Summary
Eljack SM, Mustafa M. Learning–based stacking and caching for improving network lifetime in wireless sensor networks, International Journal of Communication Systems 2020, ...(https://doi.org/10.1002/dac.4707). The above article published online on 25 December 2020 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the Editor and John Wiley and Sons Ltd. Following publication, it has come to our attention that the people named as the Guest Editors of the Special Issue were being impersonated by a fraudulent entity and the articles were not reviewed in line with the journal's peer review standards. The Editor has determined that the articles do not meet the required scholarly standards of the journal, and therefore has taken the decision to retract the article. We did not find any evidence of misconduct by the authors. The authors have been informed of the decision to retract.
Enhanced Retransmission Scheme Multihop WiMAX Networks Ismael, Fath Elrahman; Babiker, Sarah Mustafa Eljack
2019 2nd International Conference on Computer Applications & Information Security (ICCAIS)
Conference Proceeding
IEEE 802.16j Mobile Multi-hop Relay (MMR) WiMAX network uses Relay Station (RS) to extend the cell coverage area and enhances the link quality and hence the throughput. It allows the number of hops ...between the SS and the BS to be more than two hops when Non-Transparent RS (NT-RS) is used. Automatic Repeat reQuest (ARQ) protocol is applied to the MAC layer to enhance the wireless link through retransmitting the corrupted packets. The sender realizes that the packet is lost either when it receives negative feedback from the receiver or when the waiting retry timeout is expired. However, when MMR WiMAX is considered, this requires modification to the ARQ retry timeout in order to enhance the link layer and TCP performances. Therefore, this paper presents hop aware ARQ retry timeout adjustment. The proposed scheme aims to decrease the delay of error recovery caused by long retry timeout and avoid un-necessary retransmission due to short retry timeout. The performances of the proposed schemes are simulated using TCP traffic. The results showed that the link layer and TCP performances are improved significantly.
This study aims to enhance the security of Moodle system environment during the Execution of online exams, Taking into consideration the most common problems facing online exams and working to solve ...them. This was handled by improving the security performance of Moodle Quiz tool, which is one of the most important tools in the learning Management system as general and in Moodle system as well. In this paper we include two enhancement aspects: The first aspect is solving the problem of losing the answers during sudden short disconnection of the network because of the server crash or any other reasons, the second aspect is Increasing the level of confidentiality of e-Quiz by preventing accessing the Quiz from more than one computer or browser at the same time. In order to verify the efficiency of the new quiz tool features, the upgraded tool have been tested using an experimental test Moodle site.
Traditional IP based networks, Frame Relay and ATM networks have many disadvantages in the management operation of large networks such as cost, security, scalability and flexibility. To solve this, ...an MPLS-based VPN networking is introduced that can work with existing deployed backbones and allow organizations to interconnect the dispersed sites and remote workers through secure links by using public internet. In this paper we tried to provide a better understanding of services provider large networks management operation; through focusing on the MPLS VPN technology. To get get familiar with the MPLS VPN networks behavior, we chose the interaction between routing protocols as a case study to evaluate the MPLS VPN networks performance. This work mainly focus on studying the effect of the interior gateway routing protocols in the MPLS VPN networks. We chose two famous protocols for investigation (OSPF and IS-IS) and we proposed two different scenarios and simulated them by using OPNET Modeler; then a deep analyses of the network performance was provided.
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