Indian Institute of Technology Madras

Displaying 1-40 of 82 results

  • White Papers // May 2013

    Approximate Congestion Games for Load Balancing in Distributed Environment

    The use of game theoretic models has been quite successful in describing various cooperative and non-cooperative optimization problems in networks and other domains of computer systems. In this paper, the authors study an application of game theoretic models in the domain of distributed system, where nodes play a game to...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2013

    Lattice Based Forward-Secure Identity Based Encryption Scheme with Shorter Ciphertext

    In Crypto 84 conference Adi Shamir introduced the concept of identity-based cryptosystem. Identity-based cryptosystem is a public key cryptosystem in which users' public key can be any arbitrary string. For example email or phone number can be public key. Private Key corresponding to this arbitrary string is issued by Trusted...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2013

    Efficient Certificateless Online/Offline Signature with Tight Security

    Since public key cryptography is usually build using computationally expensive operation, it has been out of reach for resource constrained and low power devices. Today there are a large number of low power devices in use and they perform complex tasks. In this paper, the authors show a view of...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2012

    Compressive Sensing Framework for Signal Processing in Heterogeneous Cellular Networks

    The authors consider a heterogeneous cellular network where each base station sends a unique training signal based on its physical layer cell identity. The received signal at the Mobile Terminal (MT) is a superposition of training signals from different Base Stations (BS). Neither the identities of BS nor their channel...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2012

    SINR Order Statistics in OFDMA Systems

    In orthogonal frequency division multiple access downlink, the Signal-to-Interference-Noise Ratio (SINR) of every sub-band at each user is estimated with the aid of pilots and the channel quality (some function of SINR's) is fed back to the Base Station (BS). This information is utilized by the BS for downlink scheduling....

    Provided By Indian Institute of Technology Madras

  • White Papers // Oct 2012

    Efficient Certificateless Online/Offline Signature

    Public key cryptography usually is computationally more expensive than symmetric key systems. Due to this low power or resource constrained devices cannot make use of public key cryptosystems easily. There is a need for high security in these devices since many of these devices perform complex tasks which include interaction...

    Provided By Indian Institute of Technology Madras

  • White Papers // Oct 2012

    On Provably Secure Code-Based Signature and Signcryption Scheme

    Signcryption is a cryptographic protocol that provides authentication and confidentiality as a single primitive at a cost lower than the combined cost of sign and encryption. Due to the improved efficiency, signcryption schemes have found significant applications in areas related to E-commerce. Shor's algorithm poses a threat to number-theoretic algorithms,...

    Provided By Indian Institute of Technology Madras

  • White Papers // Aug 2012

    Outer Bounds for the Capacity Region of a Gaussian Two-Way Relay Channel

    The authors consider a three-node half-duplex Gaussian relay network where two nodes (say a, b) want to communicate with each other and the third node acts as a relay for this two way communication. Outer bounds and achievable rate regions for the possible rate pairs (Ra;Rb) for two-way communication are...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jul 2012

    ID Based Signcryption Scheme in Standard Model

    Designing an ID based signcryption scheme in the standard model is among the most interesting and important problems in cryptography. However, all the existing systems in the ID based setting, in the standard model, do not have either the unforgeability property or the indistinguishability property or both of them. In...

    Provided By Indian Institute of Technology Madras

  • White Papers // May 2012

    Optimal Sensing-Order in Cognitive Radio Networks With Cooperative Centralized Sensing

    This paper investigates the optimal sensing-order problem in multi-user, multi-channel cognitive radio networks in which channel sensing and access decisions are made sequentially by a central coordinator according to a central sensing-order. Estimates of the primary-free probabilities of the different channels are assumed to be known. Cognitive throughput, which is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Mar 2012

    Stronger Public Key Encryption Schemes Withstanding RAM Scraper Like Attacks

    Security of an encryption system is formally established through the properties of an abstract game played between a challenger and an adversary. During the game, the adversary will be provided with all information that he could obtain in an attack model so that the adversary is fully empowered to carry...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2012

    On the Security of ID Based Signcryption Schemes

    A signcryption scheme is secure only if it satisfies both the confidentiality and the unforgeability properties. All the ID based signcryption schemes presented in the standard model till now do not have either the confidentiality or the unforgeability or both of these properties. Cryptanalysis of some of the schemes have...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2012

    Strongly Unforgeable Proxy Re-Signature Schemes in the Standard Model

    Proxy re-signatures are generally used for the delegation of signatures to a semi-trusted proxy which transforms the signatures between the users of the system. Its a handy primitive for network security and automated delegations in hierarchical organizations. Though proxy re-signature schemes that are secure in the standard model are available,...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2012

    Cutting Edge at the Cell Edge: Co-Channel Interference Mitigation in Emerging Broadband Wireless Systems

    Emerging Broadband Wireless systems, such as those based on IEEE 802:16m or 3GPP LTE-A, will re-use spectrum in every sector (1 : 1 reuse) and maximize system spectrum efficiency. In so doing, the spectrum efficiency for cell-edge users is very poor in comparison with the system wide average, and nomadic...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2011

    Deterministic Identity Based Signature Scheme and Its Application for Aggregate Signatures

    The revolutionary impact offered by identity based cryptography is phenomenal. This novel mechanism was first coined by Adi Shamir in 1984. Since then, several identity based signature schemes were reported. But surprisingly, none of the identity based signature scheme is having the property of determinism and does rely on bilinear...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2011

    A Novel Multipath Approach to Security in Mobile Ad Hoc Networks (MANETs)

    In this paper, the authors present a novel encryption-less algorithm to enhance security in transmission of data packets across mobile ad hoc networks. The paper hinges on the paradigm of multipath routing and exploits the properties of polynomials. The first step in the algorithm is to transform the data such...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2011

    Rational Secret Sharing Over an Asynchronous Broadcast Channel With Information Theoretic Security

    The authors consider the problem of rational secret sharing introduced by Halpern and Teague, where the players involved in secret sharing play only if it is to their advantage. This can be characterized in the form of preferences. Players would prefer to get the secret than to not get it...

    Provided By Indian Institute of Technology Madras

  • White Papers // Aug 2011

    Dynamic Connectivity and Path Formation Time in Poisson Networks

    The connectivity of wireless networks is commonly analyzed using static geometric graphs. However, with half-duplex radios and due to interference, static or instantaneous connectivity cannot be achieved. It is not necessary, either, since packets take multiple time slots to propagate through the network. For example, if a packet traverses a...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jul 2011

    Compact CCA-Secure Encryption With Ciphertext Verifiability

    While CCA secure encryption schemes that provide ciphertext indistinguishability offer strongest form of message secrecy, the integrity of the ciphertext is often overlooked. In most of the practical applications it is required that the ciphertext should be verifiable with respect to the decrypted message in order to check whether the...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jul 2011

    Identity Based Deterministic Signature Scheme Without Forking-Lemma

    Since the discovery of identity based cryptography, a number of identity based signature schemes were reported in the literature. Although a lot of identity based signature schemes were developed, the only existing identity based deterministic signature scheme was proposed in 2005 by Javier Herranz. This signature scheme uses Schnorr signature...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2011

    Rational Secret Sharing with Honest Players over an Asynchronous Channel

    The authors consider the problem of rational secret sharing introduced by Halpern and Teague, where the players involved in secret sharing play only if it is to their advantage. This can be characterized in the form of preferences. Players would prefer to get the secret than to not get it...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2011

    Convergence Conditions for Iterative Transmission Power Control Algorithms in Wireless Networks

    Maximum power is consumed when the wireless device is transmitting and hence, transmission power is one of the important resources in wireless communication. Transmission power of a transmitter can neither be too low that the intended receiver cannot decode the signal nor can it be too high that it causes...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2011

    Robust Demand-Driven Video Multicast over Ad hoc Wireless Networks

    In this paper, the authors address the problem of video multicasting in ad hoc wireless networks. The salient characteristics of video traffic make conventional multicasting protocols perform quite poorly, hence warranting application-centric approaches in order to increase robustness to packet losses and lower the overhead. By exploiting the path-diversity and...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2011

    Grooming of Multicast Sessions in WDM Ring Networks

    This paper addresses the problem of routing and wavelength assignment of multicast sessions with sub-wavelength traffic demands. The authors consider this problem in the scenario of WDM ring networks. In order to support multicasting, individual nodes need to have the capability to duplicate traffic. The authors consider two different node...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2011

    Management Information Bus as Scalable Communication Architecture for NMS

    With the growing number of communication service offerings to customers and increased complexity of managed networks, there is a need to interconnect management systems at different levels. This requires information flow across many applications in a domain independent way. The authors propose Management Information Bus (MIB) as a scalable communication...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Guided Navigation of Friendly Object Towards Mobile Target in Wireless Sensor Networks

    Tracking mobile targets is an important wireless sensor network application in both military and civilian fields. Often, it may be necessary for sending additional resources to the vicinity of the mobile target. In such a scenario, it is pertinent to provide continuous guidance to the friendly resource moving towards the...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Some Design Considerations for a Mobile Payment Architecture

    The rapid proliferation of mobile phones now provides an opportunity to harness their potential towards financial transactions. One form of such financial transactions is mobile payments. The authors' focus, in this paper, will be on certain design considerations for a mobile payment architecture. For widespread adoption, interoperability is a key...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Feature Diversity for Emotion, Language and Speaker Verification

    In this paper, the authors describe the utilisation of the diversity of different feature representations for speaker, emotion and language verification. The underlying principle behind the method is that some features are better at discriminating some classes and other features for other classes. Studies are done on four features and...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Performance Evaluation of Open Loop Multi-User MIMO Systems

    Significant throughput gains can be achieved in a Multi-User MIMO (MU-MIMO) wireless system by exploiting the combination of multi-user scheduling and multi-user diversity. Open-Loop MU-MIMO (OL-MU-MIMO) is a codebook based precoding technique where precoders are fixed a priori at the Base Station (BS) in a known fashion and the user...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Adaptive Color Illumination for Microscopes

    Microscopes typically use a single color illumination source and the intensity of it can be varied depending on the application. They are used to observe various specimens which are usually stained to highlight the objects of interest. Automatic methods for identification of diseases from these specimens have been developed recently....

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Novel Polyphase Training Sequence Based Synchronization Estimator for OFDM

    Orthogonal Frequency Division Multiplexing (OFDM) systems are sensitive to timing and frequency estimation errors. A DFT spread modified polyphase training sequence is proposed which has better merit factor and peak to average power ratio. By using the proposed training sequence two estimators are presented for timing and frequency synchronization. The...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    An Experimental Evaluation of CUBIC TCP in a Small Buffer Regime

    CUBIC TCP is an enhancement over BIC (Binary Increase Congestion Control) with a cubic window growth function. It has been optimized for high bandwidth-delay product environments and has been the default TCP implementation in Linux since kernel-2.6.18. In this paper, the authors conduct an experimental evaluation of CUBIC TCP in...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Adaptive Push Based Data Collection Method for Online Performance Monitoring

    In telecommunication network management systems, pull and push are the conventional methods for data collection. The manager (also called client) entity manages a large number of network elements (NE, also called server) that send monitoring data to the manager. The pull approach does not depend on data changes and is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    New Approach to Joint MIMO Precoding for 2-Way AF Relay Systems

    In this paper, the authors propose methods for joint design of source relay precoders that optimize the performance of two-way Amplify and Forward (AF) Multiple Input Multiple Output (MIMO) relay systems. In particular, they propose three iterative methods to optimize the system performance. The design criteria they consider in this...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Poisson Noise Removal From Images Using the Fast Discrete Curvelet Transform

    The authors propose a strategy to combine the Variance Stabilizing Transform (VST), used for Poisson image denoising, with the Fast Discrete Curvelet Transform (FDCT). The VST transforms the Poisson image to approximately Gaussian distributed, and the subsequent denoising can be performed in the Gaussian domain. However, the performance of the...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Unitary Precoders for CQI Reliability in Closed Loop MU-MIMO OFDM Systems

    In Multi-User MIMO (MU-MIMO), the Base Station (BS) schedules multiple users simultaneously on the same resources. Closed loop MU-MIMO uses explicit feedback from each of these users for scheduling and allocation of resources. In this scheme, an estimate of the SINR experienced is fed back by each user and is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Prediction of SINR Improvement with a Directional Antenna or Antenna Array in a Cellular System

    The authors consider a reuse-1 cellular system and study the improvement in SINR possible for a fixed/nomadic receiver, from the use of an optimally oriented directional patch antenna or a Uniform Linear Array (ULA) with 2 or 4 antenna elements along with Minimum Mean Square Error (MMSE) combining. They perform...

    Provided By Indian Institute of Technology Madras

  • White Papers // Aug 2010

    Efficient and Provably Secure Identity Based Aggregate Signature Schemes With Partial and Full Aggregation

    An identity based signature allows users to sign their documents using their private keys and the signature can be verified by any user by using the identity of the signer and public parameters of the system. This allows secure communication between the users without any exchange of certificates. An aggregate...

    Provided By Indian Institute of Technology Madras

  • White Papers // Aug 2010

    CCA2 Secure Certificateless Encryption Schemes Based on RSA

    Certificateless cryptography, introduced by Al-Riyami and Paterson eliminates the key escrow problem inherent in identity based cryptosystem. In this paper, the authors present two novels and completely different RSA based adaptive chosen ciphertext secure (CCA2) certificateless encryption schemes. The new schemes are efficient when compared to other existing certificatless encryption...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jul 2010

    Identity Based Online/Offline Signcryption Scheme

    Online/Offline signcryption is a cryptographic primitive where the signcryption process is divided into two phases - online and offline phase. Most of the computations are carried out offline (where the message and the receiver identity are unavailable). The online phase does not require any heavy computations like pairing, multiplication on...

    Provided By Indian Institute of Technology Madras

  • White Papers // Oct 2012

    On Provably Secure Code-Based Signature and Signcryption Scheme

    Signcryption is a cryptographic protocol that provides authentication and confidentiality as a single primitive at a cost lower than the combined cost of sign and encryption. Due to the improved efficiency, signcryption schemes have found significant applications in areas related to E-commerce. Shor's algorithm poses a threat to number-theoretic algorithms,...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jul 2012

    ID Based Signcryption Scheme in Standard Model

    Designing an ID based signcryption scheme in the standard model is among the most interesting and important problems in cryptography. However, all the existing systems in the ID based setting, in the standard model, do not have either the unforgeability property or the indistinguishability property or both of them. In...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2012

    Compressive Sensing Framework for Signal Processing in Heterogeneous Cellular Networks

    The authors consider a heterogeneous cellular network where each base station sends a unique training signal based on its physical layer cell identity. The received signal at the Mobile Terminal (MT) is a superposition of training signals from different Base Stations (BS). Neither the identities of BS nor their channel...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2013

    Lattice Based Forward-Secure Identity Based Encryption Scheme with Shorter Ciphertext

    In Crypto 84 conference Adi Shamir introduced the concept of identity-based cryptosystem. Identity-based cryptosystem is a public key cryptosystem in which users' public key can be any arbitrary string. For example email or phone number can be public key. Private Key corresponding to this arbitrary string is issued by Trusted...

    Provided By Indian Institute of Technology Madras

  • White Papers // Nov 2012

    SINR Order Statistics in OFDMA Systems

    In orthogonal frequency division multiple access downlink, the Signal-to-Interference-Noise Ratio (SINR) of every sub-band at each user is estimated with the aid of pilots and the channel quality (some function of SINR's) is fed back to the Base Station (BS). This information is utilized by the BS for downlink scheduling....

    Provided By Indian Institute of Technology Madras

  • White Papers // Jun 2009

    A Multi-Class Bernoulli Feedback Queue with Gate Mechanism

    The authors consider a single server queue in which multi-class customers arrive ac-cording to Poisson process and service times are exponentially distributed. The server works following a gate mechanism in which arriving customers do not enter service immediately and wait to form a batch. This batch of customers get service...

    Provided By Indian Institute of Technology Madras

  • White Papers // Feb 2013

    Efficient Certificateless Online/Offline Signature with Tight Security

    Since public key cryptography is usually build using computationally expensive operation, it has been out of reach for resource constrained and low power devices. Today there are a large number of low power devices in use and they perform complex tasks. In this paper, the authors show a view of...

    Provided By Indian Institute of Technology Madras

  • White Papers // Oct 2012

    Efficient Certificateless Online/Offline Signature

    Public key cryptography usually is computationally more expensive than symmetric key systems. Due to this low power or resource constrained devices cannot make use of public key cryptosystems easily. There is a need for high security in these devices since many of these devices perform complex tasks which include interaction...

    Provided By Indian Institute of Technology Madras

  • White Papers // May 2013

    Approximate Congestion Games for Load Balancing in Distributed Environment

    The use of game theoretic models has been quite successful in describing various cooperative and non-cooperative optimization problems in networks and other domains of computer systems. In this paper, the authors study an application of game theoretic models in the domain of distributed system, where nodes play a game to...

    Provided By Indian Institute of Technology Madras

  • White Papers // May 2012

    Optimal Sensing-Order in Cognitive Radio Networks With Cooperative Centralized Sensing

    This paper investigates the optimal sensing-order problem in multi-user, multi-channel cognitive radio networks in which channel sensing and access decisions are made sequentially by a central coordinator according to a central sensing-order. Estimates of the primary-free probabilities of the different channels are assumed to be known. Cognitive throughput, which is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Adaptive Push Based Data Collection Method for Online Performance Monitoring

    In telecommunication network management systems, pull and push are the conventional methods for data collection. The manager (also called client) entity manages a large number of network elements (NE, also called server) that send monitoring data to the manager. The pull approach does not depend on data changes and is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Feature Diversity for Emotion, Language and Speaker Verification

    In this paper, the authors describe the utilisation of the diversity of different feature representations for speaker, emotion and language verification. The underlying principle behind the method is that some features are better at discriminating some classes and other features for other classes. Studies are done on four features and...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    New Approach to Joint MIMO Precoding for 2-Way AF Relay Systems

    In this paper, the authors propose methods for joint design of source relay precoders that optimize the performance of two-way Amplify and Forward (AF) Multiple Input Multiple Output (MIMO) relay systems. In particular, they propose three iterative methods to optimize the system performance. The design criteria they consider in this...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Unitary Precoders for CQI Reliability in Closed Loop MU-MIMO OFDM Systems

    In Multi-User MIMO (MU-MIMO), the Base Station (BS) schedules multiple users simultaneously on the same resources. Closed loop MU-MIMO uses explicit feedback from each of these users for scheduling and allocation of resources. In this scheme, an estimate of the SINR experienced is fed back by each user and is...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Performance Evaluation of Open Loop Multi-User MIMO Systems

    Significant throughput gains can be achieved in a Multi-User MIMO (MU-MIMO) wireless system by exploiting the combination of multi-user scheduling and multi-user diversity. Open-Loop MU-MIMO (OL-MU-MIMO) is a codebook based precoding technique where precoders are fixed a priori at the Base Station (BS) in a known fashion and the user...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Novel Polyphase Training Sequence Based Synchronization Estimator for OFDM

    Orthogonal Frequency Division Multiplexing (OFDM) systems are sensitive to timing and frequency estimation errors. A DFT spread modified polyphase training sequence is proposed which has better merit factor and peak to average power ratio. By using the proposed training sequence two estimators are presented for timing and frequency synchronization. The...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Adaptive Color Illumination for Microscopes

    Microscopes typically use a single color illumination source and the intensity of it can be varied depending on the application. They are used to observe various specimens which are usually stained to highlight the objects of interest. Automatic methods for identification of diseases from these specimens have been developed recently....

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Prediction of SINR Improvement with a Directional Antenna or Antenna Array in a Cellular System

    The authors consider a reuse-1 cellular system and study the improvement in SINR possible for a fixed/nomadic receiver, from the use of an optimally oriented directional patch antenna or a Uniform Linear Array (ULA) with 2 or 4 antenna elements along with Minimum Mean Square Error (MMSE) combining. They perform...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Some Design Considerations for a Mobile Payment Architecture

    The rapid proliferation of mobile phones now provides an opportunity to harness their potential towards financial transactions. One form of such financial transactions is mobile payments. The authors' focus, in this paper, will be on certain design considerations for a mobile payment architecture. For widespread adoption, interoperability is a key...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    An Experimental Evaluation of CUBIC TCP in a Small Buffer Regime

    CUBIC TCP is an enhancement over BIC (Binary Increase Congestion Control) with a cubic window growth function. It has been optimized for high bandwidth-delay product environments and has been the default TCP implementation in Linux since kernel-2.6.18. In this paper, the authors conduct an experimental evaluation of CUBIC TCP in...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2010

    Poisson Noise Removal From Images Using the Fast Discrete Curvelet Transform

    The authors propose a strategy to combine the Variance Stabilizing Transform (VST), used for Poisson image denoising, with the Fast Discrete Curvelet Transform (FDCT). The VST transforms the Poisson image to approximately Gaussian distributed, and the subsequent denoising can be performed in the Gaussian domain. However, the performance of the...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    EG-LDPC Codes for the Erasure Wiretap Channel

    The wiretap channel model, proposed by Wyner, has been studied by various authors from the perspectives of security, reliability and cryptographic protocols. A basic theme of these discussions has been information theoretically secure communication whose degree of secrecy can be theoretically proved. This paper explains a practical implementation of Euclidean...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Common Architecture for Decoding Turbo and LDPC Codes

    Turbo codes and Low Density Parity Check (LDPC) codes have been shown to be practical codes that can approach Shannon capacity in several communication systems. In terms of performance and implementation complexity, LDPC codes and turbo codes are highly comparable, especially at coding rates around 1/2. In many recent wireless...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Robust LLR Aided Low Feedback Precoding for Interference Alignment

    Interference alignment, as proposed in, is a joint multi-base-station precoding technique where each interfering base-station determines its precoder so as to obtain aligned interfering signals at each user. Determination of such precoders requires complete channel state information of all the interfering links to be present at all the base-stations. In...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2010

    An Algorithm for Distributed Cooperative Precoder Selection in a Cellular Network

    The performance in the downlink of a reuse 1 : 1 cellular wireless system is severely degraded due to the interference originating from adjacent cell sites. Even the spectral efficiency gains due to MIMO vanish for cell-edge users who are interference limited. Cooperative MIMO, which involves coordination amongst base stations...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    A Multicarrier CDMA Based Low Probablity of Intercept Network

    The need for covert communication in tactical battlefields has developed the ideas of Low Probability of Intercept (LPI) networks. Spread spectrum communication is used for LPI communication. Multicarrier CDMA is a new type of spread spectrum technique that has been developed in recent years. Most of the works in MC-CDMA...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Finite-SNR Diversity Multiplexing Tradeoff of SIMO Diversity Combining Schemes Under Nakagami-m Fading

    Multiple Antenna (MA) systems are fundamental in wireless communications. MA systems provide two kinds of advantages, namely diversity gain and multiplexing gain. However, there is an inherent tradeoff between the two, under slow fading conditions and is captured in under asymptotically high Signal to Noise Ratio (SNR). This is known...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Fast Approach to Speaker Identification for Large Population Using MLLR and Sufficient Statistics

    In speaker identification, most of the computational processing time is required to calculate the likelihood of the test utterance of the unknown speaker with respect to the speaker models in the database. When number of speakers in the database is in the order of 10,000 or more, then computational complexity...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Vocal Tract Length Normalization Factor Based Speaker-Cluster UBM for Speaker Verification

    In speaker verification task requires some sort of background model for the system to make decision. Most of the cases, a speaker independent large Gaussian Universal Background Model (GMM-UBM) is used. In this paper, the authors propose to use a Speaker Cluster-wise UBM (SC-UBM) for a group of target speakers....

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Discriminative Training of Gaussian Mixture Speaker Models: A New Approach

    Conventional speaker recognition systems use Gaussian Mixture Models (GMM) to model a speaker's voice based on the speaker's acoustic characteristics. This method is categorized as a non-discriminative training process, as the model-building process does not take into account the negative examples of the speaker. To increase the discriminative properties of...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    A Low-Bit Rate Segment Vocoder Using Minimum Residual Energy Criteria

    In speech coding, segment vocoders offer good intelligibility at low bit rates. A segment vocoder has four basic components: segmentation of input speech, segment quantization, residual quantization, and synthesis of speech. Most segment vocoders use a recognition approach to segment quantization. In this paper, the authors assume a different approach...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2010

    Effect of Jacobian Compensation in Linear Transformation Based VTLN Under Matched and Mis-Matched Speaker Conditions

    In this paper, the authors study the effect of use of jacobian in different Linear Transformation (LT) based methods of VTLN. In conventional VTLN, the jacobian is highly non-linear and can not be computed and hence is ignored. In the LT based VTLN, since VTLN scaling is expressed as a...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Robust Syllable Segmentation and its Application to Syllable-Centric Continuous Speech Recognition

    The focus of this paper is two-fold: to develop a knowledge-based robust syllable segmentation algorithm and to establish the importance of accurate segmentation in both the training and testing phases of a speech recognition system. A robust segmentation algorithm for segmenting the speech signal into syllables is first developed. This...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    KL Divergence Based Feature Switching in the Linguistic Search Space for Automatic Speech Recognition

    In this paper, the authors propose a novel idea for using two different feature streams in a continuous speech recognition system. Conventionally multiple feature streams are concatenated and HMMs trained to build triphone/syllable models. In this paper, instead of concatenation, they build separate subword HMMs for each of the feature...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Null-Space Exploiting Channel Shortening Prefilter (NE-CSP) for MIMO-OFDM

    In OFDM system, with fixed Cyclic Prefix (CP) length, Inter Block Interference (IBI) and inter carrier interference will be present if the Channel Impulse Response (CIR) is larger than the CP length. This problem can be mitigated by design a time domain filter at the receiver, which can shorten or...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Mean Square Robustness of Linear Game Theoretic Estimators

    Robust signal processing methods deal with design of estimators that exhibit resilience to uncertainties in the user specified inputs regarding the operating conditions. This paper would facilitate the user to choose the better estimator under the given operating conditions. The results presented here show that under different operating conditions both...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Support Vector Regression Based Autoassociative Models for Time Series Classification

    There are two paradigms for modeling varying length time series data, namely, modeling the sequence of feature vectors and modeling the sets of vectors. In this paper, the authors propose a regression based autoassociative model for modeling sets of vectors for time series data. They also propose a hybrid framework...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2010

    Network (Tree) Topology Inference Based on Prufer Sequence

    Network topology discovery is the basis for any network management application. The problem of estimating internal structure and link-level performance from end-to-end measurements is known as network tomography. This paper proposes a novel approach to discover network characteristics, in particular, tree topology from the hop count metric (distance) between OD...

    Provided By Indian Institute of Technology Madras

  • White Papers // Jan 2010

    Internet Activity Analysis Through Proxy Log

    The availability of the Internet at the click of a mouse brings with it a host of new problems. Although the World Wide Web was first started by physicists at CERN to enable collation and exchange of data, today, it is used for a wide range of applications. The requirements...

    Provided By Indian Institute of Technology Madras

  • White Papers // Dec 2009

    Mobile Payment Architectures for India

    Mobile payments are a new and alternative payment method. Instead of using traditional methods like cash, cheque, or credit cards, a customer can use a mobile phone to transfer money or to pay for goods and services. Mobile payments have numerous advantages over traditional payment methods. Apart from their apparent...

    Provided By Indian Institute of Technology Madras