In this paper, we propose a Satellite-Terrestrial Integrated Network (STIN) assisted vehicular multi-tier distributed computing (VMDC) system leveraging hybrid terahertz (THz) and radio frequency (RF) communication te...
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The importance of the concept of cyclostationarity in design and analysis of signal detectors, synchronizers, and extractors in communication systems is briefly discussed, and the central role of spectral correlation,...
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The importance of the concept of cyclostationarity in design and analysis of signal detectors, synchronizers, and extractors in communication systems is briefly discussed, and the central role of spectral correlation, in the characterization of random processes that are cyclostationary in the wide sense, is explained. A spectral correlation function that is a generalization of the power spectral density function is described, and a corresponding generalization of the Wiener-Khinchine relation and several other fundamental spectral correlation relations also are described. Explicit formulas for the spectral correlation function for various types of analog-modulated signals are derived. This includes pulse and carrier amplitude modulation, quadrature amplitude carrier modulation, and phase and frequency carrier modulation. To illustrate the differing spectral correlation characteristics of different modulation types, the magnitudes of the spectral correlation functions are graphed or described in graphical terms as the heights of surfaces above a bifrequency plane.
The concept of fast KL transform coding introduced earlier [7], [8] for first-order Markov processes and certain random fields has been extended to higher order autoregressive (AR) sequences and practical images yield...
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The concept of fast KL transform coding introduced earlier [7], [8] for first-order Markov processes and certain random fields has been extended to higher order autoregressive (AR) sequences and practical images yielding what we call recursive block coding (RBC) algorithms. In general, the rate-distortion performance for these algorithms is significantly superior to that of the conventional block KL transform algorithm. Moreover, these algorithms permit the use of small size transforms, thereby removing the need for fast transforms and making the hardware implementation of such coders more appealing. This improved performance has been verified for practical image data and results in suppression of the block-boundary effect commonly observed in traditional transform coding techniques. This is illustrated by comparing RBC with cosine transform coding using both one- and twodimensional algorithms. Examples of RBC encoded images at various rates are given.
In this paper we propose an object-based stereo image coding algorithm. The algorithm relies on modeling of the object structure using 3D wire-frame models, and motion estimation using globally rigid and locally defor...
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In this paper we propose an object-based stereo image coding algorithm. The algorithm relies on modeling of the object structure using 3D wire-frame models, and motion estimation using globally rigid and locally deformable motion models. Algorithms for the estimation of motion and structure parameters from stereo images are described. Motion parameters are used to construct predicted images at subsequent time instances by mapping the image texture on the object surface. Coding of object parameters, appearing background regions and prediction errors is investigated and experimental results with video-conference scenes are presented. The proposed algorithm is very efficient for applications like stereoscopic video transmission, and is especially suited to advanced applications such as generation and transmission of intermediate views for multiview receiver systems, as well as applications in which an object-wise editing of the bit-stream is required, such as video-production using preanalysed scenes or virtual reality applications.
In this paper we integrate motion and structure estimation in order to exploit their coherence. We propose an algorithm that uses models for object surfaces and their motion and estimates the model parameters using th...
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In this paper we integrate motion and structure estimation in order to exploit their coherence. We propose an algorithm that uses models for object surfaces and their motion and estimates the model parameters using the image intensity matching criterion. The visible scene surface is represented with a parametrically deformable, spatially adaptive, wireframe model. Object motion is first modeled using the well-known rigid motion assumption along with the quaternion rotation representation. Nonrigid motion modeling using the finite element technique is also investigated as an alternative to rigid motion modeling or as a refinement of it. A functional containing image matching and surface smoothness constraints is minimized with respect to the unknown model parameters. A discontinuity detection scheme allowing deactivation of smoothness constraints across object boundaries, is investigated. A regularization scheme using a coarse to fine strategy is employed. (C) 1997 Academic Press.
In this paper, within the prescribed performance control framework, we revisit the output tracking problem of a nonlinear system with input saturation, user-specified performance and external disturbances. To handle t...
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As a continuation of Part I, the spectral correlation function is presented for a variety of types of digitally modulated signals. These include digital pulse-amplitude, pulse-width, and pulse-position modulation, and...
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As a continuation of Part I, the spectral correlation function is presented for a variety of types of digitally modulated signals. These include digital pulse-amplitude, pulse-width, and pulse-position modulation, and various types of phase-shift keying and frequency-shift keying. The magnitudes of the spectral correlation functions are graphed as the heights of surfaces above a bifrequency plane, and these graphs are used as visual aids for comparison and contrast of the spectral correlation properties of different modulation types.
A method for estimation of the difference in the times of arrival of wavefronts of two separate sensors is introduced. The method, called SPECCORR, exploits the spectral correlation property, called spectral coherence...
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A method for estimation of the difference in the times of arrival of wavefronts of two separate sensors is introduced. The method, called SPECCORR, exploits the spectral correlation property, called spectral coherence, that essentially all modulated signals exhibit to obtain estimates that are highly tolerant to severely corruptive noise and interference. This tolerance is explained theoretically and demonstrated with simulations.< >
Ensuring end-to-end cross-layer communication security in military networks by selecting covert schemes between nodes is a key solution for military communication security. With the development of communication techno...
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The maturing of telecommunication technologies has ushered in a whole new era of applications and services in the health care environment. Teleworking, teleconsultation, multimedia conferencing and medical data distri...
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The maturing of telecommunication technologies has ushered in a whole new era of applications and services in the health care environment. Teleworking, teleconsultation, multimedia conferencing and medical data distribution are rapidly becoming commonplace in clinical practice. As a result, a set of problems arises, concerning data confidentiality and integrity. Public computer networks, such as the emerging ISDN technology, are vulnerable to eavesdropping. Therefore it is important for telemedicine applications to employ end-re-end encryption mechanisms securing the data channel from unauthorized access or modification. We propose a network access and encryption system that is both economical and easily implemented for integration in developing or existing applications, using well-known and thoroughly tested encryption algorithms. Public-key cryptography is used for session-key exchange, while symmetric algorithms are used for bulk encryption. Mechanisms for session-key generation and exchange are also provided.
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