Abstract We present a learning system that provides continuous self learning environment to the s... more Abstract We present a learning system that provides continuous self learning environment to the students. From the students' responses, this system is proven to provide 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 ...
The WiMAX mesh networks based on IEEE 802.16 standard is a key topology for the next generation w... more The WiMAX mesh networks based on IEEE 802.16 standard is a key topology for the next generation wireless networking. However, interferences from transmission of the neighboring nodes within the mesh networks are inevitable. Cross-layer design for tree-type routing and level-based centralized scheduling is proposed as the optimization strategy. The cross-layer design here is relying on the routing information in network layer and centralized scheduling in the medium access control (MAC) layer. This paper proposes a centralized scheduling algorithm that can reduce interferences by constructing routing tree with multi-channel single transceiver system in WiMAX mesh networks. In this algorithm, each node has one transceiver that can be tuned to any of the channels, intending to eliminate the secondary interference. The results of analysis show that this proposed algorithm greatly improves the length of scheduling, channel utilization ratio (CUR) and throughput.
Recent advances in satellite communication technologies in the tropical regions have led to signi... more Recent advances in satellite communication technologies in the tropical regions have led to significant increase in the demand for services and applications that require high channel quality for mobile satellite terminals. Determination and quantification of these requirements are important to optimize service quality, particularly in the Malaysian region.Moreover, the tests on current satellite propagation models were carried out at temperate regions whose environmental characteristics are much different from those in Malaysia. This difference renders these propagation models inapplicable and irrelevant to tropical regions in general. This paper presents the link characteristics observations and performance analysis with propagation measurements done in tropical region to provide an accurate database regarding rain and power arches supply (PAs) attenuations in the tropics for mobile scenarios. Hence, an extension for improving the performance assessment and analysis of satellite/transmission has been achieved. The Malaysia propagation measurement for mobile scenario (Malaysia-PMMS) enables first-hand coarse estimation and attenuation analysis, because the attenuation resulting from rain and PAs becomes easily amenable for measurement. Parallel to that, the measured attenuation has been compared with that of the simulated output at noise floor level.The underlying analytical tool is validated by measurements specific at tropical region, for dynamic model of mobile satellite links operating at higher than 10GHz.
International Journal of Antennas and Propagation, 2015
Recent advances in satellite to land mobile terminal services and technologies, which utilize hig... more Recent advances in satellite to land mobile terminal services and technologies, which utilize high frequencies with directional antennas, have made the design of an appropriate model for land mobile satellite (LMS) channels a necessity. This paper presents LMS channel model at Ku-band with features that enhance accuracy, comprehensiveness, and reliability. The effect of satellite tracking loss at different mobile terminal speeds is considered for directional mobile antenna systems, a reliable tropospheric scintillation model for an LMS scenario at tropical and temperate regions is presented, and finally a new quality indicator module for different modulation and coding schemes is included. The proposedextended LMS channel (ELMSC)model is designed based on actual experimental measurements and can be applied to narrow- and wide-band signals at different regions and at different speeds and multichannel states. The proposed model exhibits lower root mean square error (RMSE) and signific...
2010 16th Asia-Pacific Conference on Communications (APCC), 2010
A negative index metamaterial antenna is presented in this paper for ultra-wideband (UWB) applica... more A negative index metamaterial antenna is presented in this paper for ultra-wideband (UWB) applications; which operates in C and X-bands. The proposed antenna is composed of three-unit cells of left-handed metamaterial (LHM) where these LHM unit cells are composed of a combination of modified octagonal spiral resonator (OSR), octagonal split-ring resonator (OSRR), capacitance-loaded strip (CLS), and wire that exhibit negative
This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar w... more This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar waveguide-fed configuration. Simple technique of perforating the substrate and modifying the ground plane and radiator patch was used to achieve UWB for the designed antenna at smaller structure. Narrow arch-shaped slot was introduced to the patch of the proposed antenna to obtain the band rejection function around the 5.4 GHz frequency to avoid the interference with WLAN applications. The proposed antenna was fabricated and the measurement result is found in well agreement with the simulation result. In addition to the acquirable UWB bandwidth, the designed antenna is capable to exhibit high radiation efficiency and omni-directional pattern.
A double SAW resonator system was developed as a novel method for gas sensing applications. The p... more A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%. OPEN ACCESS Sensors 2015, 15 4750
ABSTRACT A comparative analysis of defected microstrip structure (DMS) with band-reject character... more ABSTRACT A comparative analysis of defected microstrip structure (DMS) with band-reject characteristic and high-Q is presented in this paper. This paper studies the parametric analysis on the different structure of DMS that consists of different length and width in order to produce good band-reject response at resonant of approximately 5.2 GHz. These types of structures are designed and simulated on Roger Duroid RO4350 with a dielectric constant, εr of 3.48 and a thickness of 0.508 mm. The optimum topology of DMS with Hashtag-shape exhibits high selectivity, sharp response as well as high attenuation in the stopband. The simulation performance results show good and promising results with high Q-factor and narrow bandwidth, and therefore could be further examined in future works during experimental works. This structure of DMS is useful for microwave applications when the undesired signals need to be removed such as in wideband systems.
2014 7th Advanced Satellite Multimedia Systems Conference and the 13th Signal Processing for Space Communications Workshop (ASMS/SPSC), 2014
Cloud impairments have significant effect on signal propagated in the satellite to land stationar... more Cloud impairments have significant effect on signal propagated in the satellite to land stationary terminals channel at frequencies above 10 GHz. With the recent satellite to land mobile terminals network technologies and services that use these frequencies, there is a lack of channel impairments modeling and analysis for such type of link. This study presents a reliable channel model of satellite-to-land mobile terminals that consider dynamic cloudy weather impairments. The cloud’s dynamic parameters and their effect on the Rician factor are modeled. The model involves modules that design multipath signals, direct clear line-of-sight (LOS) normalized signals, and cloud impairments. Results show that a considerable change occurs in the performance of the signal propagated through the cloud. The change appears as deviations in the fade depth and the variance of the propagated signal in the link between the satellite and the land mobile terminals. The channel model is a realistic approach to the link characteristics, which satellite systems designers should consider when designing high data rate satellite systems.
2008 International Conference on Innovations in Information Technology, 2008
In the last few years, demand for high speed internet access service has increased greatly so the... more In the last few years, demand for high speed internet access service has increased greatly so the IEEE 802.16 working group on broadband wireless access (BWA) is developing the worldwide interoperability for microwave access (WiMAX) standard for wireless metropolitan area networks (MANs) which aims to provide broadband wireless last mile access, easy deployment, and high speed data rate for large
This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangul... more This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 × 14 mm 2 . Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value.
2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, 2007
Abstract A multi-standard multi-band SDR baseband platform digital transceiver is proposed in thi... more Abstract A multi-standard multi-band SDR baseband platform digital transceiver is proposed in this paper, where two different multi access techniques have been used. This paper also focuses on the methods to generate VHDL models of communication systems that can be ...
Abstract In this paper, a compact 5 poles Ultra-Wideband (UWB) microwave filter is designed by us... more Abstract In this paper, a compact 5 poles Ultra-Wideband (UWB) microwave filter is designed by using a quarter wave short-circuited stubs. The UWB filter bandwidth is covered from 2.75 GHz to 10.0 GHz. This filter designed is developed from a Low Pass Chebychev prototype ...
Compact and simple bandpass filter (BPF) structure using microstrip isosceles triangular patch re... more Compact and simple bandpass filter (BPF) structure using microstrip isosceles triangular patch resonator (ITPR) is proposed. The new filter design technique is based on two main ideas: Firstly, cutting the corners of the triangular structure, to make the filter size more compact. Secondly, etching slit in staircase form near the base of the triangle, in order to improve the filter performances. The proposed filter was designed and fabricated on Taconic CER-10 substrate with a relative dielectric constant of 10 and a thickness of 0.64 mm using standard photolithography process. The final dimension of the proposed filter is measured at 5.7 mm × 7.6 mm. Measured Sparameters showed that the filter achieves a 3-dB fractional bandwidth of 55% at center frequency of 10.36 GHz, with measured insertion loss of 2.08 dB and measured return loss better than 10 dB. The measured results are in good agreement with the simulated results.
This study reports on tunable planar metamaterial design that is capable to achieve dual-band neg... more This study reports on tunable planar metamaterial design that is capable to achieve dual-band negative index of refraction responses operating in microwave regime. Its distinctive characteristic is the usage of tuning open stub-loaded stepped-impedance resonators. Parameters retrieval algorithm, and full-wave simulation of prismshaped 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 dual-band function is required. In addition to that, its design flexibility offers a various frequency bands at any possible choice, which is alterable together with any design parameters changes.
Abstract We present a learning system that provides continuous self learning environment to the s... more Abstract We present a learning system that provides continuous self learning environment to the students. From the students' responses, this system is proven to provide 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 ...
The WiMAX mesh networks based on IEEE 802.16 standard is a key topology for the next generation w... more The WiMAX mesh networks based on IEEE 802.16 standard is a key topology for the next generation wireless networking. However, interferences from transmission of the neighboring nodes within the mesh networks are inevitable. Cross-layer design for tree-type routing and level-based centralized scheduling is proposed as the optimization strategy. The cross-layer design here is relying on the routing information in network layer and centralized scheduling in the medium access control (MAC) layer. This paper proposes a centralized scheduling algorithm that can reduce interferences by constructing routing tree with multi-channel single transceiver system in WiMAX mesh networks. In this algorithm, each node has one transceiver that can be tuned to any of the channels, intending to eliminate the secondary interference. The results of analysis show that this proposed algorithm greatly improves the length of scheduling, channel utilization ratio (CUR) and throughput.
Recent advances in satellite communication technologies in the tropical regions have led to signi... more Recent advances in satellite communication technologies in the tropical regions have led to significant increase in the demand for services and applications that require high channel quality for mobile satellite terminals. Determination and quantification of these requirements are important to optimize service quality, particularly in the Malaysian region.Moreover, the tests on current satellite propagation models were carried out at temperate regions whose environmental characteristics are much different from those in Malaysia. This difference renders these propagation models inapplicable and irrelevant to tropical regions in general. This paper presents the link characteristics observations and performance analysis with propagation measurements done in tropical region to provide an accurate database regarding rain and power arches supply (PAs) attenuations in the tropics for mobile scenarios. Hence, an extension for improving the performance assessment and analysis of satellite/transmission has been achieved. The Malaysia propagation measurement for mobile scenario (Malaysia-PMMS) enables first-hand coarse estimation and attenuation analysis, because the attenuation resulting from rain and PAs becomes easily amenable for measurement. Parallel to that, the measured attenuation has been compared with that of the simulated output at noise floor level.The underlying analytical tool is validated by measurements specific at tropical region, for dynamic model of mobile satellite links operating at higher than 10GHz.
International Journal of Antennas and Propagation, 2015
Recent advances in satellite to land mobile terminal services and technologies, which utilize hig... more Recent advances in satellite to land mobile terminal services and technologies, which utilize high frequencies with directional antennas, have made the design of an appropriate model for land mobile satellite (LMS) channels a necessity. This paper presents LMS channel model at Ku-band with features that enhance accuracy, comprehensiveness, and reliability. The effect of satellite tracking loss at different mobile terminal speeds is considered for directional mobile antenna systems, a reliable tropospheric scintillation model for an LMS scenario at tropical and temperate regions is presented, and finally a new quality indicator module for different modulation and coding schemes is included. The proposedextended LMS channel (ELMSC)model is designed based on actual experimental measurements and can be applied to narrow- and wide-band signals at different regions and at different speeds and multichannel states. The proposed model exhibits lower root mean square error (RMSE) and signific...
2010 16th Asia-Pacific Conference on Communications (APCC), 2010
A negative index metamaterial antenna is presented in this paper for ultra-wideband (UWB) applica... more A negative index metamaterial antenna is presented in this paper for ultra-wideband (UWB) applications; which operates in C and X-bands. The proposed antenna is composed of three-unit cells of left-handed metamaterial (LHM) where these LHM unit cells are composed of a combination of modified octagonal spiral resonator (OSR), octagonal split-ring resonator (OSRR), capacitance-loaded strip (CLS), and wire that exhibit negative
This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar w... more This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar waveguide-fed configuration. Simple technique of perforating the substrate and modifying the ground plane and radiator patch was used to achieve UWB for the designed antenna at smaller structure. Narrow arch-shaped slot was introduced to the patch of the proposed antenna to obtain the band rejection function around the 5.4 GHz frequency to avoid the interference with WLAN applications. The proposed antenna was fabricated and the measurement result is found in well agreement with the simulation result. In addition to the acquirable UWB bandwidth, the designed antenna is capable to exhibit high radiation efficiency and omni-directional pattern.
A double SAW resonator system was developed as a novel method for gas sensing applications. The p... more A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%. OPEN ACCESS Sensors 2015, 15 4750
ABSTRACT A comparative analysis of defected microstrip structure (DMS) with band-reject character... more ABSTRACT A comparative analysis of defected microstrip structure (DMS) with band-reject characteristic and high-Q is presented in this paper. This paper studies the parametric analysis on the different structure of DMS that consists of different length and width in order to produce good band-reject response at resonant of approximately 5.2 GHz. These types of structures are designed and simulated on Roger Duroid RO4350 with a dielectric constant, εr of 3.48 and a thickness of 0.508 mm. The optimum topology of DMS with Hashtag-shape exhibits high selectivity, sharp response as well as high attenuation in the stopband. The simulation performance results show good and promising results with high Q-factor and narrow bandwidth, and therefore could be further examined in future works during experimental works. This structure of DMS is useful for microwave applications when the undesired signals need to be removed such as in wideband systems.
2014 7th Advanced Satellite Multimedia Systems Conference and the 13th Signal Processing for Space Communications Workshop (ASMS/SPSC), 2014
Cloud impairments have significant effect on signal propagated in the satellite to land stationar... more Cloud impairments have significant effect on signal propagated in the satellite to land stationary terminals channel at frequencies above 10 GHz. With the recent satellite to land mobile terminals network technologies and services that use these frequencies, there is a lack of channel impairments modeling and analysis for such type of link. This study presents a reliable channel model of satellite-to-land mobile terminals that consider dynamic cloudy weather impairments. The cloud’s dynamic parameters and their effect on the Rician factor are modeled. The model involves modules that design multipath signals, direct clear line-of-sight (LOS) normalized signals, and cloud impairments. Results show that a considerable change occurs in the performance of the signal propagated through the cloud. The change appears as deviations in the fade depth and the variance of the propagated signal in the link between the satellite and the land mobile terminals. The channel model is a realistic approach to the link characteristics, which satellite systems designers should consider when designing high data rate satellite systems.
2008 International Conference on Innovations in Information Technology, 2008
In the last few years, demand for high speed internet access service has increased greatly so the... more In the last few years, demand for high speed internet access service has increased greatly so the IEEE 802.16 working group on broadband wireless access (BWA) is developing the worldwide interoperability for microwave access (WiMAX) standard for wireless metropolitan area networks (MANs) which aims to provide broadband wireless last mile access, easy deployment, and high speed data rate for large
This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangul... more This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 × 14 mm 2 . Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value.
2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, 2007
Abstract A multi-standard multi-band SDR baseband platform digital transceiver is proposed in thi... more Abstract A multi-standard multi-band SDR baseband platform digital transceiver is proposed in this paper, where two different multi access techniques have been used. This paper also focuses on the methods to generate VHDL models of communication systems that can be ...
Abstract In this paper, a compact 5 poles Ultra-Wideband (UWB) microwave filter is designed by us... more Abstract In this paper, a compact 5 poles Ultra-Wideband (UWB) microwave filter is designed by using a quarter wave short-circuited stubs. The UWB filter bandwidth is covered from 2.75 GHz to 10.0 GHz. This filter designed is developed from a Low Pass Chebychev prototype ...
Compact and simple bandpass filter (BPF) structure using microstrip isosceles triangular patch re... more Compact and simple bandpass filter (BPF) structure using microstrip isosceles triangular patch resonator (ITPR) is proposed. The new filter design technique is based on two main ideas: Firstly, cutting the corners of the triangular structure, to make the filter size more compact. Secondly, etching slit in staircase form near the base of the triangle, in order to improve the filter performances. The proposed filter was designed and fabricated on Taconic CER-10 substrate with a relative dielectric constant of 10 and a thickness of 0.64 mm using standard photolithography process. The final dimension of the proposed filter is measured at 5.7 mm × 7.6 mm. Measured Sparameters showed that the filter achieves a 3-dB fractional bandwidth of 55% at center frequency of 10.36 GHz, with measured insertion loss of 2.08 dB and measured return loss better than 10 dB. The measured results are in good agreement with the simulated results.
This study reports on tunable planar metamaterial design that is capable to achieve dual-band neg... more This study reports on tunable planar metamaterial design that is capable to achieve dual-band negative index of refraction responses operating in microwave regime. Its distinctive characteristic is the usage of tuning open stub-loaded stepped-impedance resonators. Parameters retrieval algorithm, and full-wave simulation of prismshaped 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 dual-band function is required. In addition to that, its design flexibility offers a various frequency bands at any possible choice, which is alterable together with any design parameters changes.
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Papers by Alyani Ismail
provide an accurate database regarding rain and power arches supply (PAs) attenuations in the tropics for mobile scenarios. Hence, an extension for improving the performance assessment and analysis of satellite/transmission has been achieved. The Malaysia propagation measurement for mobile scenario (Malaysia-PMMS) enables first-hand coarse estimation and attenuation analysis, because the attenuation resulting from rain and PAs becomes easily amenable for measurement. Parallel to that, the measured attenuation has been compared with that of the simulated output at noise floor level.The underlying analytical tool is validated by measurements specific at tropical region, for dynamic model of mobile satellite links operating at higher than 10GHz.
provide an accurate database regarding rain and power arches supply (PAs) attenuations in the tropics for mobile scenarios. Hence, an extension for improving the performance assessment and analysis of satellite/transmission has been achieved. The Malaysia propagation measurement for mobile scenario (Malaysia-PMMS) enables first-hand coarse estimation and attenuation analysis, because the attenuation resulting from rain and PAs becomes easily amenable for measurement. Parallel to that, the measured attenuation has been compared with that of the simulated output at noise floor level.The underlying analytical tool is validated by measurements specific at tropical region, for dynamic model of mobile satellite links operating at higher than 10GHz.