Showing papers in "Canadian Journal of Electrical and Computer Engineering-revue Canadienne De Genie Electrique Et Informatique in 2003"

A new measure of software complexity based on cognitive weights

Abstract: One of the central problems in software engineering is the inherent complexity. Since software is the result of human creative activity, cognitive informatics plays an important role in understanding its fundamental characteristics. This paper models one of the fundamental characteristics of software, complexity, by examining the cognitive weights of basic software control structures. Based on this approach a new concept of cognitive functional size of software is developed. Comparative case studies of the cognitive complexity and physical size of 20 programs are reported. The cognitive functional size provides a foundation for cross-platform analysis of complexity, size, and comprehension effort in the design, implementation, and maintenance phases of software engineering.

An endoscopic force-position sensor grasper with minimum sensors

Abstract: This study reports on the design, fabrication, testing, and mathematical modelling of a semiconductor microstrain-gauge endoscopic tactile sensor. The sensor can measure, with reasonable accuracy, the magnitude and the position of an applied load on a grasper. The designed assembly consists of two semiconductor microstrain-gauge sensors, which are positioned at the back face of a prototype endoscopic grasper. The intensity of the applied force can be seen on a light emitting diode (LED) device. Altogether, 20 different force magnitudes for seven different locations on the endoscopic grasper are tested experimentally. The magnitudes of force vary from 0.5 to 10 N with an increment of 0.5 N. The in-house electrical amplification system for the microstrain gauges is also designed, fabricated, and tested. The sensor is insulated and can operate safely in wet environments. It exhibits high force sensitivity, good linearity, and large dynamic range. To predict the behaviour of the designed system under various loading conditions, three-dimensional finite element modelling (FEM) is used. There is a good correlation between the computed theoretical results for the force magnitudes together with their points of application and the experimental results. The miniaturized electronic device could be integrated with an endoscopic grasper.

Analysis of harmonic detection algorithms and their application to active power filters for harmonics compensation and resonance damping

Abstract: In this paper, the performance of four harmonic detection methods is evaluated in terms of accuracy, speed of convergence, computational complexity and memory requirements; operation with measurement noise and variations of the signal amplitude and fundamental frequency is considered. The harmonic detection algorithms are based on the discrete Fourier transform (DFT), the recursive discrete Fourier transform (RDFT), the Kalman filtering (KF) approach, and the instantaneous reactive power (IRP) theory. Results obtained by simulation with MATLAB/Simulink and their real-time validation with the dSPACE simulator are presented to compare the detection methods. The effectiveness of the algorithms is demonstrated in their application to the control of an active filter and a hybrid active power filter dedicated respectively to harmonics compensation and to harmonic resonance damping in industrial power systems.

A framework for UMTS air interface analysis

Abstract: An integrated approach is presented for uplink and downlink air interface capacity evaluation and traffic analysis for the multiservice Universal Mobile Telecommunications System (UMTS). Within this framework the effects of both soft handoff (SHO) and fast power control (FPC) are considered. The canonical capacity of any given service, defined as the maximum number of concurrent users of that service, is derived; and the network total load is described as a function of this parameter and the number of concurrent users. The concept of virtual slots is defined within this integrated framework to obtain an accurate estimate for the blocking probability of each service type. A number of case studies are also presented to compare the results of utilizing the proposed framework with the results of network simulation. This comparison demonstrates the accuracy and usefulness of the proposed approach for network design and dimensioning.

Power spectral density of a UWB signal with discrete quantized pulse positions

Abstract: The FCC specification for ultra-wideband (UWB) emissions states that the effective isotropic radiated power (EIRP) cannot exceed 41.3 dBm per 1 MHz bandwidth in the frequency region of 3.1 to 10.6 GHz. Hence, to achieve adequate transmit power in a UWB data link it is necessary to use a wide-bandwidth modulation scheme. This requirement presents a pair of technical challenges which are addressed in this paper. The first challenge is to realize a wide-bandwidth radiated transmitter pulse shape which adequately covers the UWB band from 3.1 to 10.6 GHz. The second challenge is to structure the modulation such that the discrete line component of the power spectral density (PSD) of the transmitted signal is minimized. This is necessary as the discrete spectral components are essentially wasted power and limit the output transmitted power due to the FCC EIRP mask. In this paper the radiated EIRP of a UWB signal based on pulse position modulation (PPM) is explored. Previous researchers have derived the PSD under the supposition that the PPM pulse delay is continuous. However, simpler and more insightful expressions are possible for the PPM PSD if the pulse delays are restricted to quantized steps, as is assumed in this paper. A network-analysis approach for determining the EIRP of the unmodulated radiated pulses is given based on spectral measurements of an experimental UWB transceiver pair. These EIRP characteristics are applied to the derived equations for the continuous and discrete portions of the PSD of the UWB signal. From this, insights emerge into optimum PPM transmitter implementation that maximizes transmit power and minimizes power losses due to the discrete spectral lines. As demonstrated in this paper, such optimization necessitates the joint design of the UWB transmitter radiated pulse shape and PPM structure.

OFDM-CPM signals for wireless communications

Abstract: A class of orthogonal frequency division multiplexingcontinuous phase modulation (OFDM-CPM) signals is introduced in which the binary data sequence is mapped to complex symbols using the concept of correlated phase states of a CPM signal. A multiple-symbol-observation receiver is used to decode the received sequence, and an investigation of bit error rate over typical wireless multipath channels with additive white Gaussian noise is presented. The performance of a variety of OFDM-CPM signals is presented and analyzed. Performance is a function of parameter and the observation interval, both of which are at the disposal of the system designer. It is shown that OFDM-CPM is a promising signalling scheme in multipath fading channels. Results for multi- and asymmetric OFDM-CPM signals are also presented. The peak-to-average power ratio (PAPR) performance of these signals is also presented, and an algorithm to reduce PAPR is proposed that is based on a multi-amplitude CPM constellation. It is shown through numerical simulations that the proposed algorithmreduces the PAPR of a 128-carrier OFDM-CPM signal by more than 4 dB.

Low-power single-bit full adder cells

Abstract: The single-bit full adder is one of the main components in almost all logic structures. The performance of logic structures is highly dependent on the adder cells. This paper discusses the performance of single-bit full adders and presents a performance analysis for those cells in CMOS technology. Fourteen single-bit full adders and three new adders, a total of different adder cells, are analyzed in terms of power and delay using 0.35, 0.25 and 0.18 µm TSMC CMOS technology. In addition, this paper discusses the charging-capability parameter of the adder cells, which represents the fan-out of each cell. The charging-capability parameter is capable of describing the performance of the adder cell in a large, as yet unbuilt structure. Hence, the performance analysis of the single-bit full adder relates the design to power, delay, and charging capability of the logic components.

Robust image-based detection of activity for traffic control

Abstract: An important application of image processing and computer vision is the development of intelligent systems for traffic monitoring, management and optimization. This paper presents a system for real-time detection of moving vehicles approaching an intersection from sequences of colour images acquired by a stationary camera. The proposed approach is developed in the context of traffic-light control systems. As the system is dedicated to outdoor applications, efficient and robust vehicle detection under various weather and illumination conditions must be achieved. To deal with these ever-changing conditions, the vehicle detection relies on motion segmentation with dynamic background representation and on an original switching algorithm using hue-saturation-value (HSV) colour mapping to achieve feature space segmentation. Experimental results using real outdoor image sequences demonstrate the systems robustness under various and difficult environmental conditions.

Analogue integrated circuit sizing with several optimization runs using heuristics for setting initial points

Abstract: Circuit sizing (i.e., determining MOSFET channel widths and lengths which result in the most appropriate and robust circuit) is an optimization process. When it is completed, there always remains a dilemma; namely, whether a better solution exists. With different starting points one can arrive at different local minima. A heuristic process, consisting of many optimization runs starting from different initial points, is proposed. It tries to find another local minimum of the cost function in every run and thus reveals some additional information about the circuit. The mathematical background of the algorithm used is described. Finally, the heuristic algorithm is tested on some real integrated operating amplifier designs. The results show that from the cost-function point of view surprisingly many equivalent solutions exist.

A reduced-complexity multistage detection algorithm for DS-CDMA systems in AWGN channels

Abstract: In this paper a new, reduced-complexity algorithm for multistage detection of direct-sequence code division multiple access (DS-CDMA) signals in additive white Gaussian noise (AWGN) channels is presented. Bit error rate performance of the new algorithm is determined via Monte Carlo simulation, and it is shown that the new algorithm, although designed to reduce computational complexity, performs better than conventional multistage detection.

Audio watermarking time-frequency characteristics

Abstract: In this paper, a novel audio watermarking scheme based on spread spectrum techniques is proposed. This technique embeds a digital watermark within an audio signal using the instantaneous mean frequency (IMF) of the signal. Audio watermarking offers a solution to data piracy and helps to protect the rights of the artists and copyright holders. The proposed content-based algorithm aims to satisfy and maximize both imperceptibility and robustness of the watermark. In addition, the technique uses the short-time Fourier transform of the original audio signal to estimate a weighted IMF of the signal. Based on the masking properties of the psychoacoustic model, the required sound pressure level of the watermark is calculated. Modulation is then performed to produce a signal-dependent watermark that is imperceptible. The proposed method allows 25 bits to be embedded and recovered within a 5 second sample of an audio signal. Experimental results have shown that the scheme is robust to common signal processing attacks including filtering, MP3 compression, additive noise and resampling with a bit error rate in the range of 013%.

A simple and fast algorithm for determining asymptotic stability of linear autonomous systems

Abstract: The method introduced here determines explicitly whether a given system has only eigenvalues with negative real parts, without determining these eigenvalues, but rather by determining the eigenvalues of a related symmetric matrix which are always real and hence easy to calculate. The new method is similarly applied to linear autonomous discrete systems where all the eigenvalues of the system matrix are required to be positioned within the unit circle in the z-plane.

A pipelined architecture for ray/bezier patch intersection computation

Abstract: An algorithm for computing ray/B ezier patch intersections is described from a hardware design perspective. This algorithm uses patch subdivision and other geometrical techniques to find a given maximum number of intersection points nearest to the ray origin. A pipeline-based hardware architecture is proposed, the number of pipeline stages required is verified by simulation, and the performance of a load-balanced implementation based on a state-of-the-art digital signal processor is estimated.

Noncoherent MT-CDMA system with post-detection diversity combining

Abstract: This paper presents a theoretical analysis of a noncoherent multitone code division multiple access (MT-CDMA) system with diversity combining in terms of average bit error rate performance. The study is carried out for both slow Rayleigh and Ricean fading frequency-selective channels with differential binary phase-shift keying (DBPSK) modulation in the indoor environment. The investigation considers post-detection diversity with maximal ratio combining. Assuming a fixed bandwidth, bit rate and transmitter power, the effect of diversity order and number of tones on the systems performance is studied. Numerical results are presented to validate the analysis and to justify the approximations made.

Iterative multiuser detection and decoding for highly correlated narrowband systems and heavily loaded CDMA systems

Abstract: When a soft-in soft-out (SISO) iterative multiuser detector cooperates with a bank of SISO single-user decoders, the multiuser system performance can be shown to converge to that of the single-user system In this paper, a novel SISO iterative detector which employs a decorrelator on the output of soft interference cancellation is proposed By making use of the advantages of decorrelating detection, the performance of the proposed system is improved with only a small complexity increase compared with pure soft interference cancellation The performance improvement is reflected in lower bit error rates at low signal-to-noise ratios and in the higher convergence speed Therefore, the proposed iterative detector is especially suitable for highly correlated narrowband systems and heavily loaded code-division multiple access (CDMA) systems Both performance analysis and simulation results are providedto show this improvement Finally, the computational complexity of the detector is analyzed

Uniform asymptotic stability of linear non-autonomous systems

Abstract: In this paper a new method is developed for obtaining necessary and sufficient conditions which, when satisfied, guarantee that a linear non-autonomous system will be uniformly asymptotically stable. The method is essentially an extension of two earlier theorems on the asymptotic stability of linear autonomous systems; these theorems, developed by the same author, are here extended to non-autonomous systems. Basically, the method consists of ascertaining whether a certain matrix is positive definite. In general, it is shown that this knowledge is necessary and sufficient to determine whether a linear non-autonomous system is exponentially stable and hence uniformly asymptotically stable.

A gate duplication technique for timing optimization

Abstract: This paper presents a timing optimization technique based on gate duplication. The relationship between gate duplication and delay reduction is first examined, and then the notion of duplication gain for selecting good candidate gates to be duplicated is introduced. The objective is to obtain maximum circuit delay reduction with the minimum number of duplications. Experiments on benchmark circuits show that this technique leads to a significant delay improvement.

A simple method for calculating the sinr in DS-CDMA systems with despreading sequences weighted by stepping chip waveforms

Abstract: This article presents a simple method for calculating the signal toi nterference-plus-noise ratio in direct sequence code division multiple access systems with despreading sequences weighted by stepping chip waveforms. The method is based on a simple equality, which gives a relation among the number of occurrences of various chip patterns belonging to random spreading sequences. It is found that there is no need to scrutinize all the chips of a random spreading sequence to determine the number of transitions that occur between two consecutive chips. Several numerical examples and computation times are provided to demonstrate the validity and significance of this method.

Analysis of dielectric-loaded annular slot array antenna

Abstract: A method is established for the analysis of annular slot array antennas loaded with dielectric layers and fed by either radial waveguide or cavity. The analysis is based on the boundary value method. The Greens functions for each region are obtained, and then the induced magnetic current over the slots is expanded into Fourier series with unknown coefficients. Boundary conditions are applied, and a matrix equation for these unknown coefficients is obtained. For narrow slots the number of unknowns equals the number of annular slots, and an extremely rapid solution is obtained. The far-field formulation is derived using the magnetic current on the dielectric layer. The method is confirmed numerically by comparing the simulation results for sample small antennas with a commercial numerical tool (IE3D), and good agreement is achieved. It is shown that adding the dielectric layers can improve the antenna directivity. In comparison with other methods, the proposed method is very efficient, and its computation efforts depend on the number of annular slots and not the size of the antenna. As an example, for a single-slot antenna the number of unknowns to be determined is only one, while in IE3D it is more than 300.

Corrugated copper membranes for use in reconfigurable ground plane antenna

Abstract: Thin-film copper membranes on silicon substrates were constructed using micromachining techniques. Membranes possessed surface corrugations 10 µm deep and ranged in size from 1.04 mm to 10.0 mm in diameter. Membranes were released using a combination of both KOH and xenon difluoride (XeF ) backside etching. Surface corrugations were made using KOH etching on the frontside of the wafer. The membranes were electrostatically actuated using a high-voltage dc supply, and flexibility was studied as a function of diameter. Measured data were compared to simulations of flat and corrugated membranes. Copper membranes were used as a reconfigurable ground plane under a microstrip transmission line. Actuation of the membranes induced phase shift in the transmitted signal. An array of five 4.3 mm diameter membranes was tested, as was a single 10.0 mm membrane, over frequencies ranging from 9.95 GHz to 35 GHz. A phase shift of 55.63?at 34.42 GHz was achieved for the array of five 4.3 mm membranes, and a phase shift of 57.93?at 35.0 GHz was achieved for the 10.0 mm membrane.

A parting word

Abstract: Maldague will take over as Co-Editors. It is a good feeling to leave the Journal in such capable hands as it can only improve and prosper under their management. As I found out after taking over as Editor, editing a Journal is not an easy task. It requires time and patience with a steep learning curve during the full cycle of the first year. All this was made possible with help I received from a number of people. During my tenure as Editor, I have been very ably supported by • Dr. Denis Laurendeau, who, as Co-Editor, provided tremendous support not only in organizing the review of papers in his area of expertise, but also in translating the abstracts of all papers into the second language, French or English, as appropriate, and They all carried the heavy burden of organizing the review of papers by independent reviewers. I know that it is not an easy job to find reviewers and organize the reviews. I would like to take this opportunity to publicly thank them all for their help and support. No journal can exist without the authors willing to submit the results of their hard work for publication in that journal. I am grateful that we continue to receive many papers and I wish to thank all authors who submitted their work to the CJECE. My only regret is that we were not always able to provide a response as promptly as I would have liked. One other group that provides valuable but silent service comprises the reviewers. Even though I do not know their names, I wish to acknowledge their help and thank them all for their service to the Journal. One other person who was indispensable in the production process is Mr. Mark Bachmann. He provided tremendous support in copy editing , proofing, typesetting and production of the Journal during my entire tenure as Editor. Mark provided very efficient, prompt and effective service, and helped in keeping the high visual standard of the Journal. Thank you very much, Mark. and the support provided by the IEEE Canada Office Administrator, Cathie Lowell, are gratefully acknowledged. In closing I wish Witold and Xavier the best of luck with the Journal in the future. A près une implication de plus de 15 années à la Revue, tout d'abord à titre d'éditeur associé de janvier 1987 à décembre 1996, et ensuite à …

A microprogrammable-processor teaching tool and its FPGA implementation

Abstract: In this paper a microprogrammable-processor teaching tool and its FPGA implementation are presented. The processor is based on a classical Am2900 architecture and is implemented in the popular Xilinx Foundation" environment. The tool helps electrical and computer engineering students to become familiar with microprogramming through development of their own instruction sets and experiments with signal flow within a processor. In addition to simulation, the complete configuration can be run on a Xilinx 4010XL FPGA. In the paper a short description of the tool is provided.

Semi-analytical approach for electromagnetic field diffusion using hertz potential

Abstract: (Paper written in French) This paper contains two parts: In the first part the Hertz vectorial potential is introduced and its possible use in solving electromagnetic diffusion problems common in electrical engineering is considered. Links between this potential and other commonly used potentials are established, and a formulation procedure using three vectorial equations is proposed. This approach has several advantages due to its simplicity and the fact that it requires only a few values for computation. This method is next applied efficiently to the interaction in the static regime between a line conductor crossed by a sine-shaped current and a finite-thickness metallic plate. In the second part, a specific field quadrature method is employed in integral form. This allows the confirmation of the methods accuracy and good numerical stability.

Low Power System-on-Chip Platform Architecture for High Performance Applications

Abstract: This paper describes work on the development of a scheme for implementation of low power high performance Digital Signal Processing intensive AMBA based System-On-Chip platforms. The scheme is based on a novel interfacing scheme which utilises the bus hierarchy within AMBA in order to allow single and multiple high performance DSP Intellectual Property cores to be integrated into the SoC platform. The paper describes the overall AMBA SoC architecture, the integration scheme, and an SoC generic wrapper which allows multiple low power high performance DSPs to be connected to the platform. Initial results are provided with a low power FIR filter core demonstrating impact of power on various sections of the platform.