Browsing by Author "Raouf, Amir Hossein Fahim"

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Cache replacement scheme based on sliding window and TTL for video on demand
(IEEE, 2018-09-25) Raouf, Amir Hossein Fahim; Abouei, J.; Raouf, Amir Hossein Fahim
In this paper, we propose a novel two-phased cache replacement algorithm based on the dataset obtained from a typical wireless mesh network. In the first phase, we aim to make a trade-off between the networks resources and refresh the cache content. To deal with this issue, we apply a sliding window to propose a new parameter, called equivalent active time, to forecast the user's behaviour pattern, i.e., make a decision whether to update the cache contents or utilize the network's resources for other services. In the second phase, we introduce, for the first time, the parameter time to live (TTL) that shows the video popularity lifetime. Our proposed cache replacement strategy uses frequency counters and the TTL information in the victim selection process to prevent the cache pollution and make better use of the cache space. Numerical results show that our replacement algorithm outperforms some existing cache replacement strategies in term of a portion of satisfied requests.
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Multi-hop quantum key distribution with passive relays over underwater turbulence channels
(The Optical Society, 2020-12-01) Raouf, Amir Hossein Fahim; Safari, M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Raouf, Amir Hossein Fahim
Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communication links. In this paper, as a potential solution to overcome range limitations, we investigate a multi-hop underwater quantum key distribution (QKD) where intermediate nodes between the source and destination nodes help the key distribution. We consider the deployment of passive relays that simply redirect the qubits to the next relay node or the receiver without any measurement. Based on the near-field analysis, we present the performance of a relay-assisted QKD scheme in terms of quantum bit error rate and secret key rate in different water types and turbulence conditions. We further investigate the effect of system parameters such as aperture size and detector field of view on the performance. Our results demonstrate under what conditions relay-assisted QKD can be beneficial and what end-to-end transmission distances can be supported with a multi-hop underwater QKD system.
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Multi-hop quantum key distribution with passive relays over underwater turbulence channels
(IEEE, 2020) Raouf, Amir Hossein Fahim; Safari, M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Raouf, Amir Hossein Fahim
Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communications. In this paper, to overcome range limitations, we investigate a multi-hop underwater quantum key distribution (QKD) where intermediate nodes help the key distribution between the source and destination nodes. We consider deployment of passive-relays which simply redirect the qubits to the next relay node or receiver without any measurement. Based on nearfield analysis, we present the performance of relay-assisted QKD scheme in clear ocean under different atmospheric conditions. We further investigate the effect of system parameters (aperture size and detector field-of-view) on the achievable distance.
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On the optimization of underwater quantum key distribution systems with time-gated SPADs
(Optica Publishing Group, 2022-08-01) Raouf, Amir Hossein Fahim; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat
In this paper, we study the effect of various transmitter and receiver parameters on the quantum bit error rate (QBER) performance of underwater quantum key distribution. We utilize a Monte Carlo approach to simulate the trajectories of emitted photons transmitting in water from the transmitter towards the receiver. Based on propagation delay results, we first determine a proper value for the bit period to avoid intersymbol interference as a result of possible multiple scattering events. Then, based on the angle of arrival of the received photons, we determine a proper field of view to limit the average number of received background noise. Finally, we determine the optimal value for the single photon avalanche diode gate time in the sense of minimizing the QBER for the selected system parameters and given propagation environment.
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Performance analysis of decoy state quantum key distribution over underwater turbulence channels
(Optica Publishing Group, 2022-06-01) Raouf, Amir Hossein Fahim; Safari, M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Raouf, Amir Hossein Fahim
Decoy state quantum key distribution protocols have been studied for atmospheric, fiber, and satellite links; however, those results are not directly applicable to underwater environments with different channel characteristics. In this paper, we investigate the fundamental performance limits of decoy state BB84 protocol over turbulent underwater channels and provide a comprehensive performance characterization.We adopt a near field analysis to determine the average power transfer over a turbulent underwater path and use this to obtain a lower bound on the secret key rate.We quantify the performance of decoy BB84 protocol in different water types assuming various turbulence conditions.We further investigate the effect of system parameters such as transmit aperture size and detector field of view on the performance.
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Performance analysis of quantum key distribution in underwater turbulence channels
Raouf, Amir Hossein Fahim; Uysal, Murat; Uysal, Murat; Durak, Kadir; Karakaya, B.; Department of Electrical and Electronics Engineering; Raouf, Amir Hossein Fahim
The current literature on quantum key distribution (QKD) is mainly limited to the transmissions over ber optic, atmospheric or satellite links and are not directly applicable to underwater environments with di erent channel characteristics. Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communication links. In the rst part of this thesis, we analyze the quantum bit error rate (QBER) and secret key rate (SKR) performance of the well-known BB84 protocol in underwater channels. As path loss model, we consider a modi ed version of Beer-Lambert formula which takes into account the e ect of scattering. We derive a closed-form expression for the wave structure function to determine the average power transfer over turbulent underwater path and use this to obtain an upper bound on QBER as well as a lower bound on SKR. Based on the derived bounds, we present the performance of BB84 protocol in di erent water types including clear, coastal and turbid water and under di erent atmospheric conditions such as clear, hazy and overcast. We further investigate the e ect of system parameters such as aperture size and detector eld-of-view on QBER and SKR performance metrics. In the second part of this thesis, as a potential solution to overcome range limitations, we investigate a multi-hop underwater QKD where intermediate nodes between the source and destination nodes help the key distribution. We consider the deployment of passive relays which simply redirect the qubits to the next relay node or the receiver without any measurement. Based on the near- eld analysis, we present the performance of relay-assisted QKD scheme in terms of quantum bit error rate and secret key rate in di erent water types and turbulence conditions. We further investigate the e ect of system parameters such as aperture size and detector eld-of-view on the performance. Our results demonstrate under what conditions relay-assisted QKD can be bene cial and what end-to-end transmission distances can be supported with a multi-hop underwater QKD system. In the last part of this thesis, we investigate the fundamental performance limits of decoy BB84 protocol over turbulent underwater channels and provide a comprehensive performance characterization. As path loss model, we consider a modi ed version of Beer-Lambert formula, which takes into account the e ect of scattering. Based on near eld analysis, we utilize the wave structure function to determine the average power transfer over turbulent underwater path and use this to obtain a lower bound on key generation rate. Based on this bound, we present the performance of decoy BB84 protocol in di erent water types (clear and coastal). We further investigate the e ect of transmit aperture size and detector eld of view.
Metadata only
Performance analysis of quantum key distribution in underwater turbulence channels
(The Optical Society, 2020) Raouf, Amir Hossein Fahim; Safari, M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Raouf, Amir Hossein Fahim
The current literature on quantum key distribution is limited mainly to transmissions over fiber optic, atmospheric, or satellite links and is not directly applicable to underwater environments with different channel characteristics. In this paper, we analyze the quantum bit error rate (QBER) and secret key rate (SKR) performance of the well-known BB84 protocol in underwater channels. As a path loss model, we consider a modified version of the Beer-Lambert formula, which takes into account the effect of scattering. We derive a closed-form expression for the wave structure function to determine the average power transfer over a turbulent underwater path and use this to obtain an upper bound on QBER as well as a lower bound on SKR. Based on the derived bounds, we present the performance of the BB84 protocol in different water types including dear, coastal, and turbid and under different atmospheric conditions such as clear, hazy, and overcast. We further investigate the effect of system parameters such as aperture size and detector field of view on QBER and SKR performance metrics.