bluuebunny/crossref_metadata_2025_split huggingface dataset:
Letter: A method of spread spectrum radar polyphase code design by nonlinear programming
Authors: Dobrosavljevic Zoran S. , Dukic Miroslav L. 
Published: September 2008

AbstractA method of spread spectrum radar polyphase code design based on the code elements' symmetry and nonlinear programming is presented. The main features of the synthesized code are the very low sidelobes in the compressed pulse and noncoherent processing. The comparison to the well‐known classes of polyphase codes is made.
Letter: Opportunistic channel for sending an extra 300 bit/s using a trellis coded modulation scheme which transmits 9.6 kbit/s on telephone lines
Authors: Sterian Corneliu‐Eugen D. 
Published: September 2008

AbstractIt is shown that the TCM scheme with 8‐D rectangular constellation designed by Tretter [1] based on a well known method invented by Wei [2] can support an opportunistic channel which can transmit 300 bits/s.
Bit error rate performances of M‐QAM orthogonal multicarrier modulation in presence of time‐selective multipath fading
Authors: Santella Giovanni 
Published: September 2008

AbstractOrthogonal Frequency Division Multiplexing (OFDM) is considered as an effective technique in high speed digital transmission under multipath fading. In this paper we theoretically analyze the behaviour of a coherent pilot‐symbol aided M‐QAM‐OFDM system in presence of time selective multipath channel. In the analyzed scheme, pilot symbols are periodically inserted to monitor the channel characteristics. The fading process experienced by the pilot symbols is used to estimate the fade characteristics at symbol‐rate through interpolation. The estimated channel is used to compensate for the random phase variation caused by the Doppler spread, so that the signal can be coherently demodulated. The bit error rate (BER) performance of this coherent OFDM modulation scheme is derived. The obtained results show that, with a reasonable amount of redundancy (frequency of the pilot symbols) introduced, the system performance approaches that of the ideal coherent demodulation, as long as a suitable channel estimate procedure is adopted.
Performance evaluation of a continuous‐phase CDMA modem operating over the 60 GHz mobile radio channel
Authors: Giannetti Filippo , Luise Marco , Reggiannini Ruggero 
Published: September 2008

AbstractThis paper (1) describes the structure and the performance of a band‐limited spread‐spectrum transmission system suited for short‐range terrestrial inter‐vehicle or vehicle‐to‐beacon radio links that features Generalized MSK as modulation format and asynchronous direct‐sequence code‐division multiple access. The Bit Error Rate (BER) performance of such a system is evaluated over a recently proposed 60 GHz short‐range mobile radio channel model. In particular, the sensitivity to a number of relevant link parameters (such as the distance between transmit and receive antennas and the receiver speed) is investigated, and the impact of code tracking errors and of differential encoding/detection of the spreading code chips on system performance is also discussed.
Letter: Optimal echo path modelling using chaotic modulated speech
Authors: Milner Simon H. , Elmirghani Jaafar M. H. , Cryan R. A. 
Published: September 2008

AbstractA novel modulating scheme is presented that allows optimal echo path modelling using, real time least mean square (LMS) system identification techniques. The systems of interest are usually based on a class of digital adaptive filters (DAFs). The modelling convergence rate derived from the optimal Wiener weights defines the performance criterion. A novel chaotic based modulation regime utilising the logistic mapping is exploited to whiten the speech power spectral density (PSD) whilst preserving the signal bandwidth requirements. The whitened signal optimises the convergence rate and allows adaptation times to be calculated without a‐priori knowledge of the speech signal's second order statistics. Software simulations are reported for an ensemble of conversational speech realisations and it is shown that the described modulation scheme significantly improves the convergence rate and guarantees optimal modelling independent of the input speech signal statistics. Furthermore, the noise whitened input signal circumvents control supervisory problems usually associated with uncoded speech inputs.
PPM transmission over a photon counting channel: Comparison among various transmission formats
Authors: Cancellieri Giovanni , Chiaraluce Franco , Gambi Ennio 
Published: September 2008

AbstractA detailed analysis for a variety of transmission formats suitable for photon communication systems is presented. More precisely, starting from the basic orthogonal pulse position modulation (PPM), here assumed as a reference, several alternative modulation schemes are discussed. They can be seen as extensions of the basic format or. equivalently, as particular cases of the most complete alphabet obtained by considering all the possible combinations of high and low levels in a transmission organized over slotted time intervals. The analysis is developed in comparative terms, looking at the three parameters which are usually invoked for performance evaluation, i.e. transmission capacity, cut‐off rate and bit error rate. Closed form expressions are given in all the examined cases, stressing the role, as figures of merit, of the transmission efficiency and the bandwidth expansion factor. At a parity of the latter parameter, it is shown that the performance of basic PPM can be improved, even significantly, by resorting to the alternative transmission formats. In particular, they maintain the spectral occupancy within acceptable limits, whereas the bit error rate can be lowered using alphabet puncturation or asymmetric error correcting codes.
Performance measurements and traffic characterization on the ATM pilot network
Authors: Louvion Jean‐Raymond , Piller Benoit 
Published: September 2008

AbstractFrom mid‐94 to end‐95 the “Performance Working Group (PWG)” of the ATM PILOT has carried out a lot of measurements (in relationship to functions available on test equipments). The results obtained were mainly related to ATM layer performance measurements (availability and non time‐related performance parameters) and to traffic characterization. Performance measurements aimed at checking the validity of the set of proposed or standardized ATM layer performance parameters, at studying the sensitivity of the parameters definitions and at obtaining early results in order to propose performance objectives for the relevant recommendations. These results have shown that the ATM layer performance is very much dependent of the observation period of time and of the physical path of the connection under test. Furthermore it has been observed that the ATM layer performance is not so sensitive to the parameter definitions and the associated thresholds. Traffic characterisation is necessary to identify what is going on in the network (will the cells be equally spaced or will they come in bursts ?). The PWG had taken the opportunity to do field trials with real traffic coming from Pilot and has carried out a range of tests on both CBR sources (carrying voice or video applications) and VBR sources (multimedia application or LAN to LAN interconnection). Two main traffic types have been observed during the tests:

CBR sources carrying voice or video applications.
VBR sources with multimedia applications or LAN to LAN interconnection using the SMDS/‐CBDS service.
Performance of open loop digital frequency estimation techniques for burst‐mode transmission
Authors: Di Girolamo Rocco , Le‐Ngoc Tho 
Published: September 2008

AbstractThis paper presents the variance analysis, and performance comparison, of the least‐squares frequency estimator (LSFE), and a specific version of the nonlinear frequency estimator (NIX). The results are obtained for the case where the received signal contains both phase and frequency errors (ΔΘ and Δfrespectively). It is shown that under rather restrictive conditions, the LSFE is a low signal‐to‐noise ratio approximation to the ML estimate of ΔfAlso considered are the effects on the moments of this estimate, if any of these conditions are violated. The latter part of the paper deals with the various versions of the NFE. The problem of phase ambiguity associated with these nonlinear estimators is investigated, and a resolution technique is proposed.
Supervised fuzzy contextual segmentation of polarimetric SAR images
Authors: Dellepiane Silvana , Fontana Franco 
Published: September 2008

AbstractIn the Remote Sensing application domain, especially for SAR (Synthetic Aperture Radar) images characterized by notable textural properties, the use of context and the integration of multipolarimetric data appear essential to improving the accuracy of classification. Methods based on the MRF approach have recently yielded good results, as they allow the development of robust processing algorithms. Unfortunately, these methods are not free of drawbacks. For instance, they suffer from high computational complexity. Given these conditions, this paper proposes the Fuzzy Contextual Segmentation (FCS) method, which integrates uncertainty and contextual information in a smgle framework through a fuzzified k‐NN approach. The membership value assigned to every site is updated by taking into account the information related to the steps of model‐matching, propagation of global context, and decision on local context. An application of the method to real SAR images is reported. Two fully polarimetric data sets were utilized to assess the performance of our algorithm. Results and error evaluation is supporting evidence for the practical effectiveness of the method.
Letter: A new stop‐and‐wait type‐II hybrid ARQ scheme using rate‐compatible convolutional codes
Authors: Taspinar Necmi 
Published: September 2008

AbstractIn this letter, a new stop‐and‐wait type‐II hybrid ARQ scheme is proposed. This scheme is obtained by using the RCC (rate‐ compatible convolutional) codes and the scheme proposed by Moeneclaey et al. A substantial throughput improvement is obtained over the generalized type‐II hybrid ARQ scheme proposed by Kallel and Haccoun for SW mode. The improvement in the throughput efficiency becomes much better for high values of h incremental coded bits especially when Es/N0 is between 3.5 dB and ‐2 dB. The proposed scheme also yields better throughput efficiency than the type‐II hybrid SW ARQ scheme proposed by Kallel when Es/N0, > 3.5 dB and Es/N0< 0.5 dB for h = 8. Moreover the throughput improvement includes all values of Es/N0 under 10 dB when h = 1. 2 and 4.
Charging and rate control for elastic traffic
Authors: Kelly Frank 
Published: September 2008

AbstractThis paper addresses the issues of charging, rate control and routing for a communication network carrying elastic traffic, such as an ATM network offering an available bit rate service. A model is described from which max‐min fairness of rates emerges as a limiting special case; more generally, the charges users are prepared to pay influence their allocated rates. In the preferred version of the model, a user chooses the charge per unit time that the user will pay; thereafter the user's rate is determined by the network according to a proportional fairness criterion applied to the rate per unit charge. A system optimum is achieved when users' choices of charges and the network's choice of allocated rates are in equilibrium.
Improved WDM packet switch architectures with output channel grouping
Authors: Binh Le Nguyen , Chong Hock Choong 
Published: September 2008

AbstractWe present two switching schemes for routing optical information signals that are transported by wavelength division multiplexed (WDM) networks with and without grouping of optical channels of different wavelength allocations. A brief account of two WDM packet switches without channel grouping are briefly described with the use of a neural network controller for routing control to illustrate the necessity for grouping wavelength channels. This leads to designs of improved WDM packet switch architectures which are described in details for wavelength routing, broadcasting and selecting wavelength channels. Optical channels with different wavelength allocations are grouped and appropriate routing algorithms are designed to enhance the throughput efficiency of the packet switch. Computer simulation is carried out to evaluate the performance of a WDM packet switching system with output channel grouping which exhibits only single intermediate stage architecture.
Letter: Neural classifiers as optimal decision devices for warped M‐QAM signal formats
Authors: Bernardini Angelo , Fina Silvia De 
Published: September 2008

AbstractThe paper is focused on the application of perceptron‐based neural networks to optimal decision for M‐QAM signals transmitted over nonlinear channels. The decision is performed by two cascaded blocks: the first denotes one of the 4 quadrants and the second selects one of the M/4 symbols. A specific initialization procedure has been adopted in order to avoid local minima. The classifier performance, for the specific application, has been evaluated by the CNR (Carrier to Noise Ratio) degradation due to nonlinearity (δCIN) for a target error rate Pe = 10−3. The results, obtained by Monte Carlo simulations, denote optimal matching with respect to upper bounds obtained with some minor simplifying hypothesis, even if the overall method's effectiveness can be adequate only for mild nonlinearity conditions.
Letter: A predictive analysis of differential attenuation on adjacent satellite paths including rain height effects
Authors: Kanellopoulos John D. , Margetis Dionysios 
Published: September 2008

AbstractInterference between adjacent Earth‐space paths can be caused by propagation effects due to differential rain attenuation. In the present paper, a modification of an existing method to predict the rain differential attenuation statistics is proposed. The modified method takes into account a more complicated but realistic model for the description of the rain height. The present results are compared with the available simulation data for the differential attenuation over pairs of paths in the Montreal area. The difference between the existing predictive results and the deduced ones after use of the modified procedure, for various geographic latitudes and climatic zones, is also examined.
Letter: Cyclical coincidence arrays and exact pdfs representing interference for some CDMA systems
Authors: Kostić Zoran , Pavlović Gordana , Titlebaum Edward L. 
Published: September 2008

AbstractA new class of coincidence (hit) arrays called cyclical hit arrays is defined. Cyclical hit arrays give insight into previously unknown properties of several sets of number theoretic frequency‐hop patterns, based on Welch‐Costas and Quadratic Congruence codes. Three theorems related to cyclical hit arrays are proved. The theorems are used to determine exact probability distribution functions of random variables which represent the number of coincidences between two arbitrary patterns from the same set of codes. The number of coincidences expresses interference levels between two users of code‐division multiple‐access (CDMA) systems which utilize the considered patterns. The obtained results can be used for computing the exact expressions for the total interference and for error probabilities in several CDMA systems.
Synchronous all‐optical code‐division multiple‐access networks
Authors: Zhang Jian‐Guo , Kwong Wing C. , Chen Lian‐Kuan , Cheung Kwok‐Wai 
Published: September 2008

AbstractA feasible architecture is proposed for implementing synchronous all‐optical code‐division multiple‐access (CDMA) networks with full channel tunability. The proposed network uses fastly programmable all‐optical CDMA encoders and decoders which are based on tunable optical delay‐lines and require only a small number of electro‐optic switches. Coding and decoding algorithms for “synchronous” prime‐sequence codes that can be rapidly performed in the optical domain are described. Moreover, a two‐wavelength scheme is presented to effectively solve the problems associated with clock distribution and frame synchronization in large‐scale synchronous CDMA networks. By using the proposed technique, all‐optical CDMA transmitters and receivers can be constructed with integrated optics and can achieve a very high processing speed.
A novel procedure for jones' parameters estimation for M‐4QAM optical systems
Authors: Cusani Roberto , Baccarelli Enzo , Galli Stefano 
Published: September 2008

AbstractA new procedure is proposed for estimating the State‐of‐Polarisation of the received optical signal in Four‐Quadrature Amplitude Modulation systems. The proposed solution, which is obtained on the basis of the Maximum Likelihood criterion, is merely electronic and operates in the presence of laser phase noise, photodetection noise and cross‐polarisation interference. It employs a suitably designed training sequence to estimate Jones' parameters in the data‐aided training mode. A proper decision‐directed procedure is then activated to lock‐in the estimated parameters in the operative mode. The variances of the resulting estimation errors are evaluated and the overall system performance is given in terms of Bit Error Probability versus signal‐to‐noise ratio. The theoretical analysis and the computer simulations show the superiority of the proposed recovery procedure with respect to alternative solutions recently proposed in literature.
Performance analysis of modified/quadrature partial response‐trellis coded modulation (M/QPR‐TCM) systems
Authors: Nuri Uçan Osman 
Published: September 2008

AbstractIn this paper, to improve bandwidth efficiency and error performance partial response signalling and trellis coded modulation is considered together of M‐QAM systems. The new system proposal is denoted as Modified/Quadrature Partial Response‐Trellis Coded Modulation (M/QPR‐TCM). Two new non‐catastrophic schemes M/6QPR‐TCM and M/9QPR‐TCM are investigated for 4QAM. Error event lower bounds of the considered schemes are analyzed in AWGN and colored noise. Analytical upper bounds for the mobile fading channel with ideal channel state information (CSI) and infinite interleaving/deinterleaving are derived. The interesting result is that, the bit error probability upper bounds of the proposed M/QPR‐TCM systems are better than the related QAM‐TCM schemes forSNRvalues greater than a threshold.
Letter: Evaluation of total radiowave attenuation statistics for slant path links from phenomenon‐based attenuation distributions
Authors: Pozhidayev Victor , Dintelmann Fritz 
Published: September 2008

AbstractThis contribution suggests a method how to combine effect‐specific cumulative distributions of attenuation to a total‐attenuation distribution as required e.g. in long‐term frequency scaling applications. The method is believed to be applicable for frequencies up to about 40 GHz. It has been tested with 20 GHz radiometric data collected near Moscow and the agreement found between our measurements and the results of this procedure is remarkably good.
Letter: Cell level modelling of H.261 coded video sequences at different bit rates
Authors: Dagiuklas Anastasios , Ghanbari Mohammed 
Published: September 2008

AbstractA video source, with a low to medium activity, coded with an H.261 type video codec can be modelled at the frame level as an M state Markov chain. For cell level modelling, the generated cells within the frame are distributed using a modulated Poisson process with interarrivals of Gamma function. Sequences with scene cuts use an. additional state in the Markov chain to represent the scene cut bit rate. The multiplexed model of N homogeneous sources is represented by a linear Markov model of N × M states. The transition probabilities in the multiplexed model are approximated by a truncated discrete normal distribution bounded within ±N states. The proposed single and multiplexed models exhibit similar cell loss performance with the real coded data at both cell and burst scale levels. The multiplexed model is then generalised to represent the aggregate traffic of several homogeneous sources at different bit rates.
RACE “MARS” project for the experimentation of multimedia interactive services: Architecture solutions and results
Authors: Bertin Christian , De Sousa Amaro F. , Figuera Gonzalo , Friedrich Manuel , Guglielmo Mario 
Published: September 2008

AbstractThis paper describes the architecture implemented in five different countries to validate, by means of tests carried out with expert users, a service architecture for the interactive retrieval of multimedia information. The service architecture definition (which corresponds to the DA VIC 1.0 Specifications) and all activities for the set‐up and running of the experiments, have been carried out within the RACE R2120 “Multimedia Audiovisual Retrieval Services” (MARS) project. A unique server and terminal architecture has been developed and put in operation at each site, while a combination of different public network solutions were used for the terminal access side. All national experiments made use of an ATM‐based transport network. The interconnections between the five countries were provided by the European ATM Pilot (EAP). The minimal testbed configuration implemented in each country consisted of one server and two terminals. After the integration and test phases, this configuration was extensively tested within the national environment to obtain the users' perception of the service.
Diamond project: Video‐on‐demand system, and trials
Authors: Van De Haar Peter G. , Schoenmakers Arno F. , Eilley Edward S. , Tedd Douglas N. , Tickell Stephen A. , Lloyd Phil R. , Badham Mark , O'Brien Steve , Poole Robin , Sampson Paul , Harding Jon , Simula Timo , Varonen Teema , Sauvala Seppo 
Published: September 2008

AbstractThe DIAMOND project (Domestic IBC Applications for Multimedia on Demand; IBC = Integrated Broadband Communications), sponsored by the EC (RACE R2105), had the objective of exploring and demonstrating the technical feasibility of providing Video On Demand (VOD) to the home, with an acceptable quality of service at an acceptable cost level. Within Philips, a Video Server (VS) and Set Top Box (STB) were developed, while Octacon developed a Service Gateway (SGW). The system was tested on both a public switched network using ADSL (Helsinki, Finland) and on a CATV network (Sligo, Ireland); both trials were of a small scale and free of charge. The purpose of this paper is to present an overview of the overall system as developed for the DIAMOND trials, together with user evaluation results from the Helsinki trial.
HD‐SAT: Digital HDTV‐broadcasting by satellite and cable networks with commonality for terrestrial broadcasting
Authors: Dosch Christoph , Lavan Ethan 
Published: September 2008

AbstractThis paper introduces the HD‐SAT project, describes its main characteristics as well as the results of the system demonstration which was performed jointly with the dTTb project, (digital terrestrial television broadcasting) during the Montreux International Television Exhibition in June, 1995. The HD‐SAT system exploits the 20 GHz frequency band as the basis of a complete broadcast system delivering very high quality High‐Definition TV (HDTV) services over a variety of media. The satellite segment implements graceful degradation to assure the required service continuity. MPEG‐2 transmultiplexing is performed at the cable head‐end to provide an optimised transport stream for the cable channel. Maximising compliance to MPEG‐2 standards for the picture coding and DVB standards for the transmission segments results in a system open to interworking with other media and other services. This was demonstrated at the Montreux event, where the HD‐SAT system was demonstrated over live satellite and standard cable networks, and where common HD‐SAT coding and receiver hardware was used for the dTTb terrestrial and cable transmission within the joint demonstration.