Showing papers in "Aeu-international Journal of Electronics and Communications in 2019"

Energy Aware Cluster Based Multi-hop Energy Efficient Routing Protocol using Multiple Mobile Nodes (MEACBM) in Wireless Sensor Networks

Abstract: Routing in Wireless Sensor Networks (WSNs) is the most significant and the challenging issue for the researchers in terms of enhancing its performance in terms of network lifetime, energy efficiency, scalability, connectivity, throughput, etc. They have the incredible capability to interact and gather data from any physical environment with help of routing protocols. Many routing protocols based solutions have been proposed in the recent years for accomplishing the preferred level of performance in WSNs for these issues. The hierarchical heterogeneous cluster based energy efficient routing protocols are more efficient as compared to flat and location based routing protocols due to the presence of nodes heterogeneity in terms of energy level of sensor nodes which enhances the lifetime of the network. The most recent trend that extensively enhances the functionality and the performance of WSNs is the use of mobile sensor nodes. In this paper, the authors proposed a novel concept regarding mobile sensor nodes is proposed called Mobile Energy Aware Cluster Based Multi-hop (MEACBM) routing protocol for hierarchical heterogeneous WSNs which selects CHs on the basis of newly proposed probability equation which selects only that sensor node as Cluster Head (CH) which has the highest energy among other sensor nodes by introducing a new term S(i).E in the equation. It considers hierarchical heterogeneous clustering considering three levels of sensor nodes; multi-hoping for inter-cluster communication and connectivity of sensor nodes within the whole network area. In MEACBM, after the deployment of sensor nodes and formation of clusters, the whole network area is divided into sectors and inside each sector a mobile sensor node is placed which act as Mobile Data Collector (MDC) for collecting data from CHs. This technique helps in significantly reducing the energy consumption of sensor nodes for transferring information to the Base Station (BS). Simulation performance based results indicates the effectiveness of MEACBM routing protocols by comparing it with other contemporary cluster based routing protocols in terms of network lifetime, stability, throughput, number of CHs and number of dead nodes.

Neutralization technique based two and four port high isolation MIMO antennas for UWB communication

Abstract: In this paper, two compact and small size 2 × 2 and 4 × 4 multiple-input-multiple-output (MIMO) antennas are designed and fabricated for ultra-wideband applications. Using the neutralization line technique, the mutual coupling between the radiating patches is highly reduced. The overall dimension of the proposed 2 × 2 and 4 × 4 UWB MIMO antennas are 21 × 34 × 1.6 mm3 and 48 × 34 × 1.6 mm3, respectively. The measured bandwidth of 95.22% (3.51–9.89 GHz) and 96.47% (3.52–10.08 GHz) with better isolation of ≤–22 dB and ≤–23 dB for 2 port and 4 port antennas are, respectively, achieved. The measured (4 × 4 antenna) realized gain and radiation efficiency vary from 0.95 to 2.91 dB and from 70.01% to 79.87% respectively, throughout the entire frequency band. Moreover, the performance of 4 × 4 MIMO antenna, in terms of isolation, realized gain, radiation efficiency, envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), channel capacity loss (CCL) and radiation patterns are studied and corresponding results are validated with the measured results.

Design and analysis of a hexa-band frequency reconfigurable antenna for wireless communication

Abstract: A compact (33 × 16 × 1.6 mm3) and novel shaped hexa-band frequency-reconfigurable antenna with a very wide tuning band is proposed. The proposed antenna operates at two single band modes (i.e., 3.5 GHz and 4.8 GHz) and two dual band modes (i.e., 2.10 GHz, 4.15 GHz and 2.4 GHz, 5.2 GHz) depending upon the switching states. The lumped elements are used in the simulation environment to achieve tunable capacitance, which is responsible for frequency reconfigurability. The measured tuning capability of the fabricated antenna ranges from 2.1 to 5.2 GHz. The proposed antenna has a VSWR 1.3 for all the resonant bands. The radiation efficiency of the proposed structure ranges from 80.41% to 96% at the corresponding frequencies. The far field and the scattering parameters of the proposed antenna are analyzed using Computer Simulation Technology (CST) Microwave Studio 2014. The designed antenna, due to its compact and affordable geometry, can be easily integrated in the modern communication devices such as smart phones, laptops and other portable electronic devices. A prototype of the designed antenna is fabricated and measured using PIN diode switches to validate the simulation results. The proposed reconfigurable antenna demonstrates a reasonable agreement between the measured and simulated results.

Printed millimeter-wave MIMO-based slot antenna arrays for 5G networks

Abstract: In this work, a broadband millimeter-wave (mm-wave) multiple-input–multiple-output (MIMO) antenna system for upcoming fifth generation (5G) networks is presented. The MIMO antenna system is two ports and realized using two antenna arrays, aligned in opposite directions. Each array consist of three elements in each, as each element is a simple recognized printed wide-slot antenna proximity excited by microstrip line with a widened tuning stub; manipulated for operating in the Ka-band, which includes the 28 and 38 GHz bands, as potential candidates for 5G communications. An electromagnetic band-gap (EBG) reflector is placed behind the antenna structure toward the feeding network to decrease the backward radiation and improve the front-to-back (F/B) ratio. Results show that the proposed MIMO antenna system with EBG reflector provides wideband impedance bandwidth >27 GHz (from 22.5 to >50 GHz) and good radiation characteristics with a total realized gain up to 11.5 and 10.9 dBi at the two frequencies of interest, respectively. The envelope correlation coefficient (ECC) and diversity gain (DG) were evaluated and showed good MIMO performance. These remarkable features with the benefits of design simplicity and easily expansion to large-scale antenna system make the proposed design suitable for mm-wave communications.

Energy and area efficient imprecise compressors for approximate multiplication at nanoscale

Abstract: Approximate computing is a new paradigm for designing energy-efficient integrated circuits at the nanoscale. In this paper, we propose efficient imprecise 4:2 and 5:2 compressors by modifying the truth table of the exact compressors to achieve simpler logic functions with fewer output errors. The proposed approach leads to imprecise compressors with significantly fewer transistors and higher performance in comparison with their previous counterparts. Moreover, efficient approximate multipliers are designed based on the proposed imprecise compressors. The circuits are designed using FinFET as one of the leading industrial technologies and are simulated with HSPICE at 7 nm technology node. Furthermore, the approximate multipliers are used in the image processing applications, including image multiplication, sharpening and smoothing, and the peak signal to noise ratio (PSNR) and mean structure similarity index metric (MSSIM) as two important quality metrics are calculated using MATLAB. The results indicate significant improvements regarding performance, energy-efficiency, and the number of transistors compared to the other existing exact and approximate designs. The proposed 4:2 and 5:2 compressors improve the power delay product (PDP), on average by 59% and 68%, and area by 60% and 75%, respectively, in comparison with the previous designs. In addition, the proposed multipliers provide a significant compromise between hardware efficiency and accuracy for approximate computing. The proposed approximate multiplier using both imprecise 4:2 and 5:2 compressors improves the figure of merit, considering both image quality (based on PSNR and MSSIM) and energy efficiency, by 2.35 times as compared to its previous counterparts.

Reconfigurable chaotic pseudo random number generator based on FPGA

Abstract: This paper presents an FPGA Pseudo Random Number Generator (PRNG) that is based on the Lorenz and Lu chaotic systems. These two systems are used to generate four different 3D chaotic attractors. One attractor is generated from Lorenz while the other three attractors are generated from Lu. The output attractor of the proposed PRNG can be reconfigured during real time operation using an efficient hardwired shifting and multiplexing scheme. Furthermore, in order to exploit the proposed reconfiguration feature, the proposed PRNG has been embedded in an FPGA cascaded encryption processor that ciphers the input data from one up to four times successively. In each ciphering operation the PRNG is set to a new configuration and is initialized according to a part of the encryption key. The size of the encryption key can be varied according to the number of required ciphering operations. The proposed PRNG has been realized using VHDL, synthesized on Xilinx using the FPGA device XC5VLX50T, and analyzed using MATLAB and the NIST statistical suite. The proposed PRNG has utilized only 1.4% from the FPGA’s slices, achieved an operating frequency up to 78 MHz, and successfully passed all the NIST statistical tests.

Microwave Jerusalem cross absorber by metamaterial split ring resonator load to obtain polarization independence with triple band application

Abstract: Microwave Jerusalem cross (JC) absorbers are interesting for different researches such as medical imaging. The split ring resonators (SRRs) are suggested as the conventional metamaterial elements which are noticed in this paper. Loads are used for JC absorber for achieving dual and triple band characteristic at X-band and Ku-band application. We show that the JC absorber has a single resonance and the final model has triple resonance 8.6, 10.2, 11.95 GHz with absorption more than 84%. The results show that how the parasitic element can provide new capacitance and inductance to make new resonance and the current distribution revealed the new capacitance in the structures. The symmetrical arrangement of the absorber made polarization independence and also by loads. We have tried to save this quality and current distribution revealed that how the elements affected the current dispense on the metal particle and gaps. The prototype absorber is fabricated on FR-4 and simulation results are compared and confirmed with experimental.

Non-ideal memristor synapse-coupled bi-neuron Hopfield neural network: Numerical simulations and breadboard experiments

Abstract: This paper presents a third-order non-ideal memristor synapse-coupled bi-neuron Hopfield neural network (HNN), in which a non-ideal memristor synapse is employed to generate an electromagnetic induction current caused by the potential difference between two neurons. The memristive HNN model possesses an odd number of equilibrium points including one (or three, dependent on the memristor coupling strength) unstable saddle point, two unstable index-2 saddle-foci, and two (or four) stable node-foci. Bifurcation plots, local attraction basins, and phase plane plots show that the memristive HNN model behaves bi-stability of coexisting chaotic and stable point attractors, which is perfectly validated by breadboard experiments based on discrete components.

Enhanced OFDM-NOMA for next generation wireless communication: A study of PAPR reduction and sensitivity to CFO and estimation errors

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) based on Non-Orthogonal Multiple Access (NOMA) has been previously studied to fulfil the demands of high spectral efficiency, massive connectivity and resilience to frequency selectivity for the upcoming fifth generation (5G) wireless communication and beyond. NOMA enables spectrum overlapping and allows distinct users to simultaneously operate over the same frequency band, and thus enables massive connectivity. High Peak-to-Average Power Ratio (PAPR) and sensitivity to Carrier Frequency Offset (CFO) are significant demerits to deploy such a multicarrier system for 5G and beyond applications. This paper studies the problem of high PAPR and the presence of CFO with efficient pre-coding techniques and a very simplified receiver design. An improved Minimum Mean Square Error (MMSE) receiver is proposed for low-complexity Joint Equalization and CFO Compensation (JECC) in frequency domain using Banded-Matrix Implementation (BMI). Moreover, we have investigated the sensitivity of different pre-coding techniques to channel and CFO estimation errors.

Miniature microstrip branch line coupler with folded artificial transmission lines

Abstract: The present work is devoted to the miniaturization of a conventional three branch line coupler device in UHF band. The procedure for designing miniature structures based on replacing the microstrip transmission line segment with equivalent structures with the same phase shift is described. These structures are placed in free space inside the coupler. The proposed coupler operates at 1 GHz (UHF band), with good specifications. The area of the manufactured prototype of the three-branch line coupler with open-circuit conditions stubs is 909 mm2, which is 76% less than the size of the conventional device and relative bandwidth is 23.7%. The area of the manufactured prototype of the three-branch line coupler with high-resistance lines with a high-resistance segment in the form of U symbol is 1169.7 mm2, which is 69.1% less than the size of the conventional device and relative bandwidth is 34.1%.

A novel neural-based approach for design of microstrip filters

Abstract: This paper presents an intelligent design methodology of microstrip filters in which a dynamic neural network model based on Bayesian Regularization Back-Propagation (BRBP) learning algorithm is used. In this approach, a Low-Pass Filter (LPF) composed of multiple open stubs, and stepped impedance resonators is initially designed for which an Artificial Neural Network (ANN) is trained to improve the performance of the filter. The predicted and measured results of the filter verify the effectiveness of the presented method, suggesting an excellent in and out-of-band performance. According to the measurement, the filter has a very small transition band from 2.087 to 2.399 GHz with 3 and 40 dB attenuation points, respectively, leading to a sharp roll-off rate of 118.6 dB/GHz. In addition the optimized filter has an ultra-wide stopband, extending from 2.399 to 15.01 GHz with attenuation level of 22 dB are The overall size of the fabricated filter is only 0.190 λ g × 0.094 λ g , where λ g is the guided wavelength at 3 dB cut-off frequency (2.087 GHz). A performance comparison with some of the recent published LPFs presented, showing the superiority of the proposed filter.

Improving the electrical characteristics of nanoscale triple-gate junctionless FinFET using gate oxide engineering

Abstract: This paper is about the compared performance investigation of various structures of Hetero-Dielectric (HD) triple-gate FinFETs with different gate oxides in terms of Double Hetero Gate Oxide (DHGO), Triple Hetero Gate Oxide (THGO) and Quadruple Hetero Gate Oxide (QHGO) to produce lower leakage current, higher Ion/Ioff ratio, higher gm/gd and also lower Drain Induced Barrier Lowering (DIBL) than those of a conventional triple-gate FinFET. Among all of them, the best results are explored for the DHGO FinFET structure. In DHGO FinFET structure, a high-κ dielectric (κ = 22) is used on the top oxide to increase the gate control and a low-k dielectric (κ = 3.9) is used over silicon body owing to the compatibility of lattice constant of SiO2 and silicon. Mode-space drift-diffusion (DD_MS) model coupled with Schrodinger equation has been utilized in order to analyze the proposed and conventional structures in three dimensional (3D) simulation domain. Interestingly, by decreasing the thickness of the oxide layer and increasing the permittivity coefficient, the leakage current decreases, thus increasing the Ion/Ioff ratio. The DHGO FinFET structure is found to exhibit higher Ion/Ioff, lower DIBL and higher gm/gd ratio, thus proving performance superiority over the other conventional junctionless FinFET and also MOSFETs.

Design and analysis of multiplier using approximate 4-2 compressor

Abstract: Approximate computing has received significant attention as an attractive paradigm for error-tolerant applications to reduce the power consumption, delay and area with some trade-off in accuracy. This paper proposes the design of a novel approximate 4–2 compressor. A modified architecture of Dadda Multiplier is presented for the effective utilization of the proposed compressor and to reduce the error at the output. Through extensive experimental evaluation, the efficiency of the proposed compressor and multiplier are evaluated in a 45 nm standard CMOS technology and their parameters are compared with those of the state-of-the-art approximate multipliers. The results show that the proposed compressor accomplish a significant reduction in error rate compared to other approximate compressors available in the literature. In addition, the proposed multiplier shows 35%, 36% and 17% reduction in power consumption, delay and area respectively compared to those of exact multiplier. The effectiveness of multiplier is assessed by some of the image processing applications. On an average, the proposed multiplier processes images with 85% structural similarity compared to the exact output image.

Communication technologies and security challenges for internet of things: A comprehensive review

Abstract: ‘Internet of things’ (IoT) realize a network of millions of connected devices like sensors, actuators and transceivers. Being a composite system, IoT must deal with the associated problems while meeting throughput, latency, energy consumption, and security criteria. In this work, wireless technologies have been classified based on the mechanisms of physical layer, media access control layer, and network layer. The fundamentals of wireless communication and all the non-trivial interests associated with these three layers are summarized with respect to the criteria imposed by IoT. Various security threats at these layers and vulnerabilities of the standards against such attacks have also been listed out. To mitigate these problems, instead of relying on any one particular solution, more emphasis is given on the integrated approach where layer-wise solutions are provided. Thereafter, a brief analysis of the available wireless communication standards and their salient features are discussed. Research scope and challenges in IoT applications ranging from low power, low data rate, short range to extended coverage are identified, followed by possible directions to be taken. Additionally, the third generation partnership project for low-power wide area solutions to meet the IoT requirements are analyzed in detail.

Novel UWB printed metamaterial microstrip antenna based organic substrates for RF-energy harvesting applications

Abstract: In this paper, an intensive study is proposed to recycle the organic materials use for microwave applications including RF-energy harvesting. Thus, the Iraqi Palme Tree Remnants (IPTR) is exemplified for this study to create dielectric substrates. The main texture of the fabricated substrates is IPTR mixed with Nickel Oxide Nanoparticles (NONP) hosted in Polyethylene (PE) to be called INP substrates. Nevertheless, a metamaterial (MTM) printed antenna on the proposed substrate is fabricated by material printer with Sliver Nanoparticles Conductive Ink (SNPCI). The antenna performance is tested numerically/experimentally in terms of S11 spectrum and radiation patterns. It is found excellent matching bandwidths at 2.45 GHz and 5.8 GHz frequencies with acceptable gains of 1.56 dBi and 2.48 dBi, respectively. The proposed antenna bandwidth is found to start from 2.4 GHz up to more than 10 GHz. The maximum achieved gain and efficiency are found about 3.456 dBi and 78% at 9 GHz. For this, the proposed antenna provides novel performance with ultimate antenna size reduction due to the introduction of the MTM based the proposed INP substrate. Finally, the harvested RF energy by the fabricated antenna is measured and found about 15 mV with a conversation efficiency of 85% at 2.45 GHz and 17.5 mV with a conversion efficiency of 91% at 5.8 GHz.

A low-power single-ended SRAM in FinFET technology

Abstract: This paper presents a single-ended low-power 7T SRAM cell in FinFET technology. This cell enhances read performance by isolating the storage node from the read path. Moreover, disconnecting the feedback path of the cross-coupled inverters during the write operation enhances WSNM by nearly 7.7X in comparison with the conventional 8T SRAM cell. By using only one bit-line, this cell reduces power consumption and PDP compared to the conventional 8T SRAM cell by 82% and 35%, respectively.

Hyperjerk multiscroll oscillators with megastability: Analysis, FPGA implementation and a novel ANN-ring-based True Random Number Generator

Abstract: Metastable oscillators are a special case of chaotic attractors with infinite coexisting attractors. In this paper we propose a class of hyperjerk chaotic oscillators which exhibits megastability with and without forcing term. As the systems have infinite equilibrium points, all these coexisting attractors falls in the special category of hidden attractors. We have considered the unforced hyperjerk system to show the multiscrolls and also to investigate the system bifurcations. Then, the proposed hyperjerk multiscroll chaotic system has been designed as ANN-based on FPGA. TanSig activation function, used in the design of ANN-based chaotic oscillator, has been modeled using CORDIC-LUT approximation. To improve the chaos-based engineering applications, this paper presents a new dual entropy core hybrid TRNG having high speed by using the structures of ANN-based chaotic system and ring oscillator. The designs have been coded in VHDL with respect to IEEE-754-1985 number standard. The implemented new proposed TRNG unit has been synthesized for Virtex-6 FPGA chip. After the Place-Route process, FPGA chip statistics and maximum operating frequency have been given as 167.4 MHz. 1 million bit stream generated by the proposed TRNG has been subjected to NIST-800-22 randomness tests and it has successfully passed all of the randomness tests.

Electronically tunable memristor based on VDCC

Abstract: In this study, a simple memristor circuit using only one Voltage Differencing Current Conveyor (VDCC), two PMOS transistors and one grounded capacitor, is designed. The presented memristor exhibits electronically controllable characteristics, which are superior to its counterparts. Both the memductance value and the operating frequency can be electronically tuned through voltage sources. The proposed memristor, which occupies 42.2 µm × 27.5 µm area excluding the area of the capacitor, is laid by using Cadence Environment using TSMC 0.18 µm process parameters. In addition, the proposed memristor is implemented by using discrete circuit elements on the breadboard and detailed analyses are given by changing the values of the discrete circuit elements. All results are compatible with the previous studies.

Pseudorandom number generator based on enhanced Hénon map and its implementation

Abstract: This paper presents a pseudorandom number generator (PRNG) based on enhanced Henon map (EHM) and its implementation in software and hardware for chaos-based cryptosystems with high processing such as image or video encryption. The proposed EHM presents better statistical properties and higher key sensitivity in comparison with classic Henon map (CHM) by means of numerical tests such as bifurcation diagrams, largest Lyapunov exponent, Gottwald-Melbourne test, and histograms. The proposed 8-bit PRNG-EHM algorithm is implemented in MATLAB (software) and in FPGA technology (hardware) for experimental results. In hardware implementation, we use VHDL language and the Altera DE2-115 FPGA board with RS-232 serial port communication for data extraction, which are analyzed with MATLAB. In both software and hardware level, the proposed PRNG-EHM passes the randomness NIST 800-22 statistical tests. For first time in literature, a comprehensive security analysis from a cryptographic point of view is presented for hardware implementation such as key space analysis, key sensitivity, floating frequency, histograms, autocorrelation, correlation, entropy, and performance. Comparisons of proposed PRNG-EHM with recent similar schemes show main advantages in security capabilities for cryptographic applications. According with the results, the proposed scheme can be used in chaos-based cryptographic applications at software or hardware implementation.

Analysis of AlGaN/GaN HEMT using discrete field plate technique for high power and high frequency applications

Abstract: In this paper, the RF and DC characteristics of AlGaN/GaN High electron mobility transistor is analysed using discrete field plate technique. Surprisingly, it reduces the device parasitic capacitance exhibiting very low CGS and CGD of 5.8 × 10−13 F/mm and 4.2 × 10−13 F/mm respectively to improve the cut off frequency (fT) from 17.5 GHz to 20 GHz. The discrete field plate suppresses the maximum electric field between gate and drain region to achieve the high breakdown voltage of 330 V. The maximum transconductance (gm) achieved is 275 mS/mm, ensuring the better DC operation of the device. The simulated results clearly show that, the discrete field plate HEMTs are superior in performance over conventional GaN FP-HEMTs for future high frequency and high power applications.

A novel compact fractal UWB antenna with triple reconfigurable notch reject bands applications

Abstract: A compact, circular UWB fractal antenna with triple reconfigurable notch rejection bands is proposed. It rejects the crowded frequency bands WiMAX, WLAN and X band interferences produced in UWB communication systems. The proposed fractal structure consists of a basic circular patch with circular fractal iterations. By employing this new structure of fractals, the overall size of antenna is reduced 53% to 21 × 25 mm, in comparison with traditional circular monopole antenna. The implemented antenna operates at 3.1–10 GHz. Re-configurability is realized by designing slots and split ring resonators in desired frequencies with the attached PIN diodes. WLAN band rejection was realized by creating a pair of optimized L-shaped slots in the ground plane. By etching a split ring resonator and a U-shaped slot, X and WiMAX bands were also rejected. Furthermore, by attaching diodes to aforementioned slots and designating the diodes on/off, different bands can be included or rejected. In time domain, the antenna properties are evaluated by a figure of merit called fidelity factor. Finally, the antenna properties are measured in anechoic chamber and the results agrees with simulation findings.

Low-profile wideband circularly polarized MIMO antenna with polarization diversity for WLAN applications

Abstract: In this paper, a low-profile wideband circularly polarized (CP) multiple-input multiple-output (MIMO) antenna is presented for wireless local area network (WLAN) applications. The antenna is designed with the help of two truncated corner square patches and parasitic periodic metallic plates. A prototype of the proposed antenna is fabricated and measured. The measurements indicate that the proposed MIMO antenna has usable bandwidth of 13.7%. By properly designing the configuration of the metallic plates, high port isolation of better than 20 dB is achieved. In addition, the diversity performance in terms of envelop correlation coefficient (ECC) is also calculated, showing satisfactory MIMO characteristics. Finally, compared to the other reported CP MIMO antennas in literature, the proposed design possesses exclusive features including low profile structure and wide operating bandwidth.

A compact UWB monopole patch antenna with reconfigurable Band-notched characteristics for Wi-MAX and WLAN applications

Abstract: A compact planar monopole elliptical UWB antenna with a microstrip band-stop filter using a Slot-Type Split-Ring Resonator (ST-SRR) is analyzed and presented in this paper. In order to improve the impedance matching and operating bandwidth of the proposed antenna, a partial defected ground plan is utilized. The ST-SRR structure is inserted into the center of the feed line of the UWB antenna to achieve notch band characteristics to reject interference with the wireless local area network (WLAN) IEEE802.11a/h/j/n (5.15–5.35 GHz, 5.25–5.35 GHz, 5.47–5.725 GHz, 5.725–5.825 GHz) and Wi-Max (IEEE802.16 3.30–3.80 GHz). A pin diode is inserted in the ST-SRR structure in order to achieve reconfigurability in the notch band function. The measured result shows that the proposed antenna operates over 2.7 to 14.9 GHz with a fractional bandwidth of 138.63% for S11 ≤ −10 dB. By controlling the PIN diode at OFF and ON states, the notch bands of the proposed UWB can be switched in the range of 3.43–3.75 GHz and 4.87–6.40 GHz, respectively. Good agreement between the simulated and measured results is achieved. The obtained results show that the proposed antenna is a good candidate for reconfigurable UWB communication applications.

A novel ITI-shaped isolation structure placed between two-port CPW-fed dual-band MIMO antenna for high isolation

Abstract: In this paper, a novel structure of CPW-Fed MIMO antenna is presented for dual-band applications covering 2.4/5.8 GHz ISM band, 2300 MHz LTE-4G band, HiperLAN (5–6 GHz) and IEEE C-bands. A Rectangle-Split-Ring-Resonator (RSRR) slot has been embedded in the patch antenna to create a band-notch centered around 3.74 GHz in order to isolate the high traffic of 3.5 GHz WiMAX band and convert a wideband antenna into a dual-band antenna which is mainly focused on the WLAN bands. A modified ground structure is implemented to control and achieve a higher impedance bandwidth (IBW) up to 64% in the upper band, ranging from 3.90 to 7.55 GHz while the lower band, ranges from 2.24 to 2.90 GHz with an IBW of 26%. A novel ITI-shaped isolation structure is designed and placed between the patch antennas, which are separated by a center-to-center distance of 0.35λ0, helping in achieving a minimum measured isolation of 24 dB across the dual-band. The design has been fabricated on an FR-4 substrate of dimension 72 × 56 × 0.8 mm3 with a minimum measured gain of 2.5 dBi across the operating bands.

Multiple-input bulk-driven quasi-floating-gate MOS transistor for low-voltage low-power integrated circuits

Abstract: This brief presents the first experimental results of the multiple-input bulk-driven quasi-floating-gate (MI-BD-QFG) MOS transistor (MOST) which is suitable for low-voltage (LV) low-power (LP) integrated circuits design. The MI-BD-QFG MOST is an extension to the principle of the bulk-driven quasi-floating-gate (BD-QFG) MOST. However, unlike the BD-QFG the MI-BD-QFG MOST offers multiple-input that simplifies specific CMOS topologies and reduce their power consumption. To confirm the advantages of the MI-BD-QFG MOST a Differential Difference Current Conveyor (DDCC) with very simple CMOS structure has been designed and fabricated in a standard n-well 0.18 µm CMOS process from TSMC with total chip area 350 µm × 78 µm. The fabricated circuit uses a 0.5 V power supply, consumes 1.7 µW power and offers near rail-to-rail input common mode range.

Ultra-thin flexible fractal antenna for 2.45 GHz application with wideband harmonic rejection

Abstract: This paper presents, the design, and characterization of a coplanar waveguide (CPW) fed ultra-thin, low-profile, and flexible fractal antenna with a wideband harmonic rejection for 2.45-GHz ISM band spectrum applications. The antenna consists of rectangular fractal patches and a stub, etched on a very thin substrate. The fractal patch is utilized to achieve miniaturization of 30% with respect to conventional quadrilateral patch antenna. A rectangular stub is introduced perpendicular to the feedline to minimize the harmonics over a wide frequency band 3.3–11.0 GHz. Simulated and measured results demonstrate that the antenna offers an operating band 2.276–2.72 GHz, which fully covers the ISM band (2.4–2.5 GHz). Along with this, the antenna exhibits promising radiation characteristics of omnidirectional gain around 2.2 dBi and radiation efficiency of better than 95%. The proposed antenna has a compact overall size of 0.24λo × 0.20λo × 0.0005λo (λo is the free-space wavelength at 2.45 GHz) along with other advantages, including ultra-thin geometry and wide harmonic rejection. These features make the proposed antenna become a potential candidate for ISM band applications.

Dynamical behavior and image encryption application of a memristor-based circuit system

Abstract: Memristive system and encryption technology are two hot topics in the study of nonlinear dynamics. In this paper, we introduce a memristor-based circuit system and conventionally explore its dynamical behavior by analyzing phase portraits, time series, Lyapunov exponents and bifurcation diagrams. It is found that this system exhibits abundant dynamics such as multi-stability, transient dynamics and antimonotonicity. As it is difficult to reproduce the accurate dynamics because of the extremely sensitive dependence on initial conditions and system parameter, and this system can be recommendable for secure encryption application. Consequently, by virtue of the excellent characteristics of the memristive system, we design a chaotic image encryption algorithm based on dynamic DNA operation and dynamic diffusion (CIEA-4D). The pixel updating, permutation, DNA operation and diffusion of the encryption algorithm are all closely related to the plain image, which strongly enhances the security since a tiny change in plain image will influence the whole encryption process. What’s more, the algorithm has a high operational efficiency for the parallel computing of DNA operation, the pre-acquired chaotic sequence and hash values of plaintext images.

Performance analysis of full-duplex decode-and-forward relay system with energy harvesting over Nakagami-m fading channels

Abstract: In this paper, we analyze the performance of the full-duplex relay system, wherein two terminal nodes operate in the half-duplex mode and the relay node with decode-and-forward scheme operates in the full-duplex mode. We consider the replenishes energy from radio frequency (RF) for the source and the relay nodes through the power beacon (PB) combine with the case of imperfect self-interference cancellation (SIC) at the full-duplex relay. To increase the collected energy for the source and the relay, on the other hand decreasing the complexity for the high power amplifier at the PB, we assume that the PB has multiple antennas. Using theoretical analysis, we obtain the closed-form of the exact outage probability of the system over Nakagami-m fading channels. Furthermore, the exact expression for the symbol error probability of the system is derived to evaluate the system performance with different modulation schemes. Based on this analysis, the impact of the antenna numbers, m parameters, the time duration for harvesting and the residual self-interference are considered. The Monte-Carlo simulations are used to demonstrate the correctness of numerical results.

Fractional order integrator/differentiator: FPGA implementation and FOPID controller application

Abstract: This paper introduces two FPGA based design approaches of the fractional order integrator and differentiator using Grunwald Letnikov (GL) definition where fixed window and linear approximation approaches are considered. The main advantage of the linear approximation method is that it reduces the huge memory of the fractional order systems. One of the top applications of fractional calculus is the fractional order Proportional Integral Derivative (FOPID) controller. It has gained a great attention in academic studies and in industrial applications. The proposed approaches have been used as building blocks to implement FOPID controller. Oscilloscope experimental results for several cases are presented for GL and the fractional order PID controller. The proposed designs have been implemented based on Verilog Hardware Description Language (HDL) and realized on Nexys 4 Artix-7 FPGA XC7A100T. Moreover, a comparison between the proposed FPGA Implementation results for the GL operator and previous work has been investigated.

Metamaterial based superstrate towards the isolation and gain enhancement of MIMO antenna for WLAN application

Abstract: This paper presents the implementation of metamaterial based superstrate inspired multiple input multiple output (MIMO) antenna with enhanced isolation and gain. Superstrate consist of novel hexagonal nested loop double negative (DNG) metamaterial is placed above the MIMO antenna and it exhibits isolation performance better than 24 dB over the entire WLAN band (5.68–6.05 GHz) with a remarkable peak gain of 7.98 dBi. Superstrate reduces the mutual coupling (MC) between the antenna elements by absorbing the near field component of the magnetic field. Reflection coefficient, transmission coefficient and radiation properties further confirm the performance of the proposed design for wireless applications. The prototype of the proposed design is fabricated and validated through measurement that shows good agreement with the simulation result.