University of Leeds

Displaying 1-26 of 26 results

  • White Papers // Jan 2012

    Quantum Cryptography With Generalized Bases and Dimensions of Photon States

    Quantum Key Distribution (QKD) is a secure key sharing technology with unconditional security. Certain well-known protocols for QKD have been presented, which claim their security by means of higher eavesdropping error-rates. A generalized quantum key distribution protocol that can be optimized for arbitrary number of bases and dimensions of photon...

    Provided By University of Leeds

  • White Papers // Sep 2011

    Adaptive Modulation for LDPC Coded-OFDM Based Powerline Communication System

    As a result of the impairments generated by the consumer electronic devices on power line channel extensive research has been carried out to mitigate the deteriorating effects. In this paper, the performance of an OFDM based power line communication system is evaluated under OPERA proposed power line channel. An adaptive...

    Provided By University of Leeds

  • White Papers // Jun 2011

    Energy-Efficiency in Cloud Computing Environments: Towards Energy Savings Without Performance Degradation

    Due to all the pollutants generated by it and the steady increases in its rates, energy consumption is causing serious environmental and economic problems. In this paper, the growing use and adoption of ICTs is being highlighted not only as one of the principal problem sources but also as one...

    Provided By University of Leeds

  • White Papers // Jan 2011

    Using the Cognitive Walkthrough to Improve the Design of a Visual Programming Experiment

    Visual programming languages aim to promote usability, but are rarely examined for it. One reason is the difficulty of designing successful experimental evaluations. The authors propose the Cognitive Walkthrough as an aid to improve experimental designs. This is a novel application of an HCI-derived technique designed for evaluating interfaces rather...

    Provided By University of Leeds

  • White Papers // Oct 2010

    Equal Opportunity And Disability

    The fact that the position of people with disabilities can be categorized along with those of women and ethnic minorities is an important question. It is for example accepted that the special needs of the disabled and of women may well differ in certain respects (although many solutions to specific...

    Provided By University of Leeds

  • White Papers // Aug 2010

    OPTIMIS: A Holistic Approach to Cloud Service Provisioning

    The authors present the fundamentals for a toolkit for scalable and dependable service platforms and architectures that enable flexible and dynamic provisioning of cloud services. The innovations behind the toolkit are aimed at optimizing the whole service life cycle, including service construction, deployment, and operation, on a basis of aspects...

    Provided By University of Leeds

  • White Papers // Jul 2010

    Model-Driven Development of Adaptable Service-Oriented Business Processes

    Businesses typically structure their activities with workflows, which are often implemented in a rather static fashion in their IT systems. Now-a-days, system requirements change rapidly as businesses try to maintain their competitive edge, calling for similar agility of the IT systems. To this paper, the authors present StPowla, an approach...

    Provided By University of Leeds

  • White Papers // Feb 2010

    Outage Probability Analysis of Cognitive Radio Networks Under Self-Coexistence Constraint

    Cognitive Radio Networks (CRNs) are envisioned to eradicate the artificial scarcity caused by today's stringent spectrum allocation policy. In this paper, the authors develop a statistical framework to model the outage probability at any arbitrary primary/licensed user, while operating in the presence of a collocated secondary network/CRN. A system model...

    Provided By University of Leeds

  • White Papers // Feb 2010

    The Sensoria Reference Modelling Language

    In this paper, the authors provide an overview of SRML - the Sensoria Reference Modelling Language. SRML offers a technology-agnostic framework in which business services and activities can be modeled independently of the languages in which components are implemented and the network protocols through which they communicate. From a methodological...

    Provided By University of Leeds

  • White Papers // Dec 2009

    Transmit Beamforming for MISO Frequency-Selective Channels With Total and Per-Antenna Power Constraints

    The authors consider the problem of transmit BeamForming (BF) design for Cyclic Prefixed (CP) transmissions over MISO frequency selective channels. Both CP single carriers (SC) and Orthogonal Frequency Division Multiplexing (OFDM) systems are investigated. To reduce receiver complexity, frequency domain BF is adopted. The BF is designed by minimizing the...

    Provided By University of Leeds

  • White Papers // Sep 2009

    Semi-Blind Locally Optimum Detection for Spectrum Sensing in Cognitive Radio

    Spectrum sensing in cognitive radio becomes a challenging task when the signals received at the secondary users' transmitters exhibit low power. Locally Optimum Detectors (LOD) are therefore desirable, thanks to their optimality in the low SNR regime. Here, the authors assume that the primary user transmits a training sequence, and...

    Provided By University of Leeds

  • White Papers // Jun 2009

    Wireless Networks With Retransmission Diversity and Carrier-Sense Multiple Access

    Network Diversity Multiple Access protocols (NDMA) have been shown to considerably outperform previously proposed algorithms. However, several issues in their analysis remain unsolved, particularly under the assumption of imperfect collision-multiplicity detection in asymmetrical system configurations (i.e., configurations where the users have different channel and queuing statistics). To partially fill this...

    Provided By University of Leeds

  • White Papers // Jun 2009

    Towards Quality of Service in the Cloud

    Quality of Service (QoS) plays a critical role in the affective reservation of resources within service oriented distributed systems and has been widely investigated in the now well established paradigm of Grid Computing. The emergence of a new paradigm, Cloud Computing, continues the natural evolution of Distributed Systems to cater...

    Provided By University of Leeds

  • White Papers // May 2009

    inContext - Interaction and Context-based Technologies for Collaborative Teams

    Much of today's teamwork is based on Collaborative Working Environments (CWEs). These are supporting team members participating in multiple projects at the same time, with the work spanning multiple organizations and the team members working on the move. Virtual, nimble, and mobile teams evolve and merge reflecting the vibrant nature...

    Provided By University of Leeds

  • White Papers // May 2009

    Locally Optimum Detection for Spectrum Sensing in Cognitive Radio

    Spectrum sensing is a key feature in cognitive radio networks. The authors propose a Locally Optimum (LO) detector, which is known to be optimum at low SNR. This is desirable in cognitive radio since the primary user's signal may exhibit a very low power at the cognitive user's transmitter. They...

    Provided By University of Leeds

  • White Papers // Apr 2009

    An Integrated Intrusion Detection and Diagnosis for Clouds

    Improving dependability of Cloud computing is critical to the realization of its potential as a technology to facilitate the development of large-scale, flexible computing infrastructures, available on-demand to meet computation requirements of compute intensive workloads. However, unique characteristics such as; Diversity, Flexibility and Mobility inherited by such systems require dedicated...

    Provided By University of Leeds

  • White Papers // Apr 2009

    A Generalized Geometry-Inclusive Fading Model for Adhoc Wireless Networks

    A new generic statistical fading model for wireless adhoc networks is proposed. Besides small scale fading, the authors' proposed model incorporates the variations due to geometry, i.e. statistical distribution of transmission and reception distances. The geometry-inclusive fading model presented can also be considered as a generalization of several prior studies....

    Provided By University of Leeds

  • White Papers // Apr 2009

    Full-Rank and Rank-Deficient Precoding Schemes for Single-Carrier Block Transmissions

    In block-mode transmission, inserting a Cyclic Prefix (CP) between two consecutive blocks provides an efficient way of removing inter-block interference and simplifies equalization of frequency-selective channels at the receiver. Here, the authors address optimal training design for channel estimation in such systems. Their investigations focus on affine precoding schemes. In...

    Provided By University of Leeds

  • White Papers // Apr 2009

    Extension of GPS Broadcast Ephemeris to Determine Satellite Velocity and Acceleration

    This paper presents an expansion of the algorithm provided in the GPS ICD to include the precise real-time computation in ECEF coordinate of the velocity and acceleration components of the satellite orbit besides the position components using the broadcast ephemeris. Precise satellite velocity and acceleration data are needed for applications...

    Provided By University of Leeds

  • White Papers // Apr 2009

    The Coexistence of 802.11b/g and Bluetooth: An Experimental Comparison in LoS Conditions

    This paper presents experimental results for TCP throughput performance of the IEEE 802.11b/g standard in the presence of Bluetooth (BT) interference. The throughput of an IEEE 802.11b/g network is measured in a LoS environment. The results demonstrate that 802.11g is substantially more sensitive to BT interference than 802.11b. Currently, the...

    Provided By University of Leeds

  • White Papers // Feb 2009

    Data Detection in Cooperative STBC-OFDM Systems With Multiple Frequency Offsets

    This paper addresses the problem of data detection in cooperative Space-Time Block Coded (STBC) Orthogonal Frequency Division Multiplexing (OFDM) systems in the presence of multiple Carrier Frequency Offsets (CFO). An Enhanced Iterative Maximum-Likelihood Detector (EIMLD) is proposed. This method consists of first removing Inter-Carrier Interference (ICI), and then performing iterative...

    Provided By University of Leeds

  • White Papers // Jan 2009

    Multipath Diversity and Coding Gains of Cyclic-Prefixed Single Carrier Systems

    The multipath diversity and coding gain metrics for Cyclic-Prefixed Single-Carrier (SC-CP) systems, which characterize the Bit Error Rate (BER) at high SNR, have not been carefully studied in the literature. The authors first show that, unlike OFDM, the diversity and coding gains for SC-CP are data realization-dependent. Then, they show...

    Provided By University of Leeds

  • White Papers // Dec 2008

    Timing and Frequency Synchronization for OFDM Based Cooperative Systems

    In this paper, the authors investigate the timing and Carrier Frequency Offset (CFO) synchronization problem in decode and forward cooperative systems operating over frequency selective channels. A training sequence which consists of one OFDM block having a tile structure in the frequency domain is proposed to perform synchronization. Timing offsets...

    Provided By University of Leeds

  • White Papers // Sep 2008

    Applications of QKD Network for High Performance Distributed Computing

    Quantum Key Distribution (QKD) is a point to point secure key generation technology which provides unconditional security. To exploit the security of QKD for large scale practical communication, it must be used in a network fashion. BBN DARPA quantum network and SECOQC network of secrets are the examples of such...

    Provided By University of Leeds

  • White Papers // Apr 2008

    From BPEL to SRML: A Formal Transformational Approach

    The SENSORIA Reference Modeling Language (SRML) provides primitives for modeling business processes in a technology agnostic way. At the core of SRML is the notion of module as a composition of tightly coupled components and loosely coupled, dynamically discovered services. This paper presents an encoding of BPEL processes into SRML...

    Provided By University of Leeds

  • White Papers // Dec 2007

    Towards Feature Interactions in Business Processes

    The feature interaction problem is generally associated with conflicting features causing undesirable effects. However, in this paper, the authors report on a situation where the combination of features (as policies) and service-targeted business processes yields non-negative effects. They consider business processes as base systems and policies as a feature mechanism...

    Provided By University of Leeds

  • White Papers // Oct 2010

    Equal Opportunity And Disability

    The fact that the position of people with disabilities can be categorized along with those of women and ethnic minorities is an important question. It is for example accepted that the special needs of the disabled and of women may well differ in certain respects (although many solutions to specific...

    Provided By University of Leeds

  • White Papers // Jan 2011

    Using the Cognitive Walkthrough to Improve the Design of a Visual Programming Experiment

    Visual programming languages aim to promote usability, but are rarely examined for it. One reason is the difficulty of designing successful experimental evaluations. The authors propose the Cognitive Walkthrough as an aid to improve experimental designs. This is a novel application of an HCI-derived technique designed for evaluating interfaces rather...

    Provided By University of Leeds

  • White Papers // Jan 2009

    Multipath Diversity and Coding Gains of Cyclic-Prefixed Single Carrier Systems

    The multipath diversity and coding gain metrics for Cyclic-Prefixed Single-Carrier (SC-CP) systems, which characterize the Bit Error Rate (BER) at high SNR, have not been carefully studied in the literature. The authors first show that, unlike OFDM, the diversity and coding gains for SC-CP are data realization-dependent. Then, they show...

    Provided By University of Leeds

  • White Papers // Apr 2009

    Full-Rank and Rank-Deficient Precoding Schemes for Single-Carrier Block Transmissions

    In block-mode transmission, inserting a Cyclic Prefix (CP) between two consecutive blocks provides an efficient way of removing inter-block interference and simplifies equalization of frequency-selective channels at the receiver. Here, the authors address optimal training design for channel estimation in such systems. Their investigations focus on affine precoding schemes. In...

    Provided By University of Leeds

  • White Papers // Dec 2008

    Timing and Frequency Synchronization for OFDM Based Cooperative Systems

    In this paper, the authors investigate the timing and Carrier Frequency Offset (CFO) synchronization problem in decode and forward cooperative systems operating over frequency selective channels. A training sequence which consists of one OFDM block having a tile structure in the frequency domain is proposed to perform synchronization. Timing offsets...

    Provided By University of Leeds

  • White Papers // Dec 2009

    Transmit Beamforming for MISO Frequency-Selective Channels With Total and Per-Antenna Power Constraints

    The authors consider the problem of transmit BeamForming (BF) design for Cyclic Prefixed (CP) transmissions over MISO frequency selective channels. Both CP single carriers (SC) and Orthogonal Frequency Division Multiplexing (OFDM) systems are investigated. To reduce receiver complexity, frequency domain BF is adopted. The BF is designed by minimizing the...

    Provided By University of Leeds

  • White Papers // Feb 2009

    Data Detection in Cooperative STBC-OFDM Systems With Multiple Frequency Offsets

    This paper addresses the problem of data detection in cooperative Space-Time Block Coded (STBC) Orthogonal Frequency Division Multiplexing (OFDM) systems in the presence of multiple Carrier Frequency Offsets (CFO). An Enhanced Iterative Maximum-Likelihood Detector (EIMLD) is proposed. This method consists of first removing Inter-Carrier Interference (ICI), and then performing iterative...

    Provided By University of Leeds

  • White Papers // May 2009

    Locally Optimum Detection for Spectrum Sensing in Cognitive Radio

    Spectrum sensing is a key feature in cognitive radio networks. The authors propose a Locally Optimum (LO) detector, which is known to be optimum at low SNR. This is desirable in cognitive radio since the primary user's signal may exhibit a very low power at the cognitive user's transmitter. They...

    Provided By University of Leeds

  • White Papers // Jun 2009

    Wireless Networks With Retransmission Diversity and Carrier-Sense Multiple Access

    Network Diversity Multiple Access protocols (NDMA) have been shown to considerably outperform previously proposed algorithms. However, several issues in their analysis remain unsolved, particularly under the assumption of imperfect collision-multiplicity detection in asymmetrical system configurations (i.e., configurations where the users have different channel and queuing statistics). To partially fill this...

    Provided By University of Leeds

  • White Papers // Sep 2009

    Semi-Blind Locally Optimum Detection for Spectrum Sensing in Cognitive Radio

    Spectrum sensing in cognitive radio becomes a challenging task when the signals received at the secondary users' transmitters exhibit low power. Locally Optimum Detectors (LOD) are therefore desirable, thanks to their optimality in the low SNR regime. Here, the authors assume that the primary user transmits a training sequence, and...

    Provided By University of Leeds

  • White Papers // Apr 2009

    Extension of GPS Broadcast Ephemeris to Determine Satellite Velocity and Acceleration

    This paper presents an expansion of the algorithm provided in the GPS ICD to include the precise real-time computation in ECEF coordinate of the velocity and acceleration components of the satellite orbit besides the position components using the broadcast ephemeris. Precise satellite velocity and acceleration data are needed for applications...

    Provided By University of Leeds

  • White Papers // Apr 2009

    A Generalized Geometry-Inclusive Fading Model for Adhoc Wireless Networks

    A new generic statistical fading model for wireless adhoc networks is proposed. Besides small scale fading, the authors' proposed model incorporates the variations due to geometry, i.e. statistical distribution of transmission and reception distances. The geometry-inclusive fading model presented can also be considered as a generalization of several prior studies....

    Provided By University of Leeds

  • White Papers // Feb 2010

    Outage Probability Analysis of Cognitive Radio Networks Under Self-Coexistence Constraint

    Cognitive Radio Networks (CRNs) are envisioned to eradicate the artificial scarcity caused by today's stringent spectrum allocation policy. In this paper, the authors develop a statistical framework to model the outage probability at any arbitrary primary/licensed user, while operating in the presence of a collocated secondary network/CRN. A system model...

    Provided By University of Leeds

  • White Papers // Jun 2011

    Energy-Efficiency in Cloud Computing Environments: Towards Energy Savings Without Performance Degradation

    Due to all the pollutants generated by it and the steady increases in its rates, energy consumption is causing serious environmental and economic problems. In this paper, the growing use and adoption of ICTs is being highlighted not only as one of the principal problem sources but also as one...

    Provided By University of Leeds

  • White Papers // Apr 2009

    An Integrated Intrusion Detection and Diagnosis for Clouds

    Improving dependability of Cloud computing is critical to the realization of its potential as a technology to facilitate the development of large-scale, flexible computing infrastructures, available on-demand to meet computation requirements of compute intensive workloads. However, unique characteristics such as; Diversity, Flexibility and Mobility inherited by such systems require dedicated...

    Provided By University of Leeds

  • White Papers // Aug 2010

    OPTIMIS: A Holistic Approach to Cloud Service Provisioning

    The authors present the fundamentals for a toolkit for scalable and dependable service platforms and architectures that enable flexible and dynamic provisioning of cloud services. The innovations behind the toolkit are aimed at optimizing the whole service life cycle, including service construction, deployment, and operation, on a basis of aspects...

    Provided By University of Leeds

  • White Papers // Sep 2011

    Adaptive Modulation for LDPC Coded-OFDM Based Powerline Communication System

    As a result of the impairments generated by the consumer electronic devices on power line channel extensive research has been carried out to mitigate the deteriorating effects. In this paper, the performance of an OFDM based power line communication system is evaluated under OPERA proposed power line channel. An adaptive...

    Provided By University of Leeds

  • White Papers // Jan 2012

    Quantum Cryptography With Generalized Bases and Dimensions of Photon States

    Quantum Key Distribution (QKD) is a secure key sharing technology with unconditional security. Certain well-known protocols for QKD have been presented, which claim their security by means of higher eavesdropping error-rates. A generalized quantum key distribution protocol that can be optimized for arbitrary number of bases and dimensions of photon...

    Provided By University of Leeds

  • White Papers // Feb 2010

    The Sensoria Reference Modelling Language

    In this paper, the authors provide an overview of SRML - the Sensoria Reference Modelling Language. SRML offers a technology-agnostic framework in which business services and activities can be modeled independently of the languages in which components are implemented and the network protocols through which they communicate. From a methodological...

    Provided By University of Leeds

  • White Papers // May 2009

    inContext - Interaction and Context-based Technologies for Collaborative Teams

    Much of today's teamwork is based on Collaborative Working Environments (CWEs). These are supporting team members participating in multiple projects at the same time, with the work spanning multiple organizations and the team members working on the move. Virtual, nimble, and mobile teams evolve and merge reflecting the vibrant nature...

    Provided By University of Leeds

  • White Papers // Apr 2008

    From BPEL to SRML: A Formal Transformational Approach

    The SENSORIA Reference Modeling Language (SRML) provides primitives for modeling business processes in a technology agnostic way. At the core of SRML is the notion of module as a composition of tightly coupled components and loosely coupled, dynamically discovered services. This paper presents an encoding of BPEL processes into SRML...

    Provided By University of Leeds

  • White Papers // Jul 2010

    Model-Driven Development of Adaptable Service-Oriented Business Processes

    Businesses typically structure their activities with workflows, which are often implemented in a rather static fashion in their IT systems. Now-a-days, system requirements change rapidly as businesses try to maintain their competitive edge, calling for similar agility of the IT systems. To this paper, the authors present StPowla, an approach...

    Provided By University of Leeds

  • White Papers // Dec 2007

    Towards Feature Interactions in Business Processes

    The feature interaction problem is generally associated with conflicting features causing undesirable effects. However, in this paper, the authors report on a situation where the combination of features (as policies) and service-targeted business processes yields non-negative effects. They consider business processes as base systems and policies as a feature mechanism...

    Provided By University of Leeds

  • White Papers // Sep 2008

    Applications of QKD Network for High Performance Distributed Computing

    Quantum Key Distribution (QKD) is a point to point secure key generation technology which provides unconditional security. To exploit the security of QKD for large scale practical communication, it must be used in a network fashion. BBN DARPA quantum network and SECOQC network of secrets are the examples of such...

    Provided By University of Leeds

  • White Papers // Jun 2009

    Towards Quality of Service in the Cloud

    Quality of Service (QoS) plays a critical role in the affective reservation of resources within service oriented distributed systems and has been widely investigated in the now well established paradigm of Grid Computing. The emergence of a new paradigm, Cloud Computing, continues the natural evolution of Distributed Systems to cater...

    Provided By University of Leeds

  • White Papers // Apr 2009

    The Coexistence of 802.11b/g and Bluetooth: An Experimental Comparison in LoS Conditions

    This paper presents experimental results for TCP throughput performance of the IEEE 802.11b/g standard in the presence of Bluetooth (BT) interference. The throughput of an IEEE 802.11b/g network is measured in a LoS environment. The results demonstrate that 802.11g is substantially more sensitive to BT interference than 802.11b. Currently, the...

    Provided By University of Leeds