Ali A. Hammadi

Dr. Ali A. Hammadi

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Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 November 2022 in IEEE Transactions on Vehicular Technology
Verified
Journal Article
Closed access
MBMohammed S. Bahbahani
Mohammed S. Bahbahani
EAEmad Alsusaz
Emad Alsusaz
AHAli A. Hammadi
Ali A. Hammadi
Future vehicular wireless applications, such as autonomous and remote driving, will demand High Throughput Ultra-Reliable Low Latency Communication (HT-URLLC) unsupported by current wireless standards. Hybrid network designs that combine Millimeter-Wave (mmWave) and Sub-6GHz communications were recently proposed to establish HTURLLC in Vehicle-To-Everything (V2X) networks. To enable such integration, new Medium Access Control (MAC) protocols must be developed. As such, we consider a linear vehicular network, in which vehicles driving closely in the same lane utilize both front and rear directional mmWave antennas to form a Lane Cluster (LC). Data packets, then, propagate forwards and backwards along the LC towards its terminals in a multihop fashion. In turn, the LC terminals utilize omnidirectional antennas at Sub-6GHz frequencies to disseminate the cluster's packets to nearby LCs, Road Side Units (RSUs), and cellular base stations. To resolve the channel contention between subsequent LC members, we devised a two-timeslot MAC scheme with a schedule alignment mechanism. Additionally, we developed centralized and distributed schedule coordination protocols aligning the schedules of adjacent LCs to mitigate cross-lane interference due to antenna beam misalignment. The proposed protocols were evaluated using VEINS (extension of OMNET++ network simulator) and compared against the CSMA-CA scheme of IEEE 802.11p under different parameters and scenarios. The results show that the proposed linear topology along with the scheduling protocols can potentially achieve HT-URLLC while addressing the mmWave practicality issues.

10 March 2022 in IEEE/ACM Transactions on Networking
Verified
Journal Article
Open access
ZNZaid H Nasralla
Zaid H Nasralla
TETaisir E. H. Elgorashi
Taisir E. H. Elgorashi
AHAli A. Hammadi
Ali A. Hammadi
MMMohamed O. I. Musa
Mohamed O. I. Musa
JEJaafar M. H. Elmirghani
Jaafar M. H. Elmirghani
A disaster may not necessarily demolish the telecommunications infrastructure, but instead it might affect the national grid and cause blackouts, consequently disrupting the network operation unless there is an alternative power source(s). In disaster-resilient networks, fiber cut, datacenter destruction, and node isolation have been studied before with different scenarios, but the power outage impact has not been investigated before. In this paper, power outages are considered, and the telecommunication network performance is evaluated during a blackout. A mixed Integer Linear Programming (MILP) model is developed to evaluate the network performance for a single node blackout under two scenarios: minimization of blocking and minimization of renewable and battery energy consumption. Insights analyzed from the MILP model results have demonstrated the trade-off between the two evaluated optimization cost functions and shown that the proposed scheme can extend the network lifetime while minimizing the required amount of backup energy.

6 May 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
AHAli A. Hammadi
Ali A. Hammadi
ZNZaid H Nasralla
Zaid H Nasralla
As the Internet grows in capacity, the energy consumption of Information and Communication Technologies (ICT) are significantly increasing. Significant research efforts on energy conservation have been devoted to devise different technological solutions to address raised concerns surrounding the power consumption of networking equipment and its impact firstly on the emission of greenhouse gases and secondly on electricity bills. In this work, we investigate energy-efficient physical topologies for NSF IP over wavelength-division multiplexing (WDM) network for the purpose of minimizing energy consumption by redesigning its current physical connectivity. We implement different network topologies, such as implementing the small-world, scale-free (SFN), and random networks on the NSF network, then evaluate and compare its physical properties and network power consumption with the current NSF topology design using a mixed-integer linear programming model, all with the aim of minimizing the network total power consumption. The evaluation shall optimize and minimize the embodied energy consumption of network equipment in the IP and optical layers. Results have demonstrated that the implementation of the proposed energy-minimized topology designs can significantly improve the node’s clustering coefficient, reduce network’s diameter, and reduce energy consumption of the NSF IP over WDM network to 28% if compared with the current design implementation.