Salina Abdul Samad

National University of Malaysia, Putrajaya, Putrajaya, Malaysia

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Publications (152)31.53 Total impact

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    ABSTRACT: Orthogonal frequency-division multiplexing is now one of the most important modulation techniques due to its advantages. Despite its ability to overcome the equalization problem, multipath fading channels, and other issues, this system has a serious problem concerning the high output peaks with respect to the average power, which is called the peak-to-average power ratio (PAPR). Selected mapping (SLM), partial transmitted sequence, and amplitude clipping and filtering are some efficient methods to reduce the PAPR. In a previous work, we slid a single-phase rotation vector on the data sequence in the frequency domain to reduce the PAPR and the complexity compared to the conventional SLM. In this paper, we present a novel method that utilizes the same approach of our previous work, but it processes the data after the inverse fast Fourier transform block (time-domain operations) using a modified version of the SLM scheme, which has less computational complexity than the conventional one. The mathematical derivations and the simulation results show that the PAPR, the computational complexity, and the side information were reduced significantly by the proposed method.
    Circuits Systems and Signal Processing 08/2014; · 0.98 Impact Factor
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    ABSTRACT: The development of implanted devices is essential because of their direct effect on the lives and safety of humanity. This paper presents the current issues and challenges related to all methods used to harvest energy for implantable biomedical devices. The advantages, disadvantages, and future trends of each method are discussed. The concept of harvesting energy from environmental sources and human body motion for implantable devices has gained a new relevance. In this review, the harvesting kinetic, electromagnetic, thermal and infrared radiant energies are discussed. Current issues and challenges related to the typical applications of these methods for energy harvesting are illustrated. Suggestions and discussion of the progress of research on implantable devices are also provided. This review is expected to increase research efforts to develop the battery-less implantable devices with reduced over hole size, low power, high efficiency, high data rate, and improved reliability and feasibility. Based on current literature, we believe that the inductive coupling link is the suitable method to be used to power the battery-less devices. Therefore, in this study, the power efficiency of the inductive coupling method is validated by MATLAB based on suggested values. By further researching and improvements, in the future the implantable and portable medical devices are expected to be free of batteries.
    BioMedical Engineering OnLine 06/2014; 13(1):79. · 1.61 Impact Factor
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    Journal of Mechanics in Medicine and Biology 04/2014; 14(5):1450062-1-1450062-23. · 0.76 Impact Factor
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    Journal of Mechanics in Medicine and Biology 03/2014; 14(5):1450062 (23 pages). · 0.76 Impact Factor
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    Journal of Mechanics in Medicine and Biology14. 03/2014; 14(5):1450062 (23 pages).
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    ABSTRACT: Abstract Use of transcutaneous inductive links is a widely known method for the wireless powering of bio-implanted devices such as implanted microsystems. The design of the coil for inductive links is generally not optimal. In this study, inductive links were used on the basis of the small loop antenna theory to reduce the effects of lateral coil misalignments on the biological human tissue model at 13.56 MHz. The tissue, which measures 60 mm×70 mm×5 mm, separates the reader and the implanted coils. The aligned coils and the lateral misalignment coils were investigated in different parametric x-distance misalignments. The optimal coil layout was developed on the basis of the layout rules presented in previous studies. Results show that the gain around the coils, which were separated by wet and dry skin, was constant and confirmed the omnidirectional radiation pattern even though the lateral misalignment between coils was smaller or greater than the implanted coil radius. This misalignment can be <4 mm or >6 mm up to 8 mm. Moreover, coil misalignments and skin condition do not affect the efficient performance of the coil.
    Biomedizinische Technik/Biomedical Engineering 01/2014; · 1.16 Impact Factor
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    ABSTRACT: Abstract|This paper deals with the design of small-sized bio- implanted spiral circular coils (pancake) with an operating frequency of 13.56 MHz. The external and internal coils' geometric dimensions are dout = 56 mm, din = 10mm and dout = 11:6 mm, din = 5 mm, respectively, in which the electrical performance is veri¯ed through the commercial ¯eld solver High Frequency Structural Simulator (HFSS 13.0), which employs the ¯nite-element method (FEM) technique. Mathematical models for the proposed coils are developed. The simulation is performed-based on the developmental model in the air and at depths 6mm in a human biological tissue of dry and wet skin. The results demonstrate that the external and internal coils have maximum near-¯eld gains of 54.15 dB and 53.30 dB in air. The maximum gains of the external coil contacted the wet and dry skin are 49.80 dB and 48.95 dB, respectively. The maximum gains of the internal coil at depths of 6mm in the wet and dry tissue are 41.80 dB and 41.40 dB, respectively. However, the external coil radiation e±ciencies on wet- and dry-skin are 92% and 90%, respectively, compared with that on air. The internal coil radiation e±ciencies on wet- and dry-skin are 78.4% and 77.6%, respectively, compared with that on air. In this study, the speci¯c absorption rate (SAR) and radiated power results of the internal coil are investigated using SEMCAD 16.4 software. The SAR and power loss studies show that the designed implanted coil has a negligible e®ect on the wet and dry skin and can be ignored.
    Progress In Electromagnetics Research M 08/2013; 32:181-200.
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    ABSTRACT: Abstract|This paper deals with the design of small-sized bio- implanted spiral circular coils (pancake) with an operating frequency of 13.56 MHz. The external and internal coils' geometric dimensions are dout = 56 mm, din = 10mm and dout = 11:6 mm, din = 5 mm, respectively, in which the electrical performance is veri¯ed through the commercial ¯eld solver High Frequency Structural Simulator (HFSS 13.0), which employs the ¯nite-element method (FEM) technique. Mathematical models for the proposed coils are developed. The simulation is performed-based on the developmental model in the air and at depths 6mm in a human biological tissue of dry and wet skin. The results demonstrate that the external and internal coils have maximum near-¯eld gains of 54.15 dB and 53.30 dB in air. The maximum gains of the external coil contacted the wet and dry skin are 49.80 dB and 48.95 dB, respectively. The maximum gains of the internal coil at depths of 6mm in the wet and dry tissue are 41.80 dB and 41.40 dB, respectively. However, the external coil radiation e±ciencies on wet- and dry-skin are 92% and 90%, respectively, compared with that on air. The internal coil radiation e±ciencies on wet- and dry-skin are 78.4% and 77.6%, respectively, compared with that on air. In this study, the speci¯c absorption rate (SAR) and radiated power results of the internal coil are investigated using SEMCAD 16.4 software. The SAR and power loss studies show that the designed implanted coil has a negligible e®ect on the wet and dry skin and can be ignored.
    Progress In Electromagnetics Research 08/2013; 32:181-200. · 5.30 Impact Factor
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    ABSTRACT: OFDM is an important modulation technique currently in development in the field of communications systems. OFDM signals can combat multipath propagation and fading channels and can support large data rates. However, OFDM systems are multicarrier systems and experience problems due to the required summation of sinusoids when the in-phase subcarriers are combined, which produces high power peaks. The large power envelope fluctuations that occur at the output cause in-band and out-of-band distortions that result in degraded BER performance. The literature contains many qualified approaches to resolving the peak-to-average power ratio problem, including selected mapping, partial transmit sequence, and amplitude clipping techniques. The simplest technique is the amplitude clipping technique, and the selected mapping and partial transmit sequence techniques are excessively complicated for real-time implementation. In this paper, we suggest a modification to the amplitude clipping method to produce a novel clipping technique called the side information supported amplitude clipping (SI-SAC) method. The SI-SAC technique involves sending certain bits of extra information so that the receiver can recover all of the clipped data. The SI-SAC technique does not add computational complexity to the system, and simulation results show that the proposed method is superior to the conventional method. The peak-to-average power ratio was reduced by ≈2.5 dB, and the magnitude of the mean squared error vector is the same as that of the original signal that is not clipped. In contrast, the conventional amplitude clipping method produces a mean squared error vector with a large magnitude. Copyright © 2012 John Wiley & Sons, Ltd.
    International Journal of Circuit Theory and Applications 01/2013; · 1.29 Impact Factor
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    ABSTRACT: Peak power reduction techniques in orthogonal frequency division multiplexing (OFDM) has been an important subject for many researchers for over 20 years. In this letter, we propose a side-information-free technique that is based on the concept of random variable (RV) transformation. The suggested method transforms RVs into other RVs, aiming to reshape the constellation that will consequently produce OFDM symbols with a reduced peak-to-average power ratio. The proposed method has no limitation on the mapping type or the mapping order and has no significant effect on the bit error rate performance compared to other methods presented in the literature. Additionally, the computational complexity does not increase.
    Etri Journal 01/2013; 35(4):714-717. · 0.74 Impact Factor
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    Saad Mutashar, M A Hannan, Salina A Samad
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    ABSTRACT: This paper presented a modified low-power recovery system for implanted micro-system devices to stimulate nerves and muscles. The modified system based on ASK modulation techniques and efficient class-E power amplifier, and operated at low-frequency band 13.56 MH Z to avoid the tissue damage according to the industrial, scientific, medical (ISM) band, with low modulation index 15.6% to achieve minimum power consumption. The improved inductive power link, self-threshold voltage cancellation's rectifier and efficient voltage regulator are presented to offer a very stable low-power supply 1.8 DC voltage to the implanted devices even in any change of implanted resistance. The design based on 0.35 CMOS technology. The mathematical model is given. The design is simulated using OrCAD PSpice 16.2 software tools and for real-time simulation, the electronic workbench MULISIM 11 has been used to simulate the class-E power amplifier.
    Asian Journal of Scientific Research 11/2012; 2(11):633-640.
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    Information Technology Journal 09/2012; 11(9):1184-1192.
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    ABSTRACT: This paper presents a fully integrated system for implanted micro-system devices with e±cient power and data transfer based on amplitude shift keying (ASK) modulation techniques. A proposed e±cient class-E power ampli¯er is presented. The design presents a full transcutaneous inductive powering system to transfer power and data from an outside human body to implanted devices such as implanted microsystems to stimulate and monitor the nerves and muscles with low band frequency of 13.56 MHz according to the industrialÀscienti¯cÀmedical (ISM) band to avoid the tissue damage. A novel ASK demodulator powered with 1.9 V is proposed with a power recovery system. The modulation index is 13% and the modulation rate 7.3% with data rate 1 Mbit/s, and with power e±ciency 66%. The system has been designed using 0.35-m fabricated CMOS technology. The mathematical model is given and the design is simulated using OrCAD PSpice 16.2 software tool and for real-time simulation, the electronic workbench MULISIM 11 has been used to simulate the class-E power ampli¯er.
    Journal of Mechanics in Medicine and Biology 08/2012; · 0.76 Impact Factor
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    ABSTRACT: This paper presented a modified efficient inductive powering link based on ASK modulator and proposed efficient class-E power amplifier. The design presents the external part which is located outside the body to transfer power and data to the implanted devices such as implanted Microsystems to stimulate and monitoring the nerves and muscles. The system operated with low band frequency 10MH Z according to industrial-scientific – medical (ISM) band to avoid the tissue heating. For external part, the modulation index is 11.1% and the modulation rate 7.2% with data rate 1 Mbit/s assuming Tbit = 1us. The system has been designed using 0.35-µm fabricated CMOS technology. The mathematical model is given and the design is simulated using OrCAD P Spice 16.2 software tool and for real-time simulation, the electronic workbench MULISIM 11 has been used.
    ICBCBBE 2012 : International Conference on Bioinformatics, Computational Biology and Biomedical Engineering; 08/2012
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    ABSTRACT: __ Inductive coupling link is widely used in transcutaneous power transmission to transfer data and power to the implanted biomedical devices such as implanted micro-sensor system. The inductive coupling variables play a strong rule in coupling efficiency. In this paper the coupling link variables is investigated and analyzed. The resonant frequency 13.56 MH Z was used according to industrial, scientific and medical (ISM) band. Results show that the voltage gain V gain of the inductive links is depended of coupling factor K and resistive load R load (implanted device). The voltage gain increase with increasing the implanted resistance with constant K. Simulation show that when R load =400 the V gain will be in maximum value, and when R losd =200the V gain will be in minimum value and approximately 4v. With these results, the system operation is satisfied the requirement of the implanted devices power. Theoretical and simulation is done using software OrCAD-P spice 16.2. Keywords-component ; Biomedical implanted devices, energy harvesting, inductive coupling links, Low band frequency (ISM).
    IEEE2012 4th International Conference on Intelligent and Advanced Systems (ICIAS2012); 06/2012
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    ABSTRACT: In recent years, there has been an increasing interest in speech recognition in terms of accuracy. In this paper, the implementation of a speech recognition system in a speaker-independent isolated Malay digit was discussed. The system is developed applying Hierarchical K-means clustering approach that combines the K-means and the Hierarchical algorithm. To recognize the Malay speech digits, the Mel Frequency Cepstral Coefficient technique (MFCC) is used to extract speech features, Hierarchical K-means used as a clustering technique for training and testing of the feature's vectors. The performance of the system was evaluated. And the overall speech recognition accuracy attained 87.5% which is considerably satisfactory.
    International Conference on System Engineering and Modeling; 04/2012
  • Roshahliza M. Ramli, Ali O. Abid Noor, Salina Abdul Samad
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    ABSTRACT: In this paper, a special adaptive line enhancer (ALE) structure is developed and tested. The ALE is based on a combination of adaptive filtering and an adaptive nonlinear neural network (ADNN). The main objective of the work is to reduce the background noise from the signal of interest. The proposed structure consists of a three-layer feed forward network with partially connected layers to achieve fast processing. The feedback error is used to train the ADNN. This system is simulated with different levels of interference signals. A comparison analysis of the proposed structure with a classical adaptive least mean square (LMS) line enhancer is presented in this paper. The nonlinear ADNN approach investigated here exhibited noticeable improvements over the traditional NLMS approach.
    Proceedings of the 11th WSEAS international conference on Electronics, Hardware, Wireless and Optical Communications, and proceedings of the 11th WSEAS international conference on Signal Processing, Robotics and Automation, and proceedings of the 4th WSEAS international conference on Nanotechnology; 02/2012
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    ABSTRACT: Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices.
    Sensors 01/2012; 12(1):297-319. · 2.05 Impact Factor
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    Galley proof in Information Technology Journal. 01/2012;
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    ABSTRACT: This paper presents a performance evaluation of a radio frequency identification (RFID) signal-transmission framework in software-defined radio (SDR) using phase shift keying and quadrature amplitude modulation schemes. The RFID signals were compared within the SDR framework with respect to SDR performance. The SDR system performance was evaluated by analyzing signal transmission, estimating bit-error rate and comparing signal-to-noise ratios (SNR), with satisfactory results. The eye diagrams were also computed and compared with the SNR to evaluate the SDR signal-transmission performance.
    ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 01/2012; · 0.39 Impact Factor

Publication Stats

229 Citations
31.53 Total Impact Points

Institutions

  • 1997–2013
    • National University of Malaysia
      • • Department of Electrical, Electronic and Systems Engineering
      • • Institute of Microengineering and Nanoelectronics
      Putrajaya, Putrajaya, Malaysia
  • 2006
    • University of Nottingham
      Nottigham, England, United Kingdom
  • 2003–2005
    • Multimedia University
      • Faculty of Information Science and Technology
      Kuala Lumpor, Kuala Lumpur, Malaysia