R Badlishah Ahmad
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Preferred name
R Badlishah Ahmad
Official Name
R Badlishah, Ahmad
Alternative Name
Ahmad, R. Badlishah
Ahmad, B.
Badlishah Ahmad, R.
Ahmad, Rashidi
Ahmad, Badlisha
Ahmed, R. Badlishah
Ahmad, R. B.
Badlishah, R.
Ahmad, R. Badli
Ahmed, Rbadlishah
Main Affiliation
Scopus Author ID
57194844651
Researcher ID
U-3211-2019

Research Output

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Hybrid OCDMA/WDM system using Spectral Direct Detection technique for Gigabit Passive Optical Network application

2017-01-01 , S.M. Monirul Islam , Nasim Ahmed , Sharafat Ali , Rahman M. , Syed Alwee Aljunid Syed Junid , R Badlishah Ahmad

This study a hybrid Optical Code Division Multiple Access (OCDMA) over Wavelength Division Multiplexing (WDM) network is proposed to supporting large numbers of subscribers for Gigabit Passive Optical Network (GPON). Gigabit Passive Optical Network (GPON) is a developing innovation for satisfying high transfer speed interest of clients with long separation scope. In this study, the Modified Double Weight (MDW) code is used as signature address to designing the system regarding this code can accommodate huge number of simultaneously active users. The simulation model of GPON systems is derived by Spectral Direct Detection (SDD) technique which has been developed for the analysis of feasibility and implementation issues of the application. The aim was to analyse the impact of the most important parameters of the components that are needed for new network elements. On the basis of the results achieved (e.g., =10-10) the optimal of the GPON system for 20 km fibre length. Hence, this system can be considered as a promising solution for gigabit passive optical network application.

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On the effectiveness of congestion control mechanisms for remote healthcare monitoring system in IoT environment - A review

2017-01-03 , Wan Aida Nadia Wan Abdullah , Naimah Yaakob , R Badlishah Ahmad , Amiza Amir , Siti Asilah Yah

A progressive advancement in biosensors and wireless technology are the major contributors to the realization of continuous remote health monitoring system (RHMS). Wireless Body Area Network (WBAN) is part of this technology due to the deployment of multiple sensors such as Electrocardiogram (ECG) to collect vital body signals for processing and diagnosis. Among the benefits offered by this technology include remote monitoring of patient's health status and early detection of abnormalities in the collected signals. Once detected, several preventive measurements can be taken. However, this system needs to encounter some challenges in the wireless network such as delay, packet loss and throughput due to network congestion when transmitting and receiving a bulk of multiple data. Generally, the presence of these problems in transmitting vital body signals may result in incorrect medical diagnosing which can increase mortality rate and cause severe impact to the overall system's performance. Thus, a suitable design of congestion control mechanism is urgently needed in designing a reliable and efficient remote health monitoring system.

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Minimum Power Allocation Cooperative Communication based on Health-Care WBAN

2020-03-20 , Hammood D.A. , Alkhayyat A. , Hasliza A Rahim @ Samsuddin , R Badlishah Ahmad

Energy is limited resource in the Wireless Body Area Network (WBAN). Finding optimal and minimum required transmission power that can achieve a certain level of utility while utilizing as little power for transmission as possible plays an important role in reducing energy consumption. In this paper, we found the required transmission power of four transmission modes: the direct transmission mode, the dual-hop transmission mode, and two incremental cooperative transmission modes with Rayleigh channel fading.

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Modeling and performance evaluation of antennas coated using monolayer graphene in the millimeter and sub-millimeter wave bands

2021-08-01 , Gatte M.T. , Soh Ping Jack , Kadhim R.A. , Abd H.J. , R Badlishah Ahmad

In the applications of millimeter and sub-millimeter wave, the conductivity of metal parts in electronic devices can easily degrade when conventional metals like copper are employed. Furthermore, oxidation may arise when such devices are utilized in severe environmental conditions. To avoid this, conventional conductors such as copper can be coated with other non-active materials to inhibit this problem. Monolayer graphene is used in this study as a coating layers for copper in millimeter-wave antennas. Two types of graphene coatings are investigated: non-doped and doped monolayer graphene. These coatings can either be used as the patch, ground or both conducting layers of a microstrip patch antenna. Results showed that coating using doped graphene improves the performance of antenna in terms of gain, radiated power and radiation efficiency by 11.81%, 8.48%, and 11.48%, respectively, compared to antennas made using copper and coated using gold and non-doped graphene at millimeter-wave frequencies. Meanwhile, at sub-millimeter wave frequencies, the metal (copper and gold)-based antenna showed worse performance compared to millimeter waves. Furthermore, coating of the conducting elements for the sub-millimeter wave antenna using doped and non-doped graphene improved gain, radiated power and radiation efficiency by 33.94%, 32.73%, and 32.01%, respectively, for the coating with doped graphene, and about 14.87%, 16.56%, and 15.72% for the coating with non-doped graphene. This indicates the suitability of graphene-based antennas in both frequency bands and the expected levels of improvements for different parameters when these antenna elements are coated with doped and non-doped graphene.

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A Review on Implementation of AES Algorithm Using Parallelized Architecture on FPGA Platform

2023-01-01 , Mohammed N.Q. , Amiza Amir , R Badlishah Ahmad , Salih M.H. , Arrfou H. , Thalji N. , Matem R. , Abbas J.K.K. , Hussien Q.M. , Abdulhassan M.M.

High-security cryptography algorithms like AES require high computational capabilities to achieve information security. Therefore, it is necessary to use parallel computing architectures that exploit modern technologies to obtain the most conceivable computational power. Various methods have been introduced to achieve parallel processing. One of them is field-programmable gate arrays (FPGAs), which have good characteristics suitable for implementing parallel architectures with lower power consumption. This paper will focus on the most important FPGA boards that were used to implement the AES cryptographic algorithm. In addition, it demonstrates the general scheme of building architecture with multiple computing processing engines to get high performance and better throughput, which is reflected in the reduced cost and energy consumption of IoT devices.

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Cross-Talk in Mechanomyographic Signals from the Forearm Muscles during Sub-Maximal to Maximal Isometric Grip Force

2014 , Md. Anamul Islam , Kenneth Sundaraj , R Badlishah Ahmad , Sebastian Sundaraj , Nizam Uddin Ahamed , Md. Asraf Ali

Purpose This study aimed: i) to examine the relationship between the magnitude of cross-talk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles with the sub-maximal to maximal isometric grip force, and with the anthropometric parameters of the forearm, and ii) to quantify the distribution of the cross-talk in the MMG signal to determine if it appears due to the signal component of intramuscular pressure waves produced by the muscle fibers geometrical changes or due to the limb tremor. Methods Twenty, right-handed healthy men (mean ± SD: age  = 26.7±3.83 y; height  = 174.47±6.3 cm; mass  = 72.79±14.36 kg) performed isometric muscle actions in 20% increment from 20% to 100% of the maximum voluntary isometric contraction (MVIC). During each muscle action, MMG signals generated by each muscle were detected using three separate accelerometers. The peak cross-correlations were used to quantify the cross-talk between two muscles. Results The magnitude of cross-talk in the MMG signals among the muscle groups ranged from, R2(x, y) = 2.45-62.28%. Linear regression analysis showed that the magnitude of cross-talk increased linearly (r2 = 0.857-0.90) with the levels of grip force for all the muscle groups. The amount of cross-talk showed weak positive and negative correlations (r2 = 0.016-0.216) with the circumference and length of the forearm respectively, between the muscles at 100% MVIC. The cross-talk values significantly differed among the MMG signals due to: limb tremor (MMGTF), slow firing motor unit fibers (MMGSF) and fast firing motor unit fibers (MMGFF) between the muscles at 100% MVIC (p<0.05, η2 = 0.47-0.80). Significance The results of this study may be used to improve our understanding of the mechanics of the forearm muscles during different levels of the grip force.

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Pilot spacing controller in orthogonal frequency division multiplexing systems

2020-03-20 , Hassan M.S.A. , R Badlishah Ahmad , Norazila Shoib

As the backbone of the fifth generation, 5G communications, Orthogonal Frequency Division Multiplexing, OFDM is seen to be reliable in addressing Inter-symbol Interference, ISI issues as well as providing high-speed access to broadband. Channel estimation and tracking are generally carried out by transmitting known pilot symbols in given positions of the frequency-time grid. However, the use of a fixed amount of pilot for all channel circumstances is hugely detrimental. Several methods, especially on block-type and comb-type pilot arrangement, have presented. In this paper, the method of determining the pilot space depends on the current channel quality. The proposed technique focused on improving estimation and bandwidth in time-varying and frequency-selective fading channels without increasing the complexity and sacrifice the bandwidth efficiency of the OFDM system.

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Green Nanocomposite-Based Metamaterial Electromagnetic Absorbers: Potential, Current Developments and Future Perspectives

2020-01-01 , Yah N.F.N. , Rahim H.A. , Soh Ping Jack , Abdulmalek M. , R Badlishah Ahmad , Muzammil Jusoh , Seng L.Y. , Jamaluddin M.H. , Mohd Najib Mohd Yasin

The use of the natural materials instead of conventional materials as electromagnetic absorbers promotes environmental sustainability, cost-effectiveness, and ease of accessibility. Furthermore, these materials may also be designed as absorbers and as reinforcements in building materials in a lightweight form. The absorbing ability of composite materials can be customized based on the chosen fillers. Specifically, magnetic and dielectric fillers can be incorporated to improve the absorption of a composite material compared to traditional materials. This work aims to review recent developments of electromagnetic absorbers enabled by nanocomposites, metamaterial and metasurface-based, as well as green composite alternatives. First, the background concepts of electromagnetic wave absorption and reflection will be presented, followed by the assessment techniques in determining electromagnetic properties of absorbing materials. Next, the state-of-the-art absorbers utilizing different materials will be presented and their performances are compared. This review concludes with a special focus on the future perspective of the potential of metamaterial based nanocellulose composites as ultrathin and broadband electromagnetic absorbers.

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Traffic engineering provisioning of multipath link failure recovery in distributed SDN controller environment

2024-02-08 , Kelian V.H. , Mohd Warip M.N. , R Badlishah Ahmad , Ehkan P. , Fazrul Faiz Zakaria , Mohd Zaizu Ilyas

A revolutionary networking technology called Software-Defined Networking (SDN) enables better networking flexibility. In contrast to the conventional network, it provides another option for network development. SDN is characterized by the separation of the control and data planes in network architecture, implementation, and management. The central component of the network is the controller, which constitutes the control plane. The appropriate selection of a controller, along with determining the number and placement of controllers, plays a crucial role in optimizing resource utilization and guaranteeing network availability and network performance. Since SDN is still in its beginnings of development, it is virtually certain that further study will be needed in areas like design, particularly on the control plane, since the architecture directly affects the network's total performance. Furthermore, despite its intended purpose of managing networks on a large scale, SDN still presents challenges in effectively addressing network dynamics, such as the occurrence of link failures. This study presents a concept for the implementation of an SDN architecture. The proposed approach involves utilizing an Open Network Operating System (ONOS) open-source distributed SDN controller. The purpose of this implementation is to analyze network performance metrics and assess network availability. This study investigates the distributed SDN controller's performance on different scale networks: NSF, AEON, and TM topologies. Several metrics have been analyzed, including throughput, link failure detection, and Round-Trip-Time (RTT). The experiments use Mininet for emulation and Wireshark for real-time data packet capture and analysis. According to the study results, there is a positive correlation between network design complexity and controller load. The experiment emphasizes the resilience of distributed controllers, such as ONOS, in effectively recovering from link failures. This research will help academics and businesspeople who use distributed SDN controllers choose a controller and evaluate its effectiveness on the analyzed network architectures.

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A comprehensive performance evaluation of MIPv6 and PMIPv6 mobility management protocols in wireless mesh network

2021-01-01 , Hoh W.S. , Yoon S.K. , Ong B.L. , R Badlishah Ahmad

Wireless communication is becoming essential due to the dramatic increase in the usage of mobile devices. The high demand for real-time or instant services requires wireless Internet networks which can support different Quality of Service (QoS) guarantees and different traffic characteristics. All Internet network mobile device services are supported by mobility management protocols. In this paper, we compare the performance of the MIPv6 and PMIPv6 mobility management protocols in the Wireless Mesh Network (WMN) environment. We identify and analyze the MIPv6 and PMIPv6 mobility management protocols' characteristics by using performance indicators. The performance comparison of MIPv6 and PMIPv6 mobility management protocols was conducted in terms of throughput, latency, and packet loss ratio. Based on the conducted experimental results, we summarize the performances for MIPv6 and PMIPv6 mobility management protocols in the Wireless Mesh Network environment. The results obtained indicate that PMIPv6 generally outperforms MIPv6. In future work, the evaluation of HMPIv6, FMIPv6, and FHMIPv6 is proposed.

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