Saaidal Azzuhri - Academia.edu (original) (raw)
Papers by Saaidal Azzuhri
Laser Physics Letters, 2016
Wireless Personal Communications, 2016
Optical Engineering, 2016
Applied Optics, 2016
In this paper, stable dual-wavelength generation using a strain technique for a ytterbium-doped f... more In this paper, stable dual-wavelength generation using a strain technique for a ytterbium-doped fiber laser is successfully demonstrated. A microfiber-based Mach-Zehnder interferometer is inserted into the laser ring cavity and stretched using the xyz translation stage. Four sets of dual-wavelength output lasing are obtained when the strain is applied onto a microfiber. The dual-wavelength output possesses spacing between 7.12 and 11.59 nm, with displacement from 2 to 190 μm from the central wavelength. The obtained side-mode suppression ratio is ∼48 dBm, while the maximum power fluctuation and wavelength shift are less than 0.6 dB and 0.01 nm, respectively. The results demonstrate that this setup generates a stable dual-wavelength laser in the 1 μm region.
Mobile ad-hoc networks are infrastructure-free and highly dynamics wireless networks. There are m... more Mobile ad-hoc networks are infrastructure-free and highly dynamics wireless networks. There are many routing protocols for Mobile Ad Hoc Networks (MANET). One of the popular routing protocols is Optimized Link State Routing (OLSR). OLSR was developed to work independently from higher-layer protocols and it creates an underlying architecture for communication without the help of traditional fixed-position routers. In addition, OLSR attempts to maintain the communication routes for the mobile nodes that have limited transmission range. This paper discusses the OLSR implementation in terms of battery power status and its advantages particularly pertaining to the relationship between the power status function with the OLSR by modify some of the OLSR source code. The study also focuses on maximizing the use of the battery power sources. The results from the experiment show that the usage of the battery power sources left was maximally used when the “Willingness†for the nodes...
Journal of Modern Optics, 2015
Laser Physics, 2015
In this work, we demonstrate a simple Q-switched pulsed ring ytterbium-doped fiber laser based on... more In this work, we demonstrate a simple Q-switched pulsed ring ytterbium-doped fiber laser based on a few-layer TI:Bi 2 Se 3 saturable absorber (SA). Few-layer bismuth selenide within a suspension was induced onto a fiber ferrule at room temperature via an optical deposition method, resulting in a simple SA for the laser. Stable Q-switched pulsed lasing was achieved at a low pump threshold of 122.2 mW at 974 nm. The pulse repetition rate ranged from 18.97 to 45.41 kHz, and the narrowest pulse width and the maximum pulse energy were 13.1 μs and 5.88 nJ respectively. Results indicated that TI:Bi 2 Se 3 was also compatible with the 1 μm waveband, and hence could be considered a potential broadband SA for passively modelocked and Q-switched optical fiber lasers.
Journal of the European Optical Society: Rapid Publications, 2015
This paper describes a dual wavelength single longitudinal mode (SLM) demonstration for a propose... more This paper describes a dual wavelength single longitudinal mode (SLM) demonstration for a proposed ytterbium-doped fiber laser. A dualtapered Mach-Zehnder interferometer (MZI) was inserted into the laser ring cavity setup to ensure a stable dual wavelength and SLM operation. The consequent dual wavelength lasing operation had a wavelength spacing of 0.94 nm and a side mode suppression ratio (SMSR) of 50 dB, with the linewidth of this setup measured as 294.15 kHz. A stability test allowed for a measurement of max power fluctuation as less than 0.8 dB for each wavelength and which was indicative of a stable dual wavelength operation.
Laser Physics, 2015
This paper describes the setup and experimental results for an entirely centred erbium-doped fibe... more This paper describes the setup and experimental results for an entirely centred erbium-doped fiber laser with passively mode-locked output. The gain medium of the ring laser cavity configuration comprises a 3 m length of two-core optical fiber, wherein an undoped outer core region of 9.38 μm diameter surrounds a 4.00 μm diameter central core region doped with erbium ions at 400 ppm concentration. The generated stable soliton mode-locking output has a central wavelength of 1533 nm and pulses that yield an average output power of 0.33 mW with a pulse energy of 31.8 pJ. The pulse duration is 0.7 ps and the measured output repetition rate of 10.37 MHz corresponds to a 96.4 ns pulse spacing in the pulse train.
38th Annual IEEE Conference on Local Computer Networks - Workshops, 2013
Typically, many multi-hop wireless networks rely on routing protocols to form end-to-end routes t... more Typically, many multi-hop wireless networks rely on routing protocols to form end-to-end routes to deliver data packets from the sources to the respective destinations. In the case of link failures occur due to interference or node mobility, these protocols will try to reroute. When no alternative route is found, packets will be dropped as a result. As a way to improve the packet delivery ratio, these protocols can be extended to support the storecarry-forward features. We propose a hybrid approach to enable dynamic switching between mode of communication according to the link conditions. This is different from other existing solutions where the switching occur only when the end-to-end route fails, and packets will be delivered using another communication mode for the rest of the routing path. In this paper, we present the implementation of incorporating the dynamic switching into two routing protocols (AODV and OLSR) and conduct a performance study for the two hybrid protocols in a number of simulation based scenarios.
Australasian Telecommunication Networks and Applications Conference (ATNAC) 2012, 2012
Routing protocols are used to discover, maintain, and repair routes between pairs of nodes in wir... more Routing protocols are used to discover, maintain, and repair routes between pairs of nodes in wireless ad-hoc networks. In order to handle dynamic network topologies caused by node mobility, many routing protocols are designed with multiple features and parameters to effectively discover routes and to quickly detect link breaks. In this paper, we compare the performance of four popular routing protocols, AODV, DYMO, OLSR and HWMP, in terms of the Packet Delivery Ratio (PDR) metric, and analyse the various reasons for packet loss in scenarios where nodes are mobile. We also explore key protocol parameters and how their choice impacts the protocol performance. Based on our simulation results, we find that the way in which protocols detect link breaks is critical for overall network performance. We therefore specifically explore how the choice of link break detection parameters can improve protocol performance. We further explore other protocol variations and features and their potential for performance improvements.
2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008
Optimized Link State Protocol (OLSR) is a popular mobile ad-hoc network protocol. This paper disc... more Optimized Link State Protocol (OLSR) is a popular mobile ad-hoc network protocol. This paper discusses a multi-platform deployment of OLSR on multiple environments including the Linux platform, Windows platform and also PDA platform. Requirements that are needed to setup OLSR network will also be described and the comparison of the OLSR implementation on a different platform is discussed further
2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008
Mobility management is crucial for wireless connectivity which has become popular among mobile us... more Mobility management is crucial for wireless connectivity which has become popular among mobile users nowadays. Mobile IP has been developed in order to enable mobile appliances, such as notebooks, mobile phones and PDA. One of the crucial problems that need to be tackled is mobile network handover. Handover in Mobile IPv6 happens when a mobile node moves from one coverage area to another. However there are latency issues and possible packet loss during handover. This project focuses on MIPL (Mobile IP for Linux) handover analysis, particularly in simultaneous mobile nodes movement and consecutive mobility in Mobile IPv6, by looking at different scenarios and aspects. Findings on measurement of handover latency for Simultaneous Mobility were also included in this project, together with the consecutive mobility observation. Various experiments were conducted to determine the handoff latency between the mobile nodes. The testbed network experiments also identify the differences between standard Mobile IPv6 procedure and MIPL implementation in terms of Return Routability process, which is crucial for mobile nodes handoff latency improvements.
2010 Australasian Telecommunication Networks and Applications Conference, 2010
Wireless Mesh Networks (WMNs) have become one of the popular key technology and solution for the ... more Wireless Mesh Networks (WMNs) have become one of the popular key technology and solution for the new wireless implementation especially for wireless end user. One of the widely used routing protocols in WMNs is Ad-Hoc On-Demand Distance Vector (AODV) protocols. In this paper, we investigate the performance of AODV in situations of link failures due to mobility of nodes and consequent route recovery mechanism using ns2 simulators. We defined a different set of threshold for routing protocols to do local repair based on the link breaks location with respect to the total number of hops from source to destination. Packet Delivery Ratio (PDR) and Normalized Routing Load (NRL) or overhead were used as performance metrics in our simulations. For link-failure detection, HELLO message and Link Layer Feedback (LLF) were used separately in the simulations. Simulations were done by varying the number of sourcedestination pair and speed of the mobile node.
2010 7th International Conference on Ubiquitous Intelligence & Computing and 7th International Conference on Autonomic & Trusted Computing, 2010
2010 4th International Conference on Signal Processing and Communication Systems, 2010
One of the key challenges for routing protocols in wireless multi-hop networks is to deal with li... more One of the key challenges for routing protocols in wireless multi-hop networks is to deal with link failures, and to repair the routes in these situations. In the Ad-hoc On Demand Distance Vector (AODV) protocol, routes can either be repaired by re-establishing a new route from scratch starting from the source node (Source Repair), or they can be locally repaired by the node that detects the link break along the endto-end path (Local Repair). In some situations Source Repair will lead to better performance, in other situations Local Repair will be the more appropriate choice. In this work, we explore a flexible, parameterised approach in deciding on which of these two route repair strategies to use in the event of a link break. We define a Local Repair Threshold parameter that determines how far along the end-to-end path that a link break needs to occur in order to initiate Local Repair, as opposed to Source Repair. Our simulation results show that the optimal choice of the Local Repair Threshold, in terms of Packet Delivery Ratio, depends on the network load. We show that a flexible, parameterised and adaptive approach to choosing the Local Repair Threshold, can improve the Packet Delivery Ratio by up to 37% (in absolute terms), compared to the approach employed by standard AODV. We also show a significant potential improvement of up to 18% over the route repair strategy employed by the Dynamic On demand MANET (DYMO) routing protocol, which is based on AODV.
ABSTRACT With the explosive growth in Internet usage over the last decade, the need for a larger ... more ABSTRACT With the explosive growth in Internet usage over the last decade, the need for a larger address space is unavoidable, since all the addresses in IPv4 are nearly fully occupied. IPv6 (Deering & Hinden, 1998), with 128-bit addresses compared to IPv4 with 32-bit addresses and other advantages (like auto-configuration and IP mobility), can overcome many of the problems that IPv4 had before. One of the requirements for the modern Internet is IP mobility support. In IPv4, a special router is needed to act as a foreign agent in the visited/foreign network and the need of a network element in the home network known as a home agent for a mobile host. IPv6 does away with the need for the foreign agent and operates in any location without any special support from a local router. Route optimization is inherent in IPv6, and this feature eliminates the triangle-routing (routing through the home agent) problem that exists in IPv4. IPv6 enjoys many network optimizations that are already built in within IPv6.
2004 IEEE Region 10 Conference TENCON 2004., 2004
The concern on electromagnetic fields (EMF) which may has detrimental effects on human health has... more The concern on electromagnetic fields (EMF) which may has detrimental effects on human health has heightened public awareness towards the overhead power transmission lines. Frequency of the electrical power lines is typically in the range of 50/60 Hz and yet is classified as extremely low frequency (ELF). Recent studies conducted, are concentrating mainly towards the existence of Electric Field Intensity (E-field) and Magnetic Flux Density (B-field).
Laser Physics Letters, 2016
Wireless Personal Communications, 2016
Optical Engineering, 2016
Applied Optics, 2016
In this paper, stable dual-wavelength generation using a strain technique for a ytterbium-doped f... more In this paper, stable dual-wavelength generation using a strain technique for a ytterbium-doped fiber laser is successfully demonstrated. A microfiber-based Mach-Zehnder interferometer is inserted into the laser ring cavity and stretched using the xyz translation stage. Four sets of dual-wavelength output lasing are obtained when the strain is applied onto a microfiber. The dual-wavelength output possesses spacing between 7.12 and 11.59 nm, with displacement from 2 to 190 μm from the central wavelength. The obtained side-mode suppression ratio is ∼48 dBm, while the maximum power fluctuation and wavelength shift are less than 0.6 dB and 0.01 nm, respectively. The results demonstrate that this setup generates a stable dual-wavelength laser in the 1 μm region.
Mobile ad-hoc networks are infrastructure-free and highly dynamics wireless networks. There are m... more Mobile ad-hoc networks are infrastructure-free and highly dynamics wireless networks. There are many routing protocols for Mobile Ad Hoc Networks (MANET). One of the popular routing protocols is Optimized Link State Routing (OLSR). OLSR was developed to work independently from higher-layer protocols and it creates an underlying architecture for communication without the help of traditional fixed-position routers. In addition, OLSR attempts to maintain the communication routes for the mobile nodes that have limited transmission range. This paper discusses the OLSR implementation in terms of battery power status and its advantages particularly pertaining to the relationship between the power status function with the OLSR by modify some of the OLSR source code. The study also focuses on maximizing the use of the battery power sources. The results from the experiment show that the usage of the battery power sources left was maximally used when the “Willingness†for the nodes...
Journal of Modern Optics, 2015
Laser Physics, 2015
In this work, we demonstrate a simple Q-switched pulsed ring ytterbium-doped fiber laser based on... more In this work, we demonstrate a simple Q-switched pulsed ring ytterbium-doped fiber laser based on a few-layer TI:Bi 2 Se 3 saturable absorber (SA). Few-layer bismuth selenide within a suspension was induced onto a fiber ferrule at room temperature via an optical deposition method, resulting in a simple SA for the laser. Stable Q-switched pulsed lasing was achieved at a low pump threshold of 122.2 mW at 974 nm. The pulse repetition rate ranged from 18.97 to 45.41 kHz, and the narrowest pulse width and the maximum pulse energy were 13.1 μs and 5.88 nJ respectively. Results indicated that TI:Bi 2 Se 3 was also compatible with the 1 μm waveband, and hence could be considered a potential broadband SA for passively modelocked and Q-switched optical fiber lasers.
Journal of the European Optical Society: Rapid Publications, 2015
This paper describes a dual wavelength single longitudinal mode (SLM) demonstration for a propose... more This paper describes a dual wavelength single longitudinal mode (SLM) demonstration for a proposed ytterbium-doped fiber laser. A dualtapered Mach-Zehnder interferometer (MZI) was inserted into the laser ring cavity setup to ensure a stable dual wavelength and SLM operation. The consequent dual wavelength lasing operation had a wavelength spacing of 0.94 nm and a side mode suppression ratio (SMSR) of 50 dB, with the linewidth of this setup measured as 294.15 kHz. A stability test allowed for a measurement of max power fluctuation as less than 0.8 dB for each wavelength and which was indicative of a stable dual wavelength operation.
Laser Physics, 2015
This paper describes the setup and experimental results for an entirely centred erbium-doped fibe... more This paper describes the setup and experimental results for an entirely centred erbium-doped fiber laser with passively mode-locked output. The gain medium of the ring laser cavity configuration comprises a 3 m length of two-core optical fiber, wherein an undoped outer core region of 9.38 μm diameter surrounds a 4.00 μm diameter central core region doped with erbium ions at 400 ppm concentration. The generated stable soliton mode-locking output has a central wavelength of 1533 nm and pulses that yield an average output power of 0.33 mW with a pulse energy of 31.8 pJ. The pulse duration is 0.7 ps and the measured output repetition rate of 10.37 MHz corresponds to a 96.4 ns pulse spacing in the pulse train.
38th Annual IEEE Conference on Local Computer Networks - Workshops, 2013
Typically, many multi-hop wireless networks rely on routing protocols to form end-to-end routes t... more Typically, many multi-hop wireless networks rely on routing protocols to form end-to-end routes to deliver data packets from the sources to the respective destinations. In the case of link failures occur due to interference or node mobility, these protocols will try to reroute. When no alternative route is found, packets will be dropped as a result. As a way to improve the packet delivery ratio, these protocols can be extended to support the storecarry-forward features. We propose a hybrid approach to enable dynamic switching between mode of communication according to the link conditions. This is different from other existing solutions where the switching occur only when the end-to-end route fails, and packets will be delivered using another communication mode for the rest of the routing path. In this paper, we present the implementation of incorporating the dynamic switching into two routing protocols (AODV and OLSR) and conduct a performance study for the two hybrid protocols in a number of simulation based scenarios.
Australasian Telecommunication Networks and Applications Conference (ATNAC) 2012, 2012
Routing protocols are used to discover, maintain, and repair routes between pairs of nodes in wir... more Routing protocols are used to discover, maintain, and repair routes between pairs of nodes in wireless ad-hoc networks. In order to handle dynamic network topologies caused by node mobility, many routing protocols are designed with multiple features and parameters to effectively discover routes and to quickly detect link breaks. In this paper, we compare the performance of four popular routing protocols, AODV, DYMO, OLSR and HWMP, in terms of the Packet Delivery Ratio (PDR) metric, and analyse the various reasons for packet loss in scenarios where nodes are mobile. We also explore key protocol parameters and how their choice impacts the protocol performance. Based on our simulation results, we find that the way in which protocols detect link breaks is critical for overall network performance. We therefore specifically explore how the choice of link break detection parameters can improve protocol performance. We further explore other protocol variations and features and their potential for performance improvements.
2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008
Optimized Link State Protocol (OLSR) is a popular mobile ad-hoc network protocol. This paper disc... more Optimized Link State Protocol (OLSR) is a popular mobile ad-hoc network protocol. This paper discusses a multi-platform deployment of OLSR on multiple environments including the Linux platform, Windows platform and also PDA platform. Requirements that are needed to setup OLSR network will also be described and the comparison of the OLSR implementation on a different platform is discussed further
2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008
Mobility management is crucial for wireless connectivity which has become popular among mobile us... more Mobility management is crucial for wireless connectivity which has become popular among mobile users nowadays. Mobile IP has been developed in order to enable mobile appliances, such as notebooks, mobile phones and PDA. One of the crucial problems that need to be tackled is mobile network handover. Handover in Mobile IPv6 happens when a mobile node moves from one coverage area to another. However there are latency issues and possible packet loss during handover. This project focuses on MIPL (Mobile IP for Linux) handover analysis, particularly in simultaneous mobile nodes movement and consecutive mobility in Mobile IPv6, by looking at different scenarios and aspects. Findings on measurement of handover latency for Simultaneous Mobility were also included in this project, together with the consecutive mobility observation. Various experiments were conducted to determine the handoff latency between the mobile nodes. The testbed network experiments also identify the differences between standard Mobile IPv6 procedure and MIPL implementation in terms of Return Routability process, which is crucial for mobile nodes handoff latency improvements.
2010 Australasian Telecommunication Networks and Applications Conference, 2010
Wireless Mesh Networks (WMNs) have become one of the popular key technology and solution for the ... more Wireless Mesh Networks (WMNs) have become one of the popular key technology and solution for the new wireless implementation especially for wireless end user. One of the widely used routing protocols in WMNs is Ad-Hoc On-Demand Distance Vector (AODV) protocols. In this paper, we investigate the performance of AODV in situations of link failures due to mobility of nodes and consequent route recovery mechanism using ns2 simulators. We defined a different set of threshold for routing protocols to do local repair based on the link breaks location with respect to the total number of hops from source to destination. Packet Delivery Ratio (PDR) and Normalized Routing Load (NRL) or overhead were used as performance metrics in our simulations. For link-failure detection, HELLO message and Link Layer Feedback (LLF) were used separately in the simulations. Simulations were done by varying the number of sourcedestination pair and speed of the mobile node.
2010 7th International Conference on Ubiquitous Intelligence & Computing and 7th International Conference on Autonomic & Trusted Computing, 2010
2010 4th International Conference on Signal Processing and Communication Systems, 2010
One of the key challenges for routing protocols in wireless multi-hop networks is to deal with li... more One of the key challenges for routing protocols in wireless multi-hop networks is to deal with link failures, and to repair the routes in these situations. In the Ad-hoc On Demand Distance Vector (AODV) protocol, routes can either be repaired by re-establishing a new route from scratch starting from the source node (Source Repair), or they can be locally repaired by the node that detects the link break along the endto-end path (Local Repair). In some situations Source Repair will lead to better performance, in other situations Local Repair will be the more appropriate choice. In this work, we explore a flexible, parameterised approach in deciding on which of these two route repair strategies to use in the event of a link break. We define a Local Repair Threshold parameter that determines how far along the end-to-end path that a link break needs to occur in order to initiate Local Repair, as opposed to Source Repair. Our simulation results show that the optimal choice of the Local Repair Threshold, in terms of Packet Delivery Ratio, depends on the network load. We show that a flexible, parameterised and adaptive approach to choosing the Local Repair Threshold, can improve the Packet Delivery Ratio by up to 37% (in absolute terms), compared to the approach employed by standard AODV. We also show a significant potential improvement of up to 18% over the route repair strategy employed by the Dynamic On demand MANET (DYMO) routing protocol, which is based on AODV.
ABSTRACT With the explosive growth in Internet usage over the last decade, the need for a larger ... more ABSTRACT With the explosive growth in Internet usage over the last decade, the need for a larger address space is unavoidable, since all the addresses in IPv4 are nearly fully occupied. IPv6 (Deering & Hinden, 1998), with 128-bit addresses compared to IPv4 with 32-bit addresses and other advantages (like auto-configuration and IP mobility), can overcome many of the problems that IPv4 had before. One of the requirements for the modern Internet is IP mobility support. In IPv4, a special router is needed to act as a foreign agent in the visited/foreign network and the need of a network element in the home network known as a home agent for a mobile host. IPv6 does away with the need for the foreign agent and operates in any location without any special support from a local router. Route optimization is inherent in IPv6, and this feature eliminates the triangle-routing (routing through the home agent) problem that exists in IPv4. IPv6 enjoys many network optimizations that are already built in within IPv6.
2004 IEEE Region 10 Conference TENCON 2004., 2004
The concern on electromagnetic fields (EMF) which may has detrimental effects on human health has... more The concern on electromagnetic fields (EMF) which may has detrimental effects on human health has heightened public awareness towards the overhead power transmission lines. Frequency of the electrical power lines is typically in the range of 50/60 Hz and yet is classified as extremely low frequency (ELF). Recent studies conducted, are concentrating mainly towards the existence of Electric Field Intensity (E-field) and Magnetic Flux Density (B-field).