Websites by Dr. Angela Amphawan
Publications by Dr. Angela Amphawan
Journal of European Optical. Society Rap. Public. 9, 14041 (2014), Sep 2014
Radio-over-Free-Space-Optics (Ro-FSO) is a promising technology for future wireless networks. In ... more Radio-over-Free-Space-Optics (Ro-FSO) is a promising technology for future wireless networks. In this work, we have designed a hybrid orthogonal frequency division multiplexing (OFDM) Ro-FSO system for transmission of two independent channels by mode division multiplexing. Two independent 40 GHz radio signals are optically modulated at 20Gbps by mode division multiplexing of two laser modes LG00 and LG10 and transmitted over a free-space link of 20 km to 100 km. The performance of proposed Ro-FSO system is also evaluated under the effect of strong atmospheric turbulences
Journal of Optical Communications, Jul 24, 2014
Complementing wireless radio networks with free-space optics (FSO) achieves high data rates by mo... more Complementing wireless radio networks with free-space optics (FSO) achieves high data rates by modulating radio subcarriers over an optical carrier without expensive optical fiber cabling, enabling a pervasive platform for reaching underserved areas. In this paper, we review the main features of FSO for terrestrial and inter-satellite communications. Simulations of 1 Gbps data transmission through FSO links in both terrestrial and inter-satellite communications have been investigated to highlight potential atmospheric challenges in FSO.
Optik, Volume 125, Issue 18, Pages 5196–5198, Sep 2014
Free space optics (FSO) technology provides a promising solution for future broadband networks, o... more Free space optics (FSO) technology provides a promising solution for future broadband networks, offering high data transmission compared to RF technology. This work is focused on investigating the performance of an FSO system with OFDM and QAM. A 10 Gbps data stream is transmitted using a 4-level QAM sequence through the FSO system under different atmospheric conditions. Results indicate that the integration of SOA prolongs the maximum achievable distance with acceptable SNR to 185 km under clear weather conditions whereas under atmospheric fog, the maximum distance is extended to 2.5 km
International Conference on Photonics (ICP2013), Oct 2013
A six-channel 2.4GHz subcarrier multiplexing - optical code division multiple access (SCM-OCDMA) ... more A six-channel 2.4GHz subcarrier multiplexing - optical code division multiple access (SCM-OCDMA) system in conjunction with the selective excitation of LP01 and LP02 modes is presented for a multimode fiber Local Area Network. Simulation results demonstrate that mode selectivity increases the bandwidth-distance product and improves the BER performance of the channel.
International Journal of Applied Mathematics and Informatics, , Issue 3, Vol. 7, pp. 97 – 106, Oct 1, 2013
Current computing trends such as cloud computing,
file sharing and social networking promote co... more Current computing trends such as cloud computing,
file sharing and social networking promote collaboration and allow greater mobility for users. Nevertheless, these computing trends increase the vulnerability of networks to security threats and challenge network resources. An ingenious technique employed by attackers for retaining anonymity is by exploiting intermediary host computers or stepping stones to instigate attacks on other computers. This paper explores novel application of the stepping stone detection concept in addressing network threats such as spams, backdoors, proxy server intrusions and denial of service attacks. Preliminary stepping stone detection models for each security threat will be constructed and the potential detection process is delineated. These preliminary concepts and models may prove useful for further optimization of network security in conjunction with other conventional detection techniques.
International Journal of Mathematical Models and Methods in Applied Sciences, May 2013
In this paper, we present a new alternative method for text steganalysis based on an evolution al... more In this paper, we present a new alternative method for text steganalysis based on an evolution algorithm, implemented using the Java Evolution Algorithms Package (JEAP).The main objective of this paper is to detect the existence of hidden messages ased on fitness values of a text description.It is found that the detection performance has been influenced by two groups of fitness values which are good fitness value and bad fitness value. This paper provides a valuable insight into the development and enhancement of the text steganalysis domain.
International Journal of Information Communication Technologies and Human Development (IJICTHD), Jun 2014
Hospital network is evolving towards a more integrated approach by interconnecting wireless techn... more Hospital network is evolving towards a more integrated approach by interconnecting wireless technologies into backbone networks. Although various integrated network scenarios have been published in the networking literature, a generic hospital model has not yet been fully explored and it remains a challenging topic in practice. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. A good understanding of the performance of integrated networks is required for efficient design and deployment of such technologies in hospital environments. This research paper discuss on the modelling and evaluation of integrated network scenarios in hospital environments. The impact of traffic types (e.g. data, voice and video), traffic load, network size and signal strength on network performance is investigated by simulation. Three piloted case studies look at client performance in radiology Accident and Emergency (A & E and Intensive Care Unit (ICU)) scenarios. Each scenario reflects the need for various traffic types that end up distinct network behaviours. In the radiology scenario, email and File Transfer Protocol (FTP) traffic is found to perform well for medium-to-large networks. In the A & E scenario, Voice over Internet Protocol (VoIP) traffic is shown to generate very limited jitter and data loss. The performance is aligned with the Quality of Service (QoS) requirements. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate.
International Journal of Information Communication Technologies and Human Development (IJICTHD), Jun 2014
For the past ten years, heterogeneous networks wired and wireless had tended to integrate seamles... more For the past ten years, heterogeneous networks wired and wireless had tended to integrate seamlessly, offering
effective and reliable service for medical operations. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. As a multiplexing hospital model, the implementation certainly presents some challenges. The major technical and performance issues involve are as following. The operating parameters should keep aligned to the Quality of Service (QoS) requirement throughout simulation. Bandwidth utilisation of wireless networking is a challenging issue for real-time multimedia transmission. IEEE 802.11 provides relatively lower data rate than wired networks, thus the developer tends to adopt a more compromised solution: either reduce the file size or compress the image packets. Communication performance that varies constantly with the impact of signal strength, traffic load and interference. As stated radio signal senses as a curve and attenuates greatly while metallic object and
microwave exist within the active range. To ensure devices do not interfere with other electronic equipments (e.g. heart monitors), assert wireless spectrum has to be managed appropriately. This research paper aims to develop a generic hospital network scenarios using Wireless Local Area Network (WLAN) over OPNET Simulation, to evaluate the performance of the integrated network scenario for Intensive Care Units (ICU). This research makes use of computer simulation and discusses various aspects of the network design, so as to discover the performance behaviour pertaining to effect of traffic type, traffic load and network size. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate. Experiment examines the effect of signal strength in WLAN. It is convinced that -88dBm is the best signal strength threshold. Although 802.11a generates slightly lower throughput than 802.11g, this issues can be addressed by placing more APs in the service area. It is convinced that 802.11a suits the hospital environments, because it mitigates interference on the popular 2.4GHz band where most wireless devices operate. It is important for medical devices which require future upgrade and Bluetooth deployment.
International Journal of Information Technology & Computer Science, Volume 15 Issue No 1, Jun 2014
Pervasive computing devices are configured for anywhere at any time services to adapt the changes... more Pervasive computing devices are configured for anywhere at any time services to adapt the changes in the dynamic
environment with respect to the user mobility. The paper proposes a salient model for a log based anonymity handling
in pervasive networks. The model defines a resource registry and sensor object modeling. Associability between the
nodes are configured with an allied user interface in the environment. Resource registry refers to a record of
information about the sensor nodes. A log book is maintained to keep track of the service discovery issues. New device
enquiry, registration and adaption are major issues in such pervasive devices. These issues lead to unacknowledged
communication that causes anonymity. This paper defines and discusses the presence of anonymity in pervasive
environments due to aforementioned issues.
2013 IEEE Symposium on Industrial Electronics and Applications (ISIEA 2013), Sep 22, 2013
This paper examines the avalanche photodiode (APD) gain impact on spectral-amplitude coding optic... more This paper examines the avalanche photodiode (APD) gain impact on spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems based single photodiode detection (SPD) technique. Numerical results are used for inspecting the APD gain influence upon the probability density function (PDF) and signal-to-noise ratio (SNR) performance. The usage of APD over positive-intrinsic-negative (PIN) photodiode accommodates more users with improved PDF and higher SNR.
Journal of Modern Optics, Impact factor 1.166, Volume 60, Issue 20,pp. 1675-1683, Dec 2013
To address the overwhelming bandwidth increase in premise backbones, an attractive alternative fo... more To address the overwhelming bandwidth increase in premise backbones, an attractive alternative for selective mode excitation in multimode fiber (MMF) using solid-core photonic crystal fiber (PCF) is presented. The power coupling efficiency, differential mode delay, and bit-error rate performance of several structural designs of solid-core PCF waveguides are investigated for the selective excitation of mode LP01 in a MMF. The achieved coupling efficiency into mode LP01 is above 90% for PCF profiles with seven rings.
Key Engineering Materials, Advanced Materials Engineering and Technology II, Advanced Material Engineering & Technology, vol. 594-595, pp. 1037, Jan 2014
The integration of heterogeneous technologies promotes ubiquity and mobility. Optical code divisi... more The integration of heterogeneous technologies promotes ubiquity and mobility. Optical code division multiple access (OCDMA) may be deployed in conjunction to SCM to improve the spectral efficiency and enhance the data rate of subscribers in a Local Area Network (LAN). This paper compares the performance of multimode fiber to single mode fiber in the deployment of a SCM-OCDMA system with multi-diagonal (MD) codes in a LAN.
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications VII, Shizhuo Yin; Ruyan Guo, Editors, Proceedings of SPIE Vol. 8847 (SPIE, Bellingham, WA 2013), 88470Y., Sep 25, 2013
To address the overwhelming bandwidth increase in premise backbones, an attractive alternative fo... more To address the overwhelming bandwidth increase in premise backbones, an attractive alternative for selective mode excitation in multimode fiber (MMF) using solid-core photonic crystal fiber (PCF) is presented. The power coupling efficiency, differential mode delay and bit-error rate performance of several structural designs of solid-core PCF waveguides are investigated for the selective excitation of mode LP01 in a MMF. The achieved coupling efficiency into mode LP01 is above 90% for PCF profiles with seven rings.
Journal of Theoretical and Applied Information Technology, Vol. 53 Iss. 3, pp. 467-471, E-ISSN 1817-3195 / ISSN 1992-8645 , Jul 31, 2013
This paper investigates the avalanche photodiode (APD) gain effect on spectral-amplitude coding o... more This paper investigates the avalanche photodiode (APD) gain effect on spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) system using a modified-AND subtraction detection in comparison to the conventional AND detection scheme. Analytical results are presented to investigate the APD gain impact on the bit-error rate (BER) performance. In addition, we confirm the influence of the APD over the positive-intrinsic-negative (PIN) photodiode on the system performance using data transmission simulations.
International Journal of Engineering and Technology (IJET), Vol. 5 No. 1, pp. 95 - 100, Mar 2013
The demand for efficient optical communication systems has fuelled considerable research in devel... more The demand for efficient optical communication systems has fuelled considerable research in developing techniques for eradicating phase-induced intensity noise (PIIN) in spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA). This paper investigates the use of modified-AND subtraction detection technique to mitigate PIIN in SAC-OCDMA systems. The simulation results show that the modified-AND subtraction detection demonstrates better performance over the conventional AND detection approach. Furthermore, we have found that, from a transmission length of 40 km onwards, group velocity dispersion (GVD) degrades SAC-OCDMA system performance apparently. Dispersion compensating fiber (DCF) is used to lessen the influence of GVD caused by single mode fiber (SMF).
Journal of European Optical Society. Rapid Publications, Vol. 8, 13022, Imp. Fac. 1.02, Mar 2013
In this paper, we present a single photodiode detection (SPD) technique for spectral-amplitude co... more In this paper, we present a single photodiode detection (SPD) technique for spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems. The proposed technique eliminates both phase-induced intensity noise (PIIN) and multiple-access interference (MAI) in the optical domain. Analytical results show that for 35 simultaneous users transmitting at data rate of 622 Mbps, the bit-error rate (BER) = 1.4x10^-28 for SPD technique is much better compared to 9.3x10^-6 and 9.6x10^-3 for the modified-AND as well as the AND detection techniques, respectively. Moreover, we verified the improved performance afforded by the proposed technique using data transmission simulations
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Websites by Dr. Angela Amphawan
Publications by Dr. Angela Amphawan
file sharing and social networking promote collaboration and allow greater mobility for users. Nevertheless, these computing trends increase the vulnerability of networks to security threats and challenge network resources. An ingenious technique employed by attackers for retaining anonymity is by exploiting intermediary host computers or stepping stones to instigate attacks on other computers. This paper explores novel application of the stepping stone detection concept in addressing network threats such as spams, backdoors, proxy server intrusions and denial of service attacks. Preliminary stepping stone detection models for each security threat will be constructed and the potential detection process is delineated. These preliminary concepts and models may prove useful for further optimization of network security in conjunction with other conventional detection techniques.
effective and reliable service for medical operations. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. As a multiplexing hospital model, the implementation certainly presents some challenges. The major technical and performance issues involve are as following. The operating parameters should keep aligned to the Quality of Service (QoS) requirement throughout simulation. Bandwidth utilisation of wireless networking is a challenging issue for real-time multimedia transmission. IEEE 802.11 provides relatively lower data rate than wired networks, thus the developer tends to adopt a more compromised solution: either reduce the file size or compress the image packets. Communication performance that varies constantly with the impact of signal strength, traffic load and interference. As stated radio signal senses as a curve and attenuates greatly while metallic object and
microwave exist within the active range. To ensure devices do not interfere with other electronic equipments (e.g. heart monitors), assert wireless spectrum has to be managed appropriately. This research paper aims to develop a generic hospital network scenarios using Wireless Local Area Network (WLAN) over OPNET Simulation, to evaluate the performance of the integrated network scenario for Intensive Care Units (ICU). This research makes use of computer simulation and discusses various aspects of the network design, so as to discover the performance behaviour pertaining to effect of traffic type, traffic load and network size. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate. Experiment examines the effect of signal strength in WLAN. It is convinced that -88dBm is the best signal strength threshold. Although 802.11a generates slightly lower throughput than 802.11g, this issues can be addressed by placing more APs in the service area. It is convinced that 802.11a suits the hospital environments, because it mitigates interference on the popular 2.4GHz band where most wireless devices operate. It is important for medical devices which require future upgrade and Bluetooth deployment.
environment with respect to the user mobility. The paper proposes a salient model for a log based anonymity handling
in pervasive networks. The model defines a resource registry and sensor object modeling. Associability between the
nodes are configured with an allied user interface in the environment. Resource registry refers to a record of
information about the sensor nodes. A log book is maintained to keep track of the service discovery issues. New device
enquiry, registration and adaption are major issues in such pervasive devices. These issues lead to unacknowledged
communication that causes anonymity. This paper defines and discusses the presence of anonymity in pervasive
environments due to aforementioned issues.
file sharing and social networking promote collaboration and allow greater mobility for users. Nevertheless, these computing trends increase the vulnerability of networks to security threats and challenge network resources. An ingenious technique employed by attackers for retaining anonymity is by exploiting intermediary host computers or stepping stones to instigate attacks on other computers. This paper explores novel application of the stepping stone detection concept in addressing network threats such as spams, backdoors, proxy server intrusions and denial of service attacks. Preliminary stepping stone detection models for each security threat will be constructed and the potential detection process is delineated. These preliminary concepts and models may prove useful for further optimization of network security in conjunction with other conventional detection techniques.
effective and reliable service for medical operations. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. As a multiplexing hospital model, the implementation certainly presents some challenges. The major technical and performance issues involve are as following. The operating parameters should keep aligned to the Quality of Service (QoS) requirement throughout simulation. Bandwidth utilisation of wireless networking is a challenging issue for real-time multimedia transmission. IEEE 802.11 provides relatively lower data rate than wired networks, thus the developer tends to adopt a more compromised solution: either reduce the file size or compress the image packets. Communication performance that varies constantly with the impact of signal strength, traffic load and interference. As stated radio signal senses as a curve and attenuates greatly while metallic object and
microwave exist within the active range. To ensure devices do not interfere with other electronic equipments (e.g. heart monitors), assert wireless spectrum has to be managed appropriately. This research paper aims to develop a generic hospital network scenarios using Wireless Local Area Network (WLAN) over OPNET Simulation, to evaluate the performance of the integrated network scenario for Intensive Care Units (ICU). This research makes use of computer simulation and discusses various aspects of the network design, so as to discover the performance behaviour pertaining to effect of traffic type, traffic load and network size. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate. Experiment examines the effect of signal strength in WLAN. It is convinced that -88dBm is the best signal strength threshold. Although 802.11a generates slightly lower throughput than 802.11g, this issues can be addressed by placing more APs in the service area. It is convinced that 802.11a suits the hospital environments, because it mitigates interference on the popular 2.4GHz band where most wireless devices operate. It is important for medical devices which require future upgrade and Bluetooth deployment.
environment with respect to the user mobility. The paper proposes a salient model for a log based anonymity handling
in pervasive networks. The model defines a resource registry and sensor object modeling. Associability between the
nodes are configured with an allied user interface in the environment. Resource registry refers to a record of
information about the sensor nodes. A log book is maintained to keep track of the service discovery issues. New device
enquiry, registration and adaption are major issues in such pervasive devices. These issues lead to unacknowledged
communication that causes anonymity. This paper defines and discusses the presence of anonymity in pervasive
environments due to aforementioned issues.
electrical components are now being replaced by optical components. The application of optical switching
phenomena has been used to construct the design of the D flip-flop and T flip-flop based on the electro-optic
effect in a Mach–Zehnder interferometer (MZI). The MZI structures show the powerful ability to switch the
optical signal from one output port to the other. Hence, it is possible to construct some complex optical combinational digital circuits using the electro-optic-effect-based MZI structure as a basic building block. This paper
constitutes the mathematical description of the proposed device and thereafter compilation using MATLAB.
The study is carried out by simulating the proposed device with the beam propagation method.