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Signal Processing, Communications and Networking, 2008. ICSCN '08. International Conference on

Date 4-6 Jan. 2008

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Displaying Results 1 - 25 of 92
  • [Breaker page]

    Page(s): 1 - 2
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  • Message

    Page(s): iii - v
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  • Contributor listings

    Page(s): ix - x
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  • Table of contents

    Page(s): xi - xix
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  • Human Centered Multimedia Computing: A New Paradigm for the Design of Assistive and Rehabilitative Environments

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    In this paper, we describe a human centered multimedia computing (HCMC) approach to the design and development of assistive and rehabilitative environments for people with disabilities. Unlike human computer interaction (HO), which was targeted at improving the usability of computing devices, HCMC addresses a higher level of functionality where machines adapt to the users resulting in elegant interactions. At the Center for Cognitive Ubiquitous Computing (CUbiC), we are engaged in a project for individuals who are blind and visually impaired, called iCARE (information technology centric assistive and rehabilitative environment). An overview of the iCARE project components is first presented followed by a detailed discussion of one example of our research effort, namely pose angle estimation of faces towards enhancing social interactions. View full abstract»

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  • Neural Networks for Intelligent Aircraft Fault Tolerant Controllers

    Page(s): 8 - 14
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3178 KB) |  | HTML iconHTML  

    This paper presents novel schemes of using neural networks for fault-tolerant controller designs, thereby adding intelligence to existing controllers. The specific application considered is for an aircraft auto landing control under severe wind conditions and when control surface actuators get stuck. First, a neural aided control scheme using feedback-error learning is discussed in detail and then a second scheme using an adaptive back-stepping neural control scheme for handling actuator failures is briefly highlighted. Simulation studies using the full six-degree-of-freedom nonlinear aircraft model show that the above controllers are able to successfully stabilize and land the aircraft within tight touch down dispersions. View full abstract»

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  • Buffer Storage for Video Delivery

    Page(s): 15 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (341 KB) |  | HTML iconHTML  

    Communication technologies have provided bandwidth in Gigabytes and researchers are working to further enhance it. The bandwidth is still a bottleneck in many of the multimedia applications such as video-on-demand, movie-on-demand, etc. Therefore, apart from enhancement in the bandwidth it is also equally important to develop suitable techniques so that the bandwidth can be utilized efficiently. The bandwidth may be allocated through channelization. There are two modes of channelization, namely, constant and variable bandwidth channelization. In constant bandwidth channelization the server bandwidth is equally divided into logical channels, whereas in variable bandwidth channelization the server bandwidth is unevenly divided into logical channels. In variable bandwidth channelization the buffer requirement is less than that of constant bandwidth channelization. Therefore, based on variable bandwidth channelization a mathematical model is proposed to estimate the buffer requirement for a given bandwidth, taking into consideration jitter delay. The jitter delay, a non-deterministic quantity, is assumed as a random variable with uniform distribution. The buffer storage is calculated by considering a physical channel, dividing into two, three, and five logical channels. Further, the bandwidth allocation to logical channels is estimated. View full abstract»

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  • Ultra Wideband Characterization of Dielectric Loaded Monopole Trans-receive Antenna System Considering Mutual Coupling

    Page(s): 20 - 24
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    This paper presents the time domain studies of a wideband trans-receive antenna system consisting of a quarter-wave monopole loaded with an annular dielectric resonator antenna. This antenna has recently become attractive to antenna designers due to its broadband characteristics. However, while using this antenna in ultra wideband trans receive system, the time domain characterization of the whole system is required. In this paper, the transmit antenna is excited by a wideband signal. The time domain waveform of the received voltage developed at the load end of the receive antenna is presented for near field position of the receive antenna. The received voltage is found to be identical to the input waveform, which proves the wideband nature of the trans-receive system. The results are simulated using CST Microwave Studio, version 5. View full abstract»

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  • Compact Power Divider using Defected Ground Structure for Wireless Applications

    Page(s): 25 - 29
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    Use of different types of defected ground structures (DCS) has been reported in this paper to design compact power dividers in microstrip medium. Unit cell's (of DGS) equivalent circuit has been used to evaluate the performance of power divider. Based on this approach, compact two-way equal power dividers have been designed in GSM (900 MHz) band. Results show a size reduction of 35% and 32% for the power dividers using T shaped DGS and split ring DGS over the conventional power divider. View full abstract»

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  • Use of Biased Estimators for Improved Channel Estimation in OFDM Systems

    Page(s): 30 - 34
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    This paper addresses the problem of improved channel estimation in OFDM systems. It is a well known fact that the knowledge of the exact tap delay locations enables the construction of the modified least square [m-LS] estimator, which happens to be the best linear unbiased estimator [BLUE].Inherent frailties such as high condition number of the linear transformation matrix and the consequent high noise sensitivity ensures that the m-LS estimator often performs poorly at low to moderate SNRs. This motivates the usage of certain biased estimators which attack these short comings of the least square estimator. We propose two biased channel estimators, derived from the rank shaped least squares [RSLS] estimator and the generalised Liu [GL] estimator to attain superior performance. The simulation results involving downlink channel estimation in WiMAX systems vindicate the usage of the above mentioned estimators. View full abstract»

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  • Efficient Doherty Feed-forward Linear Power Amplifier for CDMA 2000 Base-Station Applications

    Page(s): 35 - 40
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    This paper presents a design of high RF power amplifier using Doherty technique. The objective of this design is to improve the efficiency of a 40-W feed-forward linear power amplifier typically used in code division multiple access (CDMA) base-station applications. The proposed design uses two identical LDMOS FETs, one of which is biased in class AB mode for carrier amplifier and the other is biased in class B mode for peak amplifier. Simulation results with single carrier CDMA signal show S.47 % improvement in efficiency for the proposed design in comparison to a conventional class AB configuration. Both, the proposed design as well as the conventional design use feed-forward technique to meet the ACPR requirement at 40-W output power. View full abstract»

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  • Efficient Realization of CORDIC based LDPC Decoder for WiMax System

    Page(s): 41 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB) |  | HTML iconHTML  

    Low-density parity-check (LDPC) codes have recently emerged due to their excellent performance in wired, wireless communication applications and in disk drives. Based on architecture-aware LDPC codes, this paper presents an efficient joint LDPC coding and decoding hardware architecture. We used a special class of quasi-cyclic low-density parity-check (QC-LDPC) codes, which have an efficient encoding algorithm due to the simple structure of their parity-check matrices. Since the parity-check matrix of a QC-LDPC code consists of circulant permutation matrices or the zero matrix, the required memory for storing it can be significantly reduced, as compared with randomly constructed LDPC codes. An encoder and a decoder are designed using Verilog-HDL and are synthesized using synopsys design compiler with ISO nm TSMC standard cell library. We used CORDIC algorithm to implement check node update unit in decoder which saves much hardware compared to conventional LUT approach. We study the optimal permutation of the bit nodes that will result in the maximum possible burst erasure correction capability for a given LDPC code. The simulation results show the burst-erasure correction capability of quasi-cyclic LDPC codes in the IEEE 802.16e (WiMax) standard. View full abstract»

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  • QR-RLS Based Adaptive Channel TEQ for OFDM Wireless LAN

    Page(s): 46 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2421 KB) |  | HTML iconHTML  

    In this paper, QR-RLS based adaptive channel TEQ (Time Domain Equalizer) to make the OFDM systems robust for delay spreads exceeding the CP (cyclic prefix) is presented. The performance of the proposed method is compared with standard LMS and exponentially weighted RLS based TEQ, in terms of computational complexity and BER. QR decomposition using Givens transformation results in better computational complexity compared to standard RLS and QRD based on gram Schmidt orthogonalization process. The simulation results show that this method gives better results as compared to the aforementioned methods. View full abstract»

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  • Multiple Maneuvering Target Tracking Using MHT and Nonlinear Non-Gaussian Kalman Filter

    Page(s): 52 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    In this paper, an algorithm for tracking multiple maneuvering targets by Multiple Hypothesis Tracking (MHT) with nonlinear non-Gaussian Kalman filter is investigated. The main challenges in multiple maneuvering targets tracking are the nonlinearity and non -Gaussianity problems. The Multiple Hypothesis Tracking (MHT) is used to detect the multiple targets in maneuverable and non-maneuverable modes. The computational requirements increase exponentially with number of tracks, the backscan depth and this can be reduced by careful design and tuning of MHT. The 1-backscan MHT algorithm is a good compromise between the two conflicting requirements of good tracking performance and limitation of computation time. The nonlinear non-Gaussian Kalman filter is used to track the target with high maneuver rate. The nonlinear non-Gaussian Kalman filter is implemented in MHT to give less probability of missing the target. The 1-backscan MHT with nonlinear non-Gaussian Kalman filter is free from computational burden by using simple probability concepts. This method of tracking also shows the reduction in the overshoot of root mean square error (RMSE). View full abstract»

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  • Prosodic Features For Language Identification

    Page(s): 57 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1342 KB) |  | HTML iconHTML  

    In this paper, we examine the effectiveness of prosodic features for language identification. Prosodic differences among world languages include variations in intonation, rhythm, and stress. These variations are represented using features derived from fundamental frequency (F0) contour, duration, and energy contour. For extracting the prosodic features, speech signal is segmented into syllable-like units by locating vowel-onset points (VOP) automatically. Various parameters are then derived to represent F0 contour, duration, and energy contour characteristics for each syllable-like unit The features obtained by concatenating the parameters derived from three consecutive syllable-like units are used to represent the prosodic characteristics of a language. The prosodic features thus derived from different languages are used to train a multilayer feedforward neural network (MLFFNN) classifier for language identification. The effectiveness of the proposed approach is verified using Oregon Graduate Institute (OGI) multi-language telephone speech corpus and National Institute of Science and Technology (NIST) 2003 language identification database. View full abstract»

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  • Automated Detection of Transition Segments for Intensity and Time-Scale Modification for Speech Intelligibility Enhancement

    Page(s): 63 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4934 KB) |  | HTML iconHTML  

    Spectral transition segments serve as landmarks for the perception of consonants. In "clear speech" mode adopted by speakers to improve intelligibility in difficult communication environments, transition segments are of increased duration and intensity. Modification of conversational speech to have acoustic properties of clear speech has been reported to improve its intelligibility. This paper presents an automated method for locating spectral transition segments in speech, and to produce natural quality resynthesized speech with intensity and time-scale modified spectral transition segments. The boundaries of spectral transition segments are located using an index derived from the rate of variation of energy and centroid frequency in five non-overlapping spectral bands. Time-scale modification is performed using harmonic plus noise model (HNM) based analysis-synthesis. The overall speech duration is kept unaltered by appropriately compressing the steady state segments. Transition segments are intensity scaled by 6 dB. The effectiveness of the method was evaluated by conducting listening tests on normal hearing subjects using VCV syllables as the test material. View full abstract»

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  • Optimizing the Comb Filters for Spectral Splitting of Speech to Reduce the Effect of Spectral Masking

    Page(s): 69 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (395 KB) |  | HTML iconHTML  

    Sensorineural hearing impairment is associated with widening of auditory filters, resulting in poor frequency selectivity with an increased susceptibility to masking. Earlier studies have shown that binaural dichotic presentation, using critical bandwidth based spectral splitting with perceptually balanced comb filters, helps in reducing the effect of spectral masking for persons with moderate bilateral sensorineural hearing impairment In spectral splitting, the speech signal is filtered using a pair of linear phase FIR comb filters with complementary magnitude responses for binaural dichotic presentation. The objective of the present study is to optimize the comb filters with respect to the number of bands and bandwidth. Three different pairs of comb filters are investigated: constant bandwidth filters, critical band based filters, and 1/3 octave bandwidth filters. Evaluation of spectral splitting schemes, using these filters, through listening tests, indicate that 1/3 octave band and critical band based filters are superior to constant bandwidth filters. View full abstract»

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  • An Intrusion Detection System Based on Multiple Level Hybrid Classifier using Enhanced C4.5

    Page(s): 75 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    Intrusion Detection System (IDS) has recently emerged as an important component for enhancing information system security. However, constructing and maintaining a misuse intrusion detection system for a network is labor ¿ intensive, since attack scenarios and patterns need to be analyzed and categorized. Moreover, the rules corresponding to the scenarios and patterns need to be carefully hand-coded. In such situations, data mining can be used to ease this inconvenience. This paper proposes a multiple level hybrid classifier for an intrusion detection system that uses a combination of tree classifiers which uses Enhanced C4.5 which rely on labeled training data and an Enhanced Fast Heuristic Clustering Algorithm for mixed data (EFHCAM). The main advantage of this approach is that the system can be trained with unlabelled data and is capable of detecting previously "unseen" attacks. Verification tests have been carried out by using the 1999 KDD Cup data set. From this work, it is observed that significant improvement has been achieved from the viewpoint of both high intrusion detection rate and reasonably low false alarm rate. View full abstract»

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  • Consolidate and Advance: An Efficient QoS Management Technique in Heterogeneous Wireless Sensor Networks

    Page(s): 80 - 85
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    Research in wireless sensor networks has become an extensive explorative area during the last few years. In this paper we emphasize the need for repositioning of the consolidating and advancing node, (CAN : Principal Node) to improve network lifetime in terms of energy and other QoS parameters such as latency and throughput. We also address issues related to its repositioning such as the time and position of relocation and the control of its movement without causing negative impact on the performance of the WSN. Mobility factor is exploited to support QoS requirements. We present a scheme called energy conserving relocation (ECR) to pursue relocation of CAN to a safe location on demand. ECR performs relocation based on the minimum energy concept of sensor nodes. The concept of repositioning adds a new dimension to the existing heterogeneous wireless sensor network. It is observed through simulation that lifetime of the network, average energy consumption and QoS parameters are much better when compared to earlier algorithms. View full abstract»

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  • Three-Tier Grid Architecture with Policy-Based Resource Selection in Grid

    Page(s): 86 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    Trust management for the selection of resources is a key issue in a grid environment. In most of the trust-based systems, intermediaries, known as brokers, are responsible for the selection of Service Providers (SPs) for consumer requests. In such models, the intermediaries gain monetary benefit for each of the transactions made through them. This may lead to favoritism & bias in the selection of suitable SPs. This challenge may be overcome by the proposed three-tier framework where the Regional Resource Administrators (RRAs), resource brokers and the SPs are arranged into three-tiers. An RRA selects a 'suitable' SP for a consumer request, based on the trust-indices and Quality of Services of the SPs nominated by various brokers. RRAs derive their compensation from registration, renewal, and audit charges paid by the broker community, not from individual transactions. RRAs serve the consumer community in a manner similar to DNS, in an 'unbiased' and 'trustworthy' manner. In this paper, our proposed architecture not only supports a choice of SP based on reputation (trust-index) but also on credentials (policy). Thereby the consumer is assigned with a trustworthy SP and the transaction is free from runtime failure as the policies have been matched with. The concept of de-registration has been introduced in two scenarios, the SPs may deregister themselves by choice and the other is the RRAs force brokers to deregister. In this model, the trust-indices of each of the entities (consumers, SPs and brokers) arc computed based on the feedback provided by other entities after each transaction. These trust-indices of brokers, consumers and SPs are updated dynamically at the RRA's and the broker's sites respectively, to ensure trustworthy services and to quicken the selection of 'suitable' SPs. Our model shows a marked improvement in job-success-rate for various percentages of malicious entities. View full abstract»

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  • Using Random Forests for Network-based Anomaly detection at Active routers

    Page(s): 93 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Network intrusion detection systems (NIDSs) is one of the primary components in any network security infrastructure. Currently, many NIDSs that are developed are rule-based systems and their performances mainly depend on the rule sets. But rules formation becomes a tedious and rime consuming task due to the enormous amount of network traffic. This is overcome by using data mining techniques. These techniques build intrusion detection models adaptively. Random forests is an efficient data mining algorithm which can be used for network intrusion detection This can be used for real time intrusion detection. In this paper, we discuss the approaches for feature selection, and optimization of parameters of random forests, compare different models, and also discuss the other method for detecting the anomalies across active networks. View full abstract»

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  • Reduction in Computational Complexity of a Fast Encryption Algorithm for Application in Voice Oriented System

    Page(s): 97 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    Security for voice is different from that for data and so most of the encryption algorithms used for data do not suit voice as voice is delay sensitive. Here, we make use of an algorithm that suits multimedia traffic because of its reduced complexity and its ability to handle large blocks of data at a time. The optimization is achieved through reduction in the instructions executed for performing the encryption and decryption which involves a number of complex multiplications. A simplified matrix multiplication scheme is used which reduces the number of instructions executed per multiplication cycle. As the key transmission, encryption and decryption phases make use of many multiplications the improved scheme helps in achieving reduction in the computational delay. Also the realization of the security algorithm is done by implementing it over a basic Client server model. View full abstract»

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  • Enhanced Hamiltonian Cycle Protection Algorithm in Survivable Networks

    Page(s): 102 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    This paper studies the protection with Hamiltonian Cycle in mesh survivable backbone networks, and proposes a new heuristic routing algorithm called Enhanced Hamiltonian Cycle Protection (EHCP) to tolerate single failure. Simulation results show that, compared with conventional HCP algorithm, EHCP can obtain significant improvement in resource utilization ratio. View full abstract»

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  • Generation of Variable-Phase Millimeter Wave Signals Using an Optical Pulse

    Page(s): 107 - 109
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    In this paper, a simple method of generation of mm-wave signal using an optical pulse source is proposed. The components required for the proposed mm-wave generator are commercially available. The phase of the generated mm-wave signal can be varied over the range of 0 to 2pi radian simply by varying the DC voltage applied to the electrooptic phase shifter. The R1N noise of the source mode-locked laser diode is calculated to be dramatically reduced through injection locking in this scheme. The phase noise of the generated mm-wave will be very small leading to a narrow linewidth of the mm-wave signal. View full abstract»

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  • Optical Characterization of Abnormalities in Various Size and Shape in Tissue Equivalent Phantoms

    Page(s): 110 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (555 KB) |  | HTML iconHTML  

    Tissue equivalent phantoms were made by mixing various combinations of wax colors with paraffin wax. Abnormalities of various size and shape were embedded into the tissue equivalent phantoms at different locations and depths to simulate real life abnormalities of tissues. The normalized back-scattered intensity (NBI) profiles at various locations on the tissue equivalent phantoms were obtained by multi-probe laser reflectometer. The laser radiations are guided by an optical fiber onto the phantoms and the backscattered radiations are collected by three optical fibers placed at a distance of 3 mm, 5 mm and 7 mm from the input fiber. The data after digitization, interpolation and filtering, are gray color-coded and displayed on the outline of the phantom. These NBI pattern vary depending on the optical characteristics of the phantom at various locations. For optical characterization the optical parameters, scattering (mu3) and absorption (mu2) coefficients and the anisotropy parameter (g) at each location on the phantom, by matching of reflectance profiles with that as simulated by a Monte Carlo simulation (MCS) procedure were determined. From the surface profile the size, location and depth of the abnormality were obtained. View full abstract»

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