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A. S. M. Badrudduza

Publications and source records attributed to A. S. M. Badrudduza.

At least 19 recordsLinked to original sources
arXiv2025

Design and Performance Analysis of Hybrid FSO/THz Relay with Aerial RIS for Future NTN-Integrated 6G Wireless Communications

In the context of emerging sixth-generation (6G) wireless networks, reconfigurable intelligent surfaces (RISs) are gaining prominence for their ability to intelligently control electromagnetic wave propagation and enhance backhaul communication performance. In this paper, we propose a novel dual-hop wireless network, where the first hop consists of a hybrid free-space optics (FSO) / terahertz (THz) link, and the second hop incorporates an aerial RIS-based radio frequency (RF) link. To provide a comprehensive performance evaluation, a comparative analysis of two switching strategies is conducted: (1) hard switching and (2) soft switching. Novel closed-form expressions are derived for key performance metrics, including outage probability and bit error rate. These expressions are then utilized to investigate the impact of various system parameters. Our proposed hybrid model demonstrates a 52.54% performance improvement over the traditional RF-FSO framework. Moreover, the integration of an aerial RIS in the second hop enhances system performance by 41.39%. Numerical findings suggest that strategically placing the aerial RIS at a lower altitude and maintaining an equal, shorter distance from both communication endpoints significantly improves overall system performance. To analyze the response under high signal-to-noise ratio (SNR) conditions, asymptotic analysis is performed, and the diversity order of the system is determined. Finally, the analytical results are validated through a Monte Carlo simulation.

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arXiv2025

An Efficient Classification Model for Cyber Text

The uprising of deep learning methodology and practice in recent years has brought about a severe consequence of increasing carbon footprint due to the insatiable demand for computational resources and power. The field of text analytics also experienced a massive transformation in this trend of monopolizing methodology. In this paper, the original TF-IDF algorithm has been modified, and Clement Term Frequency-Inverse Document Frequency (CTF-IDF) has been proposed for data preprocessing. This paper primarily discusses the effectiveness of classical machine learning techniques in text analytics with CTF-IDF and a faster IRLBA algorithm for dimensionality reduction. The introduction of both of these techniques in the conventional text analytics pipeline ensures a more efficient, faster, and less computationally intensive application when compared with deep learning methodology regarding carbon footprint, with minor compromise in accuracy. The experimental results also exhibit a manifold of reduction in time complexity and improvement of model accuracy for the classical machine learning methods discussed further in this paper.

cs.LG↗
arXiv2025

Enhancing Physical Layer Security in IoT-Based RF-FSO Integrated Networks: Multi-RIS Structures and their Impact on Secure Communication

Due to their ability to dynamically control the propagation environment, reconfigurable intelligent surfaces (RISs) offer a promising solution to address the challenges of $6$G wireless communication, especially in the context of Internet of Things (IoT) networks. This paper investigates a mixed communication model with multi-RIS-aided radio frequency (RF)-free space optics (FSO) to enhance the performance of IoT applications in complex environments. An eavesdropper is assumed to be present, attempting to intercept confidential information transmitted over the RF link. All RF links are modeled using Rician fading, while the FSO link accounts for Málaga turbulence with pointing errors, capturing real-world propagation conditions. Closed-form analytical expressions are derived for the secrecy outage probability, average secrecy capacity, and effective secrecy throughput in terms of Meijer's G function. To gain further insight, high signal-to-noise approximations of these metrics are also presented. Numerical results highlight the importance of heterodyne detection in mitigating the adverse effects of pointing errors on the FSO link. Moreover, integrating a multi-RIS structure into the proposed model significantly increases secrecy performance, achieving up to a $47.67\%$ improvement in SOP compared to conventional methods. Finally, the derived analytical results are validated through Monte Carlo simulations.

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arXiv2024

RIS-Aided Free-Space Optics Communications in A2G Networks over Inverted Gamma-Gamma Turbulent Channels

With the advent of sixth-generation networks, reconfigurable intelligent surfaces (RISs) have revolutionized wireless communications through dynamic electromagnetic wave manipulation, thereby facilitating the adaptability and unparalleled control of real-time performance evaluations. This study proposed a framework to analyze the performance of RIS-assisted free-space optics (FSO) communication over doubly inverted Gamma-Gamma (IGGG) distributions with pointing error impairments. Furthermore, a special scenario addressing secure communication in the potential presence of an eavesdropper. Consequently, we derived closed-form expressions for the outage probability, average bit error rate, average channel capacity, average secrecy capacity, and secrecy outage probability by employing an asymptotic analysis to provide deeper insights into the influence of various system parameters. Finally, we verified our analytical results through appropriate numerical simulations.

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arXiv2024

Dual Threats in RIS-Aided RF-UOWC Mixed Networks: Secrecy Performance Analysis under Simultaneous RF and UOWC Eavesdropping

In the dynamic realm of 6G technology, emphasizing security is essential, particularly for optimizing high-performance communication. A notable strategy involves the use of reconfigurable intelligent surfaces (RISs), an emerging and cost-efficient technology aimed at fortifying incoming signals, broadening coverage, and ultimately improving the overall performance of systems. In this paper, we introduce a comprehensive framework to analyze the secrecy performance of an RIS-assisted mixed radio frequency (RF) - underwater optical wireless communication (UOWC) network. Here, all the RF links undergo alpha-mu fading distribution, whereas the UOWC links experience a mixture of Exponential Generalized Gamma distribution. Specifically, we examine three potential eavesdropping situations: 1) eavesdropping on the RF link, 2) eavesdropping on the UOWC link, and 3) a simultaneous eavesdropping attack affecting both RF and UOWC links. To achieve this, we derive novel mathematical expressions such as average secrecy capacity, secrecy outage probability, strictly positive secrecy capacity, and effective secrecy throughput in closed form. Using these derived expressions, we carry out an investigation to assess the influences of fading parameters, pointing errors, receiver detection technique, underwater turbulence severity, and water salinity on the system. Furthermore, our study investigates the significance of RIS in improving secrecy performance due to the proposed model. To provide deeper insights, we also perform asymptotic analysis for the high signal-to-noise region. Finally, to verify our analytical results, we conduct Monte Carlo simulation using a computer-based technique.

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arXiv2024

Secrecy Performance Analysis of Integrated RF-UWOC IoT Networks Enabled by UAV and Underwater-RIS

In the sixth-generation (6G) Internet of Things (IoT) networks, the use of UAV-mounted base stations and reconfigurable intelligent surfaces (RIS) has been considered to enhance coverage, flexibility, and security in non-terrestrial networks (NTNs). In addition to aerial networks enabled by NTN technologies, the integration of underwater networks with 6G IoT can be considered one of the most innovative challenges in future IoT. Along with such trends in IoT, this study investigates the secrecy performance of IoT networks that integrate radio frequency (RF) UAV-based NTNs and underwater optical wireless communication (UOWC) links with an RIS. Considering three potential eavesdropping scenarios (RF signal, UOWC signal, and both), we derive closed-form expressions for secrecy performance metrics, including average secrecy capacity, secrecy outage probability, probability of strictly positive secrecy capacity, and effective secrecy throughput. Extensive numerical analyses and Monte Carlo simulations elucidate the impact of system parameters such as fading severity, the number of RIS reflecting elements, underwater turbulence, pointing errors, and detection techniques on system security. The findings offer comprehensive design guidelines for developing such a network aiming to enhance secrecy performance and ensure secure communication in diverse and challenging environments.

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arXiv2023

RIS-aided Mixed RF-FSO Wireless Networks: Secrecy Performance Analysis with Simultaneous Eavesdropping

The appearance of sixth-generation networks has resulted in the proposal of several solutions to tackle signal loss. One of these solutions is the utilization of reconfigurable intelligent surfaces (RIS), which can reflect or refract signals as required. This integration offers significant potential to improve the coverage area from the sender to the receiver. In this paper, we present a comprehensive framework for analyzing the secrecy performance of a RIS-aided mixed radio frequency (RF)-free space optics (FSO) system, for the first time. Our study assumes that a secure message is transmitted from a RF transmitter to a FSO receiver through an intermediate relay. The RF link experiences Rician fading while the FSO link experiences Málaga distributed turbulence with pointing errors. We examine three scenarios: 1) RF-link eavesdropping, 2) FSO-link eavesdropping, and 3) a simultaneous eavesdropping attack on both RF and FSO links. We evaluate the secrecy performance using analytical expressions to compute secrecy metrics such as the average secrecy capacity, secrecy outage probability, strictly positive secrecy capacity, effective secrecy throughput, and intercept probability. Our results are confirmed via Monte-Carlo simulations and demonstrate that fading parameters, atmospheric turbulence conditions, pointing errors, and detection techniques play a crucial role in enhancing secrecy performance.

cs.IT↗
arXiv2023

Effects of Co-channel Interference on RIS Empowered Wireless Networks amid Multiple Eavesdropping Attempts

This letter is concerned with the secrecy performance of reconfigurable intelligent surfaces (RIS)-aided wireless networks in the existence of multiple interferers towards the destination. To be more precise, we analyze three critical issues in the design of secure RIS-assisted networks: 1) How do interferers affect the performance of secure wireless networks? 2) Which of the two groups of eavesdroppers (i.e., colluding and non-colluding) is more severe? 3) How can RIS improve network confidentiality? To do so, we develop the analytical expression of secrecy outage probability in closed-form, along with asymptotic analysis at high signal-to-noise ratio regime to better understand the impacts of different system parameters on secrecy performance. Finally, we validate our analytical results using a computer based Monte-Carlo simulation.

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arXiv2023

Secrecy Outage Analysis of Energy Harvesting Relay-based Mixed UOWC-RF Network with Multiple Eavesdroppers

This work deals with the physical layer security performance of a dual-hop underwater optical communication (UOWC)-radio frequency (RF) network under the intruding attempts of multiple eavesdroppers via RF links. The intermediate decode and forward relay node between the underwater source and the destination transforms the optical signal into electrical form and re-transmits it to the destination node with the help of harvested energy by the relay from an integrated power beacon within the system. The source-to-relay link (UOWC) follows a mixture exponential generalized Gamma turbulence with pointing error impairments whereas all the remaining links (RF) undergo $κ-μ$ shadowed fading. With regards to the types of intruders, herein two scenarios are considered, i.e., colluding (\textit{Scenario-I}) and non-colluding (\textit{Scenario-II}) eavesdroppers and the analytical expressions of secure outage probability, probability of strictly positive secrecy capacity, and effective secrecy throughput are derived in closed form for each scenario. Furthermore, the impacts of UOWC and RF channel parameters as well as detection techniques on secrecy capacity are demonstrated, and following this a comparison between the two considered scenarios is demonstrated that reveals the collusion between the eavesdroppers imposes the most harmful threat on secrecy throughput but a better secrecy level can be attained adopting diversity at the destination and power beacon nodes along with heterodyne detection rather than intensity modulation and direct detection technique. Finally, all the derived expressions are corroborated via Monte Carlo simulations.

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arXiv2021

On the Physical Layer Security Performance over RIS-aided Dual-hop RF-UOWC Mixed Network

Since security has been one of the crucial issues for high-yield communications such as 5G and 6G, the researchers continuously come up with newer techniques to enhance the security and performance of these progressive wireless communications. Reconfigurable intelligent surface (RIS) is one of those techniques that artificially rearrange and optimize the propagation environment of electromagnetic waves to improve both spectrum and energy efficiency of wireless networks. Besides, in underwater communication, underwater optical wireless communication (UOWC) is a better alternative/replacement for conventional acoustic and radio frequency (RF) technologies. Hence, mixed RIS-aided RF-UOWC can be treated as a promising technology for future wireless networks. This work focuses on the secrecy performance of mixed dual-hop RIS-aided RF-UOWC networks under the intercepting effort of a probable eavesdropper. The RF link operates under generalized Gamma fading distribution; likewise, the UOWC link experiences the mixture exponential generalized Gamma distribution. The secrecy analysis subsumes the derivations of closed-form expressions for average secrecy capacity, exact and lower bound of secrecy outage probability, and strictly positive secrecy capacity, all in terms of Meijer G functions. Capitalizing on these derivations, the effects of heterodyne and intensity modulation/direct detection systems, underwater turbulence resulting from air bubble levels, temperature gradients, and salinity gradients, are measured. Unlike conventional models that merely deal with thermally uniform scenarios, this proposed model is likely to be unique in terms of dealing with secrecy analysis of a temperature gradient RIS-aided RF-UOWC network. Lastly, the derivations are validated via Monte-Carlo simulations.

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arXiv2021

Opportunistic Relay Selection over Generalized Fading and Inverse Gamma Composite Fading Mixed Multicast Channels: A Secrecy Tradeoff

The secrecy performance of realistic wireless multicast scenarios can be significantly deteriorated by the simultaneous occurrence of multipath and shadowing. To resolve this security threat, in this work an opportunistic relaying-based dual-hop wireless multicast framework is proposed in which the source dispatches confidential information to a bunch of receivers via intermediate relays under the wiretapping attempts of multiple eavesdroppers. Two scenarios, i.e. non-line of sight (NLOS) and line of sight (LOS) communications along with the multiplicative and LOS shadowing are considered where the first scenario assumes eta-mu and eta-mu/inverse Gamma (IG) composite fading channels and the latter one follows kappa-mu and kappa-mu/IG composite fading channels as the source to relay and relay to receiver's as well as eavesdropper's links, respectively. Secrecy analysis is accomplished by deriving closed-form expressions of three familiar secrecy measures i.e. secure outage probability for multicasting, probability of non-zero secrecy multicast capacity, and ergodic secrecy multicast capacity. We further capitalize on those expressions to observe the effects of all system parameters which are again corroborated via Monte-Carlo simulations. Our observations indicate that a secrecy tradeoff between the number of relays and number of receivers, eavesdroppers, and shadowing parameters can be established to maintain the admissible security level by decreasing the detrimental influences of fading, shadowing, the number of multicast receivers and eavesdroppers.

cs.IT↗
arXiv2021

Enhancing Security of TAS/MRC Based Mixed RF-UOWC System with Induced Underwater Turbulence Effect

Post commercial deployment of fifth-generation (5G) technologies, the consideration of sixth-generation (6G) networks is drawing remarkable attention from research communities. Researchers suggest that similar to 5G, 6G technology must be human-centric where high secrecy together with high data rate will be the key features. These challenges can be easily overcome utilizing PHY security techniques over high-frequency free-space or underwater optical wireless communication (UOWC) technologies. But in long-distance communication, turbulence components drastically affect the optical signals, leading to the invention of the combination of radio-frequency (RF) links with optical links. This work deals with the secrecy performance analysis of a mixed RF-UOWC system where an eavesdropper tries to intercept RF communications. RF and optical links undergo $η-μ$ and mixture exponential generalized Gamma distributions, respectively. To keep pace with the high data rate of optical technologies, we exploit the antenna selection scheme at the source and maximal ratio combining diversity at the relay and eavesdropper, while the eavesdropper is unaware of the antenna selection scheme. We derive closed-form expressions of average secrecy capacity, secrecy outage probability, and strictly positive secrecy capacity to demonstrate the impacts of the system parameters on the secrecy behavior. Finally, the expressions are corroborated via Monte-Carlo simulations.

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arXiv2021

Opportunistic Relay in Multicast Channels with Generalized Shadowed Fading Effects: A Physical Layer Security Perspective

Through ordinary transmissions over wireless multicast networks are greatly hampered due to the simultaneous presence of fading and shadowing of wireless channels, secure transmissions can be enhanced by properly exploiting random attributes of the propagation medium. This study focuses on the utilization of those attributes to enhance the physical layer security (PLS) performance of a dual-hop wireless multicast network over kappa-mu shadow-fading channel under the wiretapping attempts of multiple eavesdroppers. In order to improve the secrecy level, the best relay selection strategy among multiple relays is employed. Performance analysis is carried out based on the mathematical modeling in terms of analytical expressions of non-zero secrecy capacity probability, secure outage probability, and ergodic secrecy capacity over multicast relay networks. Capitalizing on those expressions, the effects of system parameters, i.e., fading, shadowing, the number of antennas, destination receivers, eavesdroppers, and relays, on the secrecy performance are investigated. Numerical results show that the detrimental impacts caused by fading and shadowing can be remarkably mitigated using the well-known opportunistic relaying technique. Moreover, the proposed model unifies secrecy analysis of several classical models, thereby exhibiting enormous versatility than the existing works.

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arXiv2021

On Effective Secrecy Throughput of Underlay Spectrum Sharing $α$-$μ$/ Málaga Hybrid Model under Interference-and-Transmit Power Constraints

The underlay cognitive radio-based hybrid radio frequency / free-space optical (RF / FSO) systems have been emerged as a promising technology due to its ability to eliminate spectrum scarcity and spectrum under-utilization problems. Consequently, this work analyzes the physical layer security aspects of a cognitive RF / FSO hybrid network that includes a primary user, a secondary source, a secondary receiver, and an eavesdropper where the secret communication takes place between two legitimate secondary peers over the RF and FSO links simultaneously, and the eavesdropper can overhear the RF link only. In particular, the maximum transmit power limitation at the secondary user as well as the permissible interference power restriction at the primary user are also taken into consideration. All the RF links are modeled with $α$-$μ$ fading whereas the FSO link undergoes Málaga (M) turbulence with link blockage and pointing error impairments. At the receiver, the selection combining diversity technique is utilized to select the signal with the best electrical signal-to-ratio (SNR). Moreover, the closed-form expressions for the secrecy outage probability, probability of strictly positive secrecy capacity, and effective secrecy throughput are derived to analyze the secrecy performance. Besides, the impacts of fading, primary-secondary interference, detection techniques, link blockage probability, atmospheric turbulence, and pointing error are examined. Finally, Monte-Carlo simulations are performed to corroborate the derived expressions.

cs.IT↗
arXiv2021

On the Intercept Probability and Secure Outage Analysis of Mixed ($α$-$κ$-$μ$)-shadowed and Málaga Turbulent Model

This work deals with the secrecy performance analysis of a dual-hop RF-FSO DF relaying network composed of a source, a relay, a destination, and an eavesdropper. We assume the eavesdropper is located close to the destination and overhears the relay's transmitted optical signal. The RF and FSO links undergo ($α$-$κ$-$μ$)-shadowed fading and unified Málaga turbulence with pointing error. The secrecy performance of the mixed system is studied by deriving closed-form analytical expressions of secure outage probability (SOP), strictly positive secrecy capacity (SPSC), and intercept probability (IP). Besides, we also derive the asymptotic SOP, SPSC, and IP upon utilizing the unfolding of Meijer's G function where the electrical SNR of the FSO link tends to infinity. Finally, the Monte-Carlo simulation is performed to corroborate the analytical expressions. Our results illustrate that fading, shadowing, detection techniques (i.e., heterodyne detection (HD) and intensity modulation and direct detection (IM/DD)), atmospheric turbulence, and pointing error significantly affect the secrecy performance. In addition, better performance is obtained exploiting the HD technique at the destination relative to IM/DD technique.

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arXiv2021

Secrecy Performance of α-κ-μ Shadowed Fading Channel

In this paper, the physical layer security aspects of a wireless framework over α-\k{appa}-μ shadowed (AKMS) fading channel are examined by acquiring closed-form novel expressions of average secrecy capacity, secure outage probability (SOP), and strictly positive secrecy capacity. The lower bound of SOP is derived along with the asymptotic expression of SOP at the high signal-to-noise ratio regime in order to achieve secrecy diversity gain. Capitalizing on these expressions, the consequences due to the simultaneous occurrence of fading and shadowing are quantified. Finally, Monte-Carlo simulations are demonstrated to assess the correctness of the expressions.

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arXiv2021

Security Analysis in Multicasting over Shadowed Rician and α-μ Fading Channels: A Dual-hop Hybrid Satellite Terrestrial Relaying Network

In this era of 5G technology, the ever-increasing demands for high data rates lead researchers to develop hybrid satellite-terrestrial (HST) networks as a substitution to the conventional cellular terrestrial systems. Since an HST network suffers from a masking effect which can be mitigated by adopting the terrestrial relaying strategy, in this work, we focus on wireless multicasting through an HST relaying net-work (HSTRN) in which a satellite sends messages to multiple terrestrial nodes via multiple relays under the wiretapping efforts of multiple eavesdroppers. Our concern is to protect the multicast messages from being eavesdropped taking advantage of the well-known opportunistic relaying technique. We consider the satellite links follow Shadowed Rician fading whereas the terrestrial links undergo alpha-mu fading. The secrecy performance of the proposed HSTRN model is accomplished by deriving expressions for the probability of nonzero secrecy multicast capacity, ergodic secrecy multicast capacity, and secure outage probability for multicasting in closed-form. Capitalizing on the derived expressions, we analyze how a perfect secrecy level can be preserved in spite of harsh channel conditions and also present a secrecy trade-off in terms of the number of relays, multicast users, and multiple eavesdroppers. Finally, the numerical analyses are corroborated via Monte-Carlo simulations.

cs.IT↗
arXiv2021

Effects of Eavesdropper on the Performance of Mixed η-μ and DGG Cooperative Relaying System

Free-space optical (FSO) channel offers line-of-sight wireless communication with high data rates and high secrecy utilizing unlicensed optical spectrum and also paves the way to the solution of the last-mile access problem. Since atmospheric turbulence is a hindrance to an enhanced secrecy performance, the mixed radio frequency (RF)-FSO system is gaining enormous research interest in recent days. But conventional FSO models except for the double generalized Gamma (DGG) model can not demonstrate secrecy performance for all ranges of turbulence severity. This reason has led us to propose a dual-hop eta-mu and unified DGG mixed RF-FSO network while considering eavesdropping at both RF and FSO hops. The security of these proposed scenarios is investigated in terms of two metrics, i.e., strictly positive secrecy capacity and secure outage probability. Exploiting these expressions, we further investigate how the secrecy performance is affected by various system parameters, i.e., fading, turbulence, and pointing errors. A demonstration is made between heterodyne detection (HD) and intensity modulation and direct detection (IM/DD) techniques while exhibiting superior secrecy performance for HD technique over IM/DD technique. Finally, all analytical results are corroborated via Monte-Carlo simulations.

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