University of Bristol

Displaying 1-40 of 65 results

  • White Papers // Jul 2013

    Evaporating Firewalls

    In this paper, the authors begin by reviewing an argument (independent from 1304.6483) suggesting that large AdS black holes dual to typical high-energy pure states of a single holographic CFT must have some structure at the horizon (i.e. a fuzzball/firewall). By weakly coupling the CFT to an auxiliary system, such...

    Provided By University of Bristol

  • White Papers // Jun 2013

    Predicting Intermediate Storage Performance for Workflow Applications

    System provisioning, resource allocation, and system configuration decisions for work flow I/O-intensive applications are complex even for expert users. One factor making the problem space more complex is that users face decisions at multiple levels: allocating resources to individual sub-systems (e.g., the application layer, the storage layer) and configuring each...

    Provided By University of Bristol

  • White Papers // Jun 2013

    Cross-Tier Application & Data Partitioning of Web Applications for Hybrid Cloud Deployment

    Hybrid cloud deployment offers flexibility in trade-o s between the cost-savings/scalability of the public cloud and control over data resources provided at a private premise. However, this flexibility comes at the expense of complexity in distributing a system over these two locations. For multi-tier web applications, this challenge manifests itself...

    Provided By University of Bristol

  • White Papers // Mar 2013

    Relay Selection for Simultaneous Information Transmission and Wireless Energy Transfer: A Tradeoff Perspective

    In certain applications, relay terminals can be employed to simultaneously deliver information and energy to a designated receiver and a Radio Frequency (RF) energy harvester, respectively. In such scenarios, the relay that is preferable for information transmission does not necessarily coincide with the relay with the strongest channel to the...

    Provided By University of Bristol

  • White Papers // Jan 2013

    On Graphs, GPUs, and Blind Dating a Workload to Processor Matchmaking Quest

    Graph processing has gained renewed attention. The increasing large scale and wealth of connected data, such as those accrued by social network applications, demand the design of new techniques and platforms to efficiently derive actionable information from large scale graphs. Hybrid systems that host processing units optimized for both fast...

    Provided By University of Bristol

  • White Papers // Dec 2012

    Password Authenticated Cluster-Based Group-Key Agreement for Smart Grid Communication

    Several multi-party systems supporting group- and cloud-based applications have been proposed in the context of Smart Grid. An important requirement of these systems is that the devices/parties need to communicate with each other as members of a group. In this paper, the authors present an efficient Group-Key (GK) management scheme...

    Provided By University of Bristol

  • White Papers // Dec 2012

    On Extracting Unit Tests From Interactive Programming Sessions

    Software engineering methodologies propose that developers should capture their efforts in ensuring that programs run correctly in repeatable and automated artifacts, such as unit tests. However, when looking at developer activities on a spectrum from exploratory testing to scripted testing the authors find that many engineering activities include bursts of...

    Provided By University of Bristol

  • White Papers // Nov 2012

    Towards Building Error Resilient GPGPU Applications

    GPUs (Graphics Processing Units) have gained wide adoption as accelerators for general purpose computing. They are widely used in error-sensitive applications, i.e. General Purpose GPU (GPGPU) applications However, the reliability implications of using GPUs are unclear. This paper presents a fault injection study to investigate the end-to-end reliability characteristics of...

    Provided By University of Bristol

  • White Papers // Nov 2012

    Full-Duplex Transmissions in Fiber-Connected Distributed Relay Antenna Systems

    Distributed Antenna Systems (DAS) have been studied extensively to improve spectral efficiency and extend coverage. Different from the previous studies that focused mostly on the enhancement of downlink or uplink performance through cooperation of distributed antennas, this paper proposes and investigates a novel communication configuration in which a fiber-connected DAS...

    Provided By University of Bristol

  • White Papers // Nov 2012

    Privacy Preserving Web Query Log Publishing: A Survey on Anonymization Techniques

    Web search queries are generally stored by search engines for the purpose of improving result ranking, query refinement, user modeling, language-based applications, and sharing data for academic research or commercial needs. Releasing Web query logs which contain valuable information for research or marketing, can breach the privacy of search engine...

    Provided By University of Bristol

  • White Papers // Sep 2012

    MANTICORE: a Framework for Partitioning Software Services for Hybrid Cloud

    Hybrid cloud deployment can be an attractive option for companies wanting to deploy software services on scalable public clouds, while still assuming local control over sensitive data resources. A hybrid deployment, despite providing better control, is difficult to design since code must be partitioned and distributed efficiently between public and...

    Provided By University of Bristol

  • White Papers // Jul 2012

    Transmit Antenna Selection for Security Enhancement in MIMO Wiretap Channels

    Information security has become a pivotal concern in wireless communications, due to the fact that the broadcast nature of the wireless medium allows eavesdroppers to intercept transmissions in the network. Traditionally, cryptographic protocols have been designed and implemented to provide security in the upper layers (e.g., the network layer), based...

    Provided By University of Bristol

  • White Papers // May 2012

    Avoiding the Disk Bottleneck in Deduplicated VM Transfer

    Data de-duplication is a commonly adopted optimization in the cloud infrastructure for optimizing the storage and the transfer of Virtual Machines (VM). Data de-duplication efficiently identifies and eliminates similarity across VM image files leading to a reduction in the amount of data that needs to be stored and/or transferred. This...

    Provided By University of Bristol

  • White Papers // May 2012

    An Optimal Energy Allocation Algorithm for Energy Harvesting Wireless Sensor Networks

    With the use of energy harvesting technologies, the lifetime of a Wireless Sensor Network (WSN) can be prolonged significantly. Unlike a traditional WSN powered by non-rechargeable batteries, the energy management policy of an energy harvesting WSN needs to take into account the energy replenishment process. In this paper, the authors...

    Provided By University of Bristol

  • White Papers // May 2012

    Dual-hop Amplify-and-Forward Transmission With Imperfect Channel Estimates at the Relay

    With reference to the typical three-node Amplify-and-Forward (AF) relaying setup, where a single relay assists the communication between a source terminal and a destination terminal, the authors investigate the effect of outdated Channel State Information (CSI) at the relay on the overall performance. In particular, they consider CSI-assisted (i.e., variable-gain)...

    Provided By University of Bristol

  • White Papers // May 2012

    Optimal Power Allocation in a Multi-Hop Decode-and-Forward Communication System

    This paper analyzes optimal power allocation schemes for a multi-hop decode-and-forward relay system in a Rayleigh fading environment at high signal-to-noise ratio. Analysis is done for two kinds of modulation schemes: M-ary phase-shift keying with coherent detection and orthogonal ??'?-ary frequency-shift keying with non-coherent detection. An optimal power allocation scheme...

    Provided By University of Bristol

  • White Papers // May 2012

    Efficient Authentication and Key Management for the Home Area Network

    Due to the extensive use of wireless technologies, security is one of the most important and challenging issues in smart grid networks. To secure data communications, strong authentication and key management mechanisms are needed. In this paper, the authors propose a mutual authentication scheme and key management protocol tailored for...

    Provided By University of Bristol

  • White Papers // May 2012

    Robust Power Allocation Designs for Cognitive Radio Networks With Cooperative Relays

    In this paper, the authors develop robust power allocation schemes for Cognitive Radio Networks (CRNs) that can operate in multiple bands with cooperative relays considering uncertainty among the channels of Secondary User (SU) network and among the channels of SU transmitters to Primary User (PU) receivers. Their objective is to...

    Provided By University of Bristol

  • White Papers // May 2012

    Power Line Network Topology Inference Using Frequency Domain Reflectometry

    Frequency Domain Reflectometry (FDR) is a technique that was proposed for fault detection in Digital Subscriber Line (DSL) cables. In this paper, the authors describe how FDR can be used to determine the topology of power line networks. To this end, they first infer distance information from the multiple signal...

    Provided By University of Bristol

  • White Papers // May 2012

    GPUs as Storage System Accelerators

    Massively multicore processors, such as Graphics Processing Units (GPUs), provide, at a comparable price, a one order of magnitude higher peak performance than traditional CPUs. This drop in the cost of computation, as any order-of-magnitude drop in the cost per unit of performance for a class of system components, triggers...

    Provided By University of Bristol

  • White Papers // May 2012

    LOS and NLOS Classification for Underwater Acoustic Localization

    The low sound speed in water makes Propagation Delay (PD) based range estimation attractive for UnderWater Acoustic Localization (UWAL). However, due to the long channel impulse response and the existence of reflecting objects, PD-based UWAL suffers from significant degradation when PD measurements of Non-Line-Of-Sight (NLOS) communication links are falsely identified...

    Provided By University of Bristol

  • White Papers // Apr 2012

    Model-Based Intrusion Detection for Home Area Networks in Smart Grids

    In this paper, the authors present a model-based Intrusion Detection System (IDS) for Home Area Networks (HANs) within the smart grid. Considering that ZigBee is the dominant technology in future HAN, the proposed IDS is designed to target ZigBee standard. Their focus is on the physical and Medium Access Control...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Key Challenges in Defending Against Malicious Socialbots

    The ease with which the authors adopt online personas and relationships has created a soft spot that cyber criminals are willing to exploit. Advances in artificial intelligence make it feasible to design bots that sense, think and act cooperatively in social settings just like human beings. In the wrong hands,...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Distance Based Heuristic for Power and Rate Allocation of Video Sensor Networks

    Video Sensor Networks (VSNs) offer an alternative to several existing surveillance technologies. However, unlike in conventional sensor network, video processing and transmission requires large amount of resources both in signal processing, i.e., encoding, and transmission of the encoded data. For such networks, an optimal encoding power and rate allocation method...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Distributed Dynamic Scheduling for Body Area Networks

    Body Area Networks (BANs), targeting everywhere anytime health monitoring, operate in license-exempt frequency bands. They require a cross layer design that jointly considers the requirements of access delay to the medium and Packet Delivery Ratio (PDR). In this paper, the authors experimentally evaluate the PDR of a BAN under static...

    Provided By University of Bristol

  • White Papers // Jan 2012

    Combinatorial Channel Signature Modulation for Wireless Ad-Hoc Networks

    In this paper, the authors introduce a novel modulation and multiplexing method which facilitates highly efficient and simultaneous communication between multiple terminals in wireless ad-hoc networks. They term this method Combinatorial Channel Signature Modulation (CCSM). The CCSM method is particularly efficient in situations where communicating nodes operate in highly time...

    Provided By University of Bristol

  • White Papers // Jun 2011

    SPECI-2 an Open-Source Framework for Predictive Simulation of Cloud-Scale Data-Centres

    The authors introduce Version 2 of SPECI (Simulation Program for Elastic Computing Infrastructure), a system for predictive simulation modelling of ultra-largescale Data-Centers (DCs), i.e. warehouse-sized facilities containing hundreds of thousands of servers, as used to provide cloud computing services. The move toward cloud computing is driving the construction of ever...

    Provided By University of Bristol

  • White Papers // Jun 2011

    Modelling Resilience in Cloud-Scale Data Centres

    The trend for cloud computing has initiated a race towards Data Centers (DC) of an ever-increasing size. The largest DCs now contain many hundreds of thousands of Virtual Machine (VM) services. Given the finite lifespan of hardware, such large DCs are subject to frequent hardware failure events that can lead...

    Provided By University of Bristol

  • White Papers // May 2011

    Analysis of the SSH Key Exchange Protocol

    The authors provide an analysis of the widely deployed SSH protocol's key exchange mechanism. They exploit the design of the SSH key exchange to perform the analysis in a modular manner. First, a shared secret key is obtained via a Diffie-Hellman key exchange. Next, a transform is applied to obtain...

    Provided By University of Bristol

  • White Papers // May 2011

    Using the Cloud to Determine Key Strengths

    The authors develop a new methodology to assess cryptographic key strength using cloud computing, by calculating the true economic cost of (symmetric- or private-) key retrieval for the most common cryptographic primitives. Although the present paper gives the current costs, more importantly it provides the tools and infrastructure to derive...

    Provided By University of Bristol

  • White Papers // Mar 2011

    Fully Homomorphic SIMD Operations

    At PKC 2010 Smart and Vercauteren presented a variant of Gentry's fully homomorphic public key encryption scheme and mentioned that the scheme could support SIMD style operations. The slow key generation process of the Smart - Vercauteren system was then addressed in a paper by Gentry and Halevi, but their...

    Provided By University of Bristol

  • White Papers // Mar 2011

    On CCA-Secure Fully Homomorphic Encryption

    It is well known that any encryption scheme which supports any form of homomorphic operation cannot be secure against adaptive chosen ciphertext attacks. The question then arises as to what is the most stringent security definition which is achievable by homomorphic encryption schemes. Prior work has shown that various schemes...

    Provided By University of Bristol

  • White Papers // Feb 2011

    Differential Fault Analysis of the Advanced Encryption Standard Using a Single Fault

    In this paper the authors present a differential fault attack that can be applied to the AES using a single fault. They demonstrate that when a single random byte fault is induced at the input of the eighth round, the AES key can be deduced using a two stage algorithm....

    Provided By University of Bristol

  • White Papers // Jan 2011

    Adaptive Pseudo-Free Groups and Applications

    A computational group is pseudo-free if an adversary cannot find solutions in this group for equations that are not trivially solvable in the free group. This notion was put forth by Rivest as a unifying abstraction of multiple group-related hardness assumptions commonly used in cryptography. Rivest's conjecture that the RSA...

    Provided By University of Bristol

  • White Papers // Jan 2011

    Efficient Two-Move Blind Signatures in the Common Reference String Model

    Blind signatures provide a mechanism for achieving privacy and anonymity whereby a user gets the signer to sign a message of his choice without the signer learning the content of the message, nor linking message/signature request pairs when he sees the final signature. In this paper, the authors construct a...

    Provided By University of Bristol

  • White Papers // Dec 2010

    Differential Fault Analysis of AES Using a Single Multiple-Byte Fault

    In this paper the authors present an improved fault attack on the Advanced Encryption Standard (AES). This paper presents an improvement on a recently published differential fault analysis of AES that requires one fault to recover the secret key being used. This attack requires that one byte entering into the...

    Provided By University of Bristol

  • White Papers // Dec 2010

    An Evaluation of Hash Functions on a Power Analysis Resistant Processor Architecture

    Cryptographic hash functions are omnipresent components in security-critical software and devices; they support, for example, digital signature and data authenticity schemes, mechanisms for key derivation, pseudo-random number generation and so on. A criteria for candidate hash functions in the SHA-3 contest is resistance against side-channel analysis which is a major...

    Provided By University of Bristol

  • White Papers // Sep 2010

    Finding Overlapping Communities in Networks by Label Propagation

    The authors propose an algorithm for finding overlapping community structure in very large networks. The algorithm is based on the label propagation technique of Raghavan, Albert, and Kumara, but is able to detect communities that overlap. Like the original algorithm, vertices have labels that propagate between neighbouring vertices so that...

    Provided By University of Bristol

  • White Papers // Sep 2010

    Improved Trace-Driven Cache-Collision Attacks against Embedded AES Implementations

    In this paper the authors present two attacks that exploit cache events, which are visible in some side channel, to derive a secret key used in an implementation of AES. The first is an improvement of an adaptive chosen plaintext attack presented at ACISP 2006. The second is a new...

    Provided By University of Bristol

  • White Papers // Sep 2010

    A Family of Key Agreement Mechanisms for Mission Critical Communications for Secure Mobile Ad Hoc and Wireless Mesh Internetworking

    Future wireless networks like mobile ad hoc networks and wireless mesh networks are expected to play important role in demanding communications such as mission critical communications. MANETs are ideal for emergency cases where the communication infrastructure has been completely destroyed and there is a need for quick set up of...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Distance Based Heuristic for Power and Rate Allocation of Video Sensor Networks

    Video Sensor Networks (VSNs) offer an alternative to several existing surveillance technologies. However, unlike in conventional sensor network, video processing and transmission requires large amount of resources both in signal processing, i.e., encoding, and transmission of the encoded data. For such networks, an optimal encoding power and rate allocation method...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Distributed Dynamic Scheduling for Body Area Networks

    Body Area Networks (BANs), targeting everywhere anytime health monitoring, operate in license-exempt frequency bands. They require a cross layer design that jointly considers the requirements of access delay to the medium and Packet Delivery Ratio (PDR). In this paper, the authors experimentally evaluate the PDR of a BAN under static...

    Provided By University of Bristol

  • White Papers // Dec 2009

    Subcarrier and Power Adaptation for Multiuser OFDMA-Based Cognitive Radio Systems

    This paper investigates the subcarrier and power allocation problem for an OFDM-based multiuser Cognitive Radio (CR) system. For CR systems it is important to keep the interference introduced to the Primary User (PU) band within a tolerable range. Since the joint subcarrier and power allocation problem is a non-convex integer...

    Provided By University of Bristol

  • White Papers // Dec 2012

    On Extracting Unit Tests From Interactive Programming Sessions

    Software engineering methodologies propose that developers should capture their efforts in ensuring that programs run correctly in repeatable and automated artifacts, such as unit tests. However, when looking at developer activities on a spectrum from exploratory testing to scripted testing the authors find that many engineering activities include bursts of...

    Provided By University of Bristol

  • White Papers // Mar 2011

    Fully Homomorphic SIMD Operations

    At PKC 2010 Smart and Vercauteren presented a variant of Gentry's fully homomorphic public key encryption scheme and mentioned that the scheme could support SIMD style operations. The slow key generation process of the Smart - Vercauteren system was then addressed in a paper by Gentry and Halevi, but their...

    Provided By University of Bristol

  • White Papers // Jan 2011

    Adaptive Pseudo-Free Groups and Applications

    A computational group is pseudo-free if an adversary cannot find solutions in this group for equations that are not trivially solvable in the free group. This notion was put forth by Rivest as a unifying abstraction of multiple group-related hardness assumptions commonly used in cryptography. Rivest's conjecture that the RSA...

    Provided By University of Bristol

  • White Papers // Dec 2010

    Differential Fault Analysis of AES Using a Single Multiple-Byte Fault

    In this paper the authors present an improved fault attack on the Advanced Encryption Standard (AES). This paper presents an improvement on a recently published differential fault analysis of AES that requires one fault to recover the secret key being used. This attack requires that one byte entering into the...

    Provided By University of Bristol

  • White Papers // Jan 2011

    Efficient Two-Move Blind Signatures in the Common Reference String Model

    Blind signatures provide a mechanism for achieving privacy and anonymity whereby a user gets the signer to sign a message of his choice without the signer learning the content of the message, nor linking message/signature request pairs when he sees the final signature. In this paper, the authors construct a...

    Provided By University of Bristol

  • White Papers // Mar 2011

    On CCA-Secure Fully Homomorphic Encryption

    It is well known that any encryption scheme which supports any form of homomorphic operation cannot be secure against adaptive chosen ciphertext attacks. The question then arises as to what is the most stringent security definition which is achievable by homomorphic encryption schemes. Prior work has shown that various schemes...

    Provided By University of Bristol

  • White Papers // Sep 2010

    Side-Channel Attacks on the McEliece and Niederreiter Public-Key Cryptosystems

    Research within "Post-quantum" cryptography has focused on development of schemes that resist quantum cryptanalysis. However, if such schemes are to be deployed, practical questions of efficiency and physical security should also be addressed; this is particularly important for embedded systems. To this end, the authors investigate issues relating to side-channel...

    Provided By University of Bristol

  • White Papers // Aug 2010

    Constructing Certificateless Encryption and ID-Based Encryption From ID-Based Key Agreement

    The authors discuss the relationship between ID-based key agreement protocols, certificateless encryption and ID-based key encapsulation mechanisms. In particular they show how in some sense ID-based key agreement is a primitive from which all others can be derived. In doing so they focus on distinctions between what they term pure...

    Provided By University of Bristol

  • White Papers // Dec 2009

    Fully Homomorphic Encryption With Relatively Small Key and Ciphertext Sizes

    The authors present a fully homomorphic encryption scheme which has both relatively small key and ciphertext size. The construction follows that of Gentry by producing a fully homomorphic scheme from a "Somewhat" homomorphic scheme. For the somewhat homomorphic scheme the public and private keys consist of two large integers (one...

    Provided By University of Bristol

  • White Papers // Feb 2011

    Differential Fault Analysis of the Advanced Encryption Standard Using a Single Fault

    In this paper the authors present a differential fault attack that can be applied to the AES using a single fault. They demonstrate that when a single random byte fault is induced at the input of the eighth round, the AES key can be deduced using a two stage algorithm....

    Provided By University of Bristol

  • White Papers // Jul 2009

    Identity Based Group Signatures From Hierarchical Identity-Based Encryption

    A number of previous papers explored the notion of identity-based group signature. The authors present a generic construction of identity-based group signatures. The construction is based on the Naor transformation of an identity-based signature out of an identity-based encryption, adjusted to hierarchical identity-based encryption. They identify sufficient conditions on the...

    Provided By University of Bristol

  • White Papers // Sep 2010

    Improved Trace-Driven Cache-Collision Attacks against Embedded AES Implementations

    In this paper the authors present two attacks that exploit cache events, which are visible in some side channel, to derive a secret key used in an implementation of AES. The first is an improvement of an adaptive chosen plaintext attack presented at ACISP 2006. The second is a new...

    Provided By University of Bristol

  • White Papers // Jun 2009

    Explicit Probabilistic Models for Databases and Networks

    Recent work in data mining and related areas has highlighted the importance of the statistical assessment of data mining results. Crucial to this endeavour is the choice of a non-trivial null model for the data, to which the found patterns can be contrasted. The most influential null models proposed so...

    Provided By University of Bristol

  • White Papers // Jul 2009

    Interference Alignment-Based Sum Capacity Bounds for Random Dense Gaussian Interference Networks

    The authors consider a dense K user Gaussian interference network formed by paired transmitters and receivers placed independently at random in a fixed spatial region. Under natural conditions on the node position distributions and signal attenuation, they prove convergence in probability of the average per-user capacity C??/K to 1/2 E...

    Provided By University of Bristol

  • White Papers // Sep 2010

    Finding Overlapping Communities in Networks by Label Propagation

    The authors propose an algorithm for finding overlapping community structure in very large networks. The algorithm is based on the label propagation technique of Raghavan, Albert, and Kumara, but is able to detect communities that overlap. Like the original algorithm, vertices have labels that propagate between neighbouring vertices so that...

    Provided By University of Bristol

  • White Papers // Sep 2009

    Seller Reputation And Trust In Pre-trade Communication

    It is shown that if there is adverse selection on seller's ability in experience goods market, credible communication can be sustained by reputation motives in spite of the inherent conflict of interests between sellers and buyers. In the absence of "Commitment" types, reputation motives are explained as a consequence of...

    Provided By University of Bristol

  • White Papers // May 2010

    Robustness Guarantees for Anonymity

    Anonymous communication protocols must achieve two seemingly contradictory goals: privacy (informally, they must guarantee the anonymity of the parties that send/receive information), and robustness (informally, they must ensure that the messages are not tampered). However, the long line of research that defines and analyzes the security of such mechanisms focuses...

    Provided By University of Bristol

  • White Papers // May 2011

    Analysis of the SSH Key Exchange Protocol

    The authors provide an analysis of the widely deployed SSH protocol's key exchange mechanism. They exploit the design of the SSH key exchange to perform the analysis in a modular manner. First, a shared secret key is obtained via a Diffie-Hellman key exchange. Next, a transform is applied to obtain...

    Provided By University of Bristol

  • White Papers // May 2011

    Using the Cloud to Determine Key Strengths

    The authors develop a new methodology to assess cryptographic key strength using cloud computing, by calculating the true economic cost of (symmetric- or private-) key retrieval for the most common cryptographic primitives. Although the present paper gives the current costs, more importantly it provides the tools and infrastructure to derive...

    Provided By University of Bristol

  • White Papers // May 2010

    How Do Firms? Outward FDI Strategies Relate To Their Activity At Home? Empirical Evidence For The UK

    This paper investigates the structure of firms' outward FDI and their behavior at home in both manufacturing and business services sectors. UK multinationals with overseas affiliates in low-wage economies invest simultaneously in a large number of high-wage countries. The author finds that more productive multinationals operate in a greater number...

    Provided By University of Bristol

  • White Papers // Jun 2011

    SPECI-2 an Open-Source Framework for Predictive Simulation of Cloud-Scale Data-Centres

    The authors introduce Version 2 of SPECI (Simulation Program for Elastic Computing Infrastructure), a system for predictive simulation modelling of ultra-largescale Data-Centers (DCs), i.e. warehouse-sized facilities containing hundreds of thousands of servers, as used to provide cloud computing services. The move toward cloud computing is driving the construction of ever...

    Provided By University of Bristol

  • White Papers // Jun 2011

    Modelling Resilience in Cloud-Scale Data Centres

    The trend for cloud computing has initiated a race towards Data Centers (DC) of an ever-increasing size. The largest DCs now contain many hundreds of thousands of Virtual Machine (VM) services. Given the finite lifespan of hardware, such large DCs are subject to frequent hardware failure events that can lead...

    Provided By University of Bristol

  • White Papers // Sep 2010

    A Family of Key Agreement Mechanisms for Mission Critical Communications for Secure Mobile Ad Hoc and Wireless Mesh Internetworking

    Future wireless networks like mobile ad hoc networks and wireless mesh networks are expected to play important role in demanding communications such as mission critical communications. MANETs are ideal for emergency cases where the communication infrastructure has been completely destroyed and there is a need for quick set up of...

    Provided By University of Bristol

  • White Papers // Jan 2012

    Combinatorial Channel Signature Modulation for Wireless Ad-Hoc Networks

    In this paper, the authors introduce a novel modulation and multiplexing method which facilitates highly efficient and simultaneous communication between multiple terminals in wireless ad-hoc networks. They term this method Combinatorial Channel Signature Modulation (CCSM). The CCSM method is particularly efficient in situations where communicating nodes operate in highly time...

    Provided By University of Bristol

  • White Papers // Apr 2012

    Model-Based Intrusion Detection for Home Area Networks in Smart Grids

    In this paper, the authors present a model-based Intrusion Detection System (IDS) for Home Area Networks (HANs) within the smart grid. Considering that ZigBee is the dominant technology in future HAN, the proposed IDS is designed to target ZigBee standard. Their focus is on the physical and Medium Access Control...

    Provided By University of Bristol

  • White Papers // May 2012

    An Optimal Energy Allocation Algorithm for Energy Harvesting Wireless Sensor Networks

    With the use of energy harvesting technologies, the lifetime of a Wireless Sensor Network (WSN) can be prolonged significantly. Unlike a traditional WSN powered by non-rechargeable batteries, the energy management policy of an energy harvesting WSN needs to take into account the energy replenishment process. In this paper, the authors...

    Provided By University of Bristol

  • White Papers // May 2012

    Dual-hop Amplify-and-Forward Transmission With Imperfect Channel Estimates at the Relay

    With reference to the typical three-node Amplify-and-Forward (AF) relaying setup, where a single relay assists the communication between a source terminal and a destination terminal, the authors investigate the effect of outdated Channel State Information (CSI) at the relay on the overall performance. In particular, they consider CSI-assisted (i.e., variable-gain)...

    Provided By University of Bristol

  • White Papers // May 2012

    Optimal Power Allocation in a Multi-Hop Decode-and-Forward Communication System

    This paper analyzes optimal power allocation schemes for a multi-hop decode-and-forward relay system in a Rayleigh fading environment at high signal-to-noise ratio. Analysis is done for two kinds of modulation schemes: M-ary phase-shift keying with coherent detection and orthogonal ??'?-ary frequency-shift keying with non-coherent detection. An optimal power allocation scheme...

    Provided By University of Bristol

  • White Papers // May 2012

    Efficient Authentication and Key Management for the Home Area Network

    Due to the extensive use of wireless technologies, security is one of the most important and challenging issues in smart grid networks. To secure data communications, strong authentication and key management mechanisms are needed. In this paper, the authors propose a mutual authentication scheme and key management protocol tailored for...

    Provided By University of Bristol

  • White Papers // May 2012

    Robust Power Allocation Designs for Cognitive Radio Networks With Cooperative Relays

    In this paper, the authors develop robust power allocation schemes for Cognitive Radio Networks (CRNs) that can operate in multiple bands with cooperative relays considering uncertainty among the channels of Secondary User (SU) network and among the channels of SU transmitters to Primary User (PU) receivers. Their objective is to...

    Provided By University of Bristol

  • White Papers // May 2012

    Power Line Network Topology Inference Using Frequency Domain Reflectometry

    Frequency Domain Reflectometry (FDR) is a technique that was proposed for fault detection in Digital Subscriber Line (DSL) cables. In this paper, the authors describe how FDR can be used to determine the topology of power line networks. To this end, they first infer distance information from the multiple signal...

    Provided By University of Bristol

  • White Papers // Nov 2012

    Towards Building Error Resilient GPGPU Applications

    GPUs (Graphics Processing Units) have gained wide adoption as accelerators for general purpose computing. They are widely used in error-sensitive applications, i.e. General Purpose GPU (GPGPU) applications However, the reliability implications of using GPUs are unclear. This paper presents a fault injection study to investigate the end-to-end reliability characteristics of...

    Provided By University of Bristol

  • White Papers // Jan 2013

    On Graphs, GPUs, and Blind Dating a Workload to Processor Matchmaking Quest

    Graph processing has gained renewed attention. The increasing large scale and wealth of connected data, such as those accrued by social network applications, demand the design of new techniques and platforms to efficiently derive actionable information from large scale graphs. Hybrid systems that host processing units optimized for both fast...

    Provided By University of Bristol

  • White Papers // May 2012

    Avoiding the Disk Bottleneck in Deduplicated VM Transfer

    Data de-duplication is a commonly adopted optimization in the cloud infrastructure for optimizing the storage and the transfer of Virtual Machines (VM). Data de-duplication efficiently identifies and eliminates similarity across VM image files leading to a reduction in the amount of data that needs to be stored and/or transferred. This...

    Provided By University of Bristol

  • White Papers // Mar 2012

    Key Challenges in Defending Against Malicious Socialbots

    The ease with which the authors adopt online personas and relationships has created a soft spot that cyber criminals are willing to exploit. Advances in artificial intelligence make it feasible to design bots that sense, think and act cooperatively in social settings just like human beings. In the wrong hands,...

    Provided By University of Bristol

  • White Papers // May 2012

    GPUs as Storage System Accelerators

    Massively multicore processors, such as Graphics Processing Units (GPUs), provide, at a comparable price, a one order of magnitude higher peak performance than traditional CPUs. This drop in the cost of computation, as any order-of-magnitude drop in the cost per unit of performance for a class of system components, triggers...

    Provided By University of Bristol

  • White Papers // May 2012

    LOS and NLOS Classification for Underwater Acoustic Localization

    The low sound speed in water makes Propagation Delay (PD) based range estimation attractive for UnderWater Acoustic Localization (UWAL). However, due to the long channel impulse response and the existence of reflecting objects, PD-based UWAL suffers from significant degradation when PD measurements of Non-Line-Of-Sight (NLOS) communication links are falsely identified...

    Provided By University of Bristol