Moha M'rabet Hassani

Low power and fast DCT architecture using multiplier-less method

In this paper, a low power and fast DCT (Discrete Cosine Transform) using multiplier-less method is presented with a new modified FGA (Flow-Graph Algorithm), which is derived from our previously presented FGA of DCT based on Loeffler algorithm. The multiplier-less method is based on the replacement of multiplications with a minimum number of additions and shifts. The proposed FGA is performed and compared to a previous one. The results of FPGA implementations on Altera Cyclone II show the increase of the maximum frequency, the decrease of the resources usage and the reduction of the dynamic power by 7.2 % at 120 MHz of clock frequency with a new proposed FGA algorithm. Another comparison with recent published results has been done and proves the efficiency of the proposed FGA.

VHDL implementation of an optimized 8-point FFT/IFFT processor in pipeline architecture for OFDM systems

The Fast Fourier Transform (FFT) and its inverse transform (IFFT) processor are key components in many communication systems. An optimized implementation of the 8-point FFT processor with radix-2 algorithm in R2MDC architecture is presented in this paper. The butterfly — Processing Element (PE) used in the 8-FFT processor reduces the multiplicative complexity by using a real constant multiplication in one method and eliminates the multiplicative complexity by using add and shift operations in other proposed method. The pipeline architecture R2MDC has been implemented with the 8-point module and simulation results show that this module significantly achieves a better performance with lower resource usage.

Improved implementation of a modified Discrete Cosine Transform on low-cost FPGA

In this paper, Discrete Cosine Transform hardware implementations are performed using two different modified Loeffler algorithms and are compared to the original one. The arithmetic modifications are presented and the correspondent algorithms are synthesized and implemented on a low-cost FPGA. The results show a significant increase of the maximum frequency operation with a new proposed modified Loeffler algorithm.

Design of a High-Accuracy Classifier Based on Fisher Discriminant Analysis: Application to Computer-Aided Diagnosis of Microcalcifications

In this paper we present a high accuracy computer-aided diagnosis scheme. The goal of the developed system is to classify benign and malignant microcalcifications on mammograms. It is mainly based on a combination of wavelet decomposition, feature extraction and classification methodology using Fisherpsilas linear discriminant. The contribution of wavelet decomposition is to denoise and to enhance regions of interests (ROI) containing abnormalities. Feature extraction is performed using spatial grey level dependence (SGLD) matrices. The purpose of classification is to assign an object to a certain class. Many classification methods have been described. Here we use Fishers linear discriminant. Fisherpsilas linear discriminant is particularly useful for discriminating between two classes in a multidimensional space. Since it is based only on the first and second moments of each distribution, it is not a computationally intensive method. Our results show that the developed method is effective for quantifying the classification of benign and malignant microcalcifications abnormalities with an accuracy of 95.5%.

Design optimization of the quantization and a pipelined 2D-DCT for real-time applications

The Discrete Cosine Transform (DCT) is one of the most widely used techniques for image compression. Several algorithms are proposed to implement the DCT-2D. The scaled SDCT algorithm is an optimization of the DCT-1D, which consists in gathering all the multiplications at the end. In this paper, in addition to the hardware implementation on an FPGA, an extended optimization has been performed by merging the multiplications in the quantization block without having an impact on the image quality. A simplified quantization has been performed also to keep higher the performances of the all chain. Tests using MATLAB environment have shown that our proposed approach produces images with nearly the same quality of the ones obtained using the JPEG standard. FPGA-based implementations of this proposed approach is presented and compared to other state of the art techniques. The target is an an Altera Cyclone II FPGA using the Quartus synthesis tool. Results show that our approach outperforms the other ones in terms of processing-speed, used resources and power consumption. A comparison has been done between this architecture and a distributed arithmetic based architecture.

Development of Wideband Planar Inverted-F Antennas for Wireless Application

Problem statement: Due to the rapid development in wireless communication, the antennas capable of broad-band operations are very demanding in cellular communications systems. Among various possible antennas, planar inverted-F antennas (PIFAs) have the advantages of low profile and compact size and are very suitable for present-day wireless communication application. Approach: This study demonstrates a very effective method of bandwidth enhancement for planar inverted-F antenna. It was done by optimizing the width of feed plate and shorting plate, then by adding a parasitic element. Results: The obtained results of our developed wideband antenna was an impedance bandwidth of 72.8% for S11<-10 dB from 1.74-3.54 GHz which could cover GPS, DCS, IMT-2000, 2.4GHz WLAN, 3.5 GHz WIMAX applications. Conclusion: As the antenna was successfully researched and well optimized, and desired results were achieved.

Effects of changing dimensions on the planar inverted-F antenna performances

With the rapid growth of the wireless mobile communication technology, the future technologies need a very small antenna with a good performance, the advantage of planar inverted-F antenna (PIFA) make them very popular in many applications requiring a low profile antenna. This letter is aimed at addressing this problem by investigating the effects of changing the dimensions of each parameter of the planar inverted-F antenna on the impedance bandwidth, resonance frequency and gain. It is shown that a PIFA with a good performance can be achieved by optimizing the dimensions of the radiating plate, the ground plane and the height of the antenna.

Multiband Operation and Performance Enhancement of the PIFA Antenna by Using Particle Swarm Optimization and Overlapping Method

Recently, the demand for wireless devices that support multiband frequency has increased. The integration of such technology in mobile communication system has led to a great demand in developing small size antenna with multiband operation, which is able to operate in the required system. In this paper, a novel type planar inverted F antenna (PIFA) with gridded ground plane structure and overlapping cells is presented. By controlling the overlapping size, we improve the characteristics of the proposed antenna. This antenna is developed to achieve multiband operation with small size and good performance. The particle swarm optimization (PSO) is employed to a PIFA antenna to get rid of the limitations of single band operation by searching the optimal localization and length of linear slots on the ground plane to give triband operation. This PIFA antenna can be integrated to operate for several mobile applications as Bluetooth/WLAN, WIMAX, and 4G (UMTS2100, LTE). The optimized antenna is simulated by both Ansoft HFSS and computer simulation technology microwave studio (CSTMWS) in terms of -parameters. A good agreement between simulated performances by both software types is achieved. A parametric study is made to analyze the effect of different PIFA parameters on the operating frequency and the reflection coefficient in order to enhance the antenna performances. In these frequency bands, the antenna has nearly omnidirectional radiation pattern.

Optimization by genetic algorithm of a PIFA antenna parameters for Wifi application

In this paper a genetic algorithm optimization is applied to optimize PIFA antenna parameters for wireless application. The optimization procedure is included, also two novel optimized antennas are presented. Optimized antennas reach 89.93% and 88.55% bandwidth. Miniaturization is also achieved. The reliability and efficiency of this method are proved by comparing the antenna proposed in this paper to optimal antennas.

Efficient hardware architecture for direct 2D DCT computation and its FPGA implementation

In this paper, we propose a low complexity architecture for direct 2D-DCT computation. The architecture will transform the pixels from spatial to spectral domain with the required quality constraints of the compression standards. In our previous works we introduced a new fast 2D_DCT with low computations: only 40 additions are used and no multiplications are needed. Based on that algorithm we developed in this work a new architecture to achieve the computations of the 2D DCT directly without using any transposition memory. We defined Sk functions blocks to build the 2D DCT architecture. The Sk block perform 8 function depending on the control signals of the system. The number of additions/subtractions used is 63, but no multiplication or memory transposition is needed. The architecture is suitable for usage with statistical rules to predict the zero quantized coefficients, which can considerably reduce the number of computation. We implemented the design using an FPGA Cyclone 3. The design can reach up to 244 MHz and uses 1188 logic elements, and it respect the real time video requirements.