Indian Institute of Science

Displaying 1-40 of 126 results

  • White Papers // Jan 2014

    Prediction of Queue Waiting Times for Metascheduling on Parallel Batch Systems

    Prediction of queue waiting times of jobs submitted to production parallel batch systems is important to provide overall estimates to users and can also help meta-schedulers make scheduling decisions. In this paper, the authors have developed a framework for predicting ranges of queue waiting times for jobs by employing multi-class...

    Provided By Indian Institute of Science

  • White Papers // Dec 2013

    An Improved Outer Bound on the Storage-Repair-Bandwidth Tradeoff of Exact-Repair Regenerating Codes

    In this paper, the authors establish an improved outer bound on the storage-repair-bandwidth tradeoff of regenerating codes under exact repair. The result shows that in particular, it is not possible to construct exact-repair regenerating codes that asymptotically achieve the tradeoff that holds for functional repair. While this had been shown...

    Provided By Indian Institute of Science

  • White Papers // Oct 2013

    A Closer Look at Multiple-Forking: Leveraging (In)dependence for a Tighter Bound

    The machinery of oracle replay attack of Pointcheval and Stern [PS00] plays a pivotal role in the security argument of a large class of signature schemes [ElG85, Sch91, Oka93]. In the basic version of replay attack, one runs the adversary twice on related inputs in order to solve the underlying...

    Provided By Indian Institute of Science

  • White Papers // Apr 2013

    Capacity Bounds for the Gaussian X Channel

    The authors consider bounds for the capacity region of the Gaussian X Channel (XC), a system consisting of two transmit-receive pairs, where each transmitter communicates with both the receivers. They first classify the XC into two classes, the strong XC and the mixed XC. In the strong XC, either the...

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  • White Papers // Mar 2013

    Perormance Analysis of a Node Monitoring Protocol in Ubiquitous Networks

    The proliferation of the ubiquitous applications in different sphere of life like ubiquitous health monitoring system, and ubiquitous learning system demands the network monitoring, to check whether the nodes are getting the promised resources and inputs. Dynamicity and heterogeneity of the ubiquitous network adds challenges to the monitoring of a...

    Provided By Indian Institute of Science

  • White Papers // Mar 2013

    Measurement Based Impromptu Deployment of a Multi-Hop Wireless Relay Network

    The authors study the problem of optimal sequential ("As-you-go") deployment of wireless relay nodes, as a person walks along a line of random length (with a known distribution). The objective is to create an impromptu multi-hop wireless network for connecting a packet source to be placed at the end of...

    Provided By Indian Institute of Science

  • White Papers // Mar 2013

    Wireless Network-Coded Multi-Way Relaying Using Latin Hyper-Cubes

    The two-stage protocol for physical layer network coding for the two-way relay channel first introduced in 2006, exploits the multiple access interference occurring at the relay so that the communication between the end nodes can be done using a two stage protocol. The paper deals with the information theoretic studies...

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  • White Papers // Mar 2013

    Improved IDS Using Layered CRFS With Logon Restrictions and Mobile Alerts Based on Deviant System Behaviour

    With the ever increasing number and diverse type of attacks, including new and previously unseen attacks, the effectiveness of an intrusion detection system is very important. Hence there is high demand to reduce the threat level in networks to ensure the data and services offered by them to be more...

    Provided By Indian Institute of Science

  • White Papers // Feb 2013

    SC-FDMA for Multiuser Communication on the Downlink

    Single-Carrier Frequency Division Multiple Access (SC-FDMA) has become a popular alternative to Orthogonal Frequency Division Multiple Access (OFDMA) in multiuser communication on the uplink. This is mainly due to the low Peak-to-Average Power Ratio (PAPR) of SC-FDMA compared to that of OFDMA. Long-Term Evolution (LTE) uses SC-FDMA on the uplink...

    Provided By Indian Institute of Science

  • White Papers // Jan 2013

    Language Based Security for Smartphones

    Install time permission model used in android, may provide users a control over their privacy and security and may reduce the impact of bugs and vulnerabilities in applications; however such a model becomes ineffective if users are uninformed about the behavior of these applications and their potential harms once an...

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  • White Papers // Jan 2013

    A Combinatorial Family of Near Regular LDPC Codes

    An elementary combinatorial Tanner graph construction for a family of near-regular Low Density Parity Check (LDPC) codes achieving high girth is presented. These codes are near regular in the sense that the degree of a left/right vertex is allowed to differ by at most one from the average. The construction...

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  • White Papers // Dec 2012

    Distributed Co-Phasing for Binary Consensus in Wireless Sensor Networks

    The authors address the problem of binary consensus over noisy, fading channels. They propose a new transmission model using Distributed Co-phasing that ensures the system to reach accurate consensus quite efficiently. They propose a simple linear update rule at nodes based on LMMSE and see that its performance is close...

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  • White Papers // Dec 2012

    Adaptive Scheduling in Real-Time Systems Through Period Adjustment

    Real-time system technology traditionally developed for safety critical systems, has now been extended to support multimedia systems and virtual reality. A large number of real-time application, related to multimedia and adaptive control system, require more flexibility than classical real-time theory usually permits. This paper proposes an efficient adaptive scheduling framework...

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  • White Papers // Dec 2012

    Information Capacity of an Energy Harvesting Sensor Node

    Energy harvesting sensor nodes are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting "Green Communication". In this paper, the authors focus on communicating reliably over an AWGN channel using such an energy harvesting sensor node. An important part of...

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  • White Papers // Dec 2012

    Throughput Analysis of Primary and Secondary Networks in a Shared IEEE 802.11 System

    In this paper, the authors analyze the coexistence of a primary and a secondary (cognitive) network when both networks use the IEEE 802.11 based distributed coordination function for medium access control. Specifically, they consider the problem of channel capture by a secondary network that uses spectrum sensing to determine the...

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  • White Papers // Nov 2012

    Resource Usage Monitoring in Clouds

    Monitoring of infrastructural resources in clouds plays a crucial role in providing application guarantees like performance, availability, and security. Monitoring is crucial from two perspectives - the cloud-user and the service provider. The cloud user's interest is in doing an analysis to arrive at appropriate Service-Level Agreement (SLA) demands and...

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  • White Papers // Sep 2012

    Modelling and Analysis of New Coolstreaming for P2P IPTV

    Peer to peer networks are being used extensively nowadays for file sharing, video on demand and live streaming. For IPTV, delay deadlines are more stringent compared to file sharing. Cool-streaming was the first P2P IPTV system. In this paper, the authors model New Cool-streaming (newer version of Cool-streaming) via a...

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  • White Papers // Sep 2012

    Bounds on the Sum-Rate Capacity of the Gaussian MIMO X Channel

    The authors consider the MIMO X Channel (XC), a system consisting of two transmit-receive pairs, where each transmitter communicates with both the receivers. Both the transmitters and receivers are equipped with multiple antennas. First, they derive an upper bound on the sum-rate capacity of the MIMO XC under individual power...

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  • White Papers // Aug 2012

    Decode-and-Forward Relay Beamforming for Secrecy With Imperfect CSI and Multiple Eavesdroppers

    Wireless transmissions, by their very nature, are vulnerable to eavesdropping. There has been considerable interest in the use of physical layer mechanisms to provide secure communications, whereby the eavesdropper gets no information while the intended receiver gets the information reliably. Wyner's work on secrecy capacity of discrete memoryless wiretap channels...

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  • White Papers // Jul 2012

    Factor Graph Based Joint Detection/Decoding for LDPC Coded Large-MIMO Systems

    In this paper, the authors employ message passing algorithms over graphical models to jointly detect and decode symbols transmitted over large Multiple-Input Multiple-Output (MIMO) channels with Low Density Parity Check (LDPC) coded bits. They adopt a factor graph based technique to integrate the detection and decoding operations. A Gaussian approximation...

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  • White Papers // Jul 2012

    Frequency Domain Turbo Equalization for MIMO-CPSC Systems With Large Delay Spreads

    In this paper, the authors consider low-complexity turbo equalization for Multiple-Input Multiple-Output (MIMO) Cyclic Prefixed Single Carrier (CPSC) systems in MIMO Inter-Symbol Interference (ISI) channels characterized by large delay spreads. A low-complexity graph based equalization is carried out in the frequency domain. Because of the reduction in correlation among the...

    Provided By Indian Institute of Science

  • White Papers // Jun 2012

    Secure Compute-and-Forward in a Bidirectional Relay

    Bidirectional relaying, where a relay helps two user nodes to exchange messages has been an active area of recent research. In the compute-and-forward strategy for bidirectional relaying, the relay computes a function of the two messages using the naturally-occurring sum of symbols simultaneously transmitted by user nodes in a Gaussian...

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  • White Papers // May 2012

    Diversity-Rate Trade-Off for Fading Channels With Power Control

    The authors consider a complex, additive, white Gaussian noise channel with flat fading. They study its diversity order vs transmission rate for some known power allocation schemes. The capacity region is divided into three regions. For one power allocation scheme, the diversity order is exponential throughout the capacity region. For...

    Provided By Indian Institute of Science

  • White Papers // May 2012

    LoadIQ: Learning to Identify Workload Phases From a Live Storage Trace

    Storage infrastructure in large-scale cloud data center environments must support applications with diverse, time-varying data access patterns while observing the quality of service. Deeper storage hierarchies induced by solid state and rotating media are enabling new storage management tradeoffs that do not apply uniformly to all application phases at all...

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  • White Papers // Apr 2012

    Relay Selection With Channel Probing for Geographical Forwarding in WSNs

    In a large Wireless Sensor Network (WSN) with sleep-wake cycling nodes, the authors are interested in the local decision problem faced by a node that has "Custody" of a packet and has to choose one among a set of next-hop relay nodes. Each of the relays is associated with a...

    Provided By Indian Institute of Science

  • White Papers // Apr 2012

    Capacity of a Gaussian MAC with Energy Harvesting Transmit Nodes

    The authors consider a Gaussian Multiple Access Channel (GMAC) where the users are sensor nodes powered by energy harvesters. The energy harvesters may have finite or infinite buffer to store the harvested energy. First, they find the capacity region of a GMAC powered by transmit nodes with an infinite energy...

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  • White Papers // Apr 2012

    A Novel MCMC Algorithm for Near-Optimal Detection in Large-Scale Uplink Mulituser MIMO Systems

    In this paper, the authors propose a low-complexity algorithm based on Markov Chain Monte Carlo (MCMC) technique for signal detection on the uplink in large scale multiuser Multiple Input Multiple Output (MIMO) systems with tens to hundreds of antennas at the Base Station (BS) and similar number of uplink users....

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  • White Papers // Mar 2012

    Wireless Network-Coded Three-Way Relaying Using Latin Cubes

    The design of modulation schemes for the physical layer network-coded three-way wireless relaying scenario is considered. The protocol employs two phases: Multiple Access (MA) phase and BroadCast (BC) phase with each phase utilizing one channel use. For the two-way relaying scenario, it was observed by Koike-Akino et al., that adaptively...

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  • White Papers // Mar 2012

    Performance Analysis of Adaptive Physical Layer Network Coding for Wireless Two-Way Relaying

    The analysis of modulation schemes for the physical layer network-coded two way relaying scenario is presented which employs two phases: Multiple access (MA) phase and BroadCast (BC) phase. It was shown by Koike-Akino et. al. that adaptively changing the network coding map used at the relay according to the channel...

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  • White Papers // Mar 2012

    On Secrecy Above Secrecy Capacity

    Information theoretic security is being widely studied in recent times. It provides fundamental limits of secret communication. Unlike in cryptography, the information theoretic techniques are not based on complexity of computational hardness of certain problems. Information theoretic security can also be used in a system in addition to cryptographic techniques...

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  • White Papers // Mar 2012

    Performance Analysis of Deterministic Key Allocation Schemes for Wireless Sensor Networks

    Because of the resource-constrained nature of Wireless Sensor Networks (WSNs), it is easier to use a security system based on symmetric key cryptography. However, the distribution and management of cryptographic keys pose challenges of their own. In this paper, the authors study some deterministic methods of distribution of keys to...

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  • White Papers // Mar 2012

    Wireless Network Coding for MIMO Two-Way Relaying Using Latin Rectangles

    The authors consider the two-way wireless relaying scenario shown with multiple antennas at the nodes, where data transfer takes place between the nodes A and B with the help of the relay R. It is assumed that all the three nodes operate in half-duplex mode, i.e., they cannot transmit and...

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  • White Papers // Mar 2012

    Cooperative Particle Swarm Optimization Based Receiver for Large-Dimension MIMO-ZPSC Systems

    In this paper, the authors propose a Cooperative Particle Swarm Optimization (CPSO) based channel estimation/equalization scheme for Multiple-Input Multiple-Output Zero-Padded Single-Carrier (MIMO-ZPSC) systems with large dimensions in frequency selective channels. They estimate the channel state information at the receiver in time domain using a PSO based algorithm during training phase....

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  • White Papers // Mar 2012

    Optimal Node Selection Using Estimated Data Accuracy Model in Wireless Sensor Networks

    One of the major task of wireless sensor network is to sense accurate data from the physical environment. Hence in this paper, the authors develop an estimated data accuracy model for randomly deployed sensor nodes which can sense more accurate data from the physical environment. They compare their results with...

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  • White Papers // Jan 2012

    Performance Modeling and Architecture Exploration of Network Processors

    In this paper, the authors propose a Petri net model for a commercial network processor (Intel IXP architecture) which is a multithreaded multiprocessor architecture. They consider and model three different applications viz., IPv4 forwarding, network address translation, and IP security running on IXP 2400/2850. A salient feature of the Petri...

    Provided By Indian Institute of Science

  • White Papers // Jan 2012

    Wireless Network-Coded Accumulate-Compute and Forward Two-Way Relaying

    The design of modulation schemes for the physical layer network-coded two way wireless relaying scenario is considered. It was observed by Koike-Akino et al. for the two way relaying scenario, that adaptively changing the network coding map used at the relay according to the channel conditions greatly reduces the impact...

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  • White Papers // Jan 2012

    State Dependent Attempt Rate Modeling of Single Cell IEEE 802.11 WLANs With Homogeneous Nodes and Poisson Arrivals

    Analytical models of IEEE 802.11-based WLANs are invariably based on approximations, such as the well-known mean-field approximations proposed by Bianchi for saturated nodes. In this paper, the authors provide a new approach for modeling the situation when the nodes are not saturated. They study a State Dependent Attempt Rate (SDAR)...

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  • White Papers // Dec 2011

    Optimal Deployment of Impromptu Wireless Sensor Networks

    The need for impromptu wireless networks arises in emergency situations where the team responding to the emergency, needs to deploy sensors (such as motion sensors, or even imaging sensors) and a wireless interconnection network, without any prior planning or knowledge of the terrain. In this paper, the authors consider a...

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  • White Papers // Dec 2011

    QoS Aware and Survivable Network Design for Planned Wireless Sensor Networks

    The authors study the problem of wireless sensor network design by deploying a minimum number of additional relay nodes (to minimize network cost) at a subset of given potential relay locations, in order to convey the data from already existing sensor nodes (hereafter called source nodes) to a Base Station,...

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  • White Papers // Nov 2011

    Computer Processing of Electroencephalographic Signals for Functional Connectivity Analysis of the Brain Using Graph Theoretic Techniques

    Computer processing of biomedical signals have gained a lot of importance because its extensive applications in healthcare. Extensive studies have been made on various aspects of bioengineering and in this paper, the authors consider its application to neuroscience one of the important area of study is on the functional connectivity...

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  • White Papers // Jan 2010

    Performance Analysis of Wireless Ad-Hoc Networks

    With the growing importance of wireless ad hoc networks (particularly, in applications such as wireless local area networks, and ad hoc sensor networks) it is important to develop an understanding of their performance. Performance analysis of wireless ad hoc networks is a challenging task owing to the fact that such...

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  • White Papers // Jan 2010

    Obstacle Constrained Total Area Coverage in Wireless Sensor Networks

    A Wireless Sensor Network (WSN) consists of a large number of tiny, low-powered devices, called sensors, which communicate with each other (possibly) in a multi-hop fashion. These sensors suffer from severe constraints, such as low reliability and limited battery power (or energy), processing power, storage memory, sensing range and communication...

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  • White Papers // Mar 2011

    A Transform Approach to Linear Network Coding for Acyclic Networks With Delay

    Network coding was introduced in as a means to improve the rate of transmission in networks. Linear network coding was introduced in and it was found to be sufficient to achieve the maxflow-mincut capacity in certain scenarios such as multicast. The existence problem of network coding for networks without delay...

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  • White Papers // Jan 2010

    On Network-Error Correcting Convolutional Codes Under the BSC Edge Error Model

    The performance of CNECCs under the BSC edge error model has been analyzed using theoretical bounds and simulations. A sufficient upper bound on the edge cross-over probability pe has been obtained, so that if pe is below this bound, the complexity of analysis can be reduced greatly by considering only...

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  • White Papers // Dec 2010

    Analytical Modeling of Saturation Throughput in Power Save Mode of an IEEE 802.11 Infrastructure WLAN

    The authors consider a single STAtion (STA) in the Power Save Mode (PSM) of an IEEE 802.11 infrastructure WLAN. This STA is assumed to be carrying uplink and downlink traffic via the Access Point (AP). The authors assume that the transmission queues of the AP and the STA are saturated,...

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  • White Papers // Nov 2010

    Distributed Construction of the Critical Geometric Graph in Dense Wireless Sensor Networks

    Wireless sensor networks are often modeled in terms of a dense deployment of smart sensor nodes in a two-dimensional region. Given a node deployment, the Critical Geometric Graph (CGG) over these locations (i.e., the connected Geometric Graph (GG) with the smallest radius) is a useful structure since it provides the...

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  • White Papers // Jan 2009

    FRFD MIMO Systems: Precoded V-BLAST With Limited Feedback Versus Non-Orthogonal STBC MIMO

    Full-Rate (FR) and Full-Diversity (FD) are attractive features in MIMO systems. The authors refer to systems which achieve both FR and FD simultaneously as FRFD systems. Non-orthogonal STBCs can achieve FRFD without feedback, but their ML decoding complexities are high. V-BLAST without precoding achieves FR but not FD. FRFD can...

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  • White Papers // Feb 2009

    NNRU, a Noncommutative Analogue of NTRU

    NTRU public key cryptosystem is well studied lattice-based Cryptosystem along with Ajtai-Dwork and GGH systems. Underlying NTRU is a hard mathematical problem of finding short vectors in a certain lattice. (Shamir 1997) presented a lattice-based attack by which he could find the original secret key or alternate key. Shamir concluded...

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  • White Papers // Aug 2009

    Convolutional Codes for Network-Error Correction

    In this paper, the authors introduce convolutional codes for network-error correction in the context of coherent network coding. They give a construction of convolutional codes that correct a given set of error patterns, as long as consecutive errors are separated by a certain interval. They also give some bounds on...

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  • White Papers // Mar 2009

    Modeling Multi-Cell IEEE 802.11 WLANs With Application to Channel Assignment

    The authors provide a simple and accurate analytical model for multi-cell infrastructure IEEE 802.11 WLANs. The model applies if the cell radius, R, is much smaller than the carrier sensing range, Rcs. They argue that, the condition Rcs >> R is likely to hold in a dense deployment of Access...

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  • White Papers // Sep 2010

    Delay Modelling for a Single-Hop Wireless Mesh Network Under Light Aggregate Traffic

    The IEEE 802.11 has become ubiquitous and gained widespread popularity as a protocol for wireless networks. As a result, various models have been proposed to analyze and model the parameters of interest. Since the seminal paper by Bianchi, throughput analysis of IEEE 802.11 DCF has come under much scrutiny. In...

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  • White Papers // Sep 2010

    Aggregate AP Throughputs for Long File Transfers in a WLAN Controlled by Inhomogeneous TCP Connections

    This paper is concerned with infrastructure mode WLANs that use the IEEE 802.11 DCF mechanism. The authors are interested in analytical models for evaluating the performance of TCP controlled simultaneous uploads and downloads where each connection has arbitrary TCP windows size. A detailed analysis of the aggregate throughput of TCP...

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  • White Papers // Oct 2010

    A Novel Algorithm for Cooperative Distributed Sequential Spectrum Sensing in Cognitive Radio

    Presently there is a scarcity of wireless spectrum worldwide due to an increase in wireless services. Cognitive Radios are proposed as a solution to this problem. They access the spectrum licensed to existing communication services (primary users) opportunistically and dynamically without causing much interference to the primary users. This is...

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  • White Papers // Oct 2010

    Secrecy Capacity of the Gaussian Wire-Tap Channel With Finite Complex Constellation Input

    The secrecy capacity of a discrete memoryless Gaussian Wire-Tap Channel when the input is from a finite complex constellation is studied. It is shown that the secrecy capacity curves of a finite constellation plotted against the SNR, for a fixed noise variance of the eavesdropper's channel has a global maximum...

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  • White Papers // Oct 2010

    State Dependent Attempt Rate Modeling of Single Cell IEEE 802.11 WLANs With Homogeneous Nodes and Poisson Packet Arrivals

    Analytical models for IEEE 802.11-based WLANs are invariably based on approximations, such as the well-known decoupling approximation proposed by Bianchi for modeling single cell WLANs consisting of saturated nodes. In this paper, the authors provide a new approach to model the situation when the nodes are not saturated. They study...

    Provided By Indian Institute of Science

  • White Papers // Dec 2009

    Tunable Locally-Optimal Geographical Forwarding in Wireless Sensor Networks With Sleep-Wake Cycling Nodes

    The authors consider a wireless sensor network whose main function is to detect certain infrequent alarm events, and to forward alarm packets to a base station, using geographical forwarding. The nodes know their locations, and they sleep-wake cycle, waking up periodically but not synchronously. In this situation, when a node...

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  • White Papers // Aug 2009

    Key Distribution Scheme Without Deployment Knowledge

    Many basic key distribution schemes specifically tuned to wireless sensor networks have been proposed in the literature. Recently, several researchers have proposed schemes in which they have used group-based deployment models and assumed predeployment knowledge of the expected locations of nodes. They have shown that these schemes achieve better performance...

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  • White Papers // Aug 2009

    High-Rate, Distributed Training-Embedded Complex Orthogonal Designs for Relay Networks

    Distributed Space-Time Block Codes (DSTBCs) from Complex Orthogonal Designs (CODs) (both square and non-square CODs other than the Alamouti design) are known to lose their Single-Symbol ML Decodable (SSD) property when used in two-hop wireless relay networks using amplify and forward protocol. For such a network, in this paper, a...

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  • White Papers // Mar 2011

    Transaction-Based QoS Management in a Hybrid Wireless Superstore Environment

    Hybrid wireless networks are extensively used in the superstores, marketplaces, malls, etc. and provide high QoS (Quality of Service) to the end-users has become a challenging task. In this paper, the authors propose a policy-based transaction-aware QoS management architecture in a hybrid wireless superstore environment. The proposed scheme operates at...

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  • White Papers // Jun 2011

    Theory and Algorithms for Hop-Count-Based Localization With Random Geometric Graph Models of Dense Sensor Networks

    The authors consider a network in which several service providers offer wireless access to their respective subscribed customers through potentially multi-hop routes. If providers cooperate by jointly deploying and pooling their resources, such as spectrum and infrastructure (e.g., base stations), and agree to serve each others' customers, their aggregate payoffs,...

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  • White Papers // Jan 2011

    Delay Optimal Schedule for a 2-Hop Vehicular Relay Network

    The authors study a scheduling problem in a mobile network scenario where vehicles are used as relays. A fixed source node wants to transfer a file of a known size to a fixed destination node, located beyond its communication range. In the absence of any infrastructure connecting the two nodes,...

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  • White Papers // Jan 2011

    Analytical Model for an IEEE 802.11 WLAN Using DCF With Two Types of VoIP Calls

    The authors formulate an analytical model for capacity evaluation of an infrastructure IEEE 802.11 based network carrying full-duplex packet telephone calls when different types of codecs are used for voice calls. The analysis of the model utilizes the attempt rate results from a well known fixed-point based saturation analysis. The...

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  • White Papers // Jul 2009

    Robust THP Transceiver Designs for Multiuser MIMO Downlink With Imperfect CSIT

    The authors present robust joint nonlinear transceiver designs for multiuser Multiple-Input Multiple-Output (MIMO) downlink in the presence of imperfections in the Channel State Information at the Transmitter (CSIT). The Base Station (BS) is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas....

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  • White Papers // Jan 2011

    Energy Efficient Mobile Base Stations Placement Algorithms in Wireless Sensor Networks

    Increasing network lifetime is important in wireless sensor/ad-hoc networks. In this paper, the authors are concerned with algorithms to increase network lifetime and amount of data delivered during the lifetime by deploying multiple mobile base stations in the sensor network field. Specifically, they allow multiple mobile base stations to be...

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  • White Papers // Sep 2008

    Experiences With WM: A Centralised Scheduling Approach for Performance Management of IEEE 802.11 Wireless LANs

    In the authors' earlier work they proposed WLAN Manager (orWM) a centralised controller for QoS management of infrastructure WLANs based on the IEEE 802.11 DCF standards. The WM approach is based on queueing and scheduling packets in a device that sits between all traffic flowing between the APs and the...

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  • White Papers // Oct 2011

    Quality of Service for I/O Workloads in Multicore Virtualized Servers

    Emerging trend of multi-core servers promises to be the panacea for all data-center issues with system virtualization as the enabling technology. System virtualization allows one to create virtual replicas of the physical system, over which independent virtual machines can be created, complete with their own, individual operating systems, software, and...

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  • White Papers // Dec 2010

    Data Accuracy Estimation for Spatially Correlated Data in Wireless Sensor Networks Under Distributed Clustering

    The main purpose of this paper is to construct a distributed clustering algorithm such that each distributed cluster can perform the data accuracy at their respective cluster head node before data aggregation and transmit the data to the sink node. The authors investigate that the data are spatially correlated among...

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  • White Papers // Aug 2011

    Data Accuracy Model for Distributed Clustering Algorithm Based on Spatial Data Correlation in Wireless Sensor Networks

    The main objective of this paper is to construct a distributed clustering algorithm based upon spatial data correlation among sensor nodes and perform data accuracy for each distributed cluster at their respective cluster head node. The authors investigate that due to deployment of high density of sensor nodes in the...

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  • White Papers // Oct 2011

    Joint Routing, Scheduling and Power Control For Multihop Wireless Networks With Multiple Antennas

    The authors consider the problem of Joint Routing, Scheduling and Power-control (JRSP) problem for Multi-Hop Wireless Networks (MHWN) with multiple antennas. They extend the problem and a (sub-optimal) heuristic solution method for JRSP in MHWN with single antennas. They present an iterative scheme to calculate link capacities (achievable rates) in...

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  • White Papers // Jul 2011

    Co-Evolution of Content Popularity and Delivery in Mobile P2P Networks

    Mobile P2P technology provides a scalable approach to content delivery to a large number of users on their mobile devices. In this paper, the authors study the dissemination of a single content (e.g., an item of news, a song or a video clip) among a population of mobile nodes. Each...

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  • White Papers // Aug 2008

    An Efficient Algorithm for Cooperative Spectrum Sensing in Cognitive Radio Networks

    The authors consider the problem of Spectrum Sensing in Cognitive Radio Systems. They have developed a distributed algorithm that the Secondary users can run to sense the channel cooperatively. It is based on sequential detection algorithms which optimally use the past observations. They use the algorithm on secondary users with...

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  • White Papers // Jan 2011

    Lossy Distributed Source Coding With Side Information

    In a typical sensor network scenario a goal is to monitor a spatio-temporal process through a number of inexpensive sensing nodes, the key parameter being the fidelity at which the process has to be estimated at distant locations. The authors study such a scenario in which multiple encoders transmit their...

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  • White Papers // Aug 2009

    On the Design of Location-Invariant Sensing Performance for Secondary Users

    In this paper, the authors consider the setting of one-shot spectrum hole detection for a uniformly distributed secondary network under fading and path loss. They separate the sensors that are used to detect spectral holes from the secondary transmitters, thus allowing each secondary transmitter to benefit from the decisions of...

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  • White Papers // Jan 2010

    A Practical Dirty Paper Coding Applicable for Broadcast Channel

    The authors have presented a novel dirty paper coding scheme which followed Costa's paper analytically and allowed the recoverability of the dirt. Their scheme implemented random binning in a systematic manner using a trellis and used Viterbi algorithm to quickly obtain a PIP-TCM codeword that is almost orthogonal to the...

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  • White Papers // Dec 2008

    Fast Distributed Multiple Access Based Selection With Imperfect Parameter Knowledge

    Several wireless systems that seek to exploit multiuser or spatial diversity need to opportunistically select a 'Best' node from among the many available nodes. This is done on the basis of a suitability metric that is locally known at each node, and is initially not known elsewhere. While a fast,...

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  • White Papers // Jan 2009

    Receive Antenna Selection With Imperfect Channel Knowledge From Training

    Receive Antenna Selection (AS), in which a subset of a receiver's antennas is selected based on the instantaneous channel condition, enables the receiver to benefit from having multiple antenna elements despite using significantly less hardware. However, the limited hardware resources also impose unique constraints on how channel state information, which...

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  • White Papers // Jun 2010

    Improved Large-MIMO Detection Based on Damped Belief Propagation

    In this paper, the authors consider the application of Belief Propagation (BP) to achieve near-optimal signal detection in large Multiple-Input Multiple-Output (MIMO) systems at low complexities. Large-MIMO architectures based on spatial multiplexing (V-BLAST) as well as non-orthogonal Space-Time Block Codes (STBC) from Cyclic Division Algebra (CDA) are considered. They adopt...

    Provided By Indian Institute of Science

  • White Papers // Jan 2011

    Robust MMSE Tomlinson-Harashima Precoder for Multiuser MISO Downlink With Imperfect CSI

    Non-linear precoding for the downlink of a multiuser MISO (Multiple-Input Single-Output) communication system in the presence of imperfect Channel State Information (CSI) is considered. The base station is equipped with multiple transmit antennas and each user terminal is equipped with a single receive antenna. The CSI at the transmitter is...

    Provided By Indian Institute of Science

  • White Papers // Nov 2008

    MMSE Receiver for Multiuser Interference Cancellation in Uplink OFDMA

    In uplink Orthogonal Frequency Division Multiple Access (OFDMA) systems, MultiUser Interference (MUI) occurs due to different Carrier Frequency Offsets (CFO) of different users at the receiver. In this paper, the authors present a Minimum Mean Square Error (MMSE) based approach to MUI cancellation in uplink OFDMA. They derive a recursion...

    Provided By Indian Institute of Science

  • White Papers // Sep 2011

    Reliability Modelling of Disk Subsystems With Probabilistic Model Checking

    The authors discuss how probabilistic model checking, a variant of model checking, can be useful in modelling multiple failures in disk subsystems, as it allows specification of probabilities or rates of transitions also. Probabilistic model checking can be used to not only check the correctness of formulae that are augmented...

    Provided By Indian Institute of Science