis and Improvement for Coexisting IEEE 802.16 Systems in Unlicensed Spectrum

    Today spectrum demand for wireless communication is tremendous and even keeps growing. In contrast, there are no blank spots in the spectrum map. Additional spectrum opportunities are available in unlicensed bands and so-called non-exclusively licensed bands which are currently made available. This non-exclusive spectrum can be exploited whenever a license...

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  • White Papers // Jul 2009

    Coordination Across Base Stations for Effective Control of Space Division Multiple Access Enhanced IEEE 802.16m Systems

    In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of existing and future wireless systems. Several standards support these techniques such as the wireless metropolitan area network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beam-forming and Space Division Multiple Access (SDMA) techniques,...

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  • White Papers // Jun 2009

    An IEEE 802.11 Model for the Planning of Wireless Mesh Networks

    Service-area specific optimization is a necessity for large-scale wireless networks. For this task, a model to estimate the quality of a radio network configuration is required. In the case of cellular radio networks, much work exists on models for Radio Network Planning (RNP). This work cannot be applied to optimize...

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  • White Papers // Aug 2009

    A Hybrid Solution for Vehicular Communications

    Wireless Access in Vehicular Environments (WAVE) and Universal Mobile Telecommunication System (UMTS) are two technologies that can be used for vehicular communication. WAVE realizes Car-To-X (C2X) communication with WLAN based ad-hoc networks of vehicles and roadside infrastructure. UMTS is a state-of-the-art technology for mobile communication and offers a cellular infrastructure...

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  • White Papers // May 2009

    OpenWNS - Open Wireless Network Simulator

    This paper presents the open Wireless Network Simulator (openWNS). This simulation tool was developed in the last 5 years at the department of Communication Networks (ComNets) at RWTH Aachen University and has been released as open source software recently. The openWNS is a dynamic event driven system level simulation platform...

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  • White Papers // Apr 2009

    IEEE 802.16 Coexistence Through Regular Channel Occupation

    Today's radio frequency regulation is undergoing fundamental changes. There is a high demand for radio frequency spectrum for data communication but no blank spots in the frequency assignments plan. Under the approach of coexistence and cognitive radio, spectrum is made available to systems if a license holder is not using...

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  • White Papers // Jun 2009

    A Service-Oriented Approach for In-Network Computations in Wireless Networks

    The concept of Mobile Web Services (Mob-WS) is catching pace within research communities due to rapid classification of mobile devices enabling pervasive environments. Beside consumer oriented use cases, another aspect of utilizing the potential of Mob-WS is to use them as computation resources within a wireless network. Such Mob-WS are...

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  • White Papers // Nov 2008

    OpenWNS: Open Source Wireless Network Simulator

    Technological research and innovation are pushed forward as fast as never before in history. To keep the pace up, researchers require effective methods and tools. Computer aided simulation has proved its applicability in various fields of research. It became as important as mathematical modeling and experiments. This also applies to...

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  • White Papers // Aug 2008

    Architecture for Consuming Long-Lived Mobile Web Services Over Multiple Transport Protocols

    The concept of Mobile Web Services (Mob-WS) is catching pace within research communities due to rapid classification of mobile devices enabling pervasive environments. A web service based middleware for mobile applications is a promising platform to accelerate the application development for mobile systems. This paper introduces a middleware for time...

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  • White Papers // Jun 2009

    A Multi-Mode MAC Protocol Integrating FDD and TDD for Next Generation Multi-Hop Mobile Radio Networks

    There are two basic duplexing schemes for present and future mobile radio networks, frequency-division duplexing and time-division duplexing. In general each of these methods has its benefits and drawbacks. However, both schemes are more or less appropriate under consideration of the communication environment. In future mobile radio systems typical wireless...

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  • White Papers // Jun 2009

    Theoretical Analysis of Saturation Throughput in MU-DCF

    In this paper, the calculation of saturation throughput for previously proposed Multi-User - Distributed Coordination Function (MU-DCF) is presented. MU-DCF is an IEEE 802.11 based protocol that supports Multi-User (MU)-Multiple Input-Multiple Output (MIMO) transmissions. The analysis is for two extreme case scenarios: Access Point (AP) downlink in a hotspot scenario,...

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  • White Papers // Jun 2009

    An FDD Multihop Cellular Network for 3GPP-LTE

    The future cellular radio networks like 3G-LTE are based on an OFDMA physical layer. The duplex scheme is preferably Frequency Division (FDD) because of its advantages in long range. Huge area coverage in a cost-efficient way is important problem for the early deployment. Time after time the demand in densely...

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  • White Papers // Mar 2009

    The Influence of Subchannel Diversity on the Performance of OFDMA Systems Based on IEEE 802.16

    The performance of a mobile radio system based on OFDMA is determined by the type of mapping of logical sub-channels, which are allocated for data transmissions, onto the frequency channel. The mapping scheme affects the diversity both within and between the OFDMA sub-channels. This paper provides a performance comparison of...

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  • White Papers // Jun 2009

    Opportunistic Wireless Internet Access in Vehicular Environments Using Enhanced WAVE Devices

    The emerging Car-To-Car communication (C2C) technology, known as Wireless Access in Vehicular Environments (WAVE), enables vehicles on the roadway to communicate with each other and with the roadside infrastructure. In addition to safety-relevant services, drivers may also need internet access through C2C communications for infotainment services and car maintenance services,...

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  • White Papers // Sep 2010

    A Correlation-Based MIMO Performance Model for the System Level Analysis on MAC Layer

    IMT-Advanced systems are currently in their evaluation phase. Due to the complexity of all the integrated algorithms and the multidimensional variability of the wireless channels a system evaluation is not easy and only very few large enterprises have the manpower to construct software to simulate all relevant effects. Traditionally the...

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  • White Papers // Oct 2010

    A Framework for Multi-Interfaced Service Level Agreements on Mobile Devices

    Today, the service computing research is focusing on providing efficient solutions to the challenges of the future internet applications. The major difference that is created by these applications is their ubiquitous on-the-move availability as cloud services. This means that the mobility is rapidly becoming a fundamental requirement of the future....

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  • White Papers // Sep 2010

    On Increasing the Spectral Efficiency More Than 100% by User-in-the-Control-Loop

    OFDMA has become the key technology for future cellular wireless networks like the IMT-Advanced systems IEEE 802.16m and 3GPP LTE-A. The advantage of allowing different modulation & coding schemes (PhyModes) adaptively for each radio resource is at the same time a new disadvantage because the performance is now distance-dependent from...

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  • White Papers // Aug 2010

    Interference Aware Scheduling for Ultra Wideband Networks

    Wireless Personal Area Networks (WPANs) are used for a wide variety of applications. Earlier WPANs, like Bluetooth, offer data rates only for low rate communication. Now-a-days, consumer electronic devices have high demands on communication systems, e.g. for high definition video transmission. Users expect future WPANs to act like wired systems...

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  • White Papers // Jul 2010

    The Resource-Oriented Mobile Web Server for Long-Lived Services

    The web servers are globally accepted as the backbone of the Internet. The researchers in the area of the enterprise computing have studied, analyzed and implemented several architectures to optimize the performance of the large-scale web servers. However, due to the convergence of the IT and the mobile communication domains,...

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  • White Papers // Sep 2010

    Uplink Capacity Analysis of OFDMA Based Cellular Networks with Reuse-1

    OFDMA based cellular radio networks aim to operate as close as possible to frequency reuse distance of one, where the whole spectrum would be available in every cell. Modern systems are able to adjust parameters such as transmission power, modulation, and coding separately for each frequency sub-channel on a very...

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  • White Papers // Jun 2010

    QoS and Flow Management for Future Multi-Hop Mobile Radio Networks

    Mobile radio networks of the IMT-Advanced systems family promise ubiquitous broadband access and high area coverage, with rates of several 100 Mb/s. The authors claim to guarantee QoS support in terms of low delay and guaranteed throughput. However, with the availability of flat rate plans and bandwidth-hungry applications of future...

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  • White Papers // Jun 2010

    System Level Performance Evaluation of LTE with MIMO and Relays in Reuse-1 IMT-Advanced Scenarios

    Cellular radio systems of the next generation will have to comply with the IMT-Advanced guidelines. Advanced radio techniques must be integrated into wireless systems to achieve the high spectral efficiency numbers required. Multiple antenna techniques such as MIMO are beneficial in regions of high SINR and low spatial stream correlation....

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  • White Papers // Jun 2010

    Frame Delay Distribution Analysis of IEEE 802.11 Networks Using Signal Flow Graphs

    Frame delay variance in CSMA/CA networks is large. Wireless applications may require both, limited mean delay and limited delay jitter. These parameters can be derived easily from Cumulative Distribution Function (CDF) of frame delay. This paper applies Signal Flow Graphs (SFGs) to calculate the CDF of frame delay in IEEE...

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  • White Papers // Dec 2009

    Region Coordination Across Space Division Multiple Access Enhanced Base Stations in IEEE 802.16m Systems

    In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of future wireless systems. Several standards support these techniques such as the Wireless Metropolitan Area Network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beamforming and Space Division Multiple Access (SDMA) techniques, adaptive antennas...

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  • White Papers // Apr 2010

    How Bad Is Interference in IEEE 802.16e Systems?

    This paper presents a performance model for dynamic resource allocation in cellular deployments of IEEE 802.16e-like systems. More specifically, the authors derive a framework which allows to quantify the number of VoIP calls that can be supported in downlink of such systems purely based on the average SINR per terminal....

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  • White Papers // Dec 2009

    The K - Constrained Bipartite Matching Problem: Approximation Algorithms and Applications to Wireless Networks

    In communication networks, resource assignment problems appear in several different settings. These problems are often modeled by a maximum weight matching problem in bipartite graphs and efficient matching algorithms are well known. In several applications, the corresponding matching problem has to be solved many times in a row as the...

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  • White Papers // Apr 2010

    Considering Microelectronic Trends in Advanced Wireless System Design

    Wireless communication system design has been a booming topic since the shift into the digital era in the 1990s. In the same period of time, microelectronic technologies have reached new paradigm points as they were going deeper into the sub-micron area. This paper gives an overview of these emerging constraints...

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