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Varun Jeoti

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University of Alberta

Associate Professor Dr. Fatma Susilawati Mohamad

Universiti Sultan Zainal Abidin, Terengganu, Malaysia

Universiti Malaysia Perlis (UniMAP)

A.Shakin Banu [AP/ECE]

Sebastian Baumbach

Universiti Malaysia Pahang (UMP)

Patrick Guerrero

Boston University

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Papers by Varun Jeoti

Computer aided diagnosis (CAD) tool for the analysis of calcaneofibular ligament using ultrasonographic images

Ultrasound imaging is a cost-effective diagnostic tool to imagine the internal organisms of human... more Ultrasound imaging is a cost-effective diagnostic tool to imagine the internal organisms of human beings that used routinely in the diagnosis of a number of diseases related to ligament, tendon, bone, blood flow estimation, obstetrics, etc. However, ultrasound imaging has limitations such as homogenous intensity regions, homogeneous textures, low contrast regions, enhancement artefact, limited view visualization and inaccurate qualitative/quantitative estimation. To overcome all these investigated problems, this research developed a Computer Aided Diagnosis (CAD) system that helps in efficient segmentation and Three Dimensional (3D) reconstruction of calcaneoﬁbular ligament to enhance the diagnosis. The developed CAD system would help in the achievement of enhanced segmentation results, 3D reconstruction results and statistical analysis of the injured calcaneoﬁbular ligament. Moreover, performance of the developed CAD system is analyzed based on the obtained results, which are indic...

Clinical assessment of injured ankle ATFL ligaments based on ultrasound imaging in the athletes

2016 6th International Conference on Intelligent and Advanced Systems (ICIAS), 2016

Ultrasound image segmentation is still a challenging issue in various applications to extract the... more Ultrasound image segmentation is still a challenging issue in various applications to extract the meaningful information for disease diagnosis in the athletes. Generally, ultrasound images could be suffering from some problems such as speckle, attenuation, signal dropout and shadows which make the segmentation process more complicated and inefficient. Due to these problems, traditional segmentation approaches could not be applicable. To overcome these problems, the current study proposed an automatic multilevel segmentation framework for ankle Anterior Talofibular Ligament (ATFL). This framework used the association of active contour and the particle swarm optimization method with curve evaluation and energy minimization capability to obtain the optimized segmented outcomes. It would be more efficiently detect the ATFL ligament in ultrasound images with better interpretation capability. Finally, this study presents various experimental segmented outcomes and corresponding analysis. On the basis of this analysis, the average sensitivity, specificity and accuracy of the proposed framework would be 80.73 %, 96.57 % and 94.12 % respectively.

Impacting clinical evaluation of anterior talofibular ligament injuries through analysis of ultrasound images

Biomedical engineering online, Jan 2, 2016

Anterior talofibular ligament (ATFL) is considered as the weakest ankle ligament that is most pro... more Anterior talofibular ligament (ATFL) is considered as the weakest ankle ligament that is most prone to injuries. Ultrasound imaging with its portable, non-invasive and non-ionizing radiation nature is increasingly being used for ATFL diagnosis. However, diagnosis of ATFL injuries requires its segmentation from ultrasound images that is a challenging task due to the existence of homogeneous intensity regions, homogeneous textures and low contrast regions in ultrasound images. To address these issues, this research has developed an efficient ATFL segmentation framework that would contribute to accurate and efficient diagnosis of ATFL injuries for clinical evaluation. The developed framework comprises of five computational steps to segment the ATFL ligament region. Initially, region of interest is selected from the original image, which is followed by the adaptive histogram equalization to enhance the contrast level of the ultrasound image. The enhanced contrast image is further optimi...

Toward Better Food Security Using Concepts from Industry 5.0

Sensors

The rapid growth of the world population has increased the food demand as well as the need for as... more The rapid growth of the world population has increased the food demand as well as the need for assurance of food quality, safety, and sustainability. However, food security can easily be compromised by not only natural hazards but also changes in food preferences, political conflicts, and food frauds. In order to contribute to building a more sustainable food system—digitally visible and processes measurable—within this review, we summarized currently available evidence for various information and communication technologies (ICTs) that can be utilized to support collaborative actions, prevent fraudulent activities, and remotely perform real-time monitoring, which has become essential, especially during the COVID-19 pandemic. The Internet of Everything, 6G, blockchain, artificial intelligence, and digital twin are gaining significant attention in recent years in anticipation of leveraging the creativity of human experts in collaboration with efficient, intelligent, and accurate machi...

An Improved Split-Step Wavelet Transform Method for Anomalous Radio Wave Propagation Modelling

An Anomalous tropospheric propagation caused by ducting phenomenon is a major problem in wireless... more An Anomalous tropospheric propagation caused by ducting phenomenon is a major problem in wireless com- munication. Thus, it is important to study the behavior of ra- dio wave propagation in tropospheric ducts. The Parabolic Wave Equation (PWE) method is considered most reliable to model anomalous radio wave propagation. In this work, an improved Split Step Wavelet transform Method (SSWM) is presented to solve PWE for the modeling of tropospheric propagation over finite and infinite conductive surfaces. A large number of numerical experiments are carried out to validate the performance of the proposed algorithm. De- veloped algorithm is compared with previously published techniques; Wavelet Galerkin Method (WGM) and Split-Step Fourier transform Method (SSFM). A very good agreement is found between SSWM and published techniques. It is also observed that the proposed algorithm is about six times faster than WGM and provide more details of propagation effects as compared to SSFM.

A Multi-Carrier Waveform Design for 5G and beyond Communication Systems

Mathematics

The next generation communication network (NGCN) is expected to provide higher spectral efficienc... more The next generation communication network (NGCN) is expected to provide higher spectral efficiency, low latency, large throughput and massive machine-to-machine type communications. In this regard, the design of the multi-carrier waveform (MCW) is posing a major research problem for the NGCN. To overcome the stated problem, a lot of state-of-the-art work exists that proposes various MCW alternative to the standard orthogonal frequency division multiplexing (OFDM) waveform. It is true that OFDM was used in a number of real-time communication systems of fourth generation (4G) networks. However, their use in the upcoming fifth generation (5G) network is not very feasible. This is because of the strict requirements of 5G communication systems, which also extend beyond 5G systems; hence rendering the use of OFDM infeasible for newer communication standards. To satisfy the requirements of upcoming communication networks, there is a dire need for MCWs with better flexibility. In this regar...

Surface acoustic wave modes characteristics of CMOS compatible SiO2/AlN/SiO2/Si multilayer structure with embedded electrodes

Sensors and Actuators A: Physical

In this work, a CMOS compatible surface acoustic wave (SAW) device has been simulated and analyze... more In this work, a CMOS compatible surface acoustic wave (SAW) device has been simulated and analyzed on SiO 2 /AlN/SiO 2 /Si. The simulation results have been used to characterize a typical fabricated device as well. The phase velocity, coupling coefficient, and temperature coefficient of frequency (TCF) of surface acoustic waves in the proposed structure have been investigated using the finite-element (FE) simulation. The simulation results show that a high velocity and a large effective coupling factor can be simultaneously obtained. Besides, the excellent nearly zero TCF is also achieved. The analysis further shows potential for designing high-frequency SAW devices that are CMOS compatible and temperature stable utilizing the Sezawa wave mode.

A Comparative Survey on Silicon Based and Surface Acoustic Wave (SAW) Based RFID Tags: Potentials, Challenges and Future Directions

IEEE Access

Many Automatic Identification (Auto-ID) technologies such as bar codes, magnetic stripes, Optical... more Many Automatic Identification (Auto-ID) technologies such as bar codes, magnetic stripes, Optical Character Recognition (OCR) and Electronic Article Surveillance (EAS) security tags are in existence. However, they are limited by a variety of constraints on them such as limited object rate of scan, need for Lineof-Sight (LOS) operation, very small interrogation range and poor accuracy in complex environments. Research has accordingly grown rapidly in recent years into the development of robust identification or tracking mechanisms. Radio Frequency Identification (RFID) technology using readers and RFID tags, whether passive, semi-passive or active in nature, has been deemed to be a promising candidate. Silicon based IC tags are quite popular. However, some alternative RFID technologies have also been on the rise. In particular, another special type of tag based on Surface Acoustic Wave (SAW) design also has a great potential for deployment in future identification fields due to its ruggedness against harsh conditions, metallic environments, interference, small and low cost and is being thoroughly reviewed, which is ignored in other survey papers. While other chipless RFID systems based on conductive ink, ink-tattoo and others do exist, negative aspects such as inability to survive in extreme weather, larger tag size and limited data storage capacity have severely impacted the penetration of such tags in the RFID market. Therefore, the scope of this survey article does not include chipless RFID tags. This article instead provides a comparative survey of silicon based IC and SAW based tags, which has attracted much attention from both academia and industry. The underlying characteristics, principles, advantages, and limitations of such tags are thoroughly discussed, and relevant research work followed by frequency of operation and other parameters are elaborated. This article undertakes a thorough investigation into the evolution of RFID technology and comparison into the current trend in silicon based IC and SAW based RFID tags and provides a comparison across many metrics, such as read range, tag size, tag power, availability of tag power, lifespan and more importantly, cost and security. It discusses active and passive tags under silicon based IC and SAW technology. Finally, the article reviews recent advances and provides potentials, open challenges and future research directions in such RFID tags.

Fading Characteristics in Evaporation Duct: Fade Margin for a Wireless Link in the South China Sea

IEEE Access

Evaporation ducts (ED), which are caused by a rapid decrease in the refractive index of the lower... more Evaporation ducts (ED), which are caused by a rapid decrease in the refractive index of the lower atmosphere, are known to trap radio waves between the evaporation duct layer and the sea surface. Although signal propagation and refractivity estimation in evaporation ducts have been well studied, the fading characteristics of ED must be accurately established to help determine fade margin, required for a reliable wireless communication link. In this paper, based on the percentage of occurrences of evaporation ducts, that have been measured and reported in the literature, the statistical distribution of path loss in the South China Sea is calculated for varying distances. These path loss distributions are weather-dependent and time-varying and define several slow time-varying fading characteristics. These slow fading characteristics are, what can be termed as log-lognormal in nature. Propagation in ED, being non-line-of-sight, also has a fast-fading component that is Rayleigh in nature. Once, the complete fading characteristics are known, the overall fade margin due in part; to both slow fading and fast fading can be obtained. For a distance of 100 km, approximately 99% availability can be obtained with an 88-dB fade margin while for a shorter distance of 50 km, the required total margin for 99% availability is only 50-dB.

$FIGURE 2. Annual average evaporation duct height EDH variations & percentage of occurrence in the South China Sea [19]. For long-range signal propagation over the sea, the climatol- ogy of ED is important to determine path loss variations. The time-varying height of ED and its percentage of occurrence is significant. The height varies with varying weather conditions throughout the day and night. ED depends on the profile of a number of weather dependent parameters, e.g., relative humidity (%), sea-surface temperature (°C), air tempera- ture (°C), surface pressure (mb) and surface wind speed (kts). These parameters have great effect on the occurrence of ED at each height. Relative humidity and sea-surface temperature have significant effect on varying ED height (EDH). Tropical regions of the world, that neither experience winter season nor large temperature variations between day and night have much more stable ED with good average height. The annual average variations in the height of ED have been measured previously, and the data are available in the Advanced Refrac- tive Effects Prediction System (AREPS) tool, based on a Parabolic Equations (PE) model [20]. This tool is based on the data collected from 1974 to 1980, primarily by voluntary merchant ships. The data were collected when the resolution was no better than 10° x 10°.$

$FIGURE 4. Path loss in dB for varying distance due to EDH variations. To this end, first, refractivity profile data are generated using Equation 3 for each EDH. The PE tool [20] utilizes this data and other necessary parameters to calculate path loss. For our PE tool based simulations, we kept transmitter and receiver antenna heights at 4 m, which is the optimal height for transmission within the ED as it allows the receiver to be always within EDH, at 10.5 GHz, which is also the preferred frequency in ED, as lower or higher frequencies experience more attenuation at longer distances, as observed in [12] and [18]. The vertical beam width of the antenna is 3° which is lower than the critical angle allows the signal to be confined within ED with horizontal polarization using a Gaussian antenna type. The M-profile generated in the previous section for each EDH from 4 m to 20 m is used to determine path loss values up to 100 km as shown in Figure 4.$

A Chaos-Based Substitution Box (S-Box) Design with Improved Differential Approximation Probability (DP)

Iranian Journal of Science and Technology, Transactions of Electrical Engineering

Robust Symbol Timing Synchronization for OFDM Systems Using PN Sequence

International Journal of Information and Electronics Engineering

Design of Compact Microstrip Patch Antenna for Short Distance WLAN

The Journal of The Korea Institute of Intelligent Transport Systems

Use of wavelets in marine controlled source electromagnetic method for geophysical modeling

International Journal of Applied Electromagnetics and Mechanics, 2016

On the Enlargement of Robust Region of Chaotic Tent Map for the Use in Key Based Substitution-Box (S-Box)

Journal of Computer Science, 2015

Robust chaotic maps with wide robust region are favored in cryptography as it extends the key len... more Robust chaotic maps with wide robust region are favored in cryptography as it extends the key length. Chaotic tent map has robust chaos for control parameter µ = 2. Perturbation of control parameter values beyond control parameter 2, results in orbit diverging towards infinity and trajectories vanish. Thus, to avoid trajectories diverging to infinity and to keep trajectories chaotic beyond parameter value 2, a new technique is proposed that makes use of modulo and scaling operators. The parameter space of non-smooth maps is never considered for enlargement. Herein, modified tent map results in larger parameter space that in turn can be used to design key based S-box. The recently published chaotic key based S-box with chaotic map's parameter space does not achieve large key space. For modified tent map, the modulo operation keeps trajectories in domain (0, 1) while scaling allows for uniform distribution of points in domain (0, 1). These operations keep chaotic orbits globally stable and robust. In results, the robustness of chaotic tent map and modified chaotic tent map is compared using bifurcation diagram. The improved robust region of tent map justifies the effectiveness of proposed method that results to design key based S-box.

$Research paper thumbnail of Influence of fractals on resonant frequencies of a rectangular microstrip antenna$

Influence of fractals on resonant frequencies of a rectangular microstrip antenna

2004 RF and Microwave Conference (IEEE Cat. No.04EX924), 2004

Simulation studies to investigate the influence of fractals on resonant frequencies of a rectangu... more Simulation studies to investigate the influence of fractals on resonant frequencies of a rectangular microstrip antenna are presented. The locations and number of fractals on the patch of a microstrip antenna are varied and the resonant frequencies are evaluated. The study reveals that there are specific locations and size of fractals that affect the resonant frequency of one or both

PAPR reduction in mobile WiMAX: A new ZCMT precoded random interleaved OFDMA system

Journal of Central South University, 2012

Mobile WiMAX (worldwide interoperability for microwave access) air interface adopts orthogonal fr... more Mobile WiMAX (worldwide interoperability for microwave access) air interface adopts orthogonal frequency division multiple access (OFDMA) as multiple access technique for its uplink (UL) and downlink (DL) to improve the multipath performance. All OFDMA based networks, like mobile WiMAX, experience the problem of high peak-to-average power ratio (PAPR). The high PAPR increases the complexity of analog-to-digital (A/D) and digital-to-analog (D/A) convertors, and also reduces the efficiency of RF high-power-amplifier (HPA). In this work, a new zadoff-chu matrix transform (ZCMT) precoding based random interleaved orthogonal frequency division multiple access (OFDMA) system was proposed for PAPR reduction in mobile WiMAX system. The system is based on precoding the constellation symbols with the ZCMT precoder before subcarrier mapping. The PAPR of proposed system is analyzed with the root-raised-cosine (RRC) pulse shaping to keep out of band radiation low and meet the transmission spectrum mask requirement. Simulation results show that the proposed system has better PAPR gain than the hadamard transform (WHT) precoded random interleaved OFDMA systems and the conventional random interleaved OFDMA systems. Symbol-errorrate (SER) performance of the system is also better than the conventional random interleaved OFDMA systems and the random interleaved OFDMA systems with WHT. The good improvement in PAPR significantly reduces the cost and the complexity of the transmitter.

On image compression: a DWT-DCT algorithm

Proceedings of the Sixth International Symposium on Signal Processing and its Applications (Cat.No.01EX467), 2001

Page 1. International Symposium on Signal Processing and its Applications (ISSPA), Kuala Lumpur. ... more

The Effects of Shift-invariance Property in DTℂWT-OFDM System

PAPR Analysis for OFDM Based on DTℂWT

A simple channel estimation method for mimo-ofdm in IEEE802.16A

2004 IEEE Region 10 Conference TENCON 2004., 2004

... A SIMPLE CHANNEL ESTIMATION METHOD FOR MIMO-OFDM IN IEEE802.16A Micheal Drieberg,Yew Kuan Min... more

Computer aided diagnosis (CAD) tool for the analysis of calcaneofibular ligament using ultrasonographic images

Ultrasound imaging is a cost-effective diagnostic tool to imagine the internal organisms of human... more Ultrasound imaging is a cost-effective diagnostic tool to imagine the internal organisms of human beings that used routinely in the diagnosis of a number of diseases related to ligament, tendon, bone, blood flow estimation, obstetrics, etc. However, ultrasound imaging has limitations such as homogenous intensity regions, homogeneous textures, low contrast regions, enhancement artefact, limited view visualization and inaccurate qualitative/quantitative estimation. To overcome all these investigated problems, this research developed a Computer Aided Diagnosis (CAD) system that helps in efficient segmentation and Three Dimensional (3D) reconstruction of calcaneoﬁbular ligament to enhance the diagnosis. The developed CAD system would help in the achievement of enhanced segmentation results, 3D reconstruction results and statistical analysis of the injured calcaneoﬁbular ligament. Moreover, performance of the developed CAD system is analyzed based on the obtained results, which are indic...

Clinical assessment of injured ankle ATFL ligaments based on ultrasound imaging in the athletes

2016 6th International Conference on Intelligent and Advanced Systems (ICIAS), 2016

Ultrasound image segmentation is still a challenging issue in various applications to extract the... more Ultrasound image segmentation is still a challenging issue in various applications to extract the meaningful information for disease diagnosis in the athletes. Generally, ultrasound images could be suffering from some problems such as speckle, attenuation, signal dropout and shadows which make the segmentation process more complicated and inefficient. Due to these problems, traditional segmentation approaches could not be applicable. To overcome these problems, the current study proposed an automatic multilevel segmentation framework for ankle Anterior Talofibular Ligament (ATFL). This framework used the association of active contour and the particle swarm optimization method with curve evaluation and energy minimization capability to obtain the optimized segmented outcomes. It would be more efficiently detect the ATFL ligament in ultrasound images with better interpretation capability. Finally, this study presents various experimental segmented outcomes and corresponding analysis. On the basis of this analysis, the average sensitivity, specificity and accuracy of the proposed framework would be 80.73 %, 96.57 % and 94.12 % respectively.

Impacting clinical evaluation of anterior talofibular ligament injuries through analysis of ultrasound images

Biomedical engineering online, Jan 2, 2016

Anterior talofibular ligament (ATFL) is considered as the weakest ankle ligament that is most pro... more Anterior talofibular ligament (ATFL) is considered as the weakest ankle ligament that is most prone to injuries. Ultrasound imaging with its portable, non-invasive and non-ionizing radiation nature is increasingly being used for ATFL diagnosis. However, diagnosis of ATFL injuries requires its segmentation from ultrasound images that is a challenging task due to the existence of homogeneous intensity regions, homogeneous textures and low contrast regions in ultrasound images. To address these issues, this research has developed an efficient ATFL segmentation framework that would contribute to accurate and efficient diagnosis of ATFL injuries for clinical evaluation. The developed framework comprises of five computational steps to segment the ATFL ligament region. Initially, region of interest is selected from the original image, which is followed by the adaptive histogram equalization to enhance the contrast level of the ultrasound image. The enhanced contrast image is further optimi...

Toward Better Food Security Using Concepts from Industry 5.0

Sensors

The rapid growth of the world population has increased the food demand as well as the need for as... more The rapid growth of the world population has increased the food demand as well as the need for assurance of food quality, safety, and sustainability. However, food security can easily be compromised by not only natural hazards but also changes in food preferences, political conflicts, and food frauds. In order to contribute to building a more sustainable food system—digitally visible and processes measurable—within this review, we summarized currently available evidence for various information and communication technologies (ICTs) that can be utilized to support collaborative actions, prevent fraudulent activities, and remotely perform real-time monitoring, which has become essential, especially during the COVID-19 pandemic. The Internet of Everything, 6G, blockchain, artificial intelligence, and digital twin are gaining significant attention in recent years in anticipation of leveraging the creativity of human experts in collaboration with efficient, intelligent, and accurate machi...

An Improved Split-Step Wavelet Transform Method for Anomalous Radio Wave Propagation Modelling

An Anomalous tropospheric propagation caused by ducting phenomenon is a major problem in wireless... more An Anomalous tropospheric propagation caused by ducting phenomenon is a major problem in wireless com- munication. Thus, it is important to study the behavior of ra- dio wave propagation in tropospheric ducts. The Parabolic Wave Equation (PWE) method is considered most reliable to model anomalous radio wave propagation. In this work, an improved Split Step Wavelet transform Method (SSWM) is presented to solve PWE for the modeling of tropospheric propagation over finite and infinite conductive surfaces. A large number of numerical experiments are carried out to validate the performance of the proposed algorithm. De- veloped algorithm is compared with previously published techniques; Wavelet Galerkin Method (WGM) and Split-Step Fourier transform Method (SSFM). A very good agreement is found between SSWM and published techniques. It is also observed that the proposed algorithm is about six times faster than WGM and provide more details of propagation effects as compared to SSFM.

A Multi-Carrier Waveform Design for 5G and beyond Communication Systems

Mathematics

The next generation communication network (NGCN) is expected to provide higher spectral efficienc... more The next generation communication network (NGCN) is expected to provide higher spectral efficiency, low latency, large throughput and massive machine-to-machine type communications. In this regard, the design of the multi-carrier waveform (MCW) is posing a major research problem for the NGCN. To overcome the stated problem, a lot of state-of-the-art work exists that proposes various MCW alternative to the standard orthogonal frequency division multiplexing (OFDM) waveform. It is true that OFDM was used in a number of real-time communication systems of fourth generation (4G) networks. However, their use in the upcoming fifth generation (5G) network is not very feasible. This is because of the strict requirements of 5G communication systems, which also extend beyond 5G systems; hence rendering the use of OFDM infeasible for newer communication standards. To satisfy the requirements of upcoming communication networks, there is a dire need for MCWs with better flexibility. In this regar...

Surface acoustic wave modes characteristics of CMOS compatible SiO2/AlN/SiO2/Si multilayer structure with embedded electrodes

Sensors and Actuators A: Physical

In this work, a CMOS compatible surface acoustic wave (SAW) device has been simulated and analyze... more In this work, a CMOS compatible surface acoustic wave (SAW) device has been simulated and analyzed on SiO 2 /AlN/SiO 2 /Si. The simulation results have been used to characterize a typical fabricated device as well. The phase velocity, coupling coefficient, and temperature coefficient of frequency (TCF) of surface acoustic waves in the proposed structure have been investigated using the finite-element (FE) simulation. The simulation results show that a high velocity and a large effective coupling factor can be simultaneously obtained. Besides, the excellent nearly zero TCF is also achieved. The analysis further shows potential for designing high-frequency SAW devices that are CMOS compatible and temperature stable utilizing the Sezawa wave mode.

A Comparative Survey on Silicon Based and Surface Acoustic Wave (SAW) Based RFID Tags: Potentials, Challenges and Future Directions

IEEE Access

Many Automatic Identification (Auto-ID) technologies such as bar codes, magnetic stripes, Optical... more Many Automatic Identification (Auto-ID) technologies such as bar codes, magnetic stripes, Optical Character Recognition (OCR) and Electronic Article Surveillance (EAS) security tags are in existence. However, they are limited by a variety of constraints on them such as limited object rate of scan, need for Lineof-Sight (LOS) operation, very small interrogation range and poor accuracy in complex environments. Research has accordingly grown rapidly in recent years into the development of robust identification or tracking mechanisms. Radio Frequency Identification (RFID) technology using readers and RFID tags, whether passive, semi-passive or active in nature, has been deemed to be a promising candidate. Silicon based IC tags are quite popular. However, some alternative RFID technologies have also been on the rise. In particular, another special type of tag based on Surface Acoustic Wave (SAW) design also has a great potential for deployment in future identification fields due to its ruggedness against harsh conditions, metallic environments, interference, small and low cost and is being thoroughly reviewed, which is ignored in other survey papers. While other chipless RFID systems based on conductive ink, ink-tattoo and others do exist, negative aspects such as inability to survive in extreme weather, larger tag size and limited data storage capacity have severely impacted the penetration of such tags in the RFID market. Therefore, the scope of this survey article does not include chipless RFID tags. This article instead provides a comparative survey of silicon based IC and SAW based tags, which has attracted much attention from both academia and industry. The underlying characteristics, principles, advantages, and limitations of such tags are thoroughly discussed, and relevant research work followed by frequency of operation and other parameters are elaborated. This article undertakes a thorough investigation into the evolution of RFID technology and comparison into the current trend in silicon based IC and SAW based RFID tags and provides a comparison across many metrics, such as read range, tag size, tag power, availability of tag power, lifespan and more importantly, cost and security. It discusses active and passive tags under silicon based IC and SAW technology. Finally, the article reviews recent advances and provides potentials, open challenges and future research directions in such RFID tags.

Fading Characteristics in Evaporation Duct: Fade Margin for a Wireless Link in the South China Sea

IEEE Access

Evaporation ducts (ED), which are caused by a rapid decrease in the refractive index of the lower... more Evaporation ducts (ED), which are caused by a rapid decrease in the refractive index of the lower atmosphere, are known to trap radio waves between the evaporation duct layer and the sea surface. Although signal propagation and refractivity estimation in evaporation ducts have been well studied, the fading characteristics of ED must be accurately established to help determine fade margin, required for a reliable wireless communication link. In this paper, based on the percentage of occurrences of evaporation ducts, that have been measured and reported in the literature, the statistical distribution of path loss in the South China Sea is calculated for varying distances. These path loss distributions are weather-dependent and time-varying and define several slow time-varying fading characteristics. These slow fading characteristics are, what can be termed as log-lognormal in nature. Propagation in ED, being non-line-of-sight, also has a fast-fading component that is Rayleigh in nature. Once, the complete fading characteristics are known, the overall fade margin due in part; to both slow fading and fast fading can be obtained. For a distance of 100 km, approximately 99% availability can be obtained with an 88-dB fade margin while for a shorter distance of 50 km, the required total margin for 99% availability is only 50-dB.

$FIGURE 2. Annual average evaporation duct height EDH variations & percentage of occurrence in the South China Sea [19]. For long-range signal propagation over the sea, the climatol- ogy of ED is important to determine path loss variations. The time-varying height of ED and its percentage of occurrence is significant. The height varies with varying weather conditions throughout the day and night. ED depends on the profile of a number of weather dependent parameters, e.g., relative humidity (%), sea-surface temperature (°C), air tempera- ture (°C), surface pressure (mb) and surface wind speed (kts). These parameters have great effect on the occurrence of ED at each height. Relative humidity and sea-surface temperature have significant effect on varying ED height (EDH). Tropical regions of the world, that neither experience winter season nor large temperature variations between day and night have much more stable ED with good average height. The annual average variations in the height of ED have been measured previously, and the data are available in the Advanced Refrac- tive Effects Prediction System (AREPS) tool, based on a Parabolic Equations (PE) model [20]. This tool is based on the data collected from 1974 to 1980, primarily by voluntary merchant ships. The data were collected when the resolution was no better than 10° x 10°.$

$FIGURE 4. Path loss in dB for varying distance due to EDH variations. To this end, first, refractivity profile data are generated using Equation 3 for each EDH. The PE tool [20] utilizes this data and other necessary parameters to calculate path loss. For our PE tool based simulations, we kept transmitter and receiver antenna heights at 4 m, which is the optimal height for transmission within the ED as it allows the receiver to be always within EDH, at 10.5 GHz, which is also the preferred frequency in ED, as lower or higher frequencies experience more attenuation at longer distances, as observed in [12] and [18]. The vertical beam width of the antenna is 3° which is lower than the critical angle allows the signal to be confined within ED with horizontal polarization using a Gaussian antenna type. The M-profile generated in the previous section for each EDH from 4 m to 20 m is used to determine path loss values up to 100 km as shown in Figure 4.$

A Chaos-Based Substitution Box (S-Box) Design with Improved Differential Approximation Probability (DP)

Iranian Journal of Science and Technology, Transactions of Electrical Engineering

Robust Symbol Timing Synchronization for OFDM Systems Using PN Sequence

International Journal of Information and Electronics Engineering

Design of Compact Microstrip Patch Antenna for Short Distance WLAN

The Journal of The Korea Institute of Intelligent Transport Systems

Use of wavelets in marine controlled source electromagnetic method for geophysical modeling

International Journal of Applied Electromagnetics and Mechanics, 2016

On the Enlargement of Robust Region of Chaotic Tent Map for the Use in Key Based Substitution-Box (S-Box)

Journal of Computer Science, 2015

Robust chaotic maps with wide robust region are favored in cryptography as it extends the key len... more Robust chaotic maps with wide robust region are favored in cryptography as it extends the key length. Chaotic tent map has robust chaos for control parameter µ = 2. Perturbation of control parameter values beyond control parameter 2, results in orbit diverging towards infinity and trajectories vanish. Thus, to avoid trajectories diverging to infinity and to keep trajectories chaotic beyond parameter value 2, a new technique is proposed that makes use of modulo and scaling operators. The parameter space of non-smooth maps is never considered for enlargement. Herein, modified tent map results in larger parameter space that in turn can be used to design key based S-box. The recently published chaotic key based S-box with chaotic map's parameter space does not achieve large key space. For modified tent map, the modulo operation keeps trajectories in domain (0, 1) while scaling allows for uniform distribution of points in domain (0, 1). These operations keep chaotic orbits globally stable and robust. In results, the robustness of chaotic tent map and modified chaotic tent map is compared using bifurcation diagram. The improved robust region of tent map justifies the effectiveness of proposed method that results to design key based S-box.

$Research paper thumbnail of Influence of fractals on resonant frequencies of a rectangular microstrip antenna$

Influence of fractals on resonant frequencies of a rectangular microstrip antenna

2004 RF and Microwave Conference (IEEE Cat. No.04EX924), 2004

Simulation studies to investigate the influence of fractals on resonant frequencies of a rectangu... more Simulation studies to investigate the influence of fractals on resonant frequencies of a rectangular microstrip antenna are presented. The locations and number of fractals on the patch of a microstrip antenna are varied and the resonant frequencies are evaluated. The study reveals that there are specific locations and size of fractals that affect the resonant frequency of one or both

PAPR reduction in mobile WiMAX: A new ZCMT precoded random interleaved OFDMA system

Journal of Central South University, 2012

Mobile WiMAX (worldwide interoperability for microwave access) air interface adopts orthogonal fr... more Mobile WiMAX (worldwide interoperability for microwave access) air interface adopts orthogonal frequency division multiple access (OFDMA) as multiple access technique for its uplink (UL) and downlink (DL) to improve the multipath performance. All OFDMA based networks, like mobile WiMAX, experience the problem of high peak-to-average power ratio (PAPR). The high PAPR increases the complexity of analog-to-digital (A/D) and digital-to-analog (D/A) convertors, and also reduces the efficiency of RF high-power-amplifier (HPA). In this work, a new zadoff-chu matrix transform (ZCMT) precoding based random interleaved orthogonal frequency division multiple access (OFDMA) system was proposed for PAPR reduction in mobile WiMAX system. The system is based on precoding the constellation symbols with the ZCMT precoder before subcarrier mapping. The PAPR of proposed system is analyzed with the root-raised-cosine (RRC) pulse shaping to keep out of band radiation low and meet the transmission spectrum mask requirement. Simulation results show that the proposed system has better PAPR gain than the hadamard transform (WHT) precoded random interleaved OFDMA systems and the conventional random interleaved OFDMA systems. Symbol-errorrate (SER) performance of the system is also better than the conventional random interleaved OFDMA systems and the random interleaved OFDMA systems with WHT. The good improvement in PAPR significantly reduces the cost and the complexity of the transmitter.

On image compression: a DWT-DCT algorithm

Proceedings of the Sixth International Symposium on Signal Processing and its Applications (Cat.No.01EX467), 2001

Page 1. International Symposium on Signal Processing and its Applications (ISSPA), Kuala Lumpur. ... more

The Effects of Shift-invariance Property in DTℂWT-OFDM System

PAPR Analysis for OFDM Based on DTℂWT

A simple channel estimation method for mimo-ofdm in IEEE802.16A

2004 IEEE Region 10 Conference TENCON 2004., 2004

... A SIMPLE CHANNEL ESTIMATION METHOD FOR MIMO-OFDM IN IEEE802.16A Micheal Drieberg,Yew Kuan Min... more