Indonesian Journal of Electrical Engineering and Computer Science
Visible light communications are limited by the narrow bandwidth of their sources as the light-em... more Visible light communications are limited by the narrow bandwidth of their sources as the light-emitting diodes, which restricts the high data rates transmission. A potential technique such as multi-carrier modulation is considered promising for achieving a high-speed data rate and enhancing system performance. This paper proposes turbo coding with unipolar orthogonal frequency-division multiplexing (U-OFDM) for indoor environments. The system under U-OFDM considerations can reduce the inter-symbol interference caused by multiple paths and mitigate burst errors by adopting an iterative turbo decoding. The system performance is evaluated regarding the bit error rate (BER) for the range of the signal-to-noise ratio (SNR) under receiver field-of-view (FOV) restriction. The obtained results show that the performance system of the target BER (below the threshold limit of 3.8×10−3) has a power penalty of ~9 dB for modulation order of 64 for quadrature amplitude modulation scheme, FOV of 50...
International Journal of Electronics and Communication Engineering, 2014
This paper reports on an experimental investigation into the influence of current modulation on t... more This paper reports on an experimental investigation into the influence of current modulation on the properties of a vertical-cavity surface-emitting laser (VCSEL) with a direct square wave modulation. The optical output power response, as a function of the pumping current, modulation frequency, and amplitude, is measured for an 850 nm VCSEL. We demonstrate that modulation frequency and amplitude play important roles in reducing the VCSEL’s power consumption for optical generation. Indeed, even when the biasing current is below the static threshold, the VCSEL emits optical power under the square wave modulation. The power consumed by the device to generate light is significantly reduced to > 50%, which is below the threshold current, in response to both the modulation frequency and amplitude. An operating VCSEL device at low power is very desirable for less thermal effects, which are essential for a high-speed modulation bandwidth. Keywords—VCSELs, optical power generation, power consumption, square wave modulation.
2015 17th International Conference on Transparent Optical Networks (ICTON), 2015
In this paper, the combination of radio over multimode fibre and radio over free space optical sy... more In this paper, the combination of radio over multimode fibre and radio over free space optical systems are experimentally investigated. A mode filtering technique is adopted in order to deal with the modal effects in such hybrid systems. Considering mode filtering effect, we have determined transfer function and performed link budget analysis. Measurement of the error vector magnitude (EVM) was accomplished to verify the efficiency of the proposed systems in dealing with the modal effect. The obtained results are below the 8% 3GPP-LTE EVM requirement for different free space optical channel conditions including fog and turbulence.
2016 IEEE International Conference on Communications Workshops (ICC), 2016
This paper proposes an optimum hybrid radio over multi-mode fiber and free space optics (RoMMF-FS... more This paper proposes an optimum hybrid radio over multi-mode fiber and free space optics (RoMMF-FSO) system to enhance the last mile bottleneck issues of wireless communication systems. Single mode fiber (SMF) and gradient index (GRIN) lenses are used as mode filtering techniques to optimize the system performance by mitigating the modal effects produced by multimode optical fiber networks. We characterize the system based on the beam profile, transfer function, and error vector magnitude (EVM) measurements. The results reveal that both techniques can improve the EVM performance significantly by ~19% and ~30% using a SMF filter and SMF-GRIN lenses, respectively. Furthermore, the analysis of the obtained measurements show the SMF-GRIN lenses is more effective than SMF only with lower EVM values and negligible difference in the optical launch power.
2016 10th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), 2016
In this paper, we propose a hybrid radio over multi-mode/single-mode fibre and free space optics ... more In this paper, we propose a hybrid radio over multi-mode/single-mode fibre and free space optics (RoMMF/SMF-FSO) system to enhance the 4th generation-long term evolution (4G-LTE) signal performance when used in local area access networks. A single mode fibre pigtailed gradient index lens is used to minimise the modal effect of the optical link at different turbulence strengths. The proposed system is characterised in terms of the system transfer function, error vector magnitude (EVM), and optical launch power (OLP). Results demonstrate the robustness of the proposed scheme in terms of increased available passband bandwidth by 2 GHz and improving the transmission shape by reducing the system transfer function ripple by more than 5 dB. Successful transmission of the 4G-LTE signal is achieved over a MMF/SMF-FSO channel with a 1.5 dB power penalty under the higher turbulence level (i.e., Rytov variance of 0.1).
The 4th generation- long term evolution (4G-LTE) mobile technology is widely adopted that offer b... more The 4th generation- long term evolution (4G-LTE) mobile technology is widely adopted that offer both higher capacity and efficient bandwidth usage at a global level. However, considering that in cellular networks the major data traffic mostly occurs indoor, providing high quality can be a daunting task. 4G-LTE provides strong support for both outdoor and indoor coverage by adopting enhanced NodeB (eNB) and home eNB (HeNB), respectively. This research work presents (i) a single-mode filtering technique (SMFT) as a simple design, low cost scheme to degrade the dispersion behaviour of the hybrid radio over the multi-mode fibre (MMF) and free space optics (RoMMF-FSO); (ii) the hybrid radio-over-fibre and radio-over-FSO (RoF-FSO) system as a solution to extend the indoor coverage of 4G-LTE; and (iii) the use of perfluorinated graded-index polymer-optical fibre (PF-GI-POF) for in-building networks. The results show that SMFT may increase RoMMF-FSO bandwidth by 2 GHz and enhance the error ...
This paper reports on an experimental investigation into the influence of current modulation on t... more This paper reports on an experimental investigation into the influence of current modulation on the properties of a vertical-cavity surface-emitting laser (VCSEL) with a direct square wave modulation. The optical output power response, as a function of the pumping current, modulation frequency, and amplitude, is measured for an 850 nm VCSEL. We demonstrate that modulation frequency and amplitude play important roles in reducing the VCSEL’s power consumption for optical generation. Indeed, even when the biasing current is below the static threshold, the VCSEL emits optical power under the square wave modulation. The power consumed by the device to generate light is significantly reduced to > 50%, which is below the threshold current, in response to both the modulation frequency and amplitude. An operating VCSEL device at low power is very desirable for less thermal effects, which are essential for a high-speed modulation bandwidth. Keywords—VCSELs, optical power generation, power ...
Abstract This paper presents a novel structure to simulate and achieve the all-optical plasmonic ... more Abstract This paper presents a novel structure to simulate and achieve the all-optical plasmonic logic gates. We show how the use of dielectric-metal-dielectric (DMD) plasmonic waveguides with four nanorings and three slots can realize the complete family of logic gates; including NOT, OR, AND, NOT-OR, NAND, exclusive-OR, and exclusive-NOR using the constructive and destructive optical interferences between a control signal and input signal(s). We have adopted two optical wavelengths, namely 900 nm and 1330 nm, which are used for optical communication systems. Performance has been measured using the transmission level which registered more than 100 % for all of the seven gates of both wavelengths except NOT and NOT-OR logic gates. In addition, high extinction ratio of more than 20 dB in NOT and exclusive-NOR gates has been achieved using our novel structure.
2015 20th European Conference on Networks and Optical Communications - (NOC), 2015
ABSTRACT In this paper, we have characterised Brillouin frequency shift (BFS) in single mode sili... more ABSTRACT In this paper, we have characterised Brillouin frequency shift (BFS) in single mode silica fibre. In particular, BFS was characterised in conventional Brillouin Optical Time Domain Analysis (BOTDA) at operating wavelength of 1550 nm by a pump-probe technique. In addition, we also presented Brillouin gain and Brillouin loss mechanism in BOTDA sensing system. The simulation results shows, BFS have strong linear relationship with acoustic velocity and applied strain along the sensing fibre. A frequency shift of 60 MHz was obtained for each 0.1% strain (1000 μ-strain) on fibre. From the measurement results, it was evident that the each μ-strain on the fibre the frequency shift was found as 0.06 MHz. Therefore, BOTDA sensing system based on BFS is a promoting technique for structural health monitoring.
Indonesian Journal of Electrical Engineering and Computer Science
Visible light communications are limited by the narrow bandwidth of their sources as the light-em... more Visible light communications are limited by the narrow bandwidth of their sources as the light-emitting diodes, which restricts the high data rates transmission. A potential technique such as multi-carrier modulation is considered promising for achieving a high-speed data rate and enhancing system performance. This paper proposes turbo coding with unipolar orthogonal frequency-division multiplexing (U-OFDM) for indoor environments. The system under U-OFDM considerations can reduce the inter-symbol interference caused by multiple paths and mitigate burst errors by adopting an iterative turbo decoding. The system performance is evaluated regarding the bit error rate (BER) for the range of the signal-to-noise ratio (SNR) under receiver field-of-view (FOV) restriction. The obtained results show that the performance system of the target BER (below the threshold limit of 3.8×10−3) has a power penalty of ~9 dB for modulation order of 64 for quadrature amplitude modulation scheme, FOV of 50...
International Journal of Electronics and Communication Engineering, 2014
This paper reports on an experimental investigation into the influence of current modulation on t... more This paper reports on an experimental investigation into the influence of current modulation on the properties of a vertical-cavity surface-emitting laser (VCSEL) with a direct square wave modulation. The optical output power response, as a function of the pumping current, modulation frequency, and amplitude, is measured for an 850 nm VCSEL. We demonstrate that modulation frequency and amplitude play important roles in reducing the VCSEL’s power consumption for optical generation. Indeed, even when the biasing current is below the static threshold, the VCSEL emits optical power under the square wave modulation. The power consumed by the device to generate light is significantly reduced to > 50%, which is below the threshold current, in response to both the modulation frequency and amplitude. An operating VCSEL device at low power is very desirable for less thermal effects, which are essential for a high-speed modulation bandwidth. Keywords—VCSELs, optical power generation, power consumption, square wave modulation.
2015 17th International Conference on Transparent Optical Networks (ICTON), 2015
In this paper, the combination of radio over multimode fibre and radio over free space optical sy... more In this paper, the combination of radio over multimode fibre and radio over free space optical systems are experimentally investigated. A mode filtering technique is adopted in order to deal with the modal effects in such hybrid systems. Considering mode filtering effect, we have determined transfer function and performed link budget analysis. Measurement of the error vector magnitude (EVM) was accomplished to verify the efficiency of the proposed systems in dealing with the modal effect. The obtained results are below the 8% 3GPP-LTE EVM requirement for different free space optical channel conditions including fog and turbulence.
2016 IEEE International Conference on Communications Workshops (ICC), 2016
This paper proposes an optimum hybrid radio over multi-mode fiber and free space optics (RoMMF-FS... more This paper proposes an optimum hybrid radio over multi-mode fiber and free space optics (RoMMF-FSO) system to enhance the last mile bottleneck issues of wireless communication systems. Single mode fiber (SMF) and gradient index (GRIN) lenses are used as mode filtering techniques to optimize the system performance by mitigating the modal effects produced by multimode optical fiber networks. We characterize the system based on the beam profile, transfer function, and error vector magnitude (EVM) measurements. The results reveal that both techniques can improve the EVM performance significantly by ~19% and ~30% using a SMF filter and SMF-GRIN lenses, respectively. Furthermore, the analysis of the obtained measurements show the SMF-GRIN lenses is more effective than SMF only with lower EVM values and negligible difference in the optical launch power.
2016 10th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), 2016
In this paper, we propose a hybrid radio over multi-mode/single-mode fibre and free space optics ... more In this paper, we propose a hybrid radio over multi-mode/single-mode fibre and free space optics (RoMMF/SMF-FSO) system to enhance the 4th generation-long term evolution (4G-LTE) signal performance when used in local area access networks. A single mode fibre pigtailed gradient index lens is used to minimise the modal effect of the optical link at different turbulence strengths. The proposed system is characterised in terms of the system transfer function, error vector magnitude (EVM), and optical launch power (OLP). Results demonstrate the robustness of the proposed scheme in terms of increased available passband bandwidth by 2 GHz and improving the transmission shape by reducing the system transfer function ripple by more than 5 dB. Successful transmission of the 4G-LTE signal is achieved over a MMF/SMF-FSO channel with a 1.5 dB power penalty under the higher turbulence level (i.e., Rytov variance of 0.1).
The 4th generation- long term evolution (4G-LTE) mobile technology is widely adopted that offer b... more The 4th generation- long term evolution (4G-LTE) mobile technology is widely adopted that offer both higher capacity and efficient bandwidth usage at a global level. However, considering that in cellular networks the major data traffic mostly occurs indoor, providing high quality can be a daunting task. 4G-LTE provides strong support for both outdoor and indoor coverage by adopting enhanced NodeB (eNB) and home eNB (HeNB), respectively. This research work presents (i) a single-mode filtering technique (SMFT) as a simple design, low cost scheme to degrade the dispersion behaviour of the hybrid radio over the multi-mode fibre (MMF) and free space optics (RoMMF-FSO); (ii) the hybrid radio-over-fibre and radio-over-FSO (RoF-FSO) system as a solution to extend the indoor coverage of 4G-LTE; and (iii) the use of perfluorinated graded-index polymer-optical fibre (PF-GI-POF) for in-building networks. The results show that SMFT may increase RoMMF-FSO bandwidth by 2 GHz and enhance the error ...
This paper reports on an experimental investigation into the influence of current modulation on t... more This paper reports on an experimental investigation into the influence of current modulation on the properties of a vertical-cavity surface-emitting laser (VCSEL) with a direct square wave modulation. The optical output power response, as a function of the pumping current, modulation frequency, and amplitude, is measured for an 850 nm VCSEL. We demonstrate that modulation frequency and amplitude play important roles in reducing the VCSEL’s power consumption for optical generation. Indeed, even when the biasing current is below the static threshold, the VCSEL emits optical power under the square wave modulation. The power consumed by the device to generate light is significantly reduced to > 50%, which is below the threshold current, in response to both the modulation frequency and amplitude. An operating VCSEL device at low power is very desirable for less thermal effects, which are essential for a high-speed modulation bandwidth. Keywords—VCSELs, optical power generation, power ...
Abstract This paper presents a novel structure to simulate and achieve the all-optical plasmonic ... more Abstract This paper presents a novel structure to simulate and achieve the all-optical plasmonic logic gates. We show how the use of dielectric-metal-dielectric (DMD) plasmonic waveguides with four nanorings and three slots can realize the complete family of logic gates; including NOT, OR, AND, NOT-OR, NAND, exclusive-OR, and exclusive-NOR using the constructive and destructive optical interferences between a control signal and input signal(s). We have adopted two optical wavelengths, namely 900 nm and 1330 nm, which are used for optical communication systems. Performance has been measured using the transmission level which registered more than 100 % for all of the seven gates of both wavelengths except NOT and NOT-OR logic gates. In addition, high extinction ratio of more than 20 dB in NOT and exclusive-NOR gates has been achieved using our novel structure.
2015 20th European Conference on Networks and Optical Communications - (NOC), 2015
ABSTRACT In this paper, we have characterised Brillouin frequency shift (BFS) in single mode sili... more ABSTRACT In this paper, we have characterised Brillouin frequency shift (BFS) in single mode silica fibre. In particular, BFS was characterised in conventional Brillouin Optical Time Domain Analysis (BOTDA) at operating wavelength of 1550 nm by a pump-probe technique. In addition, we also presented Brillouin gain and Brillouin loss mechanism in BOTDA sensing system. The simulation results shows, BFS have strong linear relationship with acoustic velocity and applied strain along the sensing fibre. A frequency shift of 60 MHz was obtained for each 0.1% strain (1000 μ-strain) on fibre. From the measurement results, it was evident that the each μ-strain on the fibre the frequency shift was found as 0.06 MHz. Therefore, BOTDA sensing system based on BFS is a promoting technique for structural health monitoring.
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Papers by Hassan Al-Musawi