Technische Universitat Munchen

Displaying 1-40 of 47 results

  • White Papers // Jan 2012

    Detecting Malicious Code by Model Checking

    The ease of compiling malicious code from source code in higher programming languages has increased the volatility of malicious programs: The first appearance of a new worm in the wild is usually followed by modified versions in quick succession. As demonstrated by Christodorescu and Jha, however, classical detection software relies...

    Provided By Technische Universitat Munchen

  • White Papers // Dec 2011

    Mobile Device Integration and Interaction in the Automotive Domain

    People feel very comfortable when they interact with their mobile devices by using Natural User Interfaces (NUIs). However, when they enter a vehicle, this feeling degrades rapidly, since many In-Vehicle Infotainment systems (IVIs) still do not offer natural user interfaces and use different user interface interaction paradigms. For this reason,...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2011

    Querying Uncertain Spatio-Temporal Data

    The problem of modeling and managing uncertain data has received a great deal of interest, due to its manifold applications in spatial, temporal, multimedia and sensor databases. There exists a wide range of work covering spatial uncertainty in the static (snapshot) case, where only one point of time is considered....

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2011

    Inverse Queries For Multidimensional Spaces

    Traditional spatial queries return, for a given query object q, all database objects that satisfy a given predicate, such as epsilon range and k-nearest neighbors. This paper defines and studies inverse spatial queries, which, given a subset of database objects Q and a query predicate, return all objects which, if...

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Detecting Incidents in Wireless Mesh Networks Using Flow and Routing Information

    The topology in wireless multi-hop networks can change frequently due to characteristics of the shared medium, mobility of the users, or miss-behaving and malicious nodes. Frequent topology changes typically lead to inconsistencies in the network topology since routing protocols can only cope with certain topology change rate. These incidents may...

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Animating the Formalised Semantics of a Java-Like Language

    Considerable effort has gone into the techniques of extracting executable code from formal specifications and animating them. The authors show how to apply these techniques to the large JinjaThreads formalisation. It models a substantial subset of multithreaded Java source and bytecode in Isabelle/HOL and focuses on proofs and modularity whereas...

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Constraint Solving for Program Verification: Theory and Practice by Example

    Program verification relies on the construction of auxiliary assertions describing various aspects of program behaviour, e.g., inductive invariants, resource bounds, and interpolants for characterizing reachable program states, ranking functions for approximating number of execution steps until program termination, or recurrence sets for demonstrating non-termination. Recent advances in the development of...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Distributed and Predictable Software Model Checking

    The authors present a predicate abstraction and refinement-based algorithm for software verification that is designed for the distributed execution on compute nodes that communicate via message passing, as found in today's compute clusters. A successful adaptation of predicate abstraction and refinement from sequential to distributed setting needs to address challenges...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Evaluation of Network Topology Inference in Opaque Compute Clouds Through End-to-End Measurements

    Modern Infrastructure-as-a-Service (IaaS) clouds offer an unprecedented flexibility and elasticity in terms of resource provisioning through the use of hardware virtualization. However, for the cloud customer, this virtualization also introduces an opaqueness which imposes serious obstacles for data-intensive distributed applications. In particular, the lack of network topology information, i.e. information...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Optimizing All-Nearest-Neighbor Queries With Trigonometric Pruning

    Many applications require to determine the k-nearest neighbors for multiple query points simultaneously. This task is known as all-(k)-nearest-neighbor (AkNN) query. In this paper, the authors suggest a new method for efficient AkNN query processing which is based on spherical approximations for indexing and query set representation. In this setting,...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    SIMPL Systems as a Keyless Cryptographic and Security Primitive

    The authors discuss a recent cryptographic primitive termed SIMPL system. Like Physical Unclonable Functions (PUFs), SIMPL systems are disordered, unclonable physical systems with many possible inputs and a complex input-output behavior. Contrary to PUFs, however, each SIMPL system comes with a publicly known, individual numeric description that allows its slow...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2011

    Calibrating an Efficient C++ Implementation of the ITU-R M.2135 Channel Model for Use in System-Level Simulations

    In this paper, the authors present an efficient and fully calibrated implementation of the ITU-R M.2135 channel model suitable for system level simulations of IMT-Advanced systems. The complete implementation as well as the calibration setups are freely available as open-source software on the Internet under the GNU General Public License...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    Experimental Evaluation of a Robust MAC Protocol for Network Coded Two-Way Relaying

    Wireless half-duplex relay communication between two nodes is considered. A two-way decode-and-forward relaying strategy that uses network coding at the relay should be able to increase the data throughput. A specific Medium ACcess (MAC) protocol based on a TDD/TDMA scheme is proposed that establishes robust synchronization between the terminals. An...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    Pushing HiiMap Into the Kernel: An Easy-to-Use Implementation of a Real Locator/Identifier-Split

    While the Internet in its current form delivers a wide variety of services to its users, the underlying architecture is facing more and more problems, which might inhibit its future success. Among several ideas of improvement, the so-called locator/identifier-split is the most promising. However, practically using a locator/identifier-split for testing...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    A Distributed Public Key Infrastructure Based on Threshold Cryptography for the HiiMap Next Generation Internet Architecture

    In this paper, a security extension for the HiiMap Next Generation Internet Architecture is presented. The authors regard a public key infrastructure which is integrated into the mapping infrastructure of the locator/identifier-split addressing scheme. The security approach is based on Threshold Cryptography which enables a sharing of keys among the...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2011

    Beamforming for Heterogeneously Equipped Nodes in Wireless Ad Hoc Networks

    It has long been known that adaptive beamforming has the potential to enhance the performance of wireless ad hoc networks significantly. However, due to the decentralized nature of such infrastructure-less networks, it is not straight forward to fully realize the potential performance gains of beamforming in a realistic manner. To...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2011

    The Business Perspective of Cloud Computing: Actors, Roles, and Value Networks

    With the rise of a ubiquitous provision of computing resources over the past years, cloud computing has been established as a prominent research topic. Many researchers, however, focus exclusively on the technical aspects of cloud computing, thereby neglecting the business opportunities and potentials cloud computing can offer. Enabled through this...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2010

    A Game-Theoretic Approach for Synthesizing Fault-Tolerant Embedded Systems

    In this paper, the authors present an approach for fault-tolerant synthesis by combining predefined patterns for fault-tolerance with algorithmic game solving. A non-fault-tolerant system, together with the relevant fault hypothesis and fault-tolerant mechanism templates in a pool are translated into a distributed game, and they perform an incomplete search of...

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2010

    On Optimizing Low SNR Wireless Networks Using Network Coding

    The rate optimization for wireless networks with low SNR is investigated. While the capacity in the limit of disappearing SNR per degree of freedom is known to be linear in SNR for fading and non-fading channels, the authors study the problem of operating in low SNR wireless network with given...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    A Fair and Adaptive Contention Resolution Algorithm for Time-Slotted MAC Protocol Designs

    This paper addresses the fairness of Medium Access Control (MAC) protocols that are capable of handling interference on the physical layer to a varying extent. The variation addressed is thereby not based on different physical layer techniques applied, but on differing attribute levels of the same physical layer technique. This...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    Network Coded Multi-Way Relaying With Iterative Decoding

    This paper investigates a communication system where three terminals exchange their information with each other with the help of a relay. One Joint Network and Channel Coding (JNCC) scheme (based on iterative soft information exchange between channel and network decoder) and one separate network and channel coding scheme based on...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    Power Control Versus Multiuser Detection Based Cross-Layer Design in Wireless Ad Hoc Networks

    In wireless ad hoc networks, multiple access interference is the limiting factor for the overall system performance. The lack of any central control unit necessitates a careful joint design of both, the physical and the MAC layer. Two promising technologies that address this problem are power control based cross-layer design...

    Provided By Technische Universitat Munchen

  • White Papers // May 2010

    A Study of Detecting Computer Viruses in Real-Infected Files in the N-Gram Representation With Machine Learning Methods

    Machine learning methods were successfully applied in recent years for detecting new and unseen computer viruses. The viruses were, however, detected in small virus loader files and not in real infected executable files. The authors created data sets of benign files, virus loader files and real infected executable files and...

    Provided By Technische Universitat Munchen

  • White Papers // May 2010

    Quality of Service Oriented Analysis of Cross-Layer Design in Wireless Ad Hoc Networks

    In wireless ad hoc networks, cross-layer design aims at reducing multiple access interference and thus obtaining a higher spatial reuse. In order to identify the most suitable solution for future wireless systems, the authors compared the aggregate throughput achieved by two types of cross-layer designs. While the first approach suppresses...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2010

    An Optimal Adaptive Network Coding Scheme for Minimizing Decoding Delay in Broadcast Erasure Channels

    The authors are concerned with designing feedback-based adaptive network coding schemes with the aim of minimizing decoding delay in each transmission in packet-based erasure networks. They study systems where each packet brings new information to the destination regardless of its order and require the packets to be instantaneously decodable. They...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2010

    Autonomous Beam Coordination for the Downlink of an IMT-Advanced Cellular System

    Cellular systems like Long Term Evolution Advanced (LTE-Advanced) aim at reusing the whole spectrum in each cell which leads to high inter-cell interference and thus low Signal to Interference and Noise Ratio (SINR) conditions for users at the cell edge. One way to utilize multiple antennas at the base station...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2010

    Optimal Time and Rate Allocation for a Network-Coded Bidirectional Two-Hop Communication

    The authors consider a bidirectional communication between two terminals with the help of a relay. The transmissions of the three nodes are divided in time and there is no direct link between the terminals. The allocation of the transmission time and of the rates in both directions can be asymmetric....

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2010

    Artificial Intelligence Methods for Environmental Decision Support

    Decision Support Systems for the environment have to incorporate and exploit knowledge about the phenomena and the interdependencies in the affected natural systems, i.e. a model. This paper discusses different tasks and requirements, provide a logical formalization of the tasks, and propose to use methods and techniques developed in research...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2009

    Nephele: Efficient Parallel Data Processing in the Cloud

    In recent years Cloud Computing has emerged as a promising new approach for ad-hoc parallel data processing. Major cloud computing companies have started to integrate frame-works for parallel data processing in their product portfolio, making it easy for customers to access these services and to deploy their programs. However, the...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    A Concept for Efficient System-Level Simulations of OFDMA Systems With Proportional Fair Fast Scheduling

    System-level simulations of packet-based Orthogonal Frequency-Division Multiple Access (OFDMA) cellular networks require a proper consideration of the channel-dependent fast fading/scheduling in order to produce meaningful results. However, generating the time and frequency selective fast fading channels and performing detailed channel-adaptive scheduling for each user in a multi-cellular system is computationally...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    Decentralized Inter-Cell Interference Coordination by Autonomous Spectral Reuse Decisions

    Future wireless packet switched cellular networks will require dense frequency reuse to achieve high capacity. At the same time, measures are required which limit the interference on the frequency carriers. It is assumed that central entities performing the task of interference coordination with global knowledge should be avoided. Rather, distributed...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    Cloud Computing and Computing Evolution

    The term cloud computing is sometimes used to refer to a new paradigm - some authors even speak of a new technology - that offers IT resources and services over the Internet. The technology analysts at Gartner see cloud computing as a so-called "Emerging Technology" on its way to the...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    Cloud Computing - Outsourcing 2.0 or a New Business Model for IT Provisioning?

    The term cloud computing is sometimes used to refer to a new paradigm - some authors even speak of a new technology - that flexibly offers IT resources and services over the Internet. Gartner market research sees cloud computing as a so-called "Emerging technology" on its way to the hype....

    Provided By Technische Universitat Munchen

  • White Papers // Aug 2009

    Cooperative Uplink of Two Mobile Stations With Network Coding Based on the WiMax LDPC Code

    The authors consider the uplink of two mobile stations with the help of one common relay. Recently, joint network-channel coding based on LDPC codes was proposed for this setup where the channel codes at the mobile stations and the network code at the relay form one distributed LDPC code. This...

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2009

    Outage Behavior of Bidirectional Half-Duplex Relaying Schemes

    Two-phase and three-phase decode-and-forward schemes with network coding for the two-way (bidirectional) relay channel with Rayleigh-fading are considered. All nodes are half-duplex constrained. Closed form expressions of the outage probability for the two-phase scheme and the three-phase scheme with symmetric rate and time-allocation with Gaussian distributed channel inputs are derived,...

    Provided By Technische Universitat Munchen

  • White Papers // May 2009

    Dynamic Traffic Engineering in the Future Internet

    Traffic in data networks is known to fluctuate heavily, which can result in sudden service degradation. Handling these traffic demands that are bursty and hard to predict is a major challenge. The authors present REPLEX, a distributed algorithm for fast dynamic traffic engineering that is based on game theoretic principles....

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2009

    Cloud-Based Enterprise Mashup Integration Services for B2B Scenarios

    This paper observes a huge demand for situational and ad-hoc applications desired by the mass of business end-users that cannot be fully implemented by IT departments. This is especially the case with regard to solutions that support infrequent, situational, and ad-hoc B2B scenarios. End users are not able to implement...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2009

    Design of Distributed LDPC Codes for the Time-Division Multiple-Access Relay Channel

    The time-division Multiple-Access Relay Channel (MARC) with two sources is considered. They communicate with one destination through the help of a relay. Recently, joint network-channel coding based on LDPC codes was proposed for the MARC whereas the channel codes at the sources and the network code at the relay form...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2008

    Petri Net Transformations for Business Processes - A Survey

    In process-aware information systems, business processes are often modeled in an explicit way. Roughly speaking, the available business process modeling languages can be divided into two groups. Languages from the first group are preferred by academic people but shunned by business people, and include Petri nets and process algebras. These...

    Provided By Technische Universitat Munchen

  • White Papers // Aug 2008

    Gigabit Ethernet Over Standard Step-Index Polymer Optical Fiber

    The use of standard 1-mm core-diameter step-index plastic optical fibre (SI-POF) has so far been mainly limited to distances of up to 100 meters and low bit-rates in the order of 125 Mbit/s. By use of digital signal processing, transmission performance of such optical links can be improved. A promising...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2008

    On a Quest for Good Process Models: The Cross-Connectivity Metric

    Business Process Modeling is an important corporate activity, but the understanding of what constitutes good process models is rather limited. In this paper, the authors turn to the cognitive dimensions framework and identify the understanding of the structural relationship between any pair of model elements as a hard mental operation....

    Provided By Technische Universitat Munchen

  • White Papers // May 2008

    Using Semantics to Aid Scenario-Based Analysis

    Scenario-based analysis describes customer needs and focuses on different aspects of information systems. A scenario typically has several metrics which compute specific information about transaction data, organizational structures and configuration settings. The selection and configuration of metrics is not a trivial task and normally cannot be reused over different information...

    Provided By Technische Universitat Munchen

  • White Papers // May 2007

    A Weighted Coupling Metric for Business Process Models

    Quality metrics in software engineering have shown their potential as guidance to improve software designs and make them more understandable and easier to maintain. Various efforts recently aimed at the development of quality metrics for process models. In this paper, the authors propose a new notion of coupling, which has...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2008

    Petri Net Transformations for Business Processes - A Survey

    In process-aware information systems, business processes are often modeled in an explicit way. Roughly speaking, the available business process modeling languages can be divided into two groups. Languages from the first group are preferred by academic people but shunned by business people, and include Petri nets and process algebras. These...

    Provided By Technische Universitat Munchen

  • White Papers // Aug 2008

    Gigabit Ethernet Over Standard Step-Index Polymer Optical Fiber

    The use of standard 1-mm core-diameter step-index plastic optical fibre (SI-POF) has so far been mainly limited to distances of up to 100 meters and low bit-rates in the order of 125 Mbit/s. By use of digital signal processing, transmission performance of such optical links can be improved. A promising...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2009

    Cloud-Based Enterprise Mashup Integration Services for B2B Scenarios

    This paper observes a huge demand for situational and ad-hoc applications desired by the mass of business end-users that cannot be fully implemented by IT departments. This is especially the case with regard to solutions that support infrequent, situational, and ad-hoc B2B scenarios. End users are not able to implement...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2010

    Artificial Intelligence Methods for Environmental Decision Support

    Decision Support Systems for the environment have to incorporate and exploit knowledge about the phenomena and the interdependencies in the affected natural systems, i.e. a model. This paper discusses different tasks and requirements, provide a logical formalization of the tasks, and propose to use methods and techniques developed in research...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2011

    The Business Perspective of Cloud Computing: Actors, Roles, and Value Networks

    With the rise of a ubiquitous provision of computing resources over the past years, cloud computing has been established as a prominent research topic. Many researchers, however, focus exclusively on the technical aspects of cloud computing, thereby neglecting the business opportunities and potentials cloud computing can offer. Enabled through this...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    Cloud Computing and Computing Evolution

    The term cloud computing is sometimes used to refer to a new paradigm - some authors even speak of a new technology - that offers IT resources and services over the Internet. The technology analysts at Gartner see cloud computing as a so-called "Emerging Technology" on its way to the...

    Provided By Technische Universitat Munchen

  • White Papers // Sep 2009

    Cloud Computing - Outsourcing 2.0 or a New Business Model for IT Provisioning?

    The term cloud computing is sometimes used to refer to a new paradigm - some authors even speak of a new technology - that flexibly offers IT resources and services over the Internet. Gartner market research sees cloud computing as a so-called "Emerging technology" on its way to the hype....

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2010

    On Optimizing Low SNR Wireless Networks Using Network Coding

    The rate optimization for wireless networks with low SNR is investigated. While the capacity in the limit of disappearing SNR per degree of freedom is known to be linear in SNR for fading and non-fading channels, the authors study the problem of operating in low SNR wireless network with given...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2010

    A Game-Theoretic Approach for Synthesizing Fault-Tolerant Embedded Systems

    In this paper, the authors present an approach for fault-tolerant synthesis by combining predefined patterns for fault-tolerance with algorithmic game solving. A non-fault-tolerant system, together with the relevant fault hypothesis and fault-tolerant mechanism templates in a pool are translated into a distributed game, and they perform an incomplete search of...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    SIMPL Systems as a Keyless Cryptographic and Security Primitive

    The authors discuss a recent cryptographic primitive termed SIMPL system. Like Physical Unclonable Functions (PUFs), SIMPL systems are disordered, unclonable physical systems with many possible inputs and a complex input-output behavior. Contrary to PUFs, however, each SIMPL system comes with a publicly known, individual numeric description that allows its slow...

    Provided By Technische Universitat Munchen

  • White Papers // May 2008

    Capturing Dynamic Memory Structures

    Current operating systems do not capture any information about memory regions. The first step to enable a computer system to understand itself is capturing this information. In the course of this paper, modern development methods are taken into consideration for eliciting structuring and meta data. This meta information is then...

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2008

    Tracking Mobile Phones on Interactive Tabletops

    The number of "Interactive surface" systems, especially tabletop interfaces, in public is increasing. As more and more casual users interact with such systems, they may wish to use existing computing infrastructure, such as their mobile phone, in conjunction with the new interface. In this paper, the authors present a method...

    Provided By Technische Universitat Munchen

  • White Papers // Aug 2009

    Cooperative Uplink of Two Mobile Stations With Network Coding Based on the WiMax LDPC Code

    The authors consider the uplink of two mobile stations with the help of one common relay. Recently, joint network-channel coding based on LDPC codes was proposed for this setup where the channel codes at the mobile stations and the network code at the relay form one distributed LDPC code. This...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    Experimental Evaluation of a Robust MAC Protocol for Network Coded Two-Way Relaying

    Wireless half-duplex relay communication between two nodes is considered. A two-way decode-and-forward relaying strategy that uses network coding at the relay should be able to increase the data throughput. A specific Medium ACcess (MAC) protocol based on a TDD/TDMA scheme is proposed that establishes robust synchronization between the terminals. An...

    Provided By Technische Universitat Munchen

  • White Papers // Dec 2011

    Mobile Device Integration and Interaction in the Automotive Domain

    People feel very comfortable when they interact with their mobile devices by using Natural User Interfaces (NUIs). However, when they enter a vehicle, this feeling degrades rapidly, since many In-Vehicle Infotainment systems (IVIs) still do not offer natural user interfaces and use different user interface interaction paradigms. For this reason,...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2012

    Detecting Malicious Code by Model Checking

    The ease of compiling malicious code from source code in higher programming languages has increased the volatility of malicious programs: The first appearance of a new worm in the wild is usually followed by modified versions in quick succession. As demonstrated by Christodorescu and Jha, however, classical detection software relies...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Distributed and Predictable Software Model Checking

    The authors present a predicate abstraction and refinement-based algorithm for software verification that is designed for the distributed execution on compute nodes that communicate via message passing, as found in today's compute clusters. A successful adaptation of predicate abstraction and refinement from sequential to distributed setting needs to address challenges...

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Constraint Solving for Program Verification: Theory and Practice by Example

    Program verification relies on the construction of auxiliary assertions describing various aspects of program behaviour, e.g., inductive invariants, resource bounds, and interpolants for characterizing reachable program states, ranking functions for approximating number of execution steps until program termination, or recurrence sets for demonstrating non-termination. Recent advances in the development of...

    Provided By Technische Universitat Munchen

  • White Papers // May 2009

    Dynamic Traffic Engineering in the Future Internet

    Traffic in data networks is known to fluctuate heavily, which can result in sudden service degradation. Handling these traffic demands that are bursty and hard to predict is a major challenge. The authors present REPLEX, a distributed algorithm for fast dynamic traffic engineering that is based on game theoretic principles....

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Detecting Incidents in Wireless Mesh Networks Using Flow and Routing Information

    The topology in wireless multi-hop networks can change frequently due to characteristics of the shared medium, mobility of the users, or miss-behaving and malicious nodes. Frequent topology changes typically lead to inconsistencies in the network topology since routing protocols can only cope with certain topology change rate. These incidents may...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2011

    Calibrating an Efficient C++ Implementation of the ITU-R M.2135 Channel Model for Use in System-Level Simulations

    In this paper, the authors present an efficient and fully calibrated implementation of the ITU-R M.2135 channel model suitable for system level simulations of IMT-Advanced systems. The complete implementation as well as the calibration setups are freely available as open-source software on the Internet under the GNU General Public License...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    Pushing HiiMap Into the Kernel: An Easy-to-Use Implementation of a Real Locator/Identifier-Split

    While the Internet in its current form delivers a wide variety of services to its users, the underlying architecture is facing more and more problems, which might inhibit its future success. Among several ideas of improvement, the so-called locator/identifier-split is the most promising. However, practically using a locator/identifier-split for testing...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2011

    A Distributed Public Key Infrastructure Based on Threshold Cryptography for the HiiMap Next Generation Internet Architecture

    In this paper, a security extension for the HiiMap Next Generation Internet Architecture is presented. The authors regard a public key infrastructure which is integrated into the mapping infrastructure of the locator/identifier-split addressing scheme. The security approach is based on Threshold Cryptography which enables a sharing of keys among the...

    Provided By Technische Universitat Munchen

  • White Papers // May 2010

    A Study of Detecting Computer Viruses in Real-Infected Files in the N-Gram Representation With Machine Learning Methods

    Machine learning methods were successfully applied in recent years for detecting new and unseen computer viruses. The viruses were, however, detected in small virus loader files and not in real infected executable files. The authors created data sets of benign files, virus loader files and real infected executable files and...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    A Fair and Adaptive Contention Resolution Algorithm for Time-Slotted MAC Protocol Designs

    This paper addresses the fairness of Medium Access Control (MAC) protocols that are capable of handling interference on the physical layer to a varying extent. The variation addressed is thereby not based on different physical layer techniques applied, but on differing attribute levels of the same physical layer technique. This...

    Provided By Technische Universitat Munchen

  • White Papers // Jan 2011

    Beamforming for Heterogeneously Equipped Nodes in Wireless Ad Hoc Networks

    It has long been known that adaptive beamforming has the potential to enhance the performance of wireless ad hoc networks significantly. However, due to the decentralized nature of such infrastructure-less networks, it is not straight forward to fully realize the potential performance gains of beamforming in a realistic manner. To...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    Power Control Versus Multiuser Detection Based Cross-Layer Design in Wireless Ad Hoc Networks

    In wireless ad hoc networks, multiple access interference is the limiting factor for the overall system performance. The lack of any central control unit necessitates a careful joint design of both, the physical and the MAC layer. Two promising technologies that address this problem are power control based cross-layer design...

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2010

    Autonomous Beam Coordination for the Downlink of an IMT-Advanced Cellular System

    Cellular systems like Long Term Evolution Advanced (LTE-Advanced) aim at reusing the whole spectrum in each cell which leads to high inter-cell interference and thus low Signal to Interference and Noise Ratio (SINR) conditions for users at the cell edge. One way to utilize multiple antennas at the base station...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2009

    Nephele: Efficient Parallel Data Processing in the Cloud

    In recent years Cloud Computing has emerged as a promising new approach for ad-hoc parallel data processing. Major cloud computing companies have started to integrate frame-works for parallel data processing in their product portfolio, making it easy for customers to access these services and to deploy their programs. However, the...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Evaluation of Network Topology Inference in Opaque Compute Clouds Through End-to-End Measurements

    Modern Infrastructure-as-a-Service (IaaS) clouds offer an unprecedented flexibility and elasticity in terms of resource provisioning through the use of hardware virtualization. However, for the cloud customer, this virtualization also introduces an opaqueness which imposes serious obstacles for data-intensive distributed applications. In particular, the lack of network topology information, i.e. information...

    Provided By Technische Universitat Munchen

  • White Papers // Nov 2011

    Querying Uncertain Spatio-Temporal Data

    The problem of modeling and managing uncertain data has received a great deal of interest, due to its manifold applications in spatial, temporal, multimedia and sensor databases. There exists a wide range of work covering spatial uncertainty in the static (snapshot) case, where only one point of time is considered....

    Provided By Technische Universitat Munchen

  • White Papers // Jul 2011

    Inverse Queries For Multidimensional Spaces

    Traditional spatial queries return, for a given query object q, all database objects that satisfy a given predicate, such as epsilon range and k-nearest neighbors. This paper defines and studies inverse spatial queries, which, given a subset of database objects Q and a query predicate, return all objects which, if...

    Provided By Technische Universitat Munchen

  • White Papers // Apr 2011

    Optimizing All-Nearest-Neighbor Queries With Trigonometric Pruning

    Many applications require to determine the k-nearest neighbors for multiple query points simultaneously. This task is known as all-(k)-nearest-neighbor (AkNN) query. In this paper, the authors suggest a new method for efficient AkNN query processing which is based on spherical approximations for indexing and query set representation. In this setting,...

    Provided By Technische Universitat Munchen

  • White Papers // May 2011

    Animating the Formalised Semantics of a Java-Like Language

    Considerable effort has gone into the techniques of extracting executable code from formal specifications and animating them. The authors show how to apply these techniques to the large JinjaThreads formalisation. It models a substantial subset of multithreaded Java source and bytecode in Isabelle/HOL and focuses on proofs and modularity whereas...

    Provided By Technische Universitat Munchen

  • White Papers // Jun 2010

    Network Coded Multi-Way Relaying With Iterative Decoding

    This paper investigates a communication system where three terminals exchange their information with each other with the help of a relay. One Joint Network and Channel Coding (JNCC) scheme (based on iterative soft information exchange between channel and network decoder) and one separate network and channel coding scheme based on...

    Provided By Technische Universitat Munchen

  • White Papers // Feb 2010

    Optimal Time and Rate Allocation for a Network-Coded Bidirectional Two-Hop Communication

    The authors consider a bidirectional communication between two terminals with the help of a relay. The transmissions of the three nodes are divided in time and there is no direct link between the terminals. The allocation of the transmission time and of the rates in both directions can be asymmetric....

    Provided By Technische Universitat Munchen

  • White Papers // Mar 2009

    Design of Distributed LDPC Codes for the Time-Division Multiple-Access Relay Channel

    The time-division Multiple-Access Relay Channel (MARC) with two sources is considered. They communicate with one destination through the help of a relay. Recently, joint network-channel coding based on LDPC codes was proposed for the MARC whereas the channel codes at the sources and the network code at the relay form...

    Provided By Technische Universitat Munchen