Chinese University of Hong Kong

Displaying 1-40 of 134 results

  • White Papers // Apr 2014

    Degraded-First Scheduling for MapReduce in Erasure-Coded Storage Clusters

    The authors have witnessed an increasing adoption of erasure coding in modern clustered storage systems to reduce the storage overhead of traditional 3-way replication. However, it remains an open issue of how to customize the data analytics paradigm for erasure-coded storage, especially when the storage system operates in failure mode....

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    Experiences Building Network-Coding-Based Distributed Storage Systems

    Large-scale distributed storage systems are prone to node failures. To provide fault tolerance, data is often encoded to maintain data redundancy over multiple storage nodes. If a node fails, it can be repaired by downloading data from surviving nodes and regenerating the lost data in a new node. Network coding...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    Continuous Constraint Query Evaluation For Spatiotemporal Streams

    In this paper, the authors study the evaluation of Continuous Constraint Queries (CCQs) for spatiotemporal streams. A CCQ triggers an alert whenever a configuration of constraints between streaming events in space and time are satisfied. Consider, for instance, a server that receives updates from GPS-enabled agents that report their positions...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    FPGA-Based SIMD Processor

    Although Field Programmable Gate Arrays (FPGAs) can have high performance gains over equivalent microprocessor based systems, they have the disadvantage that the design time is much higher than for an equivalent software based system. A massively parallel Single Instruction Multiple Data stream (SIMD) processor designed specifically for cryptographic key search...

    Provided By Chinese University of Hong Kong

  • White Papers // Sep 2013

    On the Speedup of Recovery in Large-Scale Erasure-Coded Storage Systems

    Modern storage systems stripe redundant data across multiple nodes to provide availability guarantees against node failures. One form of data redundancy is based on XOR-based erasure codes, which use only XOR operations for encoding and decoding. In addition to tolerating failures, a storage system must also provide fast failure recovery...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2013

    Top-K Nearest Keyword Search on Large Graphs

    k-NK is not only useful as a stand-alone query but also as a building block for tackling complex graph pattern matching problems. The key to an accurate k-NK result is precise shortest distance estimation in a graph. Based on the latest distance oracle technique, the authors build a shortest path...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2013

    NCCloud: A Network-Coding-Based Storage System in a Cloud-of-Clouds

    To provide fault tolerance for cloud storage, recent studies propose to stripe data across multiple cloud vendors. However, if a cloud suffers from a permanent failure and loses all its data, the authors need to repair the lost data with the help of the other surviving clouds to preserve data...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2013

    RevDedup: A Reverse Deduplication Storage System Optimized for Reads to Latest Backups

    De-duplication is known to effectively eliminate duplicates, yet it introduces fragmentation that degrades read performance. The authors propose RevDedup, a de-duplication system that optimizes reads to the latest backups of Virtual Machine (VM) images using reverse de-duplication. In contrast with conventional de-duplication that removes duplicates from new data, RevDedup removes...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2013

    Enabling Data Integrity Protection in Regenerating-Coding-Based Cloud Storage: Theory and Implementation

    To protect outsourced data in cloud storage against corruptions, adding fault tolerance to cloud storage, along with efficient data integrity checking and recovery procedures, becomes critical. Regenerating codes provide fault tolerance by striping data across multiple servers, while using less repair traffic than traditional erasure codes during failure recovery. Therefore,...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2013

    Limits of Provable Security for Homomorphic Encryption

    In this paper the authors revisit the question of basing cryptography on NP-hardness. If P equals NP then computationally secure encryption is impossible. Is the converse true? Despite considerable e orts, there is no candidate encryption scheme whose security can be plausibly reduced to the worst-case hardness of some NP-complete...

    Provided By Chinese University of Hong Kong

  • White Papers // May 2013

    BASIC Regenerating Code: Binary Addition and Shift for Exact Repair

    Regenerating code is a class of storage codes that achieve the optimal trade-off between storage capacity and repair bandwidth, which are two important performance metrics in data storage systems. However, existing constructions of regenerating codes rely on expensive computational operations such as finite field multiplication. The high coding and repair...

    Provided By Chinese University of Hong Kong

  • White Papers // May 2013

    Physical-Layer Multicasting by Stochastic Transmit Beamforming and Alamouti Space-Time Coding

    Consider transceiver designs in a multiuser Multi-Input Single-Output (MISO) downlink channel, where the users are to receive the same data stream simultaneously. This problem, known as physical-layer multicasting, has drawn much interest. Presently, a popularized approach is transmit beamforming, in which the beamforming optimization is handled by a rank-one approximation...

    Provided By Chinese University of Hong Kong

  • White Papers // Apr 2013

    Transmission Sequence Design and Allocation for Wide Area Ad Hoc Networks

    In this paper, the authors examine the question of designing and allocating transmission sequences to users in a mobile ad hoc network that has no spatial boundary. A basic tenet of the transmission sequence approach for addressing the media access control problem is that under normal operation conditions, there is...

    Provided By Chinese University of Hong Kong

  • White Papers // Mar 2013

    Multi-Group Multicast Beamforming in Cognitive Radio Networks Via Rank-Two Transmit Beamformed Alamouti Space-Time Coding

    In this paper, the authors consider transmit design in Multiple-Input Single-Output (MISO) Multi-group Multicast (MM) Cognitive Radio (CR) systems. Previously, Semi-Definite Relaxation (SDR)-based transmit beamforming has been very successful in transmit design. However, recent research shows that further performance gain is possible by suitably modifying the transmit structure. Here, they...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    A Cooperative Game Based Allocation for Sharing Data Center Networks

    In current IaaS datacenters, tenants are suffering unfairness since the network bandwidth is shared in a best-effort manner. To achieve predictable network performance for rented Virtual Machines (VMs), cloud providers should guarantee minimum bandwidth for VMs or allocate the network bandwidth in a fairness fashion at VM-level. At the same...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    An Experimental Study of Cascading Performance Interference in a Virtualized Environment

    In a consolidated virtualized environment, multiple Virtual Machines (VMs) are hosted atop a shared physical substrate. They share the underlying hardware resources as well as the software virtualization components. Thus, one VM can generate performance interference to another co-resident VM. This paper explores the adverse impact of performance interference from...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    Moving Big Data to the Cloud

    Cloud computing, rapidly emerging as a new computation paradigm, provides agile and scalable resource access in a utility-like fashion, especially for the processing of big data. An important open issue here is how to efficiently move the data, from different geographical locations over time, into a cloud for effective processing....

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    Coding for Linear Operator Channels Over Finite Fields

    Linear Operator Channels (LOCs) are motivated by the communications through networks employing Random Linear Network Coding (RLNC). Following the recent information theoretic results about LOCs, the authors propose two coding schemes for LOCs and evaluate their performance. These schemes can be used in networks employing RLNC without constraints on the...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    Construction of Linear Network Codes That Achieve a Rened Singleton Bound

    The network error correction problem study is to extend classical error correction coding theory to a general network setting. In Cai and Yeung, network generalizations of the Hamming bound, the Singleton bound, and the Gilbert-Varshamov bound in classical algebraic coding theory were obtained. In particular, the tightness of the Singleton...

    Provided By Chinese University of Hong Kong

  • White Papers // Dec 2012

    Upper Bounds on the Capacity of Binary Channels With Causal Adversaries

    Alice wishes to transmit a message u to Bob over a binary-input binary-output channel. To do so, she encodes u into a length-n binary vector x and transmits it over the channel. However, the channel is controlled by a malicious adversary Calvin who may observe the transmissions, and attempts to...

    Provided By Chinese University of Hong Kong

  • White Papers // Nov 2012

    Single Disk Failure Recovery for X-code-based Parallel Storage Systems

    In modern parallel storage systems (e.g., cloud storage and data centers), it is important to provide data availability guarantees against disk (or storage node) failures via redundancy coding schemes. One coding scheme is X-code, which is double-fault tolerant while achieving the optimal update complexity. When a disk/node fails, recovery must...

    Provided By Chinese University of Hong Kong

  • White Papers // Nov 2012

    Spectrum Broker by Geo-Location Database

    Geo-location database driven white space network is a very promising approach for improving secondary spectrum utilization. In this paper, the authors consider the business modeling for geo-location database driven white space network. In their proposed model, the database acts as a spectrum broker buying (reserving) bandwidth from spectrum licensees in...

    Provided By Chinese University of Hong Kong

  • White Papers // Nov 2012

    Blind Known Interference Cancellation With Parallel Real Valued Belief Propagation Algorithm

    This paper investigates interference-cancellation schemes at the receiver, in which the original data of the interference is known a priori. Such a priori knowledge is common in wireless relay networks. Directly removing the known interference requires accurate estimate of the interference channel, which may be difficult in many situations. The...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2012

    Simple and E Ective Dynamic Provisioning for Power-Proportional Data Centers

    Energy consumption represents a significant cost in data center operation. A large fraction of the energy, however, is used to power idle servers when the workload is low. Dynamic provisioning techniques aim at saving this portion of the energy, by turning o unnecessary servers. In this paper, the authors explore...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2012

    Analysis and Construction of Functional Regenerating Codes With Uncoded Repair for Distributed Storage Systems

    Modern distributed storage systems apply redundancy coding techniques to stored data. One form of redundancy is based on regenerating codes, which can minimize the repair bandwidth, i.e., the amount of data transferred when repairing a failed storage node. Existing regenerating codes mainly require surviving storage nodes encode data during repair....

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2012

    A Scalable Algorithm for Maximizing Range Sum in Spatial Databases

    This paper investigates the MaxRS problem in spatial databases. Given a set O of weighted points and a rectangular region r of a given size, the goal of the MaxRS problem is to find a location of r such that the sum of the weights of all the points covered...

    Provided By Chinese University of Hong Kong

  • White Papers // Jul 2012

    Utility Maximization in Peer-to-Peer Systems with Applications to Video Conferencing

    In this paper, the authors study the problem of utility maximization in P2P systems, in which aggregate application specific utilities are maximized by running distributed algorithms on P2P nodes, which are constrained by their uplink capacities. For certain P2P topologies, they show that routing along a linear number of trees...

    Provided By Chinese University of Hong Kong

  • White Papers // Jul 2012

    Analog Network Coding in General SNR Regime: Performance of Network Simplification

    A communication scenario where a source communicates with a destination over a directed layered relay network is considered. Each relay performs analog network coding where it scales and forwards the signals received at its input. In this scenario, the authors address the question: What portion of the maximum end-to-end achievable...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2012

    Secure Overlay Cloud Storage With Access Control and Assured Deletion

    The authors can now outsource data backups off-site to third-party cloud storage services so as to reduce data management costs. However, they must provide security guarantees for the outsourced data, which is now maintained by third parties. They design and implement FADE, a secure overlay cloud storage system that achieves...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2012

    Optical Physical-Layer Network Coding

    Physical-layer Network Coding (PNC) has been an active research area in both information theory and wireless communications in the past few years. However, its application in optical communications has not yet been explored. This paper proposes and demonstrates a practical optical PNC prototype for multicast protection in optical flow/burst/packet switching...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2012

    Functional-Repair-by-Transfer Regenerating Codes

    In a distributed storage system, a data file is distributed to several storage nodes, such that the original file can be decoded from any subset of the storage nodes of size larger than or equal to a certain threshold. Upon the failure of a storage node, the authors would like...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2012

    Congestion Games on Weighted Directed Graphs, With Applications to Spectrum Sharing

    With the advance of complex large-scale networks, it is becoming increasingly important to understand how selfish and spatially distributed individuals will share network resources without centralized co-ordinations. In this paper, the authors introduce the Graphical Congestion Game with Weighted Edges (GCGWE) as a general theoretical model to study this problem....

    Provided By Chinese University of Hong Kong

  • White Papers // May 2012

    Mitigating Power Law Delays: the Use of Polynomial Backoff in IEEE 802.11 DCF

    The IEEE 802:11 Wireless Local Area Network (WLAN) standard was originally designed for best-effort services, targeting at providing high throughput and throughput fairness. However, high system throughput does not necessarily translate to good delay performance. Recent studies show that exponential backoff, the key collision avoidance mechanism in Distributed Coordination Function...

    Provided By Chinese University of Hong Kong

  • White Papers // Apr 2012

    A Game Theoretic Analysis on Incentive Mechanisms for Wireless Ad Hoc VoD Systems

    Wireless ad hoc networks enable the wireless devices to directly communicate with each other. An emerging application in such systems is video-on-demand service that can greatly reduce the content server's workload by utilizing the nodes' resources. Such an application relies on the cooperation of all participating nodes. However, the nodes...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2012

    Implementation of Physical-Layer Network Coding

    This paper presents the first implementation of a two-way relay network based on the principle of physical layer network coding. To date, only a simplified version of Physical-layer Network Coding (PNC), called Analog Network Coding (ANC), has been successfully implemented. The advantage of ANC is that it is simple to...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2012

    A Unification of Network Coding and Routing

    For a linear network code, the encoding profile is specified by, for every output channel of a node, the set of input channels whose symbols upon which the symbol on the output channel depends. For a given single-source network coding problem, it is of fundamental interest to characterize all feasible...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2012

    NCCloud: Applying Network Coding for the Storage Repair in a Cloud-of-Clouds

    To provide fault tolerance for cloud storage, recent studies propose to stripe data across multiple cloud vendors. However, if a cloud suffers from a permanent failure and loses all its data, then the authors need to repair the lost data from other surviving clouds to preserve data redundancy. They present...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2012

    Rank-Two Transmit Beamformed Alamouti Space-Time Coding for Physical-Layer Multicasting

    In physical-layer multicasting over a multiuser MISO downlink channel, transmit beamforming using Semi-Definite Relaxation (SDR) has been a popular approach. In this paper, the authors propose a rank-2 transmit beamformed Alamouti space-time code scheme, which may be seen as a generalization of the previous SDR-based beamforming framework. The beamforming problem...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2012

    Incentive Mechanisms for Smartphone Collaboration in Data Acquisition and Distributed Computing

    This paper analyzes and compares different incentive mechanisms for a client to motivate the collaboration of smartphone users on both data acquisition and distributed computing applications. Data acquisition from a large number of users is essential to build a rich database and support emerging location-based services. The authors propose a...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2012

    Spectrum Mobility Games

    Cognitive radio gives users the ability to switch channels and make use of dynamic spectrum opportunities. However, switching channels takes time, and may affect the quality of a user's transmission. When a cognitive radio user's channel becomes unavailable, sometimes it may be better waiting until its current channel becomes available...

    Provided By Chinese University of Hong Kong

  • White Papers // Mar 2009

    Single Image Haze Removal Using Dark Channel Prior

    In this paper, the authors propose a simple but effective image prior - dark channel prior to remove haze from a single input image. The dark channel prior is a kind of statistics of the haze-free outdoor images. It is based on a key observation - most local patches in...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2011

    Structural Changes And Regional Disparity In China's Inflation

    The inflation problem in China has attracted a great deal of international attention in recent years. This paper examines the time series properties of China's CPI series. It is found that the overall inflation series and the inflation of food, tobacco, clothes, urban transport and urban housing are not persistent....

    Provided By Chinese University of Hong Kong

  • White Papers // Dec 2010

    Does Banking Competition Alleviate Or Worsen Credit Constraints Faced By Small And Medium Enterprises? Evidence From China

    Banking competition may enhance or hinder the financing of Small and Medium Enterprises (SMEs). Using a survey on the financing of China's SMEs combined with detailed bank branch information; the authors investigate how concentration in the local banking market affects the availability of credit. It is found that lower market...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2011

    Managerial Ownership Of Debt And Accounting Conservatism

    The authors examine the relation between accounting conservatism and managerial ownership of debt in the form of deferred compensation and pension benefits. Consistent with debt holdings by managers mitigating the debtholder-shareholder conflicts and reducing debtholders' demand for accounting conservatism, they find significant evidence of less conservative financial reporting at firms...

    Provided By Chinese University of Hong Kong

  • White Papers // Jul 2011

    Link Scheduling in Multi-Transmit-Receive Wireless Networks

    This paper investigates the problem of link scheduling to meet traffic demands with minimum airtime in a Multi-Transmit-Receive (MTR) wireless network. MTR networks are a new class of networks, in which each node can simultaneously transmit to a number of other nodes, or simultaneously receive from a number of other...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2010

    FADE: Secure Overlay Cloud Storage With File Assured Deletion

    While one can now outsource data backup to third-party cloud storage services so as to reduce data management costs, security concerns arise in terms of ensuring the privacy and integrity of outsourced data. The authors design FADE, a practical, implementable, and readily deployable cloud storage system that focuses on protecting...

    Provided By Chinese University of Hong Kong

  • White Papers // Dec 2008

    Collision-Tolerant Transmission With Narrow-Beam Antennas

    The application of directional antennas in wireless ad hoc networks brings numerous benefits, such as increased spatial reuse and mitigated interference. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless ad hoc networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2011

    Distributing Layered Encoded Video Through Caches

    The efficient distribution of stored information has become a major concern in the Internet which has increasingly become a vehicle for the transport of stored video. Because of the highly heterogeneous access to the Internet, researchers and engineers have argued for layered encoded video. In this paper the authors investigate...

    Provided By Chinese University of Hong Kong

  • White Papers // Mar 2011

    Corporate Ownership Structure And Bank Loan Syndicate Structure

    This paper examines the relation between corporate ownership structure and bank loan syndicate structure. The authors find that the divergence between control rights and cash-flow rights of a borrowing firm's largest ultimate owner has a significant impact on the concentration and composition of the firm's loan syndicate. When the control-ownership...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2011

    Optimal Decoding Algorithm for Asynchronous Physical-Layer Network Coding

    A key issue in Physical-layer Network Coding (PNC) is how to deal with the asynchrony between signals transmitted by multiple transmitters. That is, symbols transmitted by different transmitters could arrive at the receiver with symbol misalignment as well as relative carrier-phase offset. In this paper, the authors propose and investigate...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2010

    Applying Physical-Layer Network Coding in Wireless Networks

    A main distinguishing feature of a wireless network compared with a wired network is its broadcast nature, in which the signal transmitted by a node may reach several other nodes, and a node may receive signals from several other nodes, simultaneously. Rather than a blessing, this feature is treated more...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2009

    Soft Network Coding in Wireless Two-Way Relay Channels

    Application of network coding in wireless Two-Way Relay Channels (TWRC) has received much attention recently because of its ability to improve throughput significantly. In traditional designs, network coding operates at upper layers above (including) the link layer and it requires the input packets to be correctly decoded. However, this requirement...

    Provided By Chinese University of Hong Kong

  • White Papers // Nov 2008

    Physical Layer Network Coding Schemes Over Finite and Infinite Fields

    Direct application of network coding at the physical layer - Physical layer Network Coding (PNC) - is a promising technique for two-way relay wireless networks. In a two-way relay network, relay nodes are used to relay two-way information flows between pairs of end nodes. This paper proposes a precise definition...

    Provided By Chinese University of Hong Kong

  • White Papers // Feb 2011

    Temporal Starvation in CSMA Wireless Networks

    It is well known that links in CSMA wireless networks are prone to starvation. Prior works focused almost exclusively on equilibrium starvation. In this paper, the authors show that links in CSMA wireless networks are also susceptible to temporal starvation. Specifically, although some links have good equilibrium throughputs and do...

    Provided By Chinese University of Hong Kong

  • White Papers // May 2011

    On the Performance of TCP Over Throughput-Optimal CSMA

    An interesting distributed throughput-optimal CSMA MAC protocol, called adaptive CSMA, was proposed recently to schedule any strictly feasible rates inside the capacity region. Of particular interest is the fact that the adaptive CSMA can achieve a system utility arbitrarily close to that is achievable under a central scheduler. However, a...

    Provided By Chinese University of Hong Kong

  • White Papers // Oct 2008

    Joint Scheduling and Resource Allocation in Uplink OFDM Systems

    Orthogonal Frequency Division Multiplexing (OFDM) with dynamic scheduling and resource allocation is widely considered to be a key component of most emerging broadband wireless access networks such as WiMAX and LTE (Long Term Evolution) for 3GPP. However, scheduling and resource allocation in an OFDM system is complicated, especially in the...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2011

    On the Degree of Freedom for Multi-Source Multi-Destination Wireless Network With Multi-Layer Relays

    Degree of Freedom (DoF) region provides an approximation of capacity region in high Signal-to-Noise Ratio (SNR) regime, while sum DoF gives the scaling factor. In this correspondence, the authors analyze the DoF region and sum DoF for unicast layered multi-hop relay wireless networks with arbitrary number of source/destination/relay nodes, arbitrary...

    Provided By Chinese University of Hong Kong

  • White Papers // Sep 2011

    Attack Prevention for Collaborative Spectrum Sensing in Cognitive Radio Networks

    Collaborative spectrum sensing can significantly improve the detection performance of Secondary Unlicensed users (SUs). However, the performance of collaborative sensing is vulnerable to sensing data falsification attacks, where malicious SUs (attackers) submit manipulated sensing reports to mislead the fusion center's decision on spectrum occupancy. Moreover, attackers may not follow the...

    Provided By Chinese University of Hong Kong

  • White Papers // Jul 2011

    Throughput Computation in CSMA Wireless Networks With Collision Effects

    It is known that link throughputs of CSMA wireless networks can be computed from a time-reversible Markov chain arising from an Ideal CSMA Network model (ICN). In particular, this model yields general closed-form equations of link throughputs. However, an idealized and important assumption made in ICN is that the backoff...

    Provided By Chinese University of Hong Kong

  • White Papers // Dec 2009

    On the Performance Bounds of Practical Wireless Network Coding

    Network coding is an attracting technology that has been shown to be able to improve the throughput of wireless networks. However, there still lacks fundamental understanding on how network coding works under realistic scenarios. In this paper, the authors examine the performance of a recently proposed network coding system under...

    Provided By Chinese University of Hong Kong

  • White Papers // May 2011

    Identifying Pollution Attackers in Network-Coding Enabled Wireless Mesh Networks

    Pollution attack is a severe security problem in network-coding enabled Wireless Mesh Networks (WMNs). Under such form of attack, malicious nodes can easily create an epidemic spreading of polluted packets to deplete network resources. The authors address this security problem even when the attackers are "Intelligent" in the sense that...

    Provided By Chinese University of Hong Kong

  • White Papers // Apr 2011

    Analyzing Credit Evolution for Credit-Based Incentive Schemes in Wireless Mesh Networks

    Incentive mechanisms are often needed in Wireless Mesh Networks (WMNs) so as to encourage nodes to relay or forward packets for other nodes. However, there is a lack of understanding on the interactions between the incentive mechanisms and the underlying routing protocols, and whether the network can sustain such traffic...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2011

    On the Access Pricing Issues of Wireless Mesh Networks

    This paper studies the use of pricing as an incentive mechanism to encourage private, self-interested nodes to participate in a public wireless mesh network and cooperate in the packet forwarding service. The authors' focus is on the "Economic behavior" of the network nodes - the pricing and purchasing strategies of...

    Provided By Chinese University of Hong Kong

  • White Papers // Sep 2011

    Live Deduplication Storage of Virtual Machine Images in an Open-Source Cloud

    Deduplication is an approach of avoiding storing data blocks with identical content, and has been shown to effectively reduce the disk space for storing multi-gigabyte Virtual Machine (VM) images. However, it remains challenging to deploy deduplication in a real system, such as a cloud platform, where VM images are regularly...

    Provided By Chinese University of Hong Kong

  • White Papers // Sep 2011

    A Privacy-Preserving Defense Mechanism Against Request Forgery Attacks

    One top vulnerability in today's web applications is request forgery, in which an attacker triggers an unintentional request from a client browser to a target website and exploits the client's privileges on the website. To defend against a general class of cross-site and same-site request forgery attacks, the authors propose...

    Provided By Chinese University of Hong Kong

  • White Papers // May 2011

    An Algebraic Approach to Computing the Reliability of Internet Routing

    Evaluating the reliability of Internet routing is important for an ISP to assess existing peer relationships or establish new peer relationships. Existing algorithms for network reliability computations take all routing paths as inputs. However, these paths may not be actually available for routing because of the constraints of routing policies...

    Provided By Chinese University of Hong Kong

  • White Papers // Jul 2011

    NCFS: On the Practicality and Extensibility of a Network-Coding-Based Distributed File System

    An emerging application of network coding is to improve the robustness of distributed storage. Recent theoretical work has shown that a class of regenerating codes, which are based on the concept of network coding, can improve the data repair performance over traditional storage schemes such as erasure coding. However, there...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2010

    A Lock-Free, Cache-Efficient Multi-Core Synchronization Mechanism for Line-Rate Network Traffic Monitoring

    Line-rate data traffic monitoring in high-speed networks is essential for network management. To satisfy the line-rate requirement, one can leverage multi-core architectures to parallelize traffic monitoring so as to improve information processing capabilities over traditional uni-processor architectures. Nevertheless, realizing the full potential of multi-core architectures still needs substantial work, especially...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2011

    A Secure Cloud Backup System With Assured Deletion and Version Control

    Cloud storage is an emerging service model that enables individuals and enterprises to outsource the storage of data backups to remote cloud providers at a low cost. However, cloud clients must enforce security guarantees of their outsourced data backups. The authors present FadeVersion, a secure cloud backup system that serves...

    Provided By Chinese University of Hong Kong

  • White Papers // Apr 2011

    Assured Deletion of Digital Files on Cloud

    Cloud storage (e.g., Amazon S3) offers an abstraction of infinite storage space for clients to outsource data storage in a pay-as-you-go manner. For example, SmugMug, a photo sharing website, chose to host terabytes of photos on Amazon S3 in 2006. Thus, instead of self-maintaining data centers, enterprises can now outsource...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2011

    An Extensible Design of a Load-Aware Virtual Router Monitor in User Space

    Router virtualization enables multiple virtual routers to be hosted on a physical shared substrate, and hence facilitates network management and experimentation. One critical issue of router virtualization is resource allocation of virtual routers. The authors explore this issue in the user-space design in order to allow extensibility. They develop a...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2013

    An Experimental Study of Cascading Performance Interference in a Virtualized Environment

    In a consolidated virtualized environment, multiple Virtual Machines (VMs) are hosted atop a shared physical substrate. They share the underlying hardware resources as well as the software virtualization components. Thus, one VM can generate performance interference to another co-resident VM. This paper explores the adverse impact of performance interference from...

    Provided By Chinese University of Hong Kong

  • White Papers // Jun 2013

    Limits of Provable Security for Homomorphic Encryption

    In this paper the authors revisit the question of basing cryptography on NP-hardness. If P equals NP then computationally secure encryption is impossible. Is the converse true? Despite considerable e orts, there is no candidate encryption scheme whose security can be plausibly reduced to the worst-case hardness of some NP-complete...

    Provided By Chinese University of Hong Kong

  • White Papers // Nov 2009

    Towards Improving an Algebraic Marking Scheme for Tracing DDoS Attacks

    Distributed Denial of Service (DDoS) attacks could be considered as one of the most serious security problems to the Internet today. To locate the sources of the attack packets, the authors usually need to find the paths through which the attack packets traversed from the sources to the victim. In...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    Continuous Constraint Query Evaluation For Spatiotemporal Streams

    In this paper, the authors study the evaluation of Continuous Constraint Queries (CCQs) for spatiotemporal streams. A CCQ triggers an alert whenever a configuration of constraints between streaming events in space and time are satisfied. Consider, for instance, a server that receives updates from GPS-enabled agents that report their positions...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2013

    Top-K Nearest Keyword Search on Large Graphs

    k-NK is not only useful as a stand-alone query but also as a building block for tackling complex graph pattern matching problems. The key to an accurate k-NK result is precise shortest distance estimation in a graph. Based on the latest distance oracle technique, the authors build a shortest path...

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    FPGA-Based SIMD Processor

    Although Field Programmable Gate Arrays (FPGAs) can have high performance gains over equivalent microprocessor based systems, they have the disadvantage that the design time is much higher than for an equivalent software based system. A massively parallel Single Instruction Multiple Data stream (SIMD) processor designed specifically for cryptographic key search...

    Provided By Chinese University of Hong Kong

  • White Papers // Aug 2010

    Characterizing the Lifetime Reliability of Manycore Processors with Core-Level Redundancy

    With aggressive technology scaling, integrated circuits suffer from ever increasing wearout effects and their lifetime reliability has become a serious concern for the industry. For manycore processors that integrate a large number of processor cores on a single silicon die, introducing core-level redundancy is an effective way to alleviate this...

    Provided By Chinese University of Hong Kong

  • White Papers // Apr 2014

    Degraded-First Scheduling for MapReduce in Erasure-Coded Storage Clusters

    The authors have witnessed an increasing adoption of erasure coding in modern clustered storage systems to reduce the storage overhead of traditional 3-way replication. However, it remains an open issue of how to customize the data analytics paradigm for erasure-coded storage, especially when the storage system operates in failure mode....

    Provided By Chinese University of Hong Kong

  • White Papers // Jan 2014

    Experiences Building Network-Coding-Based Distributed Storage Systems

    Large-scale distributed storage systems are prone to node failures. To provide fault tolerance, data is often encoded to maintain data redundancy over multiple storage nodes. If a node fails, it can be repaired by downloading data from surviving nodes and regenerating the lost data in a new node. Network coding...

    Provided By Chinese University of Hong Kong