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This paper addresses the congestion problem in cellular networks through the assistance of parcel delivery drones. Drones have the primary task of parcel delivery and a secondary task of acting as relay nodes (hop) to add extra capacity in a cellular network. Base transceiver stations in the cells can admit ground user equipment to communicate directly with the drone (device-to-device communications) through in-band signalling between them. This paper proposes a novel algorithm, called CARLO, which optimizes trajectory and altitude of the drones in order to deliver physical parcels, maximize network capacity and reduce network interference. Our simulation studies show that our solution improves the network throughput while the energy inefficiency of taking detour path to assist congested cells is kept to a minimum. Moreover, it is guaranteed that parcels are delivered before deadline.

In this paper, multi-antenna transceiver for zero-padded orthogonal frequency division multiplexing (OFDM) system is designed at mmWave by integrating full-duplex unmanned aerial vehicle (UAV) into the terrestrial cellular networks. Assuming that there exist no direct communication links between the ground base station (GBS) and the mobile users due to unexpected blockages from high storied buildings in urban area, the UAV applies decode-and-forward cooperative strategy on the received OFDM signals transmitted from GBS and re-transmits to the ground mobile users and passive eavesdropper. In this proposed system, intertwining logistic map (ILM)-cosine transform aided encryption algorithm combined with artificial noise enhancing physical layer security (PLS) is introduced. Also walsh-hadamard transform technique integrated with QR-decomposition based zero forcing (ZF) block diagonalization (QR-ZF-BD) precoding for multi-user interference reduction and non-iterative clipping and filtering technique for peak to average power ratio (PAPR) reduction are utilized. In addition, Low density parity check (LDPC) and repeat and accumulate (RA) channel coding with cholesky decomposition based ZF and minimum mean square error signal detection schemes for improved bit error rate (BER) are also introduced. Numerical results demonstrate the effectiveness of the proposed system in terms of PLS for color image transmission at high order digital modulation (16-PSK and 16-QAM). At the complementary cumulative distribution function of probability level 1-6%, the estimated PAPR is found to have value of 6 dB.The three users achieve BER $= 1\times {10}^{-4}$ at signal-to-noise ratio of 1.5 dB, 4 dB and 6 dB under RA channel coding and 16-QAM digital modulation.

Cube Satellites, aka CubeSats, are a class of nano satellites that have gained popularity recently, especially for those that consider CubeSats as an emerging alternative to conventional satellites for space programs. This is because they are cost-effective, and they can be built using commercial off-the-shelf components. Moreover, CubeSats can communicate with each other in space and ground stations to carry out many functions such as remote sensing (e.g., land imaging, education), space research, wide area measurements and deep space communications. Consequently, communications between CubeSats and ground stations is critical. Any antenna design for a CubeSat needs to meet size and weight restrictions while yielding good antenna radiation performance. To date, a limited number of works have surveyed, compared and categorised the proposed antenna designs for CubeSats based on their operating frequency bands. To this end, this paper contributes to the literature by focusing on different antenna types with different operating frequency bands that are proposed for CubeSat applications. This paper reviews 48 antenna designs, which include 18 patch antennas, 5 slot antennas, 4 dipole and monopole antennas, 3 reflector antennas, 3 reflectarray antennas, 5 helical antennas, 2 metasurface antennas and 3 millimeter and sub-millimeter wave antennas. The current CubeSat antenna design challenges and design techniques to address these challenges are discussed. In addition, we classify these antennas according to their operating frequency bands, e.g., VHF, UHF, L, S, C, X, Ku, K/Ka, W and mm/sub-mm wave bands and provide an extensive qualitative comparison in terms of their size, −10 dB bandwidths, gains, reflection coefficients, and deployability. The suitability of different antenna types for different applications as well as the future trends for CubeSat antennas are also presented.

Free Space Optical (FSO) communication links are although extremely vulnerable to atmospheric adversities, multi-hop relay transmission can however, significantly improve the link performance and reliability. This paper proposes 120 Gbps DP-16 QAM modulated multi-hop serial FSO link with coherent reception for delivering medical consultation services in remote and isolated locations. Considering the current situation wherein pandemic of highly infectious nature, COVID-19 has affected millions of people globally; doctors can use the proposed high-speed architecture for “contact-less” supervision of quarantined patients and suspects through video conferencing. Each relay terminal uses an all-optical amplify-and-forward technique with Erbium-doped fiber amplifier (EDFA) and gain optimization as its core elements. As a possible last-mile application for delivering medical/health care services, the proposed link has been evaluated for reliability by exposing the link to varied atmospheric conditions. Our results reveal that at target BER of 10-5, the useful communication link range of proposed multi-hop link increments by 1.8 kms as compared to direct link that operates under similar channel conditions. Furthermore, compared to results from recent literature on high-speed FSO [30], the proposed link shows enhancement in link range by approximately 0.7 km. The analysis also reveals that as the number of relay nodes increases, the error performance of the link for different atmospheric conditions approaches a state of convergence.

Recent developments in miniaturized electronic devices with sophisticated computational capabilities and remarkably low power communication technologies involve a tendency toward powering these devices with long cycle life, high energy efficiency, fast and cheap production and lightweight power sources. Integration of piezoelectric materials and novel fabrication techniques with conventional textile processes established the emergence of a wearable technology field which can fulfill this purpose. Mechanical energy harvesters are required for multiple applications such as structural health monitoring systems, self-powered wireless sensors, and harvesting energy from body movements inexpensively. Among the variety of materials exhibiting piezoelectricity, polymers are more considered due to their many excellent properties desirable in flexible piezoelectric generators. Hence, fiber-based electronic devices have the best features for human garments such as flexibility, stretchability, permeability and lightweight, and they are ideal interface platform options between the environment, electronic devices and human body. Hence, this article starts with the fundamentals of wearable technology and materials involved and then reviews recent developments in fiber-based self-powered systems and sensors with the special focus on the piezoelectric poly(vinylidene fluoride) polymer and barium titanium oxide ceramic. In addition, a number of strategies that may improve the piezoelectric generator performance are summarized. Furthermore, the global textile market industry and the high-performance end-user such as washability and durability were reviewed. Potential difficulties, challenges and opportunities in the field of fiber-based energy generators are also explored.

In this article, a low profile circularly polarized (CP) antenna with wide 3-dB axial ratio beamwidth (ARBW) is presented. Two-pair of parallel slots are etched on a circular patch and manifested as magnetic dipoles (MDs). These narrow slots are arranged symmetrically about the axes, and one pair is orthogonal to another pair of slots. The philosophy of CP radiation across a wide angular range strongly depends on the spacing between the paired-dipoles, for example spacing of $0.22\lambda _{0}$ , two-orthogonal far-field radiated components become equal across a wide-angle. Moreover, this particular spacing between the paired-dipoles provides a symmetrical electric field distribution along the periphery of the patch, which ensures the broadside LHCP radiation with wide 3-dB ARBW of 228° and 214° at the plane of $\varphi = 0^{\circ }$ and $\varphi = 90^{\circ }$ , respectively. The measured results from the fabricated prototype exhibit good agreement with the simulated results. The antenna has impedance bandwidth (IBW) and CP bandwidth (CPBW) of 2.6% (64 MHz), and 0.9% (22 MHz), respectively. The broadside radiation holds antenna gain higher than 5 dBic across the entire CPBW.

This paper proposes a novel Quality of experience based Energy Efficient method (QEE) to distribute Peer-to-Peer (P2P) video in a mobile ad hoc network. P2P video distribution is first formulated as a resource allocation problem with the aim of maximizing the end user’s quality of experience. We studied the resource allocation problem as a linear optimization problem to provide efficient utilization of upload bandwidth and energy at each mobile node. Furthermore, scalable video coding is used, that helps maximizing the quality of experience by distributing the layered video over multiple sources using multiple paths to minimize the power consumption and the upload bandwidth at each node. The simulation results show that in the case of 10% uploader nodes in the network, and at the nodes velocity of 1 m/s; QEE method consumes 5 to 25% less power, as compared to existing methods such as; EVAN (Energy aware video streaming in wireless ad hoc network), WCNC (Assessing best strategy for adaptive streaming in mobile ad hoc network), QNE (QoE based non Energy Efficient) and NQNE (Non QoE based Non Energy Efficient). This is because the load is efficiently distributed across multiple sources in the network. Furthermore, the result also shows that for the case of 10% uploader nodes in the network QEE method achieves 10% higher Mean Opinion Score (MOS) among nodes as compared to EVAN and QNE methods as it considers path utility for streaming the video using multiple sources over multiple paths. We have also evaluated the performance of QEE under network churn and flash crown scenarios; the result shows that QEE maintains a reasonable quality under such situations.

The aim of this work is to propose a dual band millimeter wave (mmwave) MIMO antenna system for 5G technology. In addition, the arrangement of the antenna elements in an array should be in such a manner that without using the traditional decoupling structures and/or techniques, a reasonable isolation level must be achieved. To demonstrate this, a system consists of four radiating elements that are etched on a 0.508 mm-thick Rogers-5880 substrate. The dielectric constant of the substrate is 2.2 and the loss tangent is 0.0009. Each radiating element consists of three parts, an E-shaped patch, an H-shaped slot within a patch, and a transmission line. The system is resonating at two different mmwave frequencies, i.e., 28 GHz and 38 GHz with a minimum port isolation of 28 dB. The mean measured gain is found to be at 7.1 dBi at 28 GHz and 7.9 dBi at 38 GHz with average efficiency, and envelope correlation coefficient (ECC) of the system at 70%, and 0.0005 respectively. The proposed system is designed and simulated in a full-wave electromagnetic wave software Computer Simulation Technology (CST), fabricated using LPKF D104 milling machine, and measured using R&amp, SZNA67 vector network analyzer. An excellent agreement is observed between the simulated and the measured results and a detailed comparison with the previous works is also presented. Due to attributes such as low-cost, easy to fabricate, and dual-band, it is believed that this system will find its application for future 5G systems.

This chapter discusses the state of the art in dealing with the resource optimization problem for smooth delivery of video across a peer to peer (P2P) network. It further discusses the properties of using different video coding techniques such as Scalable Video Coding (SVC) and Multiple Descriptive Coding (MDC) to overcome the playback latency in multimedia streaming and maintains an adequate quality of service (QoS) among the users. The problem can be summarized as follows; Given that a video is requested by a peer in the network, what properties of SVC and MDC can be exploited to deliver the video with the highest quality, least upload bandwidth and least delay from all participating peers. However, the solution to these problems is known to be NP hard. Hence, this chapter presents the state of the art in approximation algorithms or techniques that have been proposed to overcome these issues.

This article presents a compact wideband high gain patch antenna for CubeSat. The proposed metal-only antenna mainly consists of an upper patch, a folded ramp-shaped patch and shoring pins connecting the antenna with the ground plane. By adjusting the lengths and widths of two arms of the upper F-shaped patch, a second resonant frequency is generated, and hence, the &minus, 10 dB bandwidth is increased. Moreover, the effect of arms&rsquo, lengths and widths on reflection coefficients, operating frequency and bandwidth is presented. To validate the design and the simulation results, a prototype metal-only patch antenna was fabricated and tested in a Chamber. A good agreement between the simulated and measured results is achieved. The measured results show that the fabricated prototype achieves a &minus, 10 dB bandwidth of 44.9% (1.6&ndash, 2.7 GHz), a small reflection coefficient of &minus, 24.4 dB and a high efficiency, i.e., 85% at 2.45 GHz. The radiation performance of the proposed antenna is measured, showing a peak realized gain of 8.5 dBi with cross polarization level less than &minus, 20 dB at 2.45 GHz and a 3 dB gain bandwidth of 61.22%.

The grid integration of plug-in electric vehicles (PEVs) requires a comprehensive analysis and effective control strategies to prevent any violation of the electrical constraints of the power systems. When renewable energy sources (RESs) are available, they can be used to supply the energy demand of the PEVs. In this study, a photovoltaic (PV) power plant and IoT based remote control of PEV charging are proposed as a virtual power plant (VPP). Particularly, the concept for the use of LoRaWAN to remotely monitor and control the PEV charging loads is presented. Moreover, a hierarchical VPP control (VPPC) system based on the model predictive control (MPC) method is proposed for the optimal energy management (EM) of the VPP. The EM of the VPP is scheduled based on the predicted information initially and based on the optimal values for the EM and the intermittency of PV generation, the charging rate of the PEVs is modified during the real-time process. The results of the case studies show that the proposed VPPC can minimize the energy costs to the VPP and satisfy the energy balancing for the VPP entities while fulfilling the charging demand of the PEVs under system uncertainties.

Radio Frequency Identification (RFID) is the driving technology behind many compelling applications, such as smart cities, item tracking, and Internet-of-Things (IoT). However, it is always challenging to design small size, lightweight, low-cost RFID systems with low power consumption. This work presents a low-profile, lightweight, low cost, and high gain metasurface slot antenna for Ultra High Frequency band (UHF) RFID readers. The antenna design consists of a slot antenna fed by a 50-Ω coplanar waveguide, a metasurface of 9×9 periodic unit cells based on the square closed ring resonators, and a metallic reflector. The proposed metasurface works as an artificial magnetic conductor surface and hence minimizes back lobe radiation, increasing the boresight gain at 915 MHz. The final design yields good impedance matching with a small reflection coefficient of -25.17 dB and gain of 6.61 dBi at 915 MHz operating frequency.

In this work, two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications are presented. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vectran (LIBERATOR 40) which is a highly conductive multifilament yarn spun from Liquid Crystal Polymers (LCP), on cotton fabrics. The proposed tag's design uses a Frequency Selective Surface (FSS) technique for the frequency range of 8 to 18GHz and fabricated by using commercial ZSK Technical Embroidery System JCZA. The tag design is composed of six concentric octagonal loop resonators with one unitary element. The desired data bits are obtained by a series of comparative experiments for Radar Cross Section (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data codeword is accurately retrieved with the variation of distance by up to 1.8m at 0dBm. Moreover, the experimental results include on-body RCS measurements and the bending effects on both of the tags. The tags are compared to the state of the art tags in a comparative table.

In this paper, a metal frame antenna is proposed for CubeSat communications. A $100\text{mm}\times 100\text{mm}\times 5\text{mm}$ metal frame is integrated with loop antenna on a $60\text{mm}\times 70\text{mm}$ substrate. The proposed antenna was simulated using HFSS to show its far-filed performance. The simulation results show that the antenna on CubeSat can achieve a maximum gain of 10.48dBi and dual band performance on S-band. In simulation, the reflection coefficients of the proposed antenna are −20.6dB at 2.4GHz with a narrow −10dB bandwidth of 35MHz, and −21.3dB at 2.1GHz with a narrow −10dB bandwidth of 40MHz. The measured results proved that the fabricated antenna operates on dual band centered at 2.1GHZ and 2.5GHz with −19.53dB and −16.61dB return loss respectively. The measured radiation pattern is well matched with simulation to shows good feasibility of the fabricated antenna.

In this paper, a sewed chipless octagonal-shaped RFID tag on cotton fabric is proposed for wearable applications. The tag is designed using a Frequency Selective Surface (FSS) technique and operates from 8-18GHz. The design is composed of six concentric octagonal loop resonators with one unitary element. The tag is made of silver-coated polyamide conductive fiber (HC12) and is manufactured using a commercial ZSK Technical Embroidery System JCZA. The encoded data bits are obtained by a series of Radar Cross Section (RCS) measurements inside an anechoic chamber. The experimental results obtained show that the 4-bit data codeword is accurately retrieved up to 1.8m away from the tag at 0dBm power. Moreover, the feasibility of the proposed tag for wearable and smart garment IoT applications is verified by on-body RCS measurements.

Managing and delivering data packets at high frequency e.g., ≤ 28 GHz, using vehicles through delayed tolerant networks in cities is challenging. This is because of the high attenuation of high frequency signals with the presence of obstacles in cities, e.g., buildings. To address this limitation, this paper proposes the use of drones with the ground vehicles as relays to strength the signals and hence improve the DTN performance. We model our network in Opportunistic Network Environment (ONE) simulator to study the effect and impact of using drones with ground vehicles on the performance of DTN destination-based routing protocol. The simulation results show that the use of drones with ground vehicles improves the delivery probability to about 33% and decreases the delay to about 25% as compared to the use ground vehicles without drones.

CubeSats, which are limited by size and mass, have limited functionality. These miniaturised satellites suffer from a low power budget, short radio range, low transmission speeds, and limited data storage capacity. Regardless of these limitations, CubeSats have been deployed to carry out many research missions, such as gravity mapping and the tracking of forest fires. One method of increasing their functionality and reducing their limitations is to form CubeSat networks, or swarms, where many CubeSats work together to carry out a mission. Nevertheless, the network might have intermittent connectivity and, accordingly, data communication becomes challenging in such a disjointed network where there is no contemporaneous path between source and destination due to satellites’ mobility pattern and given the limitations of range. In this survey, various inter-satellite routing protocols that are Delay Tolerant (DTN) and Non Delay Tolerant (Non-DTN) are considered. DTN routing protocols are considered for the scenarios where the network is disjointed with no contemporaneous path between a source and a destination. We qualitatively compare all of the above routing protocols to highlight the positive and negative points under different network constraints. We conclude that the performance of routing protocols used in aerospace communications is highly dependent on the evolving topology of the network over time. Additionally, the Non-DTN routing protocols will work efficiently if the network is dense enough to establish reliable links between CubeSats. Emphasis is also given to network capacity in terms of how buffer, energy, bandwidth, and contact duration influence the performance of DTN routing protocols, where, for example, flooding-based DTN protocols can provide superior performance in terms of maximizing delivery ratio and minimizing a delivery delay. However, such protocols are not suitable for CubeSat networks, as they harvest the limited resources of these tiny satellites and they are contrasted with forwarding-based DTN routing protocols, which are resource-friendly and produce minimum overheads on the cost of degraded delivery probability. From the literature, we found that quota-based DTN routing protocols can provide the necessary balance between delivery delay and overhead costs in many CubeSat missions.

Conductive biomaterials have recently gained much attention, specifically owing to their application for electrical stimulation of electrically excitable cells. Herein, flexible, electrically conducting, robust fibers composed of both an alginate biopolymer and graphene components have been produced using a wet-spinning process. These nanocomposite fibers showed better mechanical, electrical, and electrochemical properties than did single fibers that were made solely from alginate. Furthermore, with the aim of evaluating the response of biological entities to these novel nanocomposite biofibers, in vitro studies were carried out using C2C12 myoblast cell lines. The obtained results from in vitro studies indicated that the developed electrically conducting biofibers are biocompatible to living cells. The developed hybrid conductive biofibers are likely to find applications as 3D scaffolding materials for tissue engineering applications.

This paper provides a feasibility study of estimating the heartrate and the breathing rate, using the waveform spectrum recorded by impulse radio ultra wideband (IR-UWB) radar. An algorithm is proposed that helps to separate the heartrate signal from the breathing signal. Furthermore, a Kalman filter is introduced that helps to reduce the noise factor from the obtained waveforms. The simulation result shows that the proposed algorithm can effectively estimate the breathing rate up to 97-99% and the heartrate above 90 % accuracy as compared to the traditional clinical equipment such as electrocardiograph (ECG).

In this paper, a steerable Yagi-Uda antenna implemented on a dielectric is proposed for S-band CubeSat communications. The steerable Yagi antenna consists of 3 elements lying on an FR4 substrate that form an angle with the CubeSat’s surface. The key idea is to mechanically control the angle between the proposed antenna and the CubeSat’s surface to achieve steerability and hence establish inter-satellite link. A scanning angle of 60 degrees can be achieved which could potentially support a variety of CubeSat missions. The proposed antenna was simulated using HFSS to show its steerability and S11 and radiation pattern measurements were carried out. The simulation results show that the antenna provides a maximum gain of 8.877dB and reflection coefficient of -16.73dB at 2.45GHz with a -10dB bandwidth of 250MHz. The measured reflection coefficient is -14.6dB with –10dB bandwidth of 200 MHz at a resonant frequency of 2.45GHz. The radiation pattern of the fabricated antenna was measured in the anechoic chamber located at the University of Wollongong and compared with the simulation results.

This paper proposes a dual band CPW-fed slot antenna design for wireless network applications which operates at 4.9 GHz (X-band) and 7.7 GHz (C-band). The main idea is to embed two symmetrical F-shaped slits to generate a second resonant frequency. The measured results show that the antenna achieves a -10 dB bandwidths of 500 MHz at 4.9 GHz and 400 MHz at 7.7 GHz with reflection coefficients of -18 dB for both x-band and C-band. Moreover, the total gains of the proposed antenna are 5.9 dBi and 4.7 dBi at 5.1 and 7.9 GHz respectively. Measured results are in good agreement with the simulation results.

This paper analyzes the bending effects of Flexible Chip-less Bow-Tie RFID tag, which is designed and fabricated on three different polymer substrates, Polyethylene terephthalate (PET), Polytetrafluoroethylene PTFE (TEFLON) and Polyvinyl Chloride (PVC). The tag uses the Frequency Selective Surface (FSS) approach and operates within the frequency range of 4 and 18 GHz. The tag is designed using CST studio and then fabricated through a laser etching technique on low-cost polymers. The results are obtained in an anechoic chamber by performing a series of comparative experiments for Radar Cross Section (RCS) of Chipless Bow-Tie RFID tag. The bending capabilities of the tag are noted for radii curvature of 27mm and 14mm. The experimental result shows that the new Bow-Tie RFID tag is more robust and accurate with the distance variation of up to 12cm at 0dBm power and hence, it can be used to encode a bit sequence.

DelPHI [1] is a highly cited protocol that secures Ad hoc On Demand Distance Vector (AODV) routing protocol against wormhole attacks. DelPHI assumes that the underlying wireless transmission rate is constant. Under such an assumption it has a wormhole detection rate above 80%. In this work we show that DelPHI is unable to secure AODV in a multirate transmission environment because it does not take into account the variable bit rate nature of the wireless channel and assumes a constant bit rate leading to either false detection or no detection of wormhole attacks. We go on to propose an extension to DelPHI (M-DelPHI) that adapts it to the multirate 802.11 wireless channel. We propose three fundamental extensions: 1. Multirate channel, 2. Processing delay and 3. Neighbour monitoring. We provide 2 test cases that demonstrate our extension and simulate the new protocol in different environments. We show that M-DelPHI performs exceptionally well resulting in above 90% wormhole detection rate against inbound and out-of-band wormholes under the specified test conditions.

This paper proposes a Peer-to-Peer (P2P) video streaming method for Mobile Ad hoc Network (MANET). Its video streaming uses Multiple Descriptive Coding (MDC) from multiple peers to stream to a single destination using distinct and separate route paths. This method hence spreads the load across multiple sources and multiple paths, hence resulting in an even spread of load and energy use. The novel method is called Energy-Efficient Video Streaming (EEVS) has two parts: an adaptive video data collection method and a streaming method to share the video across the network. The performance of EEVS is compared to other well-known protocols in two different sets of experiments. Firstly, the data collection phase of EEVS is compared against Multiple Video Source Scheduling method (MVSS) and Hybrid Adaptive Search According to Gossip Exchange Method (HAS-A-GEM) that helps to share the information available across the nodes to every other node they meet. Secondly, the streaming phase of EEVS is compared with Enhanced Dynamic Source Routing (EDSR) and Mesh based P2P streaming using MDC (MP2P+MDC) techniques. The simulation results show that EEVS has approximately 120% and 170% less overheads than HAS-A-GEM and MVSS. The results also show that the EEVS outperforms MP2P+MDC and EDSR by efficiently managing the energy across the nodes and by distributing the load through multiple sources. Hence, this increases the network lifetime. Moreover, the average video quality received in EEVS is 30% more than MP2P+MDC and approximately 50% more than EDSR. Furthermore, the results show that EEVS reduces the streaming delay up to 165% as compared to MP2P+MDC and approximately up to 300% as compared to EDSR.

In this paper, a novel Flexible Chip-less Bow-Tie RFID tag is introduced, and its design, fabrication, testing and comparative analyses are presented. The tag uses the Frequency Selective Surface (FSS) approach with a frequency ranging from 4 to 18 GHz. The Bow-Tie design was compared an Octagonal shaped tag already published in the art. They were both designed using CST studio and fabricated through a laser etching technique on low-cost flexible Polyethylene Terephthalate (PET). Through a series of comparative experiments for Radar Cross Section (RCS), results in an anechoic chamber were obtained. The new Bow-Tie RFID tag is shown to be more robust and accurate with the variation of distance up to 1.8m at 0dBm and it can be used to encode a bit sequence.

Energy storage is a key requirement for the emerging wearable technologies. Recent progress in this direction includes the development of fiber based batteries and capacitors and even some examples of such fibers incorporated into prototype textiles. Herein we discuss the advantages of using the wet-spinning process to create nanostructured carbon based materials as wearable energy storage. The ability to control the physical, mechanical, electrical, and electrochemical properties of carbon nanotube based fibers holds great promise to develop smart polymeric structure as an energy storing materials including fibers and textiles. This is the first comprehensive review to discuss effect of nanostructured energy materials on the electrochemical properties of carbon nanotube based fibers which covers the various compositions, spinning and fabrication conditions on the performance of wearable energy storage.

Amazon, Uber Eats, and United Parcel Service (UPS) are planning to launch drone delivery services in the near future. Indeed, recently, Google has received Federal Aviation Administration (FAA) approval for its Wings delivery platform. Amazon claims that a drone logistics network is more cost-efficient and quicker than a motor vehicle delivery network. In this paper, we propose a data delivery service by the drone network in addition to parcel delivery. We propose Heuristic Flight Path Planning (HFPP) that plans a drone&rsquo, s flight path based on parcel delivery destination as well as data delivery destinations (waypoints). We further extend the solution to include drone charging stations for range extension. Our simulation studies show that our proposed method has delivered the data and consignments such that HFPP delivers up to 33% more data packets compared with Encounter-Based Routing (EBR), Epidemic, and a similar path planning method. Also, HFPP reduces the data delivery delays by up to 72% while the overhead ratio is low.

Cube satellites, aka CubeSats, are a class of tiny satellites that have become popular for space programs. This is because they can be built relatively cheaply using commercial off-the-shelf components. Moreover, CubeSats can communicate with each other, and assemble into swarms to carry out different functions: e.g., wide area measurements and sensing. Swarms of CubeSats also have the effect of increasing the contact period with ground stations allowing for a longer communications window. These capabilities require CubeSats to be equipped with an efficient, high gain, small antenna to facilitate cross-link or inter-satellite communications. Henceforth, this paper presents a high gain coplanar waveguide (CPW)–fed slot antenna for CubeSats. A key feature is the use of a metasurface superstrate structure (MSS) to significantly improve gain and reduce back-lobe emissions. This also has the advantage of minimizing interference to components inside a CubeSat. We have comprehensively evaluated the antenna using the high-frequency simulator structure (HFSS) as well as a carrying out testing on a 3 U (10 × 10 × 30 cm3) CubeSat platform. We have studied the effect of MSS element sets and their position and the effect of a 3-U CubeSat body on the performance of the proposed antenna. The experimental results confirm that our antenna achieves a return loss of 21.5 dB and a fractional impedance bandwidth (BW) of 55.91% with S11 ≤ 10 dB and has a simulated and measured gains of 9.71 and 8.8 dBi respectively at the desired frequency of 2.45 GHz. In contrast, amongst all previous S-band planar antennas that are suitable for CubeSats, the best gain is only 5.96 dB at 2.45 GHz.

This paper presents the design, fabrication and testing of two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vectran (LIBERATOR 40) which is highly conductive multifilament yarn spun from Liquid Crystal Polymers (LCP), on cotton fabrics. In contrast to the traditional RFID tag, the chipless RFID tagging, the ID code is not saved in the memory, instead, it uses the physical features of the tag to send data. The proposed tag's design uses a Frequency Selective Surface (FSS) technique for the frequency range of 8–18 GHz. These tags are designed using CST studio and precisely fabricated by using commercial ZSK Technical Embroidery System JCZA (0109–550). The tag design is composed of six concentric octagonal loop resonators with one unitary element. The electromagnetic scattering waves behaviour and Singularity Expansion Method (SEM) based circuit modelling for the octagonal-shaped tag is performed, and the coupling coefficients are evaluated. The desired data bits are obtained by a series of comparative experiments for Radar Cross Section (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data is accurately retrieved with the variation of distance by up to 1.8 m at 0 dB m. Moreover, the average transition from minimum ‘0’ to maximum 1’ is -27 dB for both designs. Furthermore, the experimental results for on-body RCS measurements and the bending effects on both tags down to 7 mm is observed. This octagonal embroidered Chipless RFID tag is a fully textile design which is compact and can be deployed commercially in various IoT applications.

In this paper, a printed Yagi antenna with an integrated balun is proposed for CubeSat communications. The printed antenna is mechanically adjustable to realize three functional states at different operating frequencies in the L-band and S-band respectively. Three different angle deployments are proposed at 10&deg, 50&deg, and 90&deg, so that the antenna operates at three different operating frequencies, namely 1.3 GHz (L-band), 2.4 GHz (S-band) and 3 GHz (S-band). The measured results of the fabricated antenna are well matched with the simulation, having frequencies of 2.82&ndash, 3.07 GHz, 1.3&ndash, 1.4 GHz and 2.38&ndash, 2.57 GHz, with similar radiation patterns. The measured gain of the antenna is 8.167 dBi at 2.4 GHz, 5.278 dBi at 1.3 GHz and 6.120 dBi at 3 GHz. Keeping within the general theme of cheap off the shelf components for CubeSats, this antenna design allows the CubeSat designers to choose from three popular frequencies, through a simple angle configuration. The main contribution of this work lies with the reconfigurable frequency, relatively high gain and simplicity of design.

Code vulnerabilities in the ladder logic of PLCs (Programmable Logic Controllers) have not been sufficiently addressed in the literature. Most of the research related to PLC threats or attacks focuses on the hardware portion of ICS (Industrial Control Systems) or SCADA (Supervisory Control and Data Acquisition) systems such as: industrial components, peripheral devices, or networks. It does not adequately discuss PLC code-level vulnerabilities and attacks. This paper provides an overview of some critical vulnerabilities within the PLC ladder logic code or program and recommends corresponding steps or methods to keep PLCs safer and more secure. The paper focuses on ladder logic code vulnerabilities and weak points that might be exploited by malicious attacks. Those weak points could be a result of intentional malicious pieces of code embedded within the ladder logic code or inadvertent ones such as bad code practices or human errors.

CubeSats are now becoming increasingly popular for space programs. This is because of their affordability. Moreover, CubeSats can be built using commercial Off-the Shelf (COTS) components. They are cost effective compared with traditional satellites. CubeSats can communicate with each other within a swarm, and with ground station. These capabilities require CubeSats to be equipped with small antennas to facilitate cross-link or downlink communications. Therefore, in this paper, we present a novel design of high gain printed Yagi-Uda antenna and a two element Yagi-Uda antenna array which can be perfectly attached on 3U CubeSat's aluminum bodies to avoid deployment. We have shown a numerical analysis of Yagi antenna array and simulated the antenna using the High Frequency Simulator Structure (HFSS). The simulation model is completed with the existing of CubeSat mental body. Our results show that the antenna array achieves good impedance matching with a return loss of − 26.47 dB at the desired frequency of 2.47 GHz, a −10dB impedance bandwidth of 134 MHz (2.396–2.530 GHz) and has a total gain of 6.41dB.

A key advance in enabling higher wireless mesh network capacity is allowing routers to transmit or receive (MTR) from multiple neighbors simultaneously over the same frequency. Achieving this capacity, however, is predicated on a link scheduler that is able to capitalize on the MTR capability of nodes to activate the maximum number of active links, and also to derive the shortest schedule that ensures all links are activated at least once. To date, existing schedulers do not consider the transmission or air-time of packet(s). Henceforth, this paper fills this gap and propose to derive the shortest superframe length, defined as the end time of the last transmitting link. Our scheduler, called A-TxRx, greedily adds links whenever a link finishes its transmission. As a result, unlike previous schedulers, links can start transmitting/receiving as soon as there is no conflict. We have evaluated the performance of A-TxRx in various network configurations, and compared it against two state-of-the-art approaches: 2P and JazzyMAC. The results show A-TxRx outperforming these algorithms significantly, especially when the network becomes denser. Specifically, the superframe length of A-TxRx is typically less than half of 2P and JazzyMAC, with 60 % more concurrently transmitting links.

We propose an algorithm that exploits the properties of Scalable Video Coding (SVC) in order to minimize the upload bandwidth at each peer. More specifically, we propose streaming different layers of the same video from different peers. The paper defines an optimization problem to handle the upload bandwidth at each peer. However, the solution to the proposed problem is NP complete. Therefore, we propose an approximation algorithm to solve this problem. In addition, seed servers are introduced in order to deal with extra load in the network. The proposed method provides better performance as compared to the current approaches that use single layer video in combination with SVC. We have compared our simulation results with the model proposed in Shabnam and Mohamed (2010). The simulation results show that the proposed model improves diversity, increases average video quality, reduces the effect of churn and manages flash crowds.

Device-to-device (D2D) communication was introduced as one of the technologies expected to tackle the increasing demand for high data rates and the growing usage of smartphones with its consequent traffic volumes. Interference is the main problem from which D2D suffers, for which several schedulers were developed. Most of the current scheduling techniques show a significant level of complexity. One way to reduce interference for D2D is to exclude some devices in a cell from D2D communication. In this paper we propose the use of a simple noise thresholding regardless of the scheduler. A device can take part in a D2D connection only if after their transmission, the value of interference in the cell remains below a specific threshold. This paper presents a comparison between the throughput of D2D devices for the case when devices are excluded based on the noise level in a cell compared to the case where no exclusion is made. In a previous work it was found that the probability distribution of device locations significantly impacted throughput. The results from two different probability distributions are presented in this paper. This study shows that when an exclusive approach is taken, the throughput per D2D device can be probabilistically guaranteed.

This paper presents a wideband C-shaped patch antenna for LibyaSat-1. The two parallel slots of the upper C-shaped path are incorporated to generate a second resonant frequency and hence broaden bandwidth. The folded patch technique is used to reduce the coaxial probe length and inductance at the feed section. In addition, the Quasi Newton method is used to achieve an operating frequency of 2.215 GHz (S-band). Our simulation results show that the antenna achieves a −10-dB impedance bandwidth of 1550 MHz (2.00–3.55 GHz), and has a total gain of 6.45 dB at 2.215GHz.

A wideband S-band F-shaped patch antenna is proposed for CubeSats communications. To broaden bandwidth, it uses two arms with different lengths to generate a second resonant frequency. The effect of the arm length and width on the return loss, resonant frequency and impedance bandwidth on a 3U CubeSat is studied. The simulation results show that the antenna achieves a wideband of 1121 MHz (1.606–2.727 GHz) with a return loss below −10 dB over the entire frequency band from 1.606 to 2.727 GHz. The antenna has a high gain of 8.51 dB and a small return loss of −32.85 dB at 2.45 GHz.

CubeSats are attracting interest from both the industry and academia because of their affordability. Specifically, they are made from commercial Off-The-Shelf (COTS) electronic circuit chips, and are thus seen as a cost effective replacement for traditional, expensive satellites. Moreover, they are expected to have higher capabilities to better support demanding missions. To date, most CubeSats rely on a single element antenna that usually has a relatively low gain and are not steerable. Thus, they are not suitable for long-distance communications and for use by missions requiring high-speed links and adjustable radiation patterns. Existing single element antennas also increase the probability of failure when establishing communication links, as the failure of the single element would lead to a disconnection. In this paper, we propose a 3×1 dipole antenna array and a cluster of three 3×1 dipole antenna arrays for CubeSats. Each array can theoretically be used on a separate frequency. Advantageously, all three arrays can be combined to enhance directivity. Our simulation results show that the proposed antenna cluster has a high gain of 5.03dB and wide directivity.

This paper addresses the data collection problem for streaming video over a decentralized MANET to improve the average video quality received among the users. The solution to such a problem is known to be NP complete. Therefore, an adaptive data collection technique is proposed to shares the video meta data available across the nodes among other nodes in the network based on node degree and level of popularity of the video. The performance of the proposed technique is calculated and compared against MVSS and HAS-A-GEM. The results show that the proposed technique significantly reduces the signalling overhead.