University of Edinburgh

Displaying 1-40 of 46 results

  • White Papers // Sep 2013

    Quantum Digital Signatures without Quantum Memory

    Quantum Digital Signatures (QDS) allow for the exchange of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with. Additionally, messages cannot be repudiated - if one recipient accepts a message, the user is guaranteed that others will accept the same message...

    Provided By University of Edinburgh

  • White Papers // May 2012

    Toward Provenance-Based Security for Configuration Languages

    Large system installations are increasingly configured using high-level, mostly-declarative languages. Often, different users contribute data that is compiled centrally and distributed to individual systems. Although the systems themselves have been developed with reliability and availability in mind, the configuration compilation process can lead to unforeseen vulnerabilities because of the lack...

    Provided By University of Edinburgh

  • White Papers // Jan 2012

    Spatial Modulation for Multiple - Antenna Wireless Systems - A Survey

    Multiple-antenna techniques constitute a key technology for modern wireless communications, which trade-off superior error performance and higher data rates for increased system complexity and cost. Among the many transmission principles that exploit multiple-antenna at either the transmitter, the receiver, or both, Spatial Modulation (SM) is a novel and recently proposed...

    Provided By University of Edinburgh

  • White Papers // Jan 2012

    Using Machine Learning to Focus Iterative Optimization

    Iterative compiler optimization has been shown to outperform static approaches. This, however, is at the cost of large numbers of evaluations of the program. This paper develops a new methodology to reduce this number and hence speed up iterative optimization. It uses predictive modelling from the domain of machine learning...

    Provided By University of Edinburgh

  • White Papers // Sep 2011

    A Uniform Dependency Language for Improving Data Quality

    A variety of dependency formalisms have been studied for improving data quality. To treat these dependencies in a uniform framework, the authors propose a simple language, Quality Improving Dependencies (QIDs). They show that previous dependencies considered for data quality can be naturally expressed as QIDs, and that different enforcement mechanisms...

    Provided By University of Edinburgh

  • White Papers // Sep 2011

    A Comparison of OFDM-Based Modulation Schemes for OWC With Clipping Distortion

    In this paper, the electrical power requirement and spectral efficiency of multi-carrier transmission schemes for Optical Wireless Communications (OWC) are compared in the presence of front-end-induced double-sided signal clipping. The two existing multi-carrier modulation techniques based on Orthogonal Frequency Division Multiplexing (OFDM), Direct-Current-biased Optical OFDM (DCO-OFDM) and Asymmetrically Clipped Optical...

    Provided By University of Edinburgh

  • White Papers // Aug 2011

    Spectral Efficiency Analysis of Mobile Femtocell Based Cellular Systems

    In this paper, the authors propose a new concept called Mobile Femtocell (MFemtocell) network, which can be considered as a practical implementation of mobile relays (more precisely, moving networks). MFemtocells can be deployed in moving vehicles, such as trains, buses, or private cars to provide enhanced user throughput, extended coverage,...

    Provided By University of Edinburgh

  • White Papers // Jul 2011

    On Optimal Investment For A Behavioural Investor In Multiperiod Incomplete Market Models

    The authors provide easily verifiable conditions for the well-posedness of the optimal investment problem for a behavioral investor in an incomplete discrete-time multiperiod financial market model, for the first time in the literature. Under suitable assumptions they also establish the existence of optimal strategies. In the paper Kahneman and Tversky...

    Provided By University of Edinburgh

  • White Papers // Feb 2011

    On the Throughput of an OFDM-Based Cellular Optical Wireless System for an Aircraft Cabin

    In this paper, a cellular optical wireless communication system based on Orthogonal Frequency Division Multiplexing (OFDM) is simulated inside an aircraft cabin. Asymmetrically Clipped Optical OFDM (ACO-OFDM) and Direct-Current-biased Optical OFDM (DCO-OFDM) transmission schemes are compared in terms of throughput and cell coverage. Cellular networks with wavelength reuse factors of...

    Provided By University of Edinburgh

  • White Papers // Feb 2011

    Double-Sided Signal Clipping in ACO-OFDM Wireless Communication Systems

    In this paper, the impact of double-sided signal clipping on Optical Wireless Communication (OWC) systems employing Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM) is investigated. Time domain signal clipping generally results from Direct Current (DC) biasing and/or from physical limitations of the transmitter front-end. These include insufficient forward biasing...

    Provided By University of Edinburgh

  • White Papers // Jan 2011

    Protocols for Web Service Invocation

    The automatic invocation of a web service by an agent is a complex task which is currently being addressed by semantic markup techniques. However, it is difficult to define the computational aspects of a web service in this approach. In this paper the authors propose a protocol-based formalism which appears...

    Provided By University of Edinburgh

  • White Papers // Jan 2011

    Balancing System Throughput and Fairness in Multi-User OFDMA-TDD Using Busy Bursts

    This paper analyses Busy Burst (BB) enabled interference avoidance for multi-user Orthogonal Frequency Division Multiple Access (OFDMA) in a Manhattan grid deployment scenario. Upon successful reception of data, the receiver transmits a BB in a time-multiplexed mini-slot. Exploiting the channel reciprocity of Time Division Duplex (TDD), an exclusion region around...

    Provided By University of Edinburgh

  • White Papers // Oct 2010

    Provenance as Dependency Analysis

    Provenance is information recording the source, derivation, or history of some information. Provenance tracking has been studied in a variety of settings, particularly database management systems; however, although many candidate definitions of provenance have been proposed, the mathematical or semantic foundations of data provenance have received comparatively little attention. In...

    Provided By University of Edinburgh

  • White Papers // Sep 2010

    From Posture to Motion: The Challenge for Real Time Wireless Inertial Motion Capture

    Networks of Wireless Inertial Measurement Units (WIMUs) allow for the real time capture of orientation data from multiple devices. Combining data from WIMUs with a rigid body model allows estimation of subject posture. However, posture information is not sufficient for full-body motion capture, the position of the subject in space...

    Provided By University of Edinburgh

  • White Papers // Jul 2010

    On the Performance of Space Shift Keying for Optical Wireless Communications

    In this paper, the authors study the performance of Space Shift Keying (SSK) modulation applied to optical wireless channels. The optical Multiple-Input-Single-Output (MISO) channel used here is obtained through measurements. The experimental setup consists of two lasers and an optical receiver. Using the channel measurements, the performance of SSK is...

    Provided By University of Edinburgh

  • White Papers // Jun 2010

    On Protection by Layout Randomization

    Layout randomization is a powerful, popular technique for software protection. The authors present it and study it in programming-language terms. More specifically, they consider layout randomization as part of an implementation for a high-level programming language; the implementation translates this language to a lower-level language in which memory addresses are...

    Provided By University of Edinburgh

  • White Papers // May 2010

    An Overview of Indoor OFDM/DMT Optical Wireless Communication Systems

    This paper is an overview of indoor OFDM (Orthogonal Frequency Division Multiplexing)/DMT (Discrete Multi-Tone) Optical Wireless (OW) communication systems. Indoor OW OFDM/DMT systems can be classified into two groups. One group produces half-wave symmetry time signal at the output of the OFDM modulator by special assignment of sub-carriers. Thus, allowing...

    Provided By University of Edinburgh

  • White Papers // Apr 2010

    Dynamic Resource Partitioning for Downlink Femto-to-Macro-Cell Interference Avoidance

    Femto-cells consist of user-deployed Home Evolved NodeBs (HeNBs) that promise substantial gains in system spectral efficiency, coverage, and data rates due to an enhanced reuse of radio resources. However, reusing radio resources in an uncoordinated, random fashion introduces potentially destructive interference to the system, both, in the femto and macro...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Use of Body Model Constraints to Improve Accuracy of Inertial Motion Capture

    Presents simulations of an algorithm for estimating linear acceleration of wireless inertial measurement units based on body model constraints. The behaviour of the proposed algorithm is compared to existing algorithms based on motion capture data from the Carnegie Mellon University motion capture corpus. The new algorithm is demonstrated to be...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    The Information Theoretic Approach to Signal Anomaly Detection for Cognitive Radio

    Efficient utilisation and sharing of limited spectrum resources in an autonomous fashion is one of the primary goals of cognitive radio. However, decentralised spectrum sharing can lead to interference scenarios that must be detected and characterised to help achieve the other goal of cognitive radio - reliable service for the...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Demand Based State Aware Channel Reconfiguration Algorithm for Multi-Channel Multi-Radio Wireless Mesh Networks

    Efficient utilization of Multi Channel - Multi Radio (MC-MR) Wireless Mesh Networks (WMNs) can be achieved only by intelligent Channel Assignment (CA) and Link Scheduling (LS). Due to the dynamic nature of traffic demand in WMNs, the CA has to be reconfigured whenever traffic demand changes, in order to achieve...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Slow Frequency Hopping for Mitigating Tidal Fading on Rural Long Distance Over-Water Wireless Links

    The authors consider the scenario where long-distance point-to-point wireless links are established over tidal estuaries to bring Internet access to rural communities living in coastal villages. Using real signal strength measurements from links in the Tegola network testbed in northwest Scotland, they highlight the significance of the tidal fading problem,...

    Provided By University of Edinburgh

  • White Papers // Feb 2010

    Minimising Loss-Induced Errors in Real Time Wireless Sensing by Avoiding Data Dependency

    The use of local processing to reduce data transmission rates, and thereby power and bandwidth requirements, is common in wireless sensor networks. Achieving the minimum possible data rate, however, is not always the optimal choice when the effects of packet loss on overall measurement error are considered. This paper presents...

    Provided By University of Edinburgh

  • White Papers // Feb 2010

    The Economic Crisis Is A Crisis For Economic Theory

    This paper examines, in the light of recent events, the origins of the difficulties that current macroeconomic models have in encompassing the sort of sudden crisis which the authors are currently observing. The reasons for this are partly due to fundamental difficulties in the underlying General Equilibrium theory and partly...

    Provided By University of Edinburgh

  • White Papers // Jan 2010

    Mass Storage Management and the Grid

    The University of Edinburgh has a significant interest in mass storage systems as it is one of the core groups tasked with the roll out of storage software for the UK's particle physics grid, GridPP. This paper presents the results of a development project to provide software interfaces between the...

    Provided By University of Edinburgh

  • White Papers // Jan 2010

    Selectively Storing XML Data in Relations

    This paper presents a new framework for users to select relevant data from an XML document and store it in an existing relational database, as opposed to previous approaches that shred the entire XML document into a newly created database of a newly designed schema. The framework is based on...

    Provided By University of Edinburgh

  • White Papers // Nov 2009

    Information Flow in Secret Sharing Protocols

    The entangled graph states have emerged as an elegant and powerful quantum resource, indeed almost all multiparty protocols can be written in terms of graph states including Measurement Based Quantum Computation (MBQC), error correction and secret sharing amongst others. In addition they are at the forefront in terms of implementations....

    Provided By University of Edinburgh

  • White Papers // Nov 2009

    Self-Organised Interference Mitigation in Wireless Networks Using Busy Bursts

    In this paper, self-organised interference management in ad hoc networks that lack any centralised control, is addressed. Using time-multiplexed Busy Bursts (BB) in a mini-slot, the receivers actively broadcast a power signal on their reserved time-frequency slot. The potential new transmitters that intend to reuse the already reserved resources can...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Reducing Training Time in a One-Shot Machine Learning-Based Compiler

    Iterative compilation of applications has proved a popular and successful approach to achieving high performance. This however, is at the cost of many runs of the application. Machine learning based approaches overcome this at the expense of a large off-line training cost. This paper presents a new approach to dramatically...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Indoor MIMO Optical Wireless Communication Using Spatial Modulation

    In this paper, a Multiple-Input Multiple-Output (MIMO) technique for indoor Optical Wireless (OW) communication is proposed. The scheme is called Optical Spatial Modulation (OSM). The key concept is based on Spatial Modulation (SM) technique. At each time instant, only one transmitter is active and the others are inactive. Each transmitter...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Asset Correlations For Credit Card Defaults

    The capital requirements formula within the Basel II Accord is based on a Merton one factor model and in the case of credit cards an asset correlation of 4% is assumed. In this paper the authors estimate the asset correlation for two datasets assuming the one factor model. The datasets...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    A Learning-Based Approach for Distributed Multi-Radio Channel Allocation in Wireless Mesh Networks

    The authors consider the distributed channel allocation problem in IEEE 802.11-based multi-radio wireless mesh networks. They develop a new scalable protocol termed LCAP for efficient and adaptive distributed multi-radio channel allocation. In LCAP, nodes autonomously learn their channel allocation based on neighborhood and channel usage information, which is obtained via...

    Provided By University of Edinburgh

  • White Papers // Jul 2009

    Line-of-Sight Infrared Wireless Path Loss Simulation in an Aircraft Cabin

    With the advent of non-coherent high-power Light Emitting Diodes (LEDs) and highly sensitive Photo-Diodes (PDs), optical wireless communication has become a viable candidate for medium range data transmission. Compared to Radio Frequency (RF) communication, it offers an almost unlimited bandwidth, license-free operation, low-cost front ends and expected high data rates....

    Provided By University of Edinburgh

  • White Papers // Jul 2009

    Understanding the Role of Multi-Rate Retry Mechanism for Effective Rate Control in 802.11 Wireless LANs

    The authors consider the Multi-Rate Retry (MRR) capability provided by current 802.11 implementations and carry out simulation-based study of its impact on performance with state-of-the-art rate control mechanisms in typical indoor wireless LAN scenarios. They find that MRR is more effective in non-congested environments, necessitating the need for a mechanism...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    A Proof-Carrying-Code Infrastructure for Resources

    This paper tackles the issue of increasing dependability of distributed systems in the presence of mobile code. To this end the authors present a complete Proof-Carrying-Code (PCC) infrastructure for independent and automatic certification of resource bounds of mobile JVM programs. This includes a certifying compiler for a high-level language, which...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    Information Content Analysis and Clustering for Signal Anomaly Detection

    An information theoretic approach to detecting unusual events in radio signals is presented. Anomalies are detected through a measure of the events' information content. Clustering is utilised to reduce false-positives while allowing a lower discrimination threshold to be used for improved anomaly detection. Experiments with a real Wireless LAN test...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    DIVINEMAN: A System for Easing Management of Broadband Wireless Access Networks

    Technical advances and the commoditzation of wireless equipment have boosted the business volume of commercial Wireless Internet Service Providers (WISPs) around the world. It is more and more common for WISPs to deploy networks exclusively based on wireless technologies both for the backbone links and for the "Last mile" access;...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    Star-Node Identification in Self-Organising Wireless Networks

    Self-configuring, hierarchical, ad hoc, wireless networks are fast becoming the focus of research in the field of wireless communications. Such networks can be considered as graphs where a node represents a transceiver unit and an edge represents a communication link between two nodes. In order to probabilistically analyze connectedness issues...

    Provided By University of Edinburgh

  • White Papers // May 2009

    Location Discovery in SpeckNets Using Relative Direction Information

    A speck is intended to be a miniature (5X5X5mm) semiconductor device that combines sensing, processing, wireless communication and energy storage capabilities. A specknet is an adhoc wireless network of specks. The location of specks in the network is useful in processing information, for reasons ranging from routing data to giving...

    Provided By University of Edinburgh

  • White Papers // May 2009

    Analytical SIR for Self-Organizing Wireless Networks

    The Signal to Interference Ratio (SIR) in the presence of multi-path fading, shadowing and path loss is a valuable parameter for studying the capacity of a wireless system. This paper presents a new generalized path loss equation that takes into account the large-scale path loss as well as the small-scale...

    Provided By University of Edinburgh

  • White Papers // Feb 2005

    Exploration Games - A Formal Foundation for UML Design Tools

    This paper extends the two-player games as used in verification to exploration games to fill this gap. An exploration game can be specified on the basis of a model which contains informally defined conditions as it is often the case with UML models. During a play the game may be...

    Provided By University of Edinburgh

  • Tools & Templates // Nov 2007

    Project Plan Template

    This is a template for project plan with information about: staff; research income; reports; bristol analyses; return to RAE; submission interface; student/finance enhancements; other enhancements. It also gives information of: business analysis system analysis & design build integration acceptance; and deployment of project.

    Provided By University of Edinburgh

  • White Papers // Nov 2009

    Information Flow in Secret Sharing Protocols

    The entangled graph states have emerged as an elegant and powerful quantum resource, indeed almost all multiparty protocols can be written in terms of graph states including Measurement Based Quantum Computation (MBQC), error correction and secret sharing amongst others. In addition they are at the forefront in terms of implementations....

    Provided By University of Edinburgh

  • White Papers // Jul 2009

    Understanding the Role of Multi-Rate Retry Mechanism for Effective Rate Control in 802.11 Wireless LANs

    The authors consider the Multi-Rate Retry (MRR) capability provided by current 802.11 implementations and carry out simulation-based study of its impact on performance with state-of-the-art rate control mechanisms in typical indoor wireless LAN scenarios. They find that MRR is more effective in non-congested environments, necessitating the need for a mechanism...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Slow Frequency Hopping for Mitigating Tidal Fading on Rural Long Distance Over-Water Wireless Links

    The authors consider the scenario where long-distance point-to-point wireless links are established over tidal estuaries to bring Internet access to rural communities living in coastal villages. Using real signal strength measurements from links in the Tegola network testbed in northwest Scotland, they highlight the significance of the tidal fading problem,...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    A Learning-Based Approach for Distributed Multi-Radio Channel Allocation in Wireless Mesh Networks

    The authors consider the distributed channel allocation problem in IEEE 802.11-based multi-radio wireless mesh networks. They develop a new scalable protocol termed LCAP for efficient and adaptive distributed multi-radio channel allocation. In LCAP, nodes autonomously learn their channel allocation based on neighborhood and channel usage information, which is obtained via...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Demand Based State Aware Channel Reconfiguration Algorithm for Multi-Channel Multi-Radio Wireless Mesh Networks

    Efficient utilization of Multi Channel - Multi Radio (MC-MR) Wireless Mesh Networks (WMNs) can be achieved only by intelligent Channel Assignment (CA) and Link Scheduling (LS). Due to the dynamic nature of traffic demand in WMNs, the CA has to be reconfigured whenever traffic demand changes, in order to achieve...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    DIVINEMAN: A System for Easing Management of Broadband Wireless Access Networks

    Technical advances and the commoditzation of wireless equipment have boosted the business volume of commercial Wireless Internet Service Providers (WISPs) around the world. It is more and more common for WISPs to deploy networks exclusively based on wireless technologies both for the backbone links and for the "Last mile" access;...

    Provided By University of Edinburgh

  • White Papers // Jun 2010

    On Protection by Layout Randomization

    Layout randomization is a powerful, popular technique for software protection. The authors present it and study it in programming-language terms. More specifically, they consider layout randomization as part of an implementation for a high-level programming language; the implementation translates this language to a lower-level language in which memory addresses are...

    Provided By University of Edinburgh

  • White Papers // Jul 2011

    On Optimal Investment For A Behavioural Investor In Multiperiod Incomplete Market Models

    The authors provide easily verifiable conditions for the well-posedness of the optimal investment problem for a behavioral investor in an incomplete discrete-time multiperiod financial market model, for the first time in the literature. Under suitable assumptions they also establish the existence of optimal strategies. In the paper Kahneman and Tversky...

    Provided By University of Edinburgh

  • White Papers // Feb 2010

    The Economic Crisis Is A Crisis For Economic Theory

    This paper examines, in the light of recent events, the origins of the difficulties that current macroeconomic models have in encompassing the sort of sudden crisis which the authors are currently observing. The reasons for this are partly due to fundamental difficulties in the underlying General Equilibrium theory and partly...

    Provided By University of Edinburgh

  • White Papers // Jan 2010

    Mass Storage Management and the Grid

    The University of Edinburgh has a significant interest in mass storage systems as it is one of the core groups tasked with the roll out of storage software for the UK's particle physics grid, GridPP. This paper presents the results of a development project to provide software interfaces between the...

    Provided By University of Edinburgh

  • White Papers // Jul 2010

    On the Performance of Space Shift Keying for Optical Wireless Communications

    In this paper, the authors study the performance of Space Shift Keying (SSK) modulation applied to optical wireless channels. The optical Multiple-Input-Single-Output (MISO) channel used here is obtained through measurements. The experimental setup consists of two lasers and an optical receiver. Using the channel measurements, the performance of SSK is...

    Provided By University of Edinburgh

  • White Papers // Jan 2011

    Balancing System Throughput and Fairness in Multi-User OFDMA-TDD Using Busy Bursts

    This paper analyses Busy Burst (BB) enabled interference avoidance for multi-user Orthogonal Frequency Division Multiple Access (OFDMA) in a Manhattan grid deployment scenario. Upon successful reception of data, the receiver transmits a BB in a time-multiplexed mini-slot. Exploiting the channel reciprocity of Time Division Duplex (TDD), an exclusion region around...

    Provided By University of Edinburgh

  • White Papers // Aug 2011

    Spectral Efficiency Analysis of Mobile Femtocell Based Cellular Systems

    In this paper, the authors propose a new concept called Mobile Femtocell (MFemtocell) network, which can be considered as a practical implementation of mobile relays (more precisely, moving networks). MFemtocells can be deployed in moving vehicles, such as trains, buses, or private cars to provide enhanced user throughput, extended coverage,...

    Provided By University of Edinburgh

  • White Papers // May 2009

    Predistortion in Optical Wireless Transmission Using OFDM

    The nonlinear characteristic of an LED (Light Emitting Diode) imposes limitations on the performance of indoor Optical Wireless (OW) systems when using intensity modulation in combination with OFDM (Orthogonal Frequency Division Multiplexing). First, the impact of the nonlinear characteristic on bit-error performance is analyzed using a commercially available LED (OSRAM,...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    The Information Theoretic Approach to Signal Anomaly Detection for Cognitive Radio

    Efficient utilisation and sharing of limited spectrum resources in an autonomous fashion is one of the primary goals of cognitive radio. However, decentralised spectrum sharing can lead to interference scenarios that must be detected and characterised to help achieve the other goal of cognitive radio - reliable service for the...

    Provided By University of Edinburgh

  • White Papers // May 2009

    Practical Considerations for Indoor Wireless Optical System Implementation Using OFDM

    This paper describes the implementation of OFDM (Orthogonal Frequency Division Multiplexing) for optical wireless systems using non-coherent light. In particular, Light Emitting Diodes (LEDs) and PhotoDiodes (PDs) are considered. The paper shows how classical OFDM is adapted to optical system constraints. Several key OFDM design issues are studied. In this...

    Provided By University of Edinburgh

  • White Papers // Nov 2009

    Self-Organised Interference Mitigation in Wireless Networks Using Busy Bursts

    In this paper, self-organised interference management in ad hoc networks that lack any centralised control, is addressed. Using time-multiplexed Busy Bursts (BB) in a mini-slot, the receivers actively broadcast a power signal on their reserved time-frequency slot. The potential new transmitters that intend to reuse the already reserved resources can...

    Provided By University of Edinburgh

  • White Papers // May 2009

    Analytical SIR for Self-Organizing Wireless Networks

    The Signal to Interference Ratio (SIR) in the presence of multi-path fading, shadowing and path loss is a valuable parameter for studying the capacity of a wireless system. This paper presents a new generalized path loss equation that takes into account the large-scale path loss as well as the small-scale...

    Provided By University of Edinburgh

  • White Papers // Feb 2011

    Double-Sided Signal Clipping in ACO-OFDM Wireless Communication Systems

    In this paper, the impact of double-sided signal clipping on Optical Wireless Communication (OWC) systems employing Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM) is investigated. Time domain signal clipping generally results from Direct Current (DC) biasing and/or from physical limitations of the transmitter front-end. These include insufficient forward biasing...

    Provided By University of Edinburgh

  • White Papers // Feb 2011

    On the Throughput of an OFDM-Based Cellular Optical Wireless System for an Aircraft Cabin

    In this paper, a cellular optical wireless communication system based on Orthogonal Frequency Division Multiplexing (OFDM) is simulated inside an aircraft cabin. Asymmetrically Clipped Optical OFDM (ACO-OFDM) and Direct-Current-biased Optical OFDM (DCO-OFDM) transmission schemes are compared in terms of throughput and cell coverage. Cellular networks with wavelength reuse factors of...

    Provided By University of Edinburgh

  • White Papers // Sep 2011

    A Comparison of OFDM-Based Modulation Schemes for OWC With Clipping Distortion

    In this paper, the electrical power requirement and spectral efficiency of multi-carrier transmission schemes for Optical Wireless Communications (OWC) are compared in the presence of front-end-induced double-sided signal clipping. The two existing multi-carrier modulation techniques based on Orthogonal Frequency Division Multiplexing (OFDM), Direct-Current-biased Optical OFDM (DCO-OFDM) and Asymmetrically Clipped Optical...

    Provided By University of Edinburgh

  • White Papers // May 2010

    An Overview of Indoor OFDM/DMT Optical Wireless Communication Systems

    This paper is an overview of indoor OFDM (Orthogonal Frequency Division Multiplexing)/DMT (Discrete Multi-Tone) Optical Wireless (OW) communication systems. Indoor OW OFDM/DMT systems can be classified into two groups. One group produces half-wave symmetry time signal at the output of the OFDM modulator by special assignment of sub-carriers. Thus, allowing...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Indoor MIMO Optical Wireless Communication Using Spatial Modulation

    In this paper, a Multiple-Input Multiple-Output (MIMO) technique for indoor Optical Wireless (OW) communication is proposed. The scheme is called Optical Spatial Modulation (OSM). The key concept is based on Spatial Modulation (SM) technique. At each time instant, only one transmitter is active and the others are inactive. Each transmitter...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    Information Content Analysis and Clustering for Signal Anomaly Detection

    An information theoretic approach to detecting unusual events in radio signals is presented. Anomalies are detected through a measure of the events' information content. Clustering is utilised to reduce false-positives while allowing a lower discrimination threshold to be used for improved anomaly detection. Experiments with a real Wireless LAN test...

    Provided By University of Edinburgh

  • White Papers // Jun 2009

    Star-Node Identification in Self-Organising Wireless Networks

    Self-configuring, hierarchical, ad hoc, wireless networks are fast becoming the focus of research in the field of wireless communications. Such networks can be considered as graphs where a node represents a transceiver unit and an edge represents a communication link between two nodes. In order to probabilistically analyze connectedness issues...

    Provided By University of Edinburgh

  • White Papers // Jul 2009

    Line-of-Sight Infrared Wireless Path Loss Simulation in an Aircraft Cabin

    With the advent of non-coherent high-power Light Emitting Diodes (LEDs) and highly sensitive Photo-Diodes (PDs), optical wireless communication has become a viable candidate for medium range data transmission. Compared to Radio Frequency (RF) communication, it offers an almost unlimited bandwidth, license-free operation, low-cost front ends and expected high data rates....

    Provided By University of Edinburgh

  • White Papers // Apr 2010

    Dynamic Resource Partitioning for Downlink Femto-to-Macro-Cell Interference Avoidance

    Femto-cells consist of user-deployed Home Evolved NodeBs (HeNBs) that promise substantial gains in system spectral efficiency, coverage, and data rates due to an enhanced reuse of radio resources. However, reusing radio resources in an uncoordinated, random fashion introduces potentially destructive interference to the system, both, in the femto and macro...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Reducing Training Time in a One-Shot Machine Learning-Based Compiler

    Iterative compilation of applications has proved a popular and successful approach to achieving high performance. This however, is at the cost of many runs of the application. Machine learning based approaches overcome this at the expense of a large off-line training cost. This paper presents a new approach to dramatically...

    Provided By University of Edinburgh

  • White Papers // Jan 2012

    Using Machine Learning to Focus Iterative Optimization

    Iterative compiler optimization has been shown to outperform static approaches. This, however, is at the cost of large numbers of evaluations of the program. This paper develops a new methodology to reduce this number and hence speed up iterative optimization. It uses predictive modelling from the domain of machine learning...

    Provided By University of Edinburgh

  • White Papers // Mar 2010

    Use of Body Model Constraints to Improve Accuracy of Inertial Motion Capture

    Presents simulations of an algorithm for estimating linear acceleration of wireless inertial measurement units based on body model constraints. The behaviour of the proposed algorithm is compared to existing algorithms based on motion capture data from the Carnegie Mellon University motion capture corpus. The new algorithm is demonstrated to be...

    Provided By University of Edinburgh

  • White Papers // Jan 2012

    Spatial Modulation for Multiple - Antenna Wireless Systems - A Survey

    Multiple-antenna techniques constitute a key technology for modern wireless communications, which trade-off superior error performance and higher data rates for increased system complexity and cost. Among the many transmission principles that exploit multiple-antenna at either the transmitter, the receiver, or both, Spatial Modulation (SM) is a novel and recently proposed...

    Provided By University of Edinburgh

  • White Papers // Oct 2010

    Provenance as Dependency Analysis

    Provenance is information recording the source, derivation, or history of some information. Provenance tracking has been studied in a variety of settings, particularly database management systems; however, although many candidate definitions of provenance have been proposed, the mathematical or semantic foundations of data provenance have received comparatively little attention. In...

    Provided By University of Edinburgh

  • White Papers // May 2012

    Toward Provenance-Based Security for Configuration Languages

    Large system installations are increasingly configured using high-level, mostly-declarative languages. Often, different users contribute data that is compiled centrally and distributed to individual systems. Although the systems themselves have been developed with reliability and availability in mind, the configuration compilation process can lead to unforeseen vulnerabilities because of the lack...

    Provided By University of Edinburgh

  • White Papers // Sep 2013

    Quantum Digital Signatures without Quantum Memory

    Quantum Digital Signatures (QDS) allow for the exchange of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with. Additionally, messages cannot be repudiated - if one recipient accepts a message, the user is guaranteed that others will accept the same message...

    Provided By University of Edinburgh

  • White Papers // Aug 2008

    CEO Overconfidence In M&A Decision Making And Its Impact On Firm Performance

    Using a large sample of over 1,900 M&A deals from 1993 to 2005, and data on more than 3,100 CEOs, the authors explore merger and acquisition activities from a behavioral perspective, and provide another explanation of M&A motives and firm stock performance. They empirically test if overconfident CEOs are more...

    Provided By University of Edinburgh

  • White Papers // Jan 2010

    Selectively Storing XML Data in Relations

    This paper presents a new framework for users to select relevant data from an XML document and store it in an existing relational database, as opposed to previous approaches that shred the entire XML document into a newly created database of a newly designed schema. The framework is based on...

    Provided By University of Edinburgh

  • White Papers // Sep 2009

    Asset Correlations For Credit Card Defaults

    The capital requirements formula within the Basel II Accord is based on a Merton one factor model and in the case of credit cards an asset correlation of 4% is assumed. In this paper the authors estimate the asset correlation for two datasets assuming the one factor model. The datasets...

    Provided By University of Edinburgh

  • White Papers // Jan 2011

    Protocols for Web Service Invocation

    The automatic invocation of a web service by an agent is a complex task which is currently being addressed by semantic markup techniques. However, it is difficult to define the computational aspects of a web service in this approach. In this paper the authors propose a protocol-based formalism which appears...

    Provided By University of Edinburgh