Farzad Tofigh | University of Technology Sydney (original) (raw)

Papers by Farzad Tofigh

IEEE Transactions on Antennas and Propagation, Mar 1, 2020

© 2020 IEEE. Noninvasive crowd estimation has remained a challenging issue among researchers. Met... more © 2020 IEEE. Noninvasive crowd estimation has remained a challenging issue among researchers. Methods such as image analysis and Wi-Fi/Bluetooth probing can always be used to identify and track people. Lately, authors have introduced a noninvasive method for crowd estimation based on ambient RF energy measurements. In this article, a polarization-insensitive multilayer metamaterial absorber is introduced to measure the variation in the available RF energy levels for crowd estimation purposes. The proposed dual-band absorber is designed to absorb and transfer the maximum of the available Wi-Fi energy to a lumped element to enable proper and accurate measurements. To evaluate the design, the proposed structure is fabricated as an array, and its performance is tested, proving perfect absorption at the desired frequencies, 2.4 and 5 GHz

Progress In Electromagnetics Research, 2010

IEEE access, 2024

The authors acknowledge the support of Food Agility CRC Ltd, funded under the Commonwealth Govern... more The authors acknowledge the support of Food Agility CRC Ltd, funded under the Commonwealth Government CRC Program. The financial and in-kind support of Robert Bosch (Australia) Pty Ltd & Robert Bosch GmbH in completing this work is also acknowledged.

2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), 2019

Green cellular network helps to decrease environmental pollution. In contrast, massive connectivi... more Green cellular network helps to decrease environmental pollution. In contrast, massive connectivity and demand for higher data rate promise the presence of new generation of cellular system (5G) and small cell networks. Hence, expectation on increasing the number of base stations (BSs), which leads to increase in energy usage. One way to improve energy consumption is by shutting down the redundant BSs while sustaining the Quality-of-Service (QoS) for each user. In this paper, we propose a dynamic structural algorithm based on transportation problem, to switch on/off the BSs in cellular networks without compromising its coverage, and maintain the networks load by neighboring cells. We use weighted graphs to translate our problem as a transportation problem and then use linear programming to solve it. The cost of transport, turning a BS into sleep mode, is illustrated as a function of energy usage,coverage area and load on the BSs. Running the propose method consecutively provides the maximum number of BSs whom are at sleep mode. The methodology explained in this paper reduces energy consumption to almost 40%, whereas maintaining all the existing loads in the network.

2018 12th International Conference on Signal Processing and Communication Systems (ICSPCS), 2018

Crowd distribution is a challenging issue in the management and design levels. This paper provide... more Crowd distribution is a challenging issue in the management and design levels. This paper provides a passive method to derive the crowd density distribution using Wi-Fi measurements on a real scenario. Six WiFi access points (AP) were deployed across two co-located platforms at a train station to monitor the platforms for a week. Based on the probability maps that are built using RSSI measurements and prior knowledge, the crowd distribution is calculated on the platform to increase the accuracy of the estimations in scenarios with sparse data collection. The estimated distribution results are compared with distributions acquired from CCTV images and final density heat maps correlate well with the acquired results from CCTV cameras.

Automatica, 2020

Abstract Of collective behaviors in networks of coupled systems, synchronization is of central im... more Abstract Of collective behaviors in networks of coupled systems, synchronization is of central importance and an extensively studied area. This is due to the fact that it is essential for the proper functioning of a wide variety of natural and engineered systems. Traditionally, uniform coupling strength has been the default choice and the synchronizability measure has been employed for analysis and enhancement of synchronizability. The main drawback of optimizing the synchronizability measure is that it can reach the Pareto frontier but not necessarily a unique point on the Pareto frontier. Additionally, the shortcoming of uniform coupling strength is that it can reach Pareto frontier in specific topologies including edge-transitive graphs. To achieve a unique optimal answer on the Pareto frontier, this paper takes a different approach and addresses the synchronizability in networks of coupled dynamical systems with nonuniform coupling strength and optimizing the synchronizability via maximizing the minimum distance between the nonzero eigenvalues of the Laplacian and the acceptable boundaries for the stability of the system. Furthermore, two solution methods, namely the concave–convex fractional programming and the Semidefinite Programming (SDP) formulations of the problem have been provided. The proposed solution methods have been compared over different topologies and branches of an arbitrary network, where the SDP based approach has shown to be less restricted and more suitable for a wider range of topologies.

IEEE Transactions on Vehicular Technology, 2019

IEEE Antennas and Wireless Propagation Letters, 2014

Using microwave energy for medical applications has been considered a long time ago. By introduci... more Using microwave energy for medical applications has been considered a long time ago. By introducing near-field focused array antennas, a new approach came out in this field. This letter introduces a near-field focused (NFF) array antenna working on 2.4 GHz that has been developed to test a new idea based on the fact that electromagnetic waves would deliver their energy in watery substances. A good tradeoff tried to be achieved in the NFF antenna's features such as small focused spot, about 100 100 mm , 45 cm depth of focus, and the size of 40 40 cm of antenna in order to perform tests of this new application.

Progress In Electromagnetics Research C, 2014

A novel compact and multiband dipole antenna with a planar fractal-inspired configuration is pres... more A novel compact and multiband dipole antenna with a planar fractal-inspired configuration is presented. Several series capacitances and a parasitic element are employed as loading. Results show that the loading improves the impedance matching and enables the proposed antenna to radiate at multiple frequency bands which are not harmonically related. In addition, the proposed loaded dipole antenna offers a high degree of miniaturization in comparing with the unloaded host dipole antenna. The simulated |S 11 | response of the proposed loaded dipole antenna shows five distinct resonant bands with the center resonant frequencies of 1.

IEEE Antennas and Wireless Propagation Letters, 2013

A novel printed Ultra Wide Band (UWB) slot antenna with reconfigurable band-notch characteristics... more A novel printed Ultra Wide Band (UWB) slot antenna with reconfigurable band-notch characteristics is presented in this letter. Proposed antenna consists of modified rectangular radiation patch with a circular and three rectangularshaped slots etched on it. Additionally, by cutting two triangularshaped slits on modified ground plane, practical fractional bandwidth of more than 120% (3.12-12.51 GHz), defined by-10 dB return loss is achieved. In order to generate single and dual bandnotch characteristics, two p-in diodes are mounted across the circular slot. The designed antenna has small size of 20×20 mm 2 with switchable single notched bands of 3.12-3.84 GHz, WiMAX, and 5-6.07 GHz, WLAN, when diode 1 and diode 2 are respectively on. Also, dual bands of 3.12-3.82 GHz and 4.9-6.06 GHz are eliminated from whole frequency band when both of diodes are concurrently on.

2020 4th Australian Microwave Symposium (AMS), 2020

Non-Foster elements have attracted considerable interest because of their role in enabling wide-b... more Non-Foster elements have attracted considerable interest because of their role in enabling wide-band electrically small antennas and metamaterials. However, the potential instability of these elements continues to be an going challenge to their realization and, hence, practical acceptance. In this paper, we present a stable floating negative impedance converter (NIC) element using a RLC (resistor-inductor-capacitor) based subcircuit as the load.

2020 IEEE 45th Conference on Local Computer Networks (LCN)

The existing lottery-based consensus algorithms, such as Proof-of-Work, and Proof-of-Stake, are m... more The existing lottery-based consensus algorithms, such as Proof-of-Work, and Proof-of-Stake, are mostly used for blockchain-based financial technology applications. Similarly, the Byzantine Fault Tolerance algorithms do provide consensus finality, yet they are either communications intensive, vulnerable to Denial-of-Service attacks, poorly scalable, or have a low faulty node tolerance level. Moreover, these algorithms are not designed for the Internet of Things systems that require near-real-time transaction confirmation, maximum fault tolerance, and appropriate transaction validation rules. Hence, we propose "Pledge," a unique Proof-of-Honesty based consensus protocol to reduce the possibility of malicious behavior during blockchain consensus. Pledge also introduces the Internet of Things centric transaction validation rules. Initial experimentation shows that Pledge is economical and secure with low communications complexity and low latency in transaction confirmation.

IEEE Internet of Things Journal

Future Internet of Things (IoT) devices are expected to be fully ubiquitous. To achieve this visi... more Future Internet of Things (IoT) devices are expected to be fully ubiquitous. To achieve this vision, a new generation of IoT devices needs to be developed, which can operate autonomously. To achieve autonomy, IoT devices must be completely wireless, both in terms of transmission and power. Further, accurate sensing is another crucial parameter of autonomy. Several wireless standards have been developed for improving the efficiency of IoT applications. However, the powering of IoT devices, sensor accuracy, and efficiency of electronic devices are open research problems in literature. With the advent of metamaterial perfect absorbers (MPAs), electromagnetic waves can be used as a source of energy, to enable sensing of the phenomenon and as a carrier for exchanging data. In this article, an extensive application-based investigation has been conducted on design principles and various methods of enhancing MPA characteristics. Moreover, the current applications that benefit from MPA, such as absorption of undesired frequencies, optical switching, energy harvesting, and sensing, are investigated. Finally, some implemented examples of MPA in industrial applications are provided along with possible directions for future work and open research areas.

2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC)

Exhibition of malicious behavior during blockchain consensus, threats against reputation systems,... more Exhibition of malicious behavior during blockchain consensus, threats against reputation systems, and high TX latency are significant issues for blockchain-based IoT systems. Hence, to mitigate such challenges we propose "Pledge", a unique Proof-of-Honesty based consensus protocol. Initial experimentation shows that Pledge is economical with low computations and communications complexity and low latency in transaction confirmation.

2020 14th European Conference on Antennas and Propagation (EuCAP)

Implementing 5G technology contributes to improve communication quality and facilitate several in... more Implementing 5G technology contributes to improve communication quality and facilitate several interesting applications in daily life such as Internet of things. Despite outstanding features of 5G, the amount of ambient electromagnetic waves will be increased significantly in the environment, which may be undesired. Ultra-wideband metamaterial perfect absorber is a promising solution to collect these undesired signals. Using lumped elements in absorber structure to increase the absorption bandwidth leads to design and fabrication process complexity. In this paper, a low profile polarization angle selective metamaterial absorber has been designed to absorb signals in the frequency range of 21.79 GHz to 53.23 GHz with more than 90% efficiency. The relative absorption bandwidth of the final structure is 83.81%. Moreover, the final structure is reasonably insensitive facing different incident angle up to 40 degree.

IEEE Transactions on Network Science and Engineering

Many engineered and natural systems are modeled as networks of coupled systems. Synchronization i... more Many engineered and natural systems are modeled as networks of coupled systems. Synchronization is one of their crucial and well-studied behaviors. Uniform coupling strength has been the benchmark practice in the majority of the literature. This paper considers nonuniform coupling strength, and a modified approach to the problem of synchronizability optimization, enabling a reduction to a spectral radius minimization problem, which can reach a unique optimal point on the Pareto Frontier. It is established that adding any edge to a connected graph can only improve synchronizability in this optimal measure. This result is utilized for developing a hierarchy between topologies. It is shown that several proposed structural parameters, including betweenness centrality, do not have any simple relationship to the optimal synchronizability measure.

Journal of Electronic Materials

IET Microwaves, Antennas & Propagation