Michael Cheffena

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Verified

Michael verified their affiliation via an institutional email.

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• PhD
• Professor (Full) at Norwegian University of Science and Technology

This research introduces a groundbreaking electronic nose (E-Nose) that integrates advanced sensing materials with machine learning. The sensing materials include molecularly imprinted polymers and multi-walled carbon nanotubes, designed for enhanced performance. An optimized extreme learning machine model enables highly selective detection and pre...

This paper presents a machine learning (ML)-assisted novel microwave-sensor for the simultaneous and selective detection of multiple volatile organic compounds (VOCs) at room temperature using molecularly imprinted polymer (MIP)/carbon nanotubes (CNTs)-based sensing layers. The synthesized materials were characterized using Fourier-transform infrar...

Accurate monitoring of isopropanol (IPA) levels is crucial for safety in industrial and laboratory settings, as high concentrations can lead to serious health issues. In this study, we present, for the first time, a dual-functional antenna sensor capable of high-performance IPA gas detection with concentration estimation and uninterrupted wireless...

In this paper, we present for the first time a highly sensitive, dual-functional antenna sensor functionalized with molybdenum disulfide/oxide heterostructures (MoS2/MoOx NFs) for selective detection of methanol gas and wireless communications, simultaneously. The proposed antenna sensor uniquely features optimized deposition of the sensing materia...

This paper, for the first time, presents a low-complexity peak-power-assisted data-aided channel estimation (DACE) scheme for both single-input single-output (SISO) and multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) wireless systems. In OFDM, high peak-power levels occur when the subcarriers align in phase and...

This article presents an optimal pilot pattern for the data‐aided channel estimation (DACE) scheme for both single‐input single‐output (SISO) and multiple‐input multiple‐output orthogonal frequency division multiplexing (MIMO‐OFDM) wireless systems. The research evaluates the performance of the DACE scheme using different comb‐type pilot patterns f...

Antenna sensors are promising microwave sensor variants that combine the benefits of easy fabrication, non-destructive detection, and robust performance with integrated communication capabilities, making them ideal for Internet-of-things (IoT) sensor nodes that require both sensing and communication. However, existing antenna sensors lack multi-fun...

Volatile organic compounds (VOCs) gases exist as important indicators in various processes such as human breath, food spoilage, plant disease, and industrial production, which makes VOC sensing a promising nondestructive detection method. Nanomaterial enabled electronic noses (e-noses) are gaining increasing attention for their exceptional ability...

The ever-growing demands from emerging industrial applications and services require revolutionary technology beyond fifth-generation (5G). The sixth-generation (6G) networks are the promising technology to satisfy the high data rate demands for future industrial applications. This paper examined wideband radio propagation characteristics at 28 GHz...

This study introduces a novel antenna sensor that incorporates molecularly imprinted polymers (MIPs) to selectively detect methanol vapor under room temperature conditions, thereby eliminating the requirement for preheating the analyte. The selection of methanol as the target analyte was based on its dual significance, serving as both a prevalent i...

In this letter, a novel molecularly imprinted polymer (MIP)-based carbon nanotube (CNT)-coated microwave sensor is developed for the selective sensing of methanol gas. First, a 2.45 GHz broadband monopole antenna with a 400 MHz 10-dB bandwidth is designed. A 5-mm Interdigitated Electrode (IDE) structure is then added to the antenna for high-precisi...

This letter reports, for the first time, a molybdenum-disulfide (MoS2)-coated microwave gas sensor for methanol gas detection. A wideband monopole antenna, resonating at 2.45 GHz for wireless applications, is fit with a 15-mm-long copper-based grating sensing element for high-precision gas sensing. When the sensor surface is coated with a highly se...

An electrochemical gas sensor has been fabricated using molecularly imprinted polymer nanoparticles (nanoMIPs) and multiwalled carbon nanotubes on screen-printed electrodes. Methanol vapour was chosen as the target due to its...

We present the design and development of a combined octagonal and square-shaped coplanar waveguide (CPW)-fed nanosilver inkjet-printed on Kapton polyimide-based flexible antenna sensor for liquid acetone/water detection which is the first of its kind. Sensing was performed by monitoring the resonant frequency and its corresponding amplitude of the...

In this work, a two-port microwave sensor is presented to characterize different dielectric materials. Most of the resonance-based microwave sensors in the state-of-the-art characterize the materials under test (MUTs) by measuring the relative resonance frequency shift from the unloaded resonance frequency. The resonance frequency of a microwave se...

In our recent publication, we introduce a novel frequency estimation method for one-dimensional complex signals in complex white Gaussian noise, named Low complexity Unitary Principal-singular-vector Utilization for Model Analysis (LUPUMA). This method stands out due to its low space and time complexity, offering uniform estimation variance across...

In this paper, we propose a novel channel-aware latency taming scheme, called Optimal Transmission Latency Taming (OTLT), to detect hidden channel state and tame the distribution tail of the packet sojourn time in Industrial Internet of Things (IIoT) devices. Specifically, we design a forward algorithm based on a hidden semi-Markov model to detect...

In this paper, an automatic antenna impedance matching technique is presented for a wide range of frequency bands where a low-complexity shallow learning model adaptively determines the component values of the matching circuit on a real-time. In general, matching networks require both the real and imaginary parts of the antenna impedance to determi...

We report a state-of-the-art molecularly imprinted polymer (MIP) based antenna sensor to detect methanol vapor at room temperature. A conductive MIP-graphite composite was synthesized with specificity to methanol and deposited on a 3.6 GHz resonant patch antenna by drop coating. The copper-layered antenna with affinity composite worked in tandem to...

Ensuring physical-layer security (PLS) in wireless communication has always been a challenge due to the broadcasting nature of the transmission. In this work, a multilevel chaotic encryption (MCE) system is proposed to improve PLS in Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems under Rayleigh fadin...

In this work, a dual‐industrial, scientific, and medical (ISM)‐band flexible slot dipole antenna is investigated. It is based on quarter‐guided‐wavelength (λ g ∕ 4 ${\lambda }_{g}\unicode{x02215}4$) stepped impedance resonator (SIR) slots fed by coplanar waveguide. Compared to the mostly used λ g ∕ 2 ${\lambda }_{g}\unicode{x02215}2$ SIR, the use o...

Wireless channel estimation is one of the challenging problems in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) wireless systems. The MIMO-OFDM exploits the spatial resources and increases the reliability and capacity of wireless systems. However, the performance of these systems depends on accurate channel e...

A novel low-cost microwave sensor system is proposed for accurate sensing of the real relative permittivity of materials under test (MUT). The proposed solution eliminates the need for using advanced measurement devices such as the vector network analyzer (VNA) for sensor characterization. The proposed sensor system is built on a software-defined r...

A novel low-cost microwave sensor system is proposed for accurate sensing of the real relative permittivity of materials under test (MUT). The proposed solution eliminates the need for using advanced measurement devices such as the vector network analyzer (VNA) for sensor characterization. The proposed sensor system is built on a software-defined r...

preprint version can be found in: https://doi.org/10.36227/techrxiv.21915093.v1 ############################################################# A novel low-cost microwave sensor system is proposed for accurate sensing of the real relative permittivity of materials under test (MUT). The proposed solution eliminates the need for using advanced measure...

In this article, a dual functional antenna system for communication and sensing applications is designed on a single substrate having a common input port. The main motivation behind the proposed design is to build an antenna system, which can work as an antenna sensor and also can communicate over a fixed band not related to the resonance frequency...

In this article, a dual-functional microwave system with a single input port that can simultaneously be used for antenna and sensor applications is presented. The dual-functional ability of the proposed system is achieved by integrating a two-port microwave sensor and a Wi-Fi antenna with a novel frequency-selective multipath filter (FSMF). The FSM...

The selective sensing of gaseous target molecules is a challenge to analytical chemistry. Selectivity may be achieved in liquids by several different methods, but many of these are not suitable for gas-phase analysis. In this review, we will focus on molecular imprinting and its application in selective binding of volatile organic compounds and atm...

In this work, a hybrid radio frequency (RF)- and acoustic-based activity recognition system was developed to demonstrate the advantage of combining two non-invasive sensors in Human Activity Recognition (HAR) systems and smart assisted living. We used a hybrid approach, employing RF and acoustic signals to recognize falling, walking, sitting on a c...

With the ongoing trends in the energy sector such as vehicular electrification and renewable energy, the Smart Grid (SG) is clearly playing a more and more important role in the electric power system industry. One essential feature of the SG is the information flow over high-speed, reliable, and secure data communication networks in order to manage...

Intelligent reflecting surface (IRS) is an emerging key technology for the fifth-generation (5G) and beyond wireless communication systems to provide more robust and reliable communication links. In this letter, we propose a mixed dual-hop free-space optical (FSO)-radio frequency (RF) communication system that serves the end user via a decode-and-f...

Intelligent reflecting surface (IRS) is an emerging key technology for the fifth-generation (5G) and beyond wireless communication systems to provide more robust and reliable communication links. In this paper, we propose a mixed dual-hop free-space optical (FSO)-radio frequency (RF) communication system that serves the end user via a decode-and-fo...

The millimeter-wave (mmWave) is expected to deliver a huge bandwidth to address the future demands for higher data rate transmissions. However, one of the major challenges in the mmWave band is the increase in signal loss as the operating frequency increases. This has attracted several research interests both from academia and the industry for indo...

Reconfigurable intelligent surfaces (RIS) is considered as a revolutionary technique to improve the wireless system performance by reconfiguring the radio wave propagation environment artificially. Motivated by the potential of RIS in vehicular networks, we analyze the secrecy outage performance of RIS-aided vehicular communications in this paper....

An experimental study on the effect of weather conditions such as solar radiation, humidity, temperature, and rain on the Long Range (LoRa) communication in a tropical region (Malaysia) via a campus environment has been carried out and analyzed. The weather parameters were obtained from an online meteorological weather station (Meteoblue) and the u...

With the ongoing trends in the energy sector such as vehicular electrification and renewable energy, smart grid is clearly playing a more and more important role in the electric power system industry. One essential feature of the smart grid is the information flow over the high-speed, reliable and secure data communication network in order to manag...

In this paper, we analyze the secrecy outage performance for more realistic eavesdropping scenario of free-space optical (FSO) communications, where the main and wiretap links are correlated. The FSO fading channels are modeled by the well-known Mlaga distribution. Exact expressions for the secrecy performance metrics such as secrecy outage probabi...

In this paper, we analyze the secrecy outage performance for more realistic eavesdropping scenario of free-space optical (FSO) communications, where the main and wiretap links are correlated. The FSO fading channels are modeled by the well-known M\'alaga distribution. Exact expressions for the secrecy performance metrics such as secrecy outage prob...

Wireless data traffic has increased significantly due to the rapid growth of smart terminals and evolving real-time technologies. With the dramatic growth of data traffic, the existing cellular networks including Fifth-Generation (5G) networks cannot fully meet the increasingly rising data rate requirements. The Sixth-Generation (6G) mobile network...

Abstract The intelligent reflecting surface (IRS) is an emerging technique to extend wireless coverage. In this letter, the performance of the hybrid automatic repeat request (hybrid ARQ) for an IRS‐assisted system is analysed. More specifically, the outage performance of the IRS‐aided system using hybrid ARQ protocol with chase combining is studie...

To cover the high demand for wireless data services for different applications in the wireless networks, different frequency bands below 6 GHz and in millimeter-wave (mm-Wave) above 24 GHz are proposed for the fifth generation (5G) of communication. The communication network is supposed to handle, among others, indoor traffic in normal situations a...

Free space optical (FSO) communication is a promising candidate for the next generation (5G and beyond) wireless communication systems, due to its merits (i.e. low latency, high data rate, and license‐free band, among others). However, atmospheric turbulence (AT) as well as pointing error (PE) are two of the main challenges with FSO communication t...

In this article, we study the physical layer security of free-space optical (FSO) communications under different eavesdropping scenarios. More specifically, the secrecy performance of FSO communication employing intensity modulation/direct detection is analyzed for the well-established Málaga channels. Three different realistic scenarios of eavesdr...

Reconfigurable intelligent surfaces (RIS) is considered as a revolutionary technique to improve the wireless system performance by reconfiguring the radio wave propagation environment artificially. Motivated by the potential of RIS in vehicular networks, we analyze the secrecy outage performance of RIS-aided vehicular communications in this paper....

Reconfigurable intelligent surfaces (RIS) is considered as a revolutionary technique to improve the wireless system performance by reconfiguring the radio wave propagation environment artificially. Motivated by the potential of RIS in vehicular networks, we analyze the secrecy outage performance of RIS-aided vehicular communications in this paper....

The flexibility of radio frequency (RF) systems and the omnipresence of power cables potentially make the cascaded power line communication (PLC)/RF system an efficient and cost-effective solution in terms of wide coverage and high-speed transmission. This letter proposes an opportunistic decode-and-forward (DF)-based multi-wire/RF relaying system...

Due to the dynamic nature of the wireless body area network (WBAN) channels, there is a need for dynamic transmission power control (TPC) to increase their energy efficiency. The existing gait-cycle-driven TPC (G-TPC) successfully achieves this objective, however, it introduces maximum buffer delay equal to the period of the gait cycle. In this stu...

The intelligent reflecting surface (IRS) is an emerging technique to extend the wireless coverage. In this letter, the performance of hybrid automatic repeat request (hybrid-ARQ) for an IRS-assisted system is analyzed. More specifically, the outage performance of the IRS-aided system using hybrid-ARQ protocol with chase combining is studied. Asympt...

This paper presents rain attenuation effects on the performance of the full-duplex link in a tropical region based on one-year measurement data at 73.5- and 83.5-GHz E-band for distances of 1.8 km (longer links) and 300 m (shorter links). The measured rain attenuations were analyzed for four links, and the throughput degradation due to rain was inv...

This paper analyses the physical layer secrecy (PLS) performance of a hybrid free space optical and radio frequency (FSO/RF) communication system under a modified selection combining scheme. The transmission scheme takes into account secrecy performance as well as diversity gain and ease of implementation. The effects of FSO link, namely the FSO at...

This letter presents the rainfall intensity and rain attenuation analysis in tropical region based on a one-year measurement using the 73.5 GHz E-band link of 1.8 km with three rain gauges installed along the path. The measured rain rate and rain attenuation were analysed and bench-marked with previous measurements and prediction models. The findin...

The α-η-κ-μ fading model is a very useful instrument to accurately describe various radio wave propagation scenarios. In this paper, we study the effective throughput performance of communication systems over the α-η-κ-μ fading channels. Novel and exact expressions for the effective throughput over α-η-κ-μ channels are derived, and the effective th...

The high frequencies of millimeter wave (mm-wave) bands have been recognized for the fifth generation (5G) and beyond wireless communication networks. However, the radio propagation channel at high frequencies can be largely influenced by rain attenuation, especially in tropical regions with high rainfall intensity. In this paper, we present the re...

Recent developments in industrial wireless sensor networks (IWSNs) have revolutionized industrial automation systems. However, harsh industrial environment poses great challenges to a time-critical and reliable wireless communication. For instance, effects of multipath fading, noise and cochannel interference can have unpredictable and time-varying...

The double shadowed Rician model was recently proposed to describe some realistic physical signal propagation phenomena, where a Rician faded signal is impacted by cascaded shadowing processes. In this Letter, the authors study the outage performance of the double shadowed Rician model. More specifically, they investigate the impact of two differen...

This paper investigates the secrecy performance of the classical Wyner’s wiretap model, where the main channel and eavesdropper channel experience correlated α-μ fading. Novel and exact expressions for the average secrecy capacity and secrecy outage probability are derived for the considered realistic scenario. The effect of correlation has been st...

In this work, finite-difference time-domain was used for the investigation of dynamic wireless body area network channel characteristics during walking, thus accounting for dynamic aspects and body postures. This involves the study of on-body, off-body, and body-to-body communication in an empty environment, at the center frequency of 2.45 GHz. The...

Wireless sensor network (WSN) plays a fundamentally important role in the realization of Internet of Things and Industry 4.0. In this letter, we study the physical layer security performance of a large-scale ad hoc and homogeneous WSN. To accurately evaluate the secrecy performance of the large-scale WSN, we take into account the randomness of the...

Industrial wireless sensor networks (IWSNs) promote innovations in industry such as structural status mapping, instrument fault diagnosing and oriented automation system associating, among others. However, due to the shared nature of the wireless propagation environment, the emerging sensor nodes (SNs) with wireless properties are vulnerable to ext...

In this paper, we study the physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system. The satellite links are assumed to follow the Shadowed-Rician fading distribution; and the channel of the terrestrial link between the relay and destination is assumed to experience the Gamma-Gamma fading. For the FS...

In this letter, we study the secrecy performance of the classic Wyner’s wiretap model, where the main and eavesdropper channels are modeled by a general and versatile $\alpha $ - $\eta $ - $\kappa $ - $\mu $ fading model. Novel and exact expressions of the average secrecy capacity and secrecy outage probability have been derived. Previous resul...

In this letter, we study the physical layer secrecy performance of the classic Wyner’s wiretap model over double Rayleigh fading channels for vehicular communications links. We derive novel and closed-form expressions for the average secrecy capacity (ASC) taking into account the effects of fading, path loss and eavesdropper location uncertainty. T...

Expansion of wireless body area networks applications, such as health-care, m-banking, and others has lead to vulnerability of privacy and personal data. An effective and unobtrusive natural method of authentication is therefore a necessity in such applications. Accelerometer-based gait recognition has become an attractive solution, however, contin...

Wireless communications and power line communications (PLC) are essential components for smart grid communications. This paper analyses the performance of a dualhop wireless-power line mixed communication setup employing a decode-and-forward relay in terms of analytical average bit error rate (BER), outage probability, and average channel capacity....

In this work, a Lognormal mixture shadowing model based on a cluster concept, is utilized in the modeling of body-to-body channels for different running and cycling activities. The mixture model addresses the inaccuracies observed using a single distribution that may not accurately represents the measurement data set. Parameters of the mixture mode...

Body-to-body wireless networks (BBWNs) have great potential to find applications in team sports activities among others. However, successful design of such systems requires great understanding of the communication channel as the movement of the body components causes time-varying shadowing and fading effects. In this study, we present results of th...

The use of indoor wireless devices has substantially increased in recent years. This escalation is due to the expansion of traditional communication devices, such as mobile phones and laptop computers, to less traditional ones, such as wirelessly communicating sensor nodes present in smart homes, office buildings, and industrial environments. The p...

In this paper, we investigate the performance of power line communication (PLC) network in the presence of jamming attacks. The legitimate nodes of the PLC network try to communicate with the anchor node of the network while the jamming node attempts to degrade the system performance. The fading, attenuation and colored noise of the PLC channel wit...

Analysis of two years of measurements from a three-site satellite beacon diversity experiment in Norway is presented. The operating frequency was 19.68 GHz, elevation angles were between 21.7° and 22°, and site separations 23, 29.7 and 50.1 km. Due to spatial decorrelation of rain, simultaneous attenuation at all sites occurs much less frequently t...

In this paper, practical sensor nodes are utilized to study the path loss effects of wireless sensor networks (WSNs) at 2.425 GHz in a ground covered by snow at different heights from the ground. The measurement results are compared with the ground reflection (Two-Ray) path loss model and ray tracing model showing significant difference. New empiri...

A simple approach of path-loss and root mean square delay spread prediction for indoor propagation environment is developed based on the room electromagnetics theory. The indoor room environment is interpreted as a lossy cavity, which is characterized by the diffuse scattering components caused by the walls and surrounding obstacles, and a possible...

Wireless sensor networks (WSNs) will play a fundamental role in the realization of Internet of Things and Industry 4.0. Arising from the presence of spatially distributed sensor nodes in a sensor network, cooperative diversity can be achieved by using the sensor nodes between a given source-destination pair as intermediate relay stations. In this p...

In this letter, a physical-statistical based channel model for off-body wireless communications is presented. The model utilizes a dynamic human walking model, which provides detailed description of the movement of the different body parts. The received signal is composed of a direct component, which might be subject to shadowing by the body parts,...

The large bandwidth available at the mmWave spectrum can open the way for a wide variety of new industrial automation capabilities. With the use of wireless smart cameras and vision technologies, applications such as remote visual monitoring and surveillance, intelligent logistics product tracking, image guided automated assembly, and fault detecti...

The wireless channel in an industrial environment behaves much differently when compared with wave propagation in home and office environments. This is due to the presence of significant noise and interference caused by large machinery and heavy multipath propagation effects induced by highly reflective structures. In this article, a comprehensive...

In this paper, we present a geometrical scattering model for a typical class of industrial indoor environments. The proposed industrial reference model takes into account scattering components arising from metallic structures and the surrounding walls of the investigated environment. Starting from the geometrical scattering model, we derive the ana...

A theoretical method for analyzing the performance of wireless body sensors in terms of channel capacity and biterror- rate (BER) in the presence of slow and fast fading effects is presented. Analytical closed-form expressions for the channel capacity and BER for implant-to-implant, implant-to-bodysurface and body-surface-to-body-surface propagatio...

In this work, a novel physical-statistical technique for simulating the industrial indoor multIPath propagation is proposed. The indoor propagation environment is described by a cubic volume in a rectangular coordinate system. The clustering behavior of the multIPath components is modeled by defining circular spaces within the propagation environme...

An automated fall detection system based on smartphone audio features is developed. The spectrogram, mel frequency cepstral coefficents (MFCCs), linear predictive coding (LPC) and matching pursuit (MP) features of different fall and no-fall sound events are extracted from experimental data. Based on the extracted audio features, four different mach...