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Articles by Mohamed Othman
Total Records ( 13 ) for Mohamed Othman
  Monir Abdullah , Mohamed Othman , Hamidah Ibrahim and Shamala Subramaniam
  Scheduling an application in data grid was significantly complex and very challenging because of its heterogeneous in nature of the grid system. When the Divisible Load Theory (DLT) model had emerged as a powerful model for modeling data-intensive grid problem, Task Data Present (TDP) model was proposed based on it. This study presented a new Adaptive TDP (ATDP) for scheduling the intensive grid applications. New closed form solution for obtaining the load allocation was derived while computation speeds and communication links are heterogeneous. Experimental results showed that the proposed model can balance the load efficiently.
  Hayder Natiq Jasem , Zuriati Ahmad Zukarnain , Mohamed Othman and Shamala Subramaniam
  As the Internet becomes increasingly heterogeneous, the issue of congestion control becomes ever more important. And the queue length and end-to-end (congestion) delays are some of the important things in term of congestion avoidance and control mechanisms. In this research we continued to study the performances of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for TCP congestion avoidance and control mechanism, we want now to evaluate the effect of using the New-AIMD algorithm to measure the queue length and end-to-end delays and we will use the NCTUns simulator to get the results after make the modification of the mechanism. And we will use the Droptail mechanism as Active Queue Management (AQM) in the bottleneck router. After implementation of our new approach with different number of flows, we will measure the delay for two types of delays (queuing delay and end-to-end delay), we expect the delay will be less with using our mechanism comparing with the mechanism in the previous study. Now and after got this results as low delay for bottleneck link case, we know the New-AIMD mechanism work as well under the network condition in the experiments.
  Aminu Mohammed and Mohamed Othman
  Data sorting is an intriguing problem that has attracted some of the most intense research efforts in the field of computer science for both its theoretical importance and its use in many applications. Quicksort is widely considered to be one of the most efficient sorting techniques, which depends on an appropriate pivot selection technique for its performance. In this study, a sequential quicksort was implemented using six different pivot selection schemes for minimizing the execution time of quicksort algorithm. The schemes were tested together using integer array data type. From the results obtained, median-of-five without random index selection scheme minimizes the execution time of quicksort algorithm by about 23-35% as compared to the other techniques. The results also indicated that there is an overhead associated with random index selection and this can affect the performance of a particular method. Thus, this factor needs to be considered in selecting an optimal pivot selection scheme.
  Zeyad Ghaleb Al-Mekhlafi , Zurina Mohd Hanapi , Mohamed Othman , Zuriati Ahmad Zukarnain and Ahmed M. Shamsan Saleh
  Recent advances in the areas of Micro-electrical Mechanical Systems (MEMS) spurred the interest of researchers in Wireless Sensor Networks (WSNs). These networks are made up of sensor nodes which have the capability to sense, process and transmit gathered data of an environmental phenomenon of interest. Such synchronization is vital for the proper coordination of the power cycles for energy conservation. Here, a large presence of fireflies employ the principle of pulse coupled oscillators for the emission of light flashes for the attraction of mating partners. With respect to WSNs, the nodes are generally unable to afford packet transmission and reception simultaneously, thus preventing complete network synchronization. This study presents a literature overview concerning the energy efficient on aspect of clock synchronization in a wireless sensor network. In addition, the idea of data transmission based on synchronization can be ensured through the optimization of energy usage periodic data capturing in the wireless sensor network. This study serves as a useful source on clock synchronization to assist WSN researchers and novices to gain a better understanding of the energy efficient on aspect of clock synchronization in a wireless sensor network and to promote effective designs and systems that address this problem.
  Nadim K.M. Madi , Zurina Bt Mohd Hanapi , Mohamed Othman and Shamala Subramaniam
  The upcoming generations of cellular networks are foreseen to deliver a ubiquitous access to the rapid growing volume of mobile users. Therein, a stunning key feature of LTE is the ability to adapt the advancement in Radio Resource Management entity which scales up its potential to deal with multi-transmission scenarios by employing novel multi-antenna techniques on eNBs. This survey come in place to enlighten the aforementioned notions and deeply investigates the principles and approaches of LTE/LTE-A packet scheduling that are adapted in either Dl or UL channels. The main purpose of the study is to come out with a preliminary conceptual design of an optimal scheduling techniques in multi-cell heterogeneous environment keeping in mind the effects of inter-cell interference on the model overall QoS. Finally, it is recommended that a wise packet scheduling model for multi-cell LTE-A should involve an optimal trade-off between several QoS parameters having in mind interference mitigation as a main concern. Whereby, performance features of the known LTE/LTE-A scheduling categories, opportunistic scheduling, ICIC and CoMP can be realized in a single model.
  Ali Mohammed Al-Sharafi , Mohamed Othman , Md. Nasir Sulaiman and Shamala Subramaniam
  AMTree protocol is an active network based protocol that makes sending packets to receivers-after source migration-an efficient process. AMTree protocol was designed and tested for one mobile source sending to the multicast group. In this research we introduce a method that allows more than one mobile source to send to the multicast session. The results show that end-to-end latencies are minimized when more than one mobile source in the group compared to latencies for group with only one source.
  Muhammad Farhan Sjaugi , Mohamed Othman and Mohd. Fadlee A. Rasid
  Although DSR can respond a route quickly, it yields a long delay when a route is rebuilt. This is because when source node receives RERR packet, it will try to find alternative routes from the route cache. If alternative routes are not available, the source node, then, will enter route discovery phase to find new routes. We introduced a new route maintenance strategy by utilizing location information, called the DISTANCE (DIstance baSed rouTe maintenANCE) algorithm. The DISTANCE algorithm works by adding another node (called bridge node) into the source list to prevent the link from failure. From the simulation result, the DISTANCE algorithm improved the performance of DSR in terms of packet sending ratio, delay and routing overhead.
  Ali Mohammed Alsahag and Mohamed Othman
  Wireless Medium Access Control (MAC) protocols such as IEEE 802.11 use distributed contention resolution mechanisms for sharing the wireless channel. In this environment, selfish hosts that fail to adhere to the MAC protocol may obtain an unfair throughput share. For example, IEEE 802.11 requires hosts competing for access to the channel to wait for a "back-off" interval, randomly selected from a specified range, before initiating a transmission. Selfish hosts may wait for smaller back-off intervals than well-behaved hosts; thereby obtaining an unfair advantage. We show in this thesis that a greedy user can substantially increase his share of bandwidth, at the expense of the other users, by slightly modifying the driver of his network adapter. This study is a complementary of DOMINO System model to enhance the detection system in the MAC layer of IEEE 802.11; our enhanced system is a piece of software to be installed in or near the Access Point. The system can detect and identify greedy stations without requiring any modification of the standard protocol. We illustrate these concepts by simulation results.
  Mohamed Othman , Esam M. Abulhirat , Zulkarnain Md Ali , Mohd Rushdan Mohd Said and Rozita Johari
  Most of public-key cryptosystems rely on one-way functions. The cryptosystems can be used to encrypt and sign messages. The LUC Cryptosystem is a cryptosystem based on Lucas Functions. The encryption process used a public key which was known publicly and the decryption used a private key which was known only by sender and receiver of the messages. The performance of LUC cryptosystem computation influenced by computation of Ve the public key process and Vd the private key process. Very large scales of computations and timing overhead involved for large values of e and d. We are presenting the so-called Doubling with Remainder compared to the existing technique. It shows better performance in LUC computations by reducing time consumed in its computations. The experimental results of existing and new algorithm are included.
  Monir Abdullah , Mohamed Othman , Hamidah Ibrahim and Shamala Subramaniam
  Problem statement: In many data grid applications, data can be decomposed into multiple independent sub-datasets and distributed for parallel execution and analysis. Approach: This property had been successfully employed by using Divisible Load Theory (DLT), which had been proved as a powerful tool for modeling divisible load problems in data-intensive grid. Results: There were some scheduling models had been studied but no optimal solution has been reached due to the heterogeneity of the grids. This study proposed a new optimal load allocation based on DLT model recursive numerical closed form solutions are derived to find the optimal workload assigned to the processing nodes. Conclusion/Recommendations: Experimental results showed that the proposed model obtained better solution than other models (almost optimal) in terms of Makespan.
  Hayder Natiq Jasem , Zuriati Ahmad Zukarnain , Mohamed Othman and hamala Subramaniam
  Problem statement: As the Internet becomes increasingly heterogeneous, the issue of congestion control becomes ever more important. And the link utilization is one of the important things in term of congestion avoidance and control mechanisms. And we can define the utilization as simply the throughput divided by the access rate. And also all the developments for the congestion control and avoidance algorithms interest about the using of network resources and use the links capacity (utilization). Approach: In this research we continued to study the performances of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for TCP congestion avoidance and control mechanism, we want now to evaluate the effect of using the AIMD algorithm after developing it to find a new approach, as we called it the New-AIMD algorithm to measure the bottleneck link utilization and use the NCTUns simulator to get the results after make the modification of the mechanism. And we will use the Droptail mechanism as Active Queue Management (AQM) in the bottleneck router. Results: After implementation of our new approach with different number of flows, we will measure the bottleneck link utilization and we will get high utilization (more than 94%) for bottleneck link with using this mechanism and avoid the collisions in the link. Conclusion: Now and after got this results as high utilization for bottleneck link, we know the New-AIMD mechanism work as well under the giving network condition in the experiments.
  Ibrahim Abdullah and Mohamed Othman
  Problem statement: Mobile Internet Protocol (MIP) is the forms of the backbone for next generation wireless internet technology to provide uninterrupted network service while a node on the move. The original MIP use Home Agent to forward the traffic. Thus, it does not have problem with simultaneous mobility, i.e., the special case when both end nodes are mobile and move at about the same time. However, MIPv6 uses location binding updates which sent directly to a correspondent node to complete its registration. Thus, MIPv6 is vulnerable to the simultaneous mobility problem which leads to the interruption of communication and cause messages lost, especially protocol messages. Approach: This article analyzed the simultaneous and successive fast mobility problems and handover latency. Then propose a mechanism by adopting technique to the mobile node’s Home Agent. Results: We simulated the proposed scheme using ns-2 and we present and analyze the performance testing for the proposed scheme by comparing it with the conventional MIPv6. Conclusion: Simulation results showed this scheme can effectively resolve simultaneous and successive mobility problems and reduce the handover latency which is affected by long registration time.
  Davood Rezaei Pour , Mohamad Rushdan Md Said , Kamel Ariffin Mohd Atan and Mohamed Othman
  Problem statement: In this study, we proposed a new 64-bit block cipher that accepted a variable-length key up to 512 bits, which was suitable for implementation in a variety of environments. Approach: The cipher algorithm was a 16-round Feistel network with a bijective function f and was made up of two key-dependent 16×16 S-boxes, bitwise rotations, and a carefully designed key schedule. Results: The block cipher, what we called NBC08, was designed to perform under the powerful operations supported in today’s computers, resulting in an improved security/performance tradeoff over existing block ciphers. Conclusion: The study concluded the differential, linear and algebraic cryptanalysis on the NBC08 and showed that the cipher cannot be analyzed by any cryptanalytic attack. The statistical test results for NBC08 did not indicate a deviation from random behavior.
 
 
 
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