Octavia A. Dobre

• Memorial University of Newfoundland

Driven by the proliferating Internet of Everything (IoE) applications, satellite communication emerges as a key enabling technology to establish an omnidirectional network architecture for global IoE service provision. IoE yields a significant paradigm shift from enhanced mobile broadband services to ultra-reliable low-latency communications. In th...

This manuscript introduces a novel energy-efficient optimization strategy for a zero-energy reconfigurable intelligent reflecting surface (Ze-RIS) supported backscatter communication system employing non-orthogonal multiple access (NOMA). The central objective is to maximize the energy efficiency of the system by optimizing the several key paramete...

This survey provides a comprehensive analysis of the integration of Reconfigurable Intelligent Surfaces (RIS) with edge computing, underscoring RIS’s critical role in advancing wireless communication networks. The examination begins by demystifying edge computing, contrasting it with traditional cloud computing, and categorizing it into several typ...

This paper investigates a computation resource optimization problem of mobile edge computing (MEC)-aided Internet-of-Things (IoT) devices with a reinforcement learning (RL) solution. Specifically, we leverage the stochastic optimization method and formulate the Lyapunov optimization technique to maximize the long-term energy efficiency, taking into...

Low Earth Orbit (LEO) satellite communication (SatCom) has drawn particular attention recently due to its high data rate services and low round-trip latency. It has low launching and manufacturing costs than Medium Earth Orbit (MEO) and Geostationary Earth Orbit (GEO) satellites. Moreover, LEO SatCom has the potential to provide global coverage wit...

Deep learning (DL)-based specific emitter identification (SEI) is a potential physical layer authentication technique for Industrial Internet-of-Things (IIoT) Security, which detects the individual emitter according to its unique signal features resulting from transmitter hardware impairments. The success of DL-based SEI often depends on sufficient...

Visible light communication (VLC) is envisioned as a core component of future wireless communication networks due to, among others, the huge unlicensed bandwidth it offers and the fact that it does not cause any interference to existing radio frequency (RF) communication systems. In order to take advantage of both RF and VLC, most research on their...

This paper investigates a novel maritime wireless surveillance scenario, where a legitimate monitor vessel moves around to eavesdrop the suspicious communication from a suspicious unmanned aerial vehicle (UAV) to a suspicious vessel with the help of a cooperative UAV. Specifically, the cooperative UAV can adjust its jamming power and trajectory to...

A frequency-domain cepstrum correlation and temporal transient filtered radio frequency fingerprints (RFF) blind extraction method is proposed for long term evolution uplink device authentication in this work. With the merits of the constant-modulus nature of the Zadoff-Chu (ZC) sequence and the cyclic prefix (CP) structure of the physical random a...

In this paper, we explore the application of reconfigurable intelligent surface (RIS) in the integrated sensing and communication network, where a full-duplex multi-antenna base station (BS) concurrently detects a target and communicates with a user equipment (UE). Our objective is to maximize the UE’s transmission rate by jointly optimizing the BS...

Originally introduced as a method to keep track of Bitcoin transactions over a peer-to-peer network, blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography into a chain held in public databases. The use of this technology has grown since its cryptocurrency creation and now store three ty...

Non-orthogonal multiple access (NOMA) has been viewed as a potential candidate for the upcoming generation of wireless communication systems. Comparing to traditional orthogonal multiple access (OMA), multiplexing users in the same time-frequency resource block can increase the number of served users and improve the efficiency of the systems in ter...

Wireless backhaul is an economical and flexible alternative to wired backhaul, however, it experiences impairments. This research proposes a new secure heterogeneous system model with unreliable wireless backhaul and imperfect channel estimation over Nakagami- $m$ fading channel. To improve the system secrecy performance, we propose three small-ce...

Spectrum sensing is of crucial importance in the satellite communication networks to address the increasingly severe spectrum scarcity problem. However, most of the spectrum sensing schemes for detecting satellite signal use the traditional reflector antennas and have poor performance, especially under the low signal-to-noise ratio (SNR). To tackle...

This letter presents a novel hybrid method that leverages deep learning to exploit the multi-resolution analysis capability of the wavelets, in order to denoise a photoplethysmography (PPG) signal. Under the proposed method, a noisy PPG sequence of length $N$ is first decomposed into $L$ detailed coefficients using the fast wavelet transform (F...

This paper studies an multi-cluster over-the-air computation (AirComp) system, where an intelligent reflecting surface (IRS) assists the signal transmission from devices to an access point (AP). The clusters are activated to compute heterogeneous functions in a time-division manner. Specifically, two types of IRS beamforming (BF) schemes are propos...

Intelligent reflecting surface (IRS) has been recently integrated with emerging communication technologies to meet the demanding requirements of communication systems. This paper investigates the deployment of multi-IRS units in a hybrid time-domain multiple access (TDMA) and non-orthogonal multiple access (NOMA) system, referred to as a multi-IRS-...

Clustered federated Multitask learning is introduced as an efficient technique when data is unbalanced and distributed amongst clients in a non-independent and identically distributed manner. While a similarity metric can provide client groups with specialized models according to their data distribution, this process can be time-consuming because t...

Reconfigurable intelligent surface (RIS) is able to create favorable reflecting channels for different users and piggyback additional data in the reflected signals. The former brings benefits to non-orthogonal multiple access (NOMA), while the latter enables a mechanism of symbiotic radio (SR). Inspired by these unique advantages, we consider a gen...

Clustered federated Multitask learning is introduced as an efficient technique when data is unbalanced and distributed amongst clients in a non-independent and identically distributed manner. While a similarity metric can provide client groups with specialized models according to their data distribution, this process can be time-consuming because t...

In this paper, we develop a conditional generative adversarial network (cGAN) semantic segmentation model to detect and classify sea-ice in scenes captured onboard of a ship. Two datasets are utilized to train the cGAN model. The images in the first dataset capture four classes: sea-ice, open water, sky, and vessel. The images in the second dataset...

p>In non-orthogonal multiple access (NOMA), user pairing, power allocation, and performance evaluation are typically performed while assuming that all users have equal symbol rates. However, such an assumption may significantly limit the design flexibility of NOMA and devalue its potential. Therefore, this paper considers a generalized scenario whe...

p>In non-orthogonal multiple access (NOMA), user pairing, power allocation, and performance evaluation are typically performed while assuming that all users have equal symbol rates. However, such an assumption may significantly limit the design flexibility of NOMA and devalue its potential. Therefore, this paper considers a generalized scenario whe...

Recent studies have demonstrated that using deep learning (DL) methods to classify drones based on radio frequency (RF) signal is effective. As known, the rich and diverse data is an important guarantee for good identification performance. In reality, due to the complexity and high dynamic of wireless environments, the costs of signal collection an...

An efficient serving of predictive management and what-if-analysis of smart cities is the only way to achieve a netzero waste target. With the aid of the enhanced learning capabilities of digital twin (DT), net-zero aims of smart cities can be obtained with highly accurate results in the prediction of wasteto- energy and candidate truck paths. Howe...

Millimeter wave (mmWave) massive multiple-input multiple-output (massive MIMO) is one of the most promising technologies for the fifth generation and beyond wireless communication system. However, a large number of antennas incur high power consumption and hardware costs, and high-frequency communications place a heavy burden on the analog-to-digit...

With the recent advances of wireless communications and signal processing techniques, the capability of wireless sensing would be integrated with communications, which benefits from dedicated communications and sensing hardware and enables new waveform design, transmission strategies, and resource allocation. In particular, a radio emission could s...

p>This paper derives symbolic models for end-to-end RIS-assisted FSO systems built on the fading model's probability density functions (PDFs) characterizing the sub-channels. We study some of the most popular models and derive closed-form expressions of PDFs, cumulative distributions, and moment-generating functions that are further exploited to an...

p>This paper derives symbolic models for end-to-end RIS-assisted FSO systems built on the fading model's probability density functions (PDFs) characterizing the sub-channels. We study some of the most popular models and derive closed-form expressions of PDFs, cumulative distributions, and moment-generating functions that are further exploited to an...

Ambient backscatter communication (AmBC) and non-orthogonal multiple access (NOMA) are two promising technologies for the future wireless communication networks owing to their high energy and spectral efficiencies. The AmBC-aided NOMA symbiotic radio is a promising technology because of possessing advantages of AmBC and NOMA. Nonetheless, when a nu...

Millimeter wave (mmWave) massive multiple-input multiple-output (massive MIMO) is one of the most promising technologies for the fifth generation and beyond wireless communication system. However, a large number of antennas incur high power consumption and hardware costs, and high-frequency communications place a heavy burden on the analog-to-digit...

Mobile edge computing (MEC) and intelligent reflecting surface (IRS) are envisioned as two promising technologies that enable massive connectivity in the future Internet of Things (IoT) networks. MEC allows IoT devices (IDs) to offload their computation intensive tasks, and thus, can prolong their lifespan. In contrast, the IRS can enhance the chan...

This letter presents a novel hybrid method that leverages deep learning to exploit the multi-resolution analysis capability of the wavelets, in order to denoise a photoplethysmography (PPG) signal. Under the proposed method, a noisy PPG sequence of length N is first decomposed into L detailed coefficients using the fast wavelet transform (FWT). The...

Spectrum awareness has a plethora of civilian and defense applications, such as spectrum resource management, adaptive transmissions, interference detection, and identification of threat signals. This paper proposes an identification neural network (INN)-based model that identifies cellular signals from three different radio access technologies, na...

In multiple-input multiple-output (MIMO) systems, channel estimation is of crucial importance to guarantee reliable recovery of ultra-high-speed MIMO signals. This paper proposes a novel channel estimation algorithm for the emerging MIMO-based orthogonal chirp-division multiplexing (OCDM) systems by utilizing the unique features of OCDM signals. In...

In this paper, we propose a variant of reconfigurable intelligent surfaces (RISs) called omni-digital-RISs (omni-DRISs), which allows both light reflection and refraction, with application to indoor visible light communication systems. The omni-DRIS contains elements which can be either reflectors or refractors, or both simultaneously. We describe...

In this paper, an intelligent reflecting surface (IRS) is leveraged to enhance the physical layer security of an integrated sensing and communication (ISAC) system in which the IRS is deployed to not only assist the downlink communication for multiple users, but also create a virtual line-of-sight (LoS) link for target sensing. In particular, we co...

Falls have always been one of the major threats to the health and well-being of elderly people, particularly for those living alone. Both wearable and non-wearable fall detection systems have already been developed. However, the fall detection systems using WiFi channel state information (CSI) have attracted a significant interest from researchers...

Federated Learning (FL) is a promising paradigm for future sixth-generation wireless systems to underpin network edge intelligence for smart cities applications. However, most of the data collected by the Internet of Things devices in such applications is unlabeled, necessitating the use of semi-supervised learning. Existing studies have introduced...

As a prominent member of the next generation multiple access (NGMA) family, non-orthogonal multiple access (NOMA) has been recognized as a promising multiple access candidate for the sixth-generation (6G) networks. This article focuses on applying NOMA in 6G networks, with an emphasis on proposing the so-called "One Basic Principle plus Four New" c...

In a time-varying massive multiple-input multiple-output (MIMO) system, the acquisition of the downlink channel state information at the base station (BS) is a very challenging task due to the prohibitively high overheads associated with downlink training and uplink feedback. In this paper, we consider the hybrid precoding structure at BS and exami...

In the design of reconfigurable intelligent surfaces (RISs)-aided visible light communication (VLC) systems, most studies have focused on the deployment of mirror arrays and metasurfaces on walls to influence signal propagation and enhance communication performance. This paper provides a new research direction in the design and performance optimiza...

Non-coherent (NC) schemes combined with massive antenna arrays are proposed to replace traditional coherent schemes in scenarios which require an excessive number of reference signals, since NC approaches avoid channel estimation and equalization. Differential M -ary phase shift keying is one of the most appealing NC schemes due to its implementa...

This paper proposes a signal-to-noise ratio (SNR) estimator based on recurrent neural network (RNN) in optical fiber communication links. The proposed estimator jointly estimates the linear and nonlinear components of the SNR. The input features of the proposed estimator are carefully designed based on a combination of the lower quartile and entrop...

To capture the advantages of unmanned aerial vehicle (UAV) and reconfigurable intelligent surface (RIS) technologies, we propose the use of multiple passive aerial RISs in a massive multiple-input multiple-output (MIMO) network. Each aerial RIS is comprised of a RIS panel attached to a UAV, the intention being to support in extending network covera...

In this paper, we investigate the energy efficiency (EE) problem under reconfigurable intelligent surface (RIS)-aided secure cell-free networks, where multiple legitimate users and eavesdroppers (Eves) exist. We formulate a max-min secure EE optimization problem by jointly designing the distributed active beamforming and artificial noise at base st...

Federated learning (FL) has recently emerged as a novel technique for training shared machine learning models in a distributed fashion while preserving data privacy. However, the application of FL in wireless networks poses a unique challenge on the mobile users (MUs)’ battery lifetime. In this letter, we aim to apply reconfigurable intelligent sur...

This paper addresses the problem of minimising latency in computation offloading with digital twin (DT) wire-less edge networks for industrial Internet-of-Things (IoT) environment via ultra-reliable and low latency communications (URLLC) links. The considered DT-aided edge networks provide a powerful computing framework to enable computation-intens...

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is becoming a prospective technology in realizing extremely low power transmission and seamless coverage for the sixth generation (6G) wireless communication era. Motivated by this, we study the secrecy performance of the STAR-RIS assisted non-orthogonal multip...

The rapid technological advances of cellular technologies will revolutionize network automation in industrial internet of things (IIoT). In this paper, we investigate the two-timescale resource allocation problem in IIoT networks with hybrid energy supply, where temporal variations of energy harvesting (EH), electricity price, channel state, and da...

Antenna arrays have a long history of more than 100 years and have evolved closely with the development of electronic and information technologies, playing an indispensable role in wireless communications and radar. With the rapid development of electronic and information technologies, the demand for all-time, all-domain, and full-space network ser...

With the rapid development of electronic and information technologies, the Internet of Everything (IoE) has become one of the trendiest topics in both academia and industry. Therein, many types of space/air/ground platforms need to be connected to networks for breaking down the isolation of information islands and providing various services. Space/...

The power consumption and hardware cost are two of the main challenges for realizing beyond fifth-generation (B5G) and sixth-generation (6G) wireless communications. Recently, the emerging reconfigurable intelligent surface (RIS) have been recognized as a promising tool for enhancing the propagation environment and improving the spectral efficiency...

Reconfigurable intelligent surfaces (RISs) and nonorthogonal multiple access (NOMA) have been recognized as key enabling techniques for the envisioned sixth generation (6G) of mobile communication networks. The key feature of RISs is to intelligently reconfigure the wireless propagation environment, which was once considered to be fixed and untunab...

Unmanned aerial vehicle (UAV) recognition is of increasing importance since UAV is widely applied and imposes threats to the public safety. Although many UAV recognition methods based on deep learning have been proposed by using the radio frequency fingerprints, they depend on a large amount of training samples or have poor performance when the tra...

Reconfigurable intelligent surface (RIS) is considered as a critical technology for future wireless communication networks. In this letter, we show that in a RIS-aided wideband THz communication system, the radiated beams steer away from the desired direction, which is known as the beam squint. Aiming to mitigate the beam squint, we utilize the ele...

Reconfigurable intelligent surfaces (RIS) have been recently introduced to optical wireless communication (OWC) networks to resolve skip areas and improve the signal-to-noise ratio at the user's end. In OWC networks, RIS are based on mirrors or metasurfaces. Metasurfaces have evolved significantly over the last few years. As a result, coding, digit...

This paper investigates reconfigurable intelligent surface (RIS)-assisted full-duplex multiple-input single-output wireless system, where the beamforming and RIS phase shifts are optimized to maximize the sum-rate for both single and distributed RIS deployment schemes. The preference of using the single or distributed RIS deployment scheme is inves...

This paper proposes a cognitive radio enabled LEO SatCom using RSMA radio access technique with the coexistence of GEO SatCom network. In particular, this work aims to maximize the sum rate of LEO SatCom by simultaneously optimizing the power budget over different beams, RSMA power allocation for users over each beam, and subcarrier user assignment...

In this letter, we propose a novel digital twin scheme supported metaverse by jointly considering the integrated model of communications, computing, and storage through the employment of mobile edge computing (MEC) and ultra-reliable and low latency communications (URLLC). The MEC-based URLLC digital twin architecture is proposed to provide powerfu...

The convergence of mobile edge computing (MEC) and blockchain is transforming the current computing services in wireless Internet-of-Things networks, by enabling task offloading with security enhancement based on blockchain mining. Yet the existing approaches for these enabling technologies are isolated, providing only tailored solutions for specif...

In this paper, an intelligent reflecting surface (IRS) is leveraged to enhance the physical layer security of an integrated sensing and communication (ISAC) system in which the IRS is deployed to not only assist the downlink communication for multiple users, but also create a virtual line-of-sight (LoS) link for target sensing. In particular, we co...

In this paper, an intelligent reflecting surface (IRS) is leveraged to enhance the physical layer security of an integrated sensing and communication (ISAC) system in which the IRS is deployed to not only assist the downlink communication for multiple users, but also create a virtual line-of-sight (LoS) link for target sensing. In particular, we co...

Recently, the process of space-time block coding (STBC) recognition has found applications in a wide range of wireless transmissions. Numerous investigations on this topic have been developed for single-carrier transmissions and a few studies have been introduced for orthogonal frequency division multiplexing (OFDM) transmissions. The previous rese...

This letter investigates reconfigurable intelligent surface (RIS)-assisted full-duplex multiple-input single-output wireless system, where the beamforming and RIS phase shifts are optimized to maximize the sum-rate for both single and distributed RIS deployment schemes. The preference of using the single or distributed RIS deployment scheme is inve...

Signal recognition has recently emerged as a key ingredient for cognitive radios with defense and industrial uses. This letter area encompasses the recognition of a broad range of transmission aspects such as modulation format, space-time mapping, channel coding form, central frequency, and data rate. Each of these aspects has been extensively rese...

The convergence of mobile edge computing (MEC) and blockchain is transforming the current computing services in wireless Internet-of-Things networks, by enabling task offloading with security enhancement based on blockchain mining. Yet the existing approaches for these enabling technologies are isolated, providing only tailored solutions for specif...

Visible light communication (VLC) is envisioned as a core component of future wireless communication networks due to, among others, the huge unlicensed bandwidth it offers and the fact that it does not cause any interference to existing radio frequency (RF) communication systems. Most research on RF and VLC coexistence has focused on hybrid designs...

Wireless underwater acoustic (UWA) networks serve several civilian and military applications. The multiple reflections and dispersion, along with the long propagation delay limit the sum rate of UWA networks. Earlier works discussed adding full-duplex (FD), relay assistance, and non-orthogonal multiple access (NOMA) to enhance the system sum rate....

Full-duplex (FD) systems have been introduced to provide high data rates for beyond fifth-generation wireless networks through simultaneous transmission of information over the same frequency resources. However, the operation of FD systems is practically limited by self-interference (SI), and efficient SI cancelers are sought to make the FD systems...

In future wireless communication systems, intelligent reflecting surface (IRS) plays an important role since it is capable of dynamically reconfiguring the channel conditions. In this paper, we apply IRS to facilitate the communication of an uplink multiple-input multiple-output non-orthogonal multiple access system. The objective is to maximize th...

Recently, research on the design of relay structure and optimal precoding matrix in massive multiple-input multiple-output (MIMO) relay systems has been proposed in many works assuming that partial or all of the channel state information (CSI) is known. However, in the practical communication systems, the CSI is unknown and needs to be estimated. I...

p>The unprecedented growth in the number of connected devices has given rise to the Internet-of-Things (IoT) and led to an increasing demand for additional computational and communication resources. Within this context, unmanned aerial vehicles (UAVs) have shown to provide extended coverage, flexibility, and reachability. Motivated by this, in this...

p>The unprecedented growth in the number of connected devices has given rise to the Internet-of-Things (IoT) and led to an increasing demand for additional computational and communication resources. Within this context, unmanned aerial vehicles (UAVs) have shown to provide extended coverage, flexibility, and reachability. Motivated by this, in this...

In this paper, we consider an energy efficient resource allocation technique for a hybrid time division multiple access (TDMA) - non-orthogonal multiple access (NOMA) system. In such a hybrid system, the available time for transmission is divided into several sub-time slots, and a sub-time slot is allocated to serve a group of users (i.e., cluster)...

p>Federated learning (FL) has recently emerged as a novel technique for training shared machine learning models in a distributed fashion while preserving data privacy. However, the application of FL in wireless networks poses a unique challenge on the mobile users (MUs)' battery lifetime. In this paper, we aim to apply reconfigurable intelligent su...

p>Federated learning (FL) has recently emerged as a novel technique for training shared machine learning models in a distributed fashion while preserving data privacy. However, the application of FL in wireless networks poses a unique challenge on the mobile users (MUs)' battery lifetime. In this paper, we aim to apply reconfigurable intelligent su...

p>This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.</p

This paper studies the application of reconfigurable intelligent surface (RIS) to cooperative non-orthogonal multiple access (C-NOMA) networks with simultaneous wireless information and power transfer (SWIPT). We aim for maximizing the rate of the strong user with guaranteed weak user's quality of service (QoS) by jointly optimizing power splitting...

Recent development of the fifth-generation (5G) of cellular networks has led to their deployment worldwide. As part of the implementation, one of the challenges that must be addressed is the skip-zone problem, which occurs when objects obstruct the transmission of signals. A signal obstruction can significantly reduce the signal-to-noise ratio in r...

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is becoming a promising technology in realizing extremely low power transmission in the sixth generation (6G) wireless communication era. Motivated by this, we study the secrecy performance of the STAR-RIS assisted non-orthogonal multiple access (NOMA) networks...

Reconfigurable intelligent surface (RIS) is considered as a critical technology for future wireless communication networks. In this letter, we discuss the electromagnetic model of the RIS-aided spatial modulation (SM) with on/off pattern, where the induction theorem is adopted. Then, we derive the received power of the target receiver and the path...

In this letter, we study a mobile edge computing (MEC) architecture with the assistance of digital twin (DT) applied for industrial automation where multiple Internet-of-Things (IoT) devices intelligently offload computing tasks to multiple MEC servers to reduce end-to-end latency. To do so, first we propose and formulate a practical end-to-end lat...

The papers in this special section focus on the use of distributed machine learning for wireless communications. With the emergence of new application scenarios (e.g., real-time and interactive services and Internet of Things) and the fast development of smart terminals, wireless data traffic has increased drastically, and the existing wireless net...

With its privacy-preserving and decentralized features, distributed learning plays an irreplaceable role in the era of wireless networks with a plethora of smart terminals, an explosion of information volume and increasingly sensitive data privacy issues. There is a tremendous increase in the number of scholars investigating how distributed learnin...

The rapid technological advances of cellular technologies will revolutionize network automation in industrial internet of things (IIoT). In this paper, we investigate the two-timescale resource allocation problem in IIoT networks with hybrid energy supply, where temporal variations of energy harvesting (EH), electricity price, channel state, and da...

Semi-supervised Federated Learning over Wireless Edge

In this paper, multiuser beam training based on hierarchical codebook for millimeter wave massive multi-input multi-output is investigated, where the base station (BS) simultaneously performs beam training with multiple user equipments (UEs). For the UEs, an alternative minimization method with a closed-form expression (AMCF) is proposed to design...