Tsinghua University

Displaying 1-40 of 99 results

  • White Papers // Aug 2012

    Distributed Scheduling for Real-Time Convergecast in Wireless Sensor Networks

    Wireless Sensor Networks (WSNs) need to support real time periodic or sporadic queries of physical environments. In this paper, the authors focus on the periodic queries. For each periodic query issued by control applications in a WSN, the data from the source sensors should be collected and/or aggregated to the...

    Provided By Tsinghua University

  • White Papers // Aug 2012

    Triggercast: Enabling Wireless Collisions Constructive

    It is generally considered that concurrent transmissions should be avoided in order to reduce collisions in wireless sensor networks. Constructive Interference (CI) envisions concurrent transmissions to positively interfere at the receiver. CI potentially allows orders of magnitude reductions in energy consumptions and improvements on link quality. In this paper, the...

    Provided By Tsinghua University

  • White Papers // Aug 2012

    Opportunistic Forwarding With Partial Centrality

    In opportunistic networks, the use of social metrics (e.g., degree, closeness and betweenness centrality) of human mobility network, has recently been shown to be an effective solution to improve the performance of opportunistic forwarding algorithms. Most of the current social-based forwarding schemes exploit some globally defined node centrality, resulting in...

    Provided By Tsinghua University

  • White Papers // May 2012

    Lightpath Rerouting in Wavelength-Routed WDM Networks

    Rerouting is a viable and cost-effective approach to decrease the blocking probability in legacy circuit-switched networks. The authors study lightpath rerouting in optical WDM networks in this paper. First, they investigate two different lightpath rerouting strategies, namely, passive rerouting and intentional rerouting. Passive rerouting means the rerouting of existing lightpaths...

    Provided By Tsinghua University

  • White Papers // Apr 2012

    Internet Resource Pricing Models, Mechanisms, and Methods

    With the fast development of video and voice network applications, CDN (Content Distribution Networks) and P2P (Peer-To-Peer) content distribution technologies have gradually matured. How to effectively use Internet resources thus has attracted more and more attentions. For the study of resource pricing, a whole pricing strategy containing pricing models, mechanisms...

    Provided By Tsinghua University

  • White Papers // Mar 2012

    Secure and Scalable Fault Localization Under Dynamic Traffic Patterns

    Compromised and mis-configured routers are a well-known problem in ISP and enterprise networks. Dataplane Fault Localization (FL) aims to identify faulty links of compromised and mis-configured routers during packet forwarding, and is recognized as an effective means of achieving high network availability. Existing secure FL protocols are path-based, which assume...

    Provided By Tsinghua University

  • White Papers // Feb 2012

    Maximum Multiflow in Wireless Network Coding

    In a multi-hop wireless network, wireless interference is crucial to the Maximum Multi-Flow (MMF) problem, which studies the maximum throughput between multiple pairs of sources and sinks. In this paper, the authors observe that network coding could help to decrease the impacts of wireless interference, and propose a framework to...

    Provided By Tsinghua University

  • White Papers // Dec 2011

    An Improved Certificateless Authenticated Key Agreement Protocol

    In this paper, the authors show that their protocol is insecure against a man-in-the-middle attack which is a severe disaster for a key agreement protocol. In addition, the authors claimed that their scheme provides a binding a long-term public key with a corresponding partial private key. In fact, their protocol...

    Provided By Tsinghua University

  • White Papers // Nov 2011

    Dynamic Bayesian Spectrum Bargaining With Non-Myopic Users

    In this paper, the authors investigate a cooperative spectrum sharing mechanism realized by a dynamic Bayesian spectrum bargaining between a pair of non-myopic primary user and secondary user. The primary user has only incomplete information of the secondary user's energy cost. They model such a bargaining process as a dynamic...

    Provided By Tsinghua University

  • White Papers // Nov 2011

    Flexible Integration of Tunneling and Translation for IPv6 Transition

    The IPv6 transition problem has become the most urgent and practical obstacle holding back the development of the next generation Internet. Various translation and tunneling techniques have been proposed to solve the transition problem. Tunneling satisfies the demand of IPv4-IPv6 traversing while translation achieves IPv4-IPv6 interconnection. However, translation faces several...

    Provided By Tsinghua University

  • White Papers // Nov 2011

    A Novel Neighbor Discovery Protocol for Ultraviolet Wireless Networks

    UltraViolet (UV) communication is an attractive option for tactical networks or environmental monitoring. The underlying UV PHY layer has unique characteristics that render previously proposed higher layer protocols for RF communications inappropriate or inefficient. Neighbor discovery is an important functional component of a UV ad hoc wireless network. While there...

    Provided By Tsinghua University

  • White Papers // Oct 2011

    A VLSI Architecture for the Node of Wireless Image Sensor Network

    This paper proposes a novel design of VLSI architecture for the node of wireless image sensor network. This architecture aims at the SoC (System on a Chip) implementation and is composed of a general purpose embedded processor and several dedicated hardware accelerators for image processing and wireless communication. The hardware...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    Provisioning Virtual Resources Adaptively in Elastic Compute Cloud Platforms

    Provisioning Virtual machines on demand is significant in elastic compute cloud for reliable service delivery. The importance and major difficulty lies in satisfying the conflicting objectives of satisfying contracted service level agreement while lowering used resource costs. In this paper, the authors propose a mathematical multi-tier framework for adaptive virtual...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    Win-Coupon: An Incentive Framework for 3G Traffic Offloading

    3G networks are currently facing severe traffic overload problems caused by excessive demands of mobile users. Offloading part of the 3G traffic through other forms of networks, such as Delay Tolerant Networks (DTNs), Wi-Fi hotspots, and Femtocells, is a promising solution. However, since these networks can only provide intermittent and...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    On the Linear Precoder Design for MIMO Channels With Finite-Alphabet Inputs and Statistical CSI

    The theoretic limit on the information rate that a communication channel can support with arbitrary low probability of error is referred to as channel capacity. This capacity is achievable with independent Gaussian distributed inputs for parallel Additive White Gaussian Noise (AWGN) channels and with correlated Gaussian inputs for Multiple-Input Multiple-Output...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    Cloud Testing-Issues, Challenges, Needs and Practice

    Cloud computing not only changes the way of obtaining computing resources (such as computers, infrastructures, data storage, and application services), but also changes the way of managing and delivering computing services, technologies, and solutions. Cloud computing leads an opportunity in offering Testing as a Service (TaaS) for SaaS and clouds....

    Provided By Tsinghua University

  • White Papers // Aug 2011

    Practical Software Model Checking Via Dynamic Interface Reduction

    Implementation-level software model checking explores the state space of a system implementation directly to find potential software defects without requiring any specification or modeling. Despite early successes, the effectiveness of this approach remains severely constrained due to poor scalability caused by state-space explosion. DEMETER makes software model checking more practical...

    Provided By Tsinghua University

  • White Papers // Aug 2011

    Contact Duration Aware Data Replication in Delay Tolerant Networks

    The recent popularization of hand-held mobile devices, such as smartphones, enables the inter-connectivity among mobile users without the support of Internet infrastructure. When mobile users move and contact each other opportunistically, they form a Delay Tolerant Network (DTN), which can be exploited to share data among them. Data replication is...

    Provided By Tsinghua University

  • White Papers // Jul 2011

    Subspace Tracking Based Channel Estimation With Rank Adaptation for OFDM Systems in Sparse Fading Channels

    This paper presents a subspace tracking based channel estimation utilizing Bi-iterative Least-Square (Bi-LS) rank adaptation method in sparse channel for OFDM systems. After modeling parameterized fading channel with sparse multipath, a general description of parametric channel estimation process based on subspace tracking is given. Then a simple Bi-iterative Least-Square (Bi-LS)...

    Provided By Tsinghua University

  • White Papers // Jul 2011

    DHOSPF: Adaptive Parallel Routing Table Computation for Next Generation Routers

    Fast convergence in Interior Gateway Protocol (IGP) is certainly critical to the widespread deployment of real time applications (such as, VOIP, IPTV, etc.). Many improvements for OSPF (Open Shortest Path First) protocol, such as fast hello and fast flooding, have been proposed to reduce the convergence time of IGP. However,...

    Provided By Tsinghua University

  • White Papers // Jun 2011

    StriD2FA: Scalable Regular Expression Matching for Deep Packet Inspection

    Deep Packet Inspection (DPI) has become one of the key components of a Network Intrusion Detection System (NIDS) and it compares packet content against a set of rules written in regular expression. The need to keep up with ever-increasing line speed has forced NIDS designers to move to hardware-based implementation...

    Provided By Tsinghua University

  • White Papers // Jun 2011

    Toward Dynamic Energy-Efficient Operation of Cellular Network Infrastructure

    The operation of cellular network infrastructure incurs significant electrical energy consumption. From the perspective of cellular network operators, reducing this consumption is not only a matter of showing environmental responsibility, but also of substantially reducing their operational expenditure. The authors discuss how dynamic operation of cellular base stations, in which...

    Provided By Tsinghua University

  • White Papers // Jun 2011

    Mitigating Control Channel Saturation in the Dynamic Channel Assignment Protocol

    Multi-channel MAC protocols that rely on a dedicated Control Channel (CC) for data channel reservation face the problem of control channel saturation. When the control channel becomes the bottleneck, data channels are not fully utilized and the spectrum allocated for the network is not used efficiently. For a popular dedicated...

    Provided By Tsinghua University

  • White Papers // May 2011

    An Intelligent Capacity Planning Model for Cloud Market

    Cloud computing is a promising way providing users computing resources. These resources are provided by means of standard computing instances. Currently, there are three price schemas including spot, reservation and on-demand in cloud market, but the average difference among these three pricing schema can be as much as 2.7 times...

    Provided By Tsinghua University

  • White Papers // May 2011

    DAC: Generic and Automatic Address Configuration for Data Center Networks

    Data center networks encode locality and topology information into their server and switch addresses for performance and routing purposes. For this reason, the traditional address configuration protocols such as DHCP require huge amount of manual input, leaving them error-prone. In this paper, the authors present DAC, a generic and automatic...

    Provided By Tsinghua University

  • White Papers // May 2011

    A Novel Joint Synchronization Algorithm for OFDM Systems Based on Single Training Symbol

    The Park's method suffers from symbol timing ambiguity and small acquisition range for carrier frequency offset, and cannot estimate sampling frequency offset. To solve these problems, a new training symbol including virtual carriers is designed, and the corresponding joint synchronization algorithm for Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed....

    Provided By Tsinghua University

  • White Papers // Apr 2011

    Resource Provisioning of Web Applications in Heterogeneous Clouds

    Cloud computing platforms provide very little guarantees regarding the performance of seemingly identical virtual machine instances. Such instances have been shown to exhibit significantly different performance from each other. This heterogeneity creates two challenges when hosting multi-tier Web applications in the Cloud. First, different machine instances have different processing capacity...

    Provided By Tsinghua University

  • White Papers // Mar 2011

    ServerSwitch: A Programmable and High Performance Platform for Data Center Networks

    As one of the fundamental infrastructures for cloud computing, Data Center Networks (DCN) have recently been studied extensively. The authors currently use pure software-based systems, FPGA based platforms, e.g., NetFPGA, or OpenFlow switches, to implement and evaluate various DCN designs including topology design, control plane and routing, and congestion control....

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Dynamic Spectrum Negotiation With Asymmetric Information

    Spectrum scarcity is becoming a serious issue due to the rapid development of wireless communication technology. Dynamic spectrum sharing can effectively improve the spectrum usage by allowing Secondary unlicensed Users (SUs) to dynamically and opportunistically share the spectrum with Primary licensed Users (PUs). In this paper, the authors investigate a...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Examining Cloud Computing From the Perspective of Grid and Computer-Supported Cooperative Work

    Cloud computing, which refers to services provisioning and consumption over the Internet, is the latest paradigm promising to deliver computing as a utility. Though it is still in its infancy and facing many challenges, cloud computing has drawn and is drawing more interest from both academia and industry. Taking grid...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Improving Routing Scalability With Aggressive Route Aggregation

    The size of the Boarder Gateway Protocol (BGP) routing table is continuously increasing, which incurs more memory demands in routers and increasing BGP update messages between peering routers as well. The RIB/FIB does not scale well with the Internet size, which is known as the routing scalability problem of the...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Guardband Analysis for Distributed OFDMA With User Heterogeneity

    This paper presents an in-depth analysis of the interference strength and required guardband width between coexistent users for distributed Orthogonal Frequency Division Multiple Access (OFDMA). In dynamic spectrum access networks, the cross-band interference between spectrally adjacent users is considered harmful with frequency guardbands inserted between spectrum blocks to eliminate the...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Dynamic Controlling of Data Streaming Applications for Cloud Computing

    Performance of data streaming applications is co-determined by both networking and computing resources, which should be allocated in an integrated and cooperative way. Dynamic controlling of resource allocation is required since unilateral redundancy in networking or computing resources may result in underutilization but not necessarily high performance since insufficiency of...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Partially Overlapping Channel Assignment Based on "Node Orthogonality" for 802.11 Wireless Networks

    In this paper, the authors investigate the problem of partially overlapping channel assignment to improve the performance of 802.11 wireless networks. They first derive a novel interference model that takes into account both the adjacent channel separation and the physical distance of the two nodes employing adjacent channels. This model...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Linear Precoding for Relay Networks With Finite-Alphabet Constraints

    In this paper, the authors investigate the optimal precoding scheme for relay networks with finite-alphabet constraints. They show that the previous work utilizing various design criteria to maximize either the diversity order or the transmission rate with the Gaussian-input assumption may lead to significant loss for a practical system with...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    DBease: Making Databases User friendly and Easily Accessible

    Structured Query Language (SQL) is a classical way to access relational databases. Although SQL is powerful to query relational databases, it is rather hard for inexperienced users to pose SQL queries, as they are required to be familiar with SQL syntax and have a thorough understanding of the underlying schema....

    Provided By Tsinghua University

  • White Papers // Jan 2011

    QoF: Towards Comprehensive Path Quality Measurement in Wireless Sensor Networks

    Due to its large scale and constrained communication radius, a wireless sensor network mostly relies on multi-hop transmissions to deliver a data packet along a sequence of nodes. It is of essential importance to measure the forwarding quality of multi-hop paths and such information shall be utilized in designing efficient...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Multi-Hop Access Pricing in Public Area WLANs

    Public area WLANs stand for WLANs deployed in public areas such as classroom and office buildings to provide Internet connections. Nevertheless, such a service may not be always available because of limited AP coverage, poor signal strength, or password authentication. Multi-hop access is a feasible approach to facilitate users without...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Channel Allocation in Wireless Data Center Networks

    Unbalanced traffic demands of different data center applications are an important issue in designing Data Center Networks (DCNs). In this paper, the authors present the exploratory investigation of utilizing wireless transmissions in DCNs. The paper aims to solve the congestion problem caused by a few hot nodes to improve the...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    SelectCast: Scalable Data Aggregation Scheme in Wireless Sensor Networks

    Data aggregation is a key energy consuming functionality in Wireless Sensor Networks (WSNs) for both data gathering applications and event-based applications, since the communication cost is often the higher-order of the computation cost. It has been shown in the literature that the achievable minimum data rate among all sensor nodes...

    Provided By Tsinghua University

  • White Papers // Apr 2009

    Higher Dimensional Blue-Noise Sampling Schemes for Curvelet-Based Seismic Data Recovery

    In combination with compressive sensing, a successful reconstruction scheme called Curvelet-based Recovery by Sparsity-promoting Inversion (CRSI) has been developed, and has proven to be useful for seismic data processing. One of the most important issues for CRSI is the sampling scheme, which can greatly affect the quality of reconstruction. Unlike...

    Provided By Tsinghua University

  • White Papers // Sep 2009

    Para-Snort: A Multi-Thread Snort on Multi-Core IA Platform

    As security threats and network bandwidth increase in a very fast pace, there is a growing interest in designing high-performance Network Intrusion Detection System (NIDS). This paper presents a parallelization strategy for the popular open-source Snort to build a high performance NIDS on multi-core IA platform. A modular design of...

    Provided By Tsinghua University

  • White Papers // Jul 2009

    A Security Model for VoIP Steganography

    In 2005, an extensive taxonomy of threats for VoIP was published by a prominent industry group. Strangely, this taxonomy does not identify stegocommunication as a threat, even though many steganographic channels have been identified in VoIP protocols. To avoid such security gaps in the future, the authors' argue that stegocommunication...

    Provided By Tsinghua University

  • White Papers // Oct 2009

    Mirror World Navigation for Mobile Users Based on Augmented Reality

    Finding a destination in unfamiliar environments of complex office building or shopping mall has been always bothering everyone in daily life. Fine-scale directional guidance, a combination of location based service and context aware service, is emerging along with the technology developments of mobile computing, wireless communication, and augmented reality. This...

    Provided By Tsinghua University

  • White Papers // May 2009

    Parallel Evidence Propagation on Multicore Processors

    In this paper designs and implements an efficient technique for parallel evidence propagation on state-of-the-art multicore processor systems. Evidence propagation is a major step in exact inference, a key problem in exploring probabilistic graphical models. This paper proposes a rerooting algorithm to minimize the critical path in evidence propagation. The...

    Provided By Tsinghua University

  • White Papers // Jul 2009

    DG-Based Energy Proportional Cloud

    As Grid and Virtual Machine technology matures, the data center infrastructure is turning green and more efficient. The Energy-Proportional Cloud is seeking to dramatically raise the energy efficiency. In this paper, it is proposed the use of Computing Usage Effectiveness (CUE) as the metrics, not Power Usage Effectiveness (PUE), which...

    Provided By Tsinghua University

  • White Papers // Dec 2010

    Trade Restrictiveness And Deadweight Loss In China's Imports

    China is believed to have gained extensively from accession to the WTO in 2001. One of the direct gains is from the lessening of Dead Weight Loss (DWL) due to tariff reduction. Conventional measures for DWL, however, are too aggregate to capture the trade policies, which are determined at a...

    Provided By Tsinghua University

  • White Papers // Dec 2009

    Battery Allocation for Wireless Sensor Network Lifetime Maximization Under Cost Constraints

    Wireless sensor networks hold the potential to open new domains to distributed data acquisition. However, such networks are prone to premature failure because some nodes deplete their batteries more rapidly than others due to workload variations, non-uniform communication, and heterogenous hardware. Many-to-one traffic patterns are common in sensor networks, further...

    Provided By Tsinghua University

  • White Papers // Dec 2009

    Leveraged Financing, Over Investment, And Boom-Bust Cycles

    It has long been argued in the history of economic thought that over investment through highly leveraged borrowing under elastic credit supply may generate large boom-bust business cycles. This paper rationalizes this idea in a dynamic general equilibrium model with infinitely lived rational agents. It shows that dynamic interactions between...

    Provided By Tsinghua University

  • White Papers // Jan 2010

    Multiple Access Network Information-Flow and Correction Codes

    Information dissemination can be optimized with the use of network coding since it maximizes the network throughput in multicast transmission scenarios. At the same time network coding is highly vulnerable to malicious attacks from rogue users. The presence of even a small number of adversarial nodes can contaminate the majority...

    Provided By Tsinghua University

  • White Papers // Sep 2010

    Joint Channel Probing and Proportional Fair Scheduling in Wireless Networks

    The design of a scheduling scheme is crucial for the efficiency and user-fairness of wireless networks. Assuming that the quality of all user channels is available to a central controller, a simple scheme which maximizes the utility function defined as the sum logarithm throughput of all users has been shown...

    Provided By Tsinghua University

  • White Papers // Oct 2010

    Ring Signature and Identity-Based Ring Signature from Lattice Basis Delegation

    In this paper, the authors propose a set of Ring Signature (RS) schemes and Identity-Based Ring Signature (IBRS) schemes using the lattice basis delegation technique due to, the schemes are unforgeable and hold anonymity in the random oracle model. Using the method in, they also extend the constructions to obtain...

    Provided By Tsinghua University

  • White Papers // May 2009

    The Distribution of Program Sizes and Its Implications: An Eclipse Case Study

    A large software system is often composed of many inter-related programs of different sizes. Using the public Eclipse dataset, the authors replicate the previous study on the distribution of program sizes. The results confirm that the program sizes follow the lognormal distribution. They also investigate the implications of the program...

    Provided By Tsinghua University

  • White Papers // Jun 2009

    A Mixed-Fractal Model for Network Traffic

    In this short paper, the authors propose a new multi-fractal flow model, aiming to provide a possible explanation for the crossover phenomena that appear in the estimation of Hurst exponent for network traffic. It is shown that crossover occurs if the network flow consists of several components with different Hurst...

    Provided By Tsinghua University

  • White Papers // Oct 2010

    The Collision Security of Tandem-DM in the Ideal Cipher Model

    The authors prove that Tandem-DM, one of the two "Classical" schemes for turning a blockcipher of 2n-bit key into a double block length hash function, has birthday-type collision resistance in the ideal cipher model. A collision resistance analysis for Tandem-DM achieving a similar birthday-type bound was already proposed by Fleischmann,...

    Provided By Tsinghua University

  • White Papers // Jan 2009

    Distinguishing Attack and Second-Preimage Attack on the CBC-Like MACs

    In this paper, the authors first present a new distinguisher on the CBC-MAC based on a block cipher in Cipher Block Chaining (CBC) mode. It can also be used to distinguish other CBC-like MACs from random functions. The main results of this paper are on the second-preimage attack on CBC-MAC...

    Provided By Tsinghua University

  • White Papers // Nov 2009

    Lumpy Investment And Corporate Tax Policy

    This paper studies the impact of corporate tax policy on the economy in the presence of both convex and nonconvex capital adjustment costs in a dynamic general equilibrium model. The authors show that corporate tax policy generates both intensive and extensive margin effects via the channel of marginal Q. Its...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Examining Cloud Computing From the Perspective of Grid and Computer-Supported Cooperative Work

    Cloud computing, which refers to services provisioning and consumption over the Internet, is the latest paradigm promising to deliver computing as a utility. Though it is still in its infancy and facing many challenges, cloud computing has drawn and is drawing more interest from both academia and industry. Taking grid...

    Provided By Tsinghua University

  • White Papers // Jun 2011

    Toward Dynamic Energy-Efficient Operation of Cellular Network Infrastructure

    The operation of cellular network infrastructure incurs significant electrical energy consumption. From the perspective of cellular network operators, reducing this consumption is not only a matter of showing environmental responsibility, but also of substantially reducing their operational expenditure. The authors discuss how dynamic operation of cellular base stations, in which...

    Provided By Tsinghua University

  • White Papers // Oct 2009

    EC2 Performance Analysis for Resource Provisioning of Service-Oriented Applications

    Cloud computing is receiving increasingly attention as it provides infinite resource capacity and "Pay-as-you-go" resource usage pattern to hosted applications. To maintain its SLA targets, resource provisioning of service-oriented applications in the cloud requires reliable performance from the cloud resources. In this paper, the authors study performance behavior of small...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Multi-Hop Access Pricing in Public Area WLANs

    Public area WLANs stand for WLANs deployed in public areas such as classroom and office buildings to provide Internet connections. Nevertheless, such a service may not be always available because of limited AP coverage, poor signal strength, or password authentication. Multi-hop access is a feasible approach to facilitate users without...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Channel Allocation in Wireless Data Center Networks

    Unbalanced traffic demands of different data center applications are an important issue in designing Data Center Networks (DCNs). In this paper, the authors present the exploratory investigation of utilizing wireless transmissions in DCNs. The paper aims to solve the congestion problem caused by a few hot nodes to improve the...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Partially Overlapping Channel Assignment Based on "Node Orthogonality" for 802.11 Wireless Networks

    In this paper, the authors investigate the problem of partially overlapping channel assignment to improve the performance of 802.11 wireless networks. They first derive a novel interference model that takes into account both the adjacent channel separation and the physical distance of the two nodes employing adjacent channels. This model...

    Provided By Tsinghua University

  • White Papers // Nov 2011

    A Novel Neighbor Discovery Protocol for Ultraviolet Wireless Networks

    UltraViolet (UV) communication is an attractive option for tactical networks or environmental monitoring. The underlying UV PHY layer has unique characteristics that render previously proposed higher layer protocols for RF communications inappropriate or inefficient. Neighbor discovery is an important functional component of a UV ad hoc wireless network. While there...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    Win-Coupon: An Incentive Framework for 3G Traffic Offloading

    3G networks are currently facing severe traffic overload problems caused by excessive demands of mobile users. Offloading part of the 3G traffic through other forms of networks, such as Delay Tolerant Networks (DTNs), Wi-Fi hotspots, and Femtocells, is a promising solution. However, since these networks can only provide intermittent and...

    Provided By Tsinghua University

  • White Papers // Aug 2011

    Contact Duration Aware Data Replication in Delay Tolerant Networks

    The recent popularization of hand-held mobile devices, such as smartphones, enables the inter-connectivity among mobile users without the support of Internet infrastructure. When mobile users move and contact each other opportunistically, they form a Delay Tolerant Network (DTN), which can be exploited to share data among them. Data replication is...

    Provided By Tsinghua University

  • White Papers // Apr 2011

    Resource Provisioning of Web Applications in Heterogeneous Clouds

    Cloud computing platforms provide very little guarantees regarding the performance of seemingly identical virtual machine instances. Such instances have been shown to exhibit significantly different performance from each other. This heterogeneity creates two challenges when hosting multi-tier Web applications in the Cloud. First, different machine instances have different processing capacity...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    On the Linear Precoder Design for MIMO Channels With Finite-Alphabet Inputs and Statistical CSI

    The theoretic limit on the information rate that a communication channel can support with arbitrary low probability of error is referred to as channel capacity. This capacity is achievable with independent Gaussian distributed inputs for parallel Additive White Gaussian Noise (AWGN) channels and with correlated Gaussian inputs for Multiple-Input Multiple-Output...

    Provided By Tsinghua University

  • White Papers // Nov 2008

    Distributed Strategy With Opportunistic Relaying and Network Coding for Power Efficiency in Two-Way Parallel Channels

    The authors consider a two-way communication assisted by parallel regenerative decode-and-forward relays operating in orthogonal channels. In the system with limited channel state information at each source and relay node, an optimum distributed power allocation strategy is proposed to minimize the total transmit power, providing a target signal-to-noise ratio at...

    Provided By Tsinghua University

  • White Papers // Feb 2010

    Opportunistic Relaying for Multi-Antenna Cooperative Decode-and-Forward Relay Networks

    In this paper, the authors investigate the relaying scheme for multi-antenna cooperative networks without channel state information at the transmitters. It is shown that the classic opportunistic relaying scheme, which allows only one relay node to forward the message, may lead to significant loss when it is extended to the...

    Provided By Tsinghua University

  • White Papers // Jan 2011

    Linear Precoding for Relay Networks With Finite-Alphabet Constraints

    In this paper, the authors investigate the optimal precoding scheme for relay networks with finite-alphabet constraints. They show that the previous work utilizing various design criteria to maximize either the diversity order or the transmission rate with the Gaussian-input assumption may lead to significant loss for a practical system with...

    Provided By Tsinghua University

  • White Papers // Aug 2009

    A Highly Efficient Protocol for Rateless Coding Aided Cooperative Cellular Networks

    Cooperative relaying has been proposed as a promising technology to provide reliable high data rate services for future wireless networks. The paper presented here focuses on a novel efficient three time-slot approach using rateless codes, Opportunistic Fountain (OF), for cellular networks with fixed relays. This scheme enjoys benefits from both...

    Provided By Tsinghua University

  • White Papers // May 2009

    Outage Performance of Half-Duplex Cooperative Relay Networks Using Rateless Codes

    The authors propose a new cooperative transmission scheme, Opportunistic Fountain (OF), based on rateless codes for half-duplex relaying. In the proposed scheme, only the most appropriate relay is permitted to forward the message using rateless codes, thus as an orthogonal transmission protocol, their scheme does not need to synchronize among...

    Provided By Tsinghua University

  • White Papers // Oct 2011

    A VLSI Architecture for the Node of Wireless Image Sensor Network

    This paper proposes a novel design of VLSI architecture for the node of wireless image sensor network. This architecture aims at the SoC (System on a Chip) implementation and is composed of a general purpose embedded processor and several dedicated hardware accelerators for image processing and wireless communication. The hardware...

    Provided By Tsinghua University

  • White Papers // Sep 2010

    Redundant Virtual Machines Management in Virtualized Cloud Platform

    Selecting and utilizing proper virtual machines in a virtualized cloud platform to achieve high availability, throughput, reliability, as well as low cost and makespan is very important. The importance lies in the adaptive resource provisioning to satisfy variant of workloads. An Adaptive Accessing Aware Algorithm (A5) is proposed in this...

    Provided By Tsinghua University

  • White Papers // Sep 2011

    Provisioning Virtual Resources Adaptively in Elastic Compute Cloud Platforms

    Provisioning Virtual machines on demand is significant in elastic compute cloud for reliable service delivery. The importance and major difficulty lies in satisfying the conflicting objectives of satisfying contracted service level agreement while lowering used resource costs. In this paper, the authors propose a mathematical multi-tier framework for adaptive virtual...

    Provided By Tsinghua University

  • White Papers // Nov 2011

    Dynamic Bayesian Spectrum Bargaining With Non-Myopic Users

    In this paper, the authors investigate a cooperative spectrum sharing mechanism realized by a dynamic Bayesian spectrum bargaining between a pair of non-myopic primary user and secondary user. The primary user has only incomplete information of the secondary user's energy cost. They model such a bargaining process as a dynamic...

    Provided By Tsinghua University

  • White Papers // Jun 2009

    Implementing Uniform Reliable Broadcast With Binary Consensus in Systems With Fair-Lossy Links

    When implementing multivalued consensus using binary consensus, previous algorithms assume the availability of uniform reliable broadcast, which is not implementable in systems with fair-lossy links. In this paper, the authors show that with binary consensus they can implement uniform reliable broadcast directly in systems with fair-lossy links, and thus the...

    Provided By Tsinghua University

  • White Papers // Aug 2010

    Detecting Altered Fingerprints

    The widespread deployment of Automated Fingerprint Identification Systems (AFIS) in law enforcement and border control applications has prompted some individuals with criminal background to evade identification by purposely altering their fingerprints. Available fingerprint quality assessment software cannot detect most of the altered fingerprints since the implicit image quality does not...

    Provided By Tsinghua University

  • White Papers // Feb 2011

    Improving Routing Scalability With Aggressive Route Aggregation

    The size of the Boarder Gateway Protocol (BGP) routing table is continuously increasing, which incurs more memory demands in routers and increasing BGP update messages between peering routers as well. The RIB/FIB does not scale well with the Internet size, which is known as the routing scalability problem of the...

    Provided By Tsinghua University