Raja Syamsul Azmir Raja Abdullah

Putra University, Malaysia, Putrajaya, Putrajaya, Malaysia

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Publications (46)5.16 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Multicast IPv6 is an efficient way of transmitting data simultaneously to a group of IPv6 users. It has the advantage of reducing the required bandwidth of IPv6 data delivery compared to unicast transmission. The data rate of multicast transmission over WLAN is confined by the user with the lowest rate in the multicast group, which is called the fixed base rate problem. This paper proposes a delivery method that incorporates both multicast and unicast transmissions to solve the fixed base rate problem. The proposed method divides the IPv6 network into two levels: multicast mode for the upper level of the network [IPv6 server to Access Point (AP)], and unicast mode for the lower level (AP to mobile nodes). To maintain the end-to-end multicast transmission, the AP is responsible for converting multicast packets to unicast packets. Such a combination enables the proposed method to inherit the advantages of both multicast and unicast transmissions. The performance of our proposed method is evaluated in a test-bed environment that considers the transmission of real-time video application. The proposed multicast-unicast is able to improve the throughput and video quality experienced by the end user, with low packet loss and transmission delay.
    Journal of Network and Systems Management 10/2014; · 0.43 Impact Factor
  • A.A. Salah, R.S.A.R. Abdullah, A. Ismail, F. Hashim, N.H.A. Aziz
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    ABSTRACT: Passive radars utilising illuminators of opportunity are being actively studied in the field of radar. In the last few years, many illuminator sources have been employed for passive radar applications. However, there have been no published results on the use of the long-term evolution (LTE) signal as a novel source for passive radar applications. For the first time an experimental investigation into the feasibility of LTE-based passive radars for detecting a moving target is presented. A theoretical analysis was conducted on a captured LTE signal in the atmosphere. This was then followed by a field experiment. The preliminary results show that the LTE signal is capable of being an illuminator for passive radars.
    Electronics Letters 01/2014; 50(7):545-547. · 1.04 Impact Factor
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    ABSTRACT: Signal denoising is directly related to sample estimation of received signals, either by estimating the equation parameters for the target reflections or the surrounding noise and clutter accompanying the data of interest. Radar signals recorded using analogue or digital devices are not immune to noise. Random or white noise with no coherency is mainly produced in the form of random electrons, and caused by heat, environment, and stray circuitry loses. These factors influence the output signal voltage, thus creating detectable noise. Differential Evolution (DE) is an effectual, competent, and robust optimisation method used to solve different problems in the engineering and scientific domains, such as in signal processing. This paper looks at the feasibility of using the differential evolution algorithm to estimate the linear frequency modulation received signal parameters for radar signal denoising. The results gave high target recognition and showed feasibility to denoise received signals.
    IEEE RF and Microwave Conference (RFM) 2013, Penang; 12/2013
  • A. Mehdizadeh, R.S.A. Raja Abdullah, F. Hashim
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    ABSTRACT: Key management is one of the challenging issues in group communications. It is generally used to secure multicast data transmission as well as preventing potential eavesdropping by malicious attackers. Group security key should be maintained for data encryption, while group key update and dissemination processes are required when a new user joins or leaves the group, which eventually lead to high communication cost. Since eavesdrop activities can be initiated by capturing the disseminated keys, higher communication cost due to frequent updates may also increase the possibility of attack of multicast transmission. In this paper, a key management scheme for IPv6 networks is proposed to reduce communication cost and therefore, fewer security risks. The obtained results from test-bed implementation show the efficiency of proposed method in terms of communication cost, number of updated paths and security index due to key updating, while at the same time achieving both forward and backward secrecy.
    Communications and Information Technologies (ISCIT), 2012 International Symposium on; 01/2012
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    ABSTRACT: This paper introduces a ground-based Multistatic Circular Synthetic Aperture Radar (MuCSAR) used to detect small objects on the ground. The received signals have been modelled and the system prototype has been developed. The proposed signal processing is also described. An experimental investigation for Foreign Object Detection application has been analysed.
    Radar Conference (RADAR), 2011 IEEE; 06/2011
  • Ahmad Fairuz Muhd Amin, Ishak Aris, Raja Syamsul Azmir Raja Abdullah, Ratna Kalos Zakiah Sahbudin
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    ABSTRACT: Embedded systems are taking on more complicated tasks as the processors involved become more powerful. The embedded systems have been widely used in many areas such as in industries, automotives, medical imaging, communications, speech recognition and computer vision. The complexity requirements in hardware and software nowadays need a flexibility system for further enhancement in any design without adding new hardware. Therefore, any changes in the design system will affect the processor that need to be changed. To overcome this problem, a System On Programmable Chip (SOPC) has been designed and developed using Field Programmable Gate Array (FPGA). A softcore processor, NIOS II 32-bit RISC, which is the microprocessor core was utilized in FPGA system together with the embedded operating system(OS), μClinux. In this paper, an example of web server is explained and demonstrated
    IOP Conference Series Materials Science and Engineering 02/2011; 17(1):012049.
  • S. Alshehri, A. Jantan, R.S.A. Raja Abdullah, Rozi Mahmud, S. Khatun, Z. Awang
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    ABSTRACT: This paper presents an experimental early breast cancer detection system in terms of heterogeneous breast phantom. The system consists of commercial Ultrawide-Band (UWB) transceivers and our developed Neural Network (NN) based Pattern Recognition (PR) software for imaging. A simple way to construct cancer- tissue and heterogeneous breast phantom using available low cost materials and their mixtures is also proposed here. The materials are: (i) A mixture of petroleum jelly, soy oil, wheat flour and water as heterogeneous tissue; (ii) A particular glass as skin; and (iii) A specific mixture of water and wheat flour as cancer- tissue. All the materials and their mixtures are considered according to the ratio of the dielectric properties of the breast tissues. To experimentally detect cancer, the UWB signals are transmitted from one side of the breast phantom and received from opposite side diagonally. By using discrete cosine transform (DCT) of the received signals, a Neural Network (NN) is trained, tested and interfaced with the UWB transceiver to form the complete system. The achieved detection rate of cancer cell's existence, size and location are approximately 100%, 93.1% and 93.3% respectively.
    Electrical, Control and Computer Engineering (INECCE), 2011 International Conference on; 01/2011
  • MIAD 2011 - Proceedings of the 2nd International Workshop on Medical Image Analysis and Description for Diagnosis Systems, Rome, Italy, January, 2011; 01/2011
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    ABSTRACT: With widespread deployment of multicast over Wireless Local Area Networks (WLANs), several issues in- cluding fixed data rate transmission, multicast key distribution security, and overlapped multicast address have to be addressed for accommodating an efficient multicast scheme for WLANs. The latter problem can be addressed by utilizing Internet Protocol version 6 (IPv6) which provides significantly more address space compare to existing IPv4. However, in multicast IPv6 over WLANs, when a mobile moves to the border of the multicast group, the data are transmitted at the lowest base rate to support more coverage area, leading to poor Quality of Service (QoS). In this paper, a novel multicast data delivery method over WLANs based on IPv6 protocol is proposed to overcome the problem of fixed base rate and security key distribution in WLANs. Specifically, the proposed method dictates a WLAN Access Point (AP) to encapsulate the multicast packets into unicast Medium Access Control (MAC) packets, and subsequently forward them to the mobile host. In addition, the AP is also responsible for updating and distributing security keys whenever a join or leave operation occurs. The results from our test-bed indicate that the proposed method significantly improve the QoS metrics (i.e., throughput and delay) compared to the existing multicast scenario, as well as able to reduce the amount of generated keys in the networks. Keywords-data rate transmission; multicast IPv6; QoS; mul- ticast over WLANs
    Proceedings of the 16th IEEE Symposium on Computers and Communications, ISCC 2011, Kerkyra, Corfu, Greece, June 28 - July 1, 2011; 01/2011
  • Asem A. Salah, Raja Syamsul Azmir Raja Abdullah, Borhanuddin Bin Mohd. Ali, Nidhal A. Odeh
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    ABSTRACT: A Low Complexity Resource Allocation Algorithm for OFDMA Cooperative Relay Networks with Fairness and QoS Guaranteed
    IEICE Transactions. 01/2011; 94-B:2328-2337.
  • Software Engineering and Computer Systems - Second International Conference, ICSECS 2011, Kuantan, Pahang, Malaysia, June 27-29, 2011, Proceedings, Part I; 01/2011
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    ABSTRACT: Internet Protocol version 6 (IPv6) over Low-power Personal Area Network (6LoWPAN) is proposed by the Internet Engineering Task Force (IETF) working group to accomplish the concept of IP-based Wireless Sensor Network (WSN). A new layer is incorporated between IPv6 network layer and 802.15.4 MAC layer, which is entitled adaptation layer. Header compression, packet fragmentation, and layer two forwarding are the main tasks of the adaptation layer. An IPv6 packet is too big regarding to the Maximum Transmission Unit (MTU) size of 802.15.4 standard thus it has to be fragmented. Breaking up a big packet to number of small fragments and attaching new headers to each fragment may affect the energy level. In this paper, we place an attention on the impact of the adaptation layer on the energy consumption of a 6LoWPAN sensor node. From our analysis, we found that the adaptation layer, in particular the fragmentation process may increase the energy consumption of a sensor node by 5 to 10 percent.
    01/2011;
  • A. R. H. Alhawari, A. Ismail, M. A. Mahdi, R. S. A. R. Abdullah
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    ABSTRACT: In this paper, we report a tunable planar metamaterial that is designed to achieve dual-band negative refractive index response in microwave regime. Its distinctive characteristic is the usage of tuning open stub-loaded stepped-impedance resonators. The frequency tunability of the second band is achievable via the adjustable open stub-loaded at the fixed tune of the first band. Parameter retrieval algorithm and full-wave simulation of prism-shaped structure were carried out to validate the negative refraction characteristics of metamaterial structure. The results predict its prospect as a very promising alternative to the conventional ones, which is compatibly applicable on various potential microwave devices especially when a dual-band function is required. In addition to that, its design flexibility offers various frequency bands at any possible choice, which alterable with the design parameters.
    01/2011;
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    ABSTRACT: Ultra-wideband (UWB) technology is a new concept in wireless short-range communication. It has numerous advantages that are resulted in producing different new products in various applications. This technology uses very short duration pulses hence occupies very large transmission bandwidth. This phenomenon may cause harmful interference in the existing wireless devices. The main objective of this study is to evaluate the effective parameters in ultra-wideband communication for indoor short-range devices. In this regard, two commercial UWB devices are utilized and effects of these devices in different experimental configurations are investigated. Three configurations including the effects of distance, narrowband spectrum, and another UWB device on bit error rate performance are evaluated. The results of the performed experiments showed the stability and amenability of the UWB technology to be used in multiple UWB devices.
    01/2011;
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    ABSTRACT: The performance of ASK over DCDM for up to seven channels is reported. The aggregate bit rate of 70Gb/s is achieved with only 160-GHz modulation bandwidth. The clock and data recovery are realized at 10-GHz clock rate, which is very economic and efficient. At 7 × 10 Gb/s, the worst receiver sensitivity of −10 dBm, OSNR of 41.5dB and chromatic dispersion tolerance of ±7ps/nm are achieved. Whereas, for the best channel, the receiver sensitivity, OSNR, and chromatic dispersion tolerance are −23.5dBm, 29dB, and ±36ps/nm, respectively. KeywordsOptical communications-Multiplexing-Duty cycle
    Photonic Network Communication 01/2010; 19(3):233-239. · 0.45 Impact Factor
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    R Mardeni, R S A Raja Abdullah, H Z M Shafri
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    ABSTRACT: Density is an important parameter to determine the strength of road, and it will ensure the safety of the use as well as maintaining the quality of road pavement. In this paper, the validation of GPR mixture model based on the microwave nondestructive free space method to determine the density of road pavement typed Hot Mix Asphalt (HMA) will be presented. The frequency range of operation used is 1.7–2.6 GHz. The attenuation is a major factor for gathering the density of road pavement predictably. The existing mixture model has been used to produce simulation data for determining the predicted complex permittivity and attenuation due to various densities of road pavement. The GPR laboratory measurement is performed where the measured attenuation due to various densities was obtained. The comparison results between measurement and simulation were investigated, and the relative errors Corresponding author: R. Mardeni (mardeni.roslee@mmu.edu.my).
    Progress In Electromagnetics Research B. 01/2010; 21:399-417.
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    Ibrahim N.K, R.S.A. Raja Abdullah, Saripan M.I
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    ABSTRACT: Problem statement: This study unveils the potential and utilization of Neural Network (NN) in radar applications for target classification. The radar system under test is a special of it kindsand known as Forward Scattering Radar (FSR). In this study the target is a ground vehicle which is represented by typical public road transport. The features from raw radar signal were extractedmanually prior to classification process using Neural Network (NN). Features given to the proposed network model are identified through radar theoretical analysis. Multi-Layer Perceptron (MLP) backpropagation neural network trained with three back-propagation algorithm was implemented and analyzed. In NN classifier, the unknown target is sent to the network trained by the known targets toattain the accurate output. Approach: Two types of classifications were analyzed. The first one is to classify the exact type of vehicle, four vehicle types were selected. The second objective is to grouped vehicle into their categories. The proposed NN architecture is compared to the K Nearest Neighbor classifier and the performance is evaluated. Results: Based on the results, the proposed NN provides a higher percentage of successful classification than the KNN classifier. Conclusion/Recommendation: The result presented here show that NN can be effectively employed in radar classification applications.
    Journal of Computer Science. 01/2009;
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    ABSTRACT: The aim of this paper is to produce and develop a new four-pole microstrip bandpass filter (BPF) structure for high selectivity applications. The microstrip BPF is designed using Chebychev lowpass prototype with passband ripple of 0.05 dB and bandwidth of 120 MHz, which operates at center frequency of 2.3 GHz. This filter is designed by using square spiral resonator structures and embedded-resonator topology with the same fundamental frequency to make it more compact; furthermore, it has high quality performance in terms of the frequency responses. The size of the compact microstrip filter is 24.74 × 21.20 mm. The proposed filter was designed, fabricated and tested. The measured results show that the minimum passband insertion loss is 2.65 dB, while the measured return loss is better than –11 dB in the passband. Very good agreement between the simulated and measured results was observed.
    Journal of Electromagnetic Waves and Applications 01/2009; 23:675-683. · 1.40 Impact Factor
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    ABSTRACT: This paper presents a new method in engineering education called a continuous-grouped-self-learning (CGSL) system. In general, based on feedbacks acquired from the student at the end of the implementation, students better understanding and appreciation to the courses been taught. Out of 60 students 71.7% admitted that this learning system has improved their study style and knowledge acquisition, which then agreed to be implemented in future. The observation shows that this system increases the appreciation to the knowledge better than conventional method. Apart from that the system also produced better students in term of responsibility, self-confidence, competitiveness, group work, and knowledge sharing. This is realized with the implementation of mock teaching assessment.
    International Education Studies. 01/2009;
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    Iman Avazpour, M. Iqbal Saripan, Abdul Jalil Nordin, Raja Syamsul Azmir Raja Abdullah
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    ABSTRACT: In the image segmentation process of positron emission tomography combined with computed tomography (PET/CT) imaging, previous works used information in CT only for segmenting the image without utilizing the information that can be provided by PET. This paper proposes to utilize the hot spot values in PET to guide the segmentation in CT, in automatic image segmentation using seeded region growing (SRG) technique. This automatic segmentation routine can be used as part of automatic diagnostic tools. In addition to the original initial seed selection using hot spot values in PET, this paper also introduces a new SRG growing criterion, the sliding windows. Fourteen images of patients having extrapulmonary tuberculosis have been examined using the above-mentioned method. To evaluate the performance of the modified SRG, three fidelity criteria are measured: percentage of under-segmentation area, percentage of over-segmentation area, and average time consumption. In terms of the under-segmentation percentage, SRG with average of the region growing criterion shows the least error percentage (51.85%). Meanwhile, SRG with local averaging and variance yielded the best results (2.67%) for the over-segmentation percentage. In terms of the time complexity, the modified SRG with local averaging and variance growing criterion shows the best performance with 5.273s average execution time. The results indicate that the proposed methods yield fairly good performance in terms of the over- and under-segmentation area. The results also demonstrated that the hot spot values in PET can be used to guide the automatic segmentation in CT image.
    Biological Procedures Online 01/2009; 11(1):241-252. · 1.30 Impact Factor