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In this article, numerically a surface plasmon resonance (SPR) biosensor is developed based on Graphene-M­­­­OS2-Au-TiO2-SiO2 hybrid structure for formalin detection. This developed sensor sensed the presence of formalin by applying attenuated total reflection (ATR). In ATR method, we developed and observed two characteristics curve, one is “SPR angle versus minimum reflectance (Rmin)” and another is “SPR frequency (SPRF) versus maximum transmittance (Tmax). In the proposed sensor, Chitosan is used as probe legend to perform specific reaction with the formalin (40% formaldehyde) as target legend. Here, graphene and MoS2 both are used as biomolecular acknowledgment element (BAE). And TiO2 as well as SiO2 bilayers are used to improve sensor sensitivity and Gold (Au) is to sharp SPR curve. In numerical results, the variation of SPRF and SPR angle for inappropriate sensing of formalin is quiet insignificant which confirms the absence of formalin. On the other hand, these variations for appropriate sensing is considerably significant that confirms the presence of formalin. At the end of this article, a study of variation of sensitivity of the proposed biosensor in corresponding to the increment of refractive index with a refractive index step 0.01 RIU is measured. In inclusion of TiO2-SiO2 bilayers with Graphene-M­­­­OS2, maximum sensitivity of 85.375% more is numerically reported.

During this corona outbreak or any situation of casualties, artificial breathing support might be necessary to the affected patients. This paper presents a porotype design and developing process of low-cost Bluetooth technology-based noninvasive volume control emergency medical ventilator for respiratory support. Arduino mega used as the main control board. The rack and pinion system are used to press the Ambu bag by which pressurized oxygen mixed air can be supply to the patient’s lung. Four control parameters like BPM, I: E ratio, Volume, and Pressure can be set by the keypad of the ventilator manually, and also it can be possible remotely by mobile application. Mechanical design is done in a Solid-work designing software platform. The hardware and PCB design are done in the Proteus software package. Finally, the prototype developed according to design, and the results are presented in this paper.

In this paper, a Kretschmann configuration based surface plasmon resonance (SPR) sensor is numerically designed using graphene-MoS2hybrid structure TiO2-SiO2nano particles for formalin detection. In this design, the observations of SPR angle versus minimum reflectance and SPR frequency (FSPR) versus maximum transmittance (Tmax) are considered. The chitosan is used as probe legend to perform reaction with the formalin (40% formaldehyde) which acts as target legend. In this paper, both graphene and MoS2are used as biomolecular acknowledgment element (BAE) and TiO2as well as SiO2bilayers is used to improve the sensitivity of the sensor. The numerical results show that the variation of FSPR and SPR angles for inappropriate sensing of formalin is quite insignificant which confirms the absence of formalin. On the other hand, these variations for appropriate sensing are considerably significant that confirm the presence of formalin. At the end of this article, the variation of sensitivity of the proposed biosensor is measured in corresponding to the increment of a refractive index with a refractive index step 0.01 refractive index unit (RIU). In inclusion of TiO2-SiO2bilayers with graphene-MoS2, a maximum sensitivity of 85.375% is numerically calculated.

Recently, InGaN grown on semipolar and non-polar orientation has caused special attraction due to reduction in the built-in polarization field and increased confinement of high energy states compared to traditional polar c-plane orientation. However, any widespread-accepted report on output power and frequency response of the InGaN blue laser in non-c-plane orientation is readily unavailable. This work strives to address an exhaustive numerical investigation into the optoelectronic performance and frequency response of In0.17Ga0.83N/GaN quantum well laser in polar (0001), non-polar (101&macr, 0) and semipolar (101&macr, 2), (112&macr, 2) and (101&macr, 1) orientations by working out a 6 &times, 6 k.p Hamiltonian at the &Gamma, point using the tensor rotation technique. It is noticed that there is a considerable dependency of the piezoelectric field, energy band gap, peak optical gain, differential gain and output power on the modification in crystal orientation. Topmost optical gain of 4367 cm&minus, 1 is evaluated in the semipolar (112&macr, 2)-oriented laser system at an emission wavelength of 448 nm when the injection carrier density is 3.7 &times, 1018 cm&minus, 3. Highest lasing power and lowest threshold current are reported to be 4.08 mW and 1.45 mA in semipolar (112&macr, 2) crystal orientation. A state-space model is formed in order to achieve the frequency response which indicates the highest magnitude (dB) response in semipolar (112&macr, 2) crystal orientation.

In this paper, a gold-coated photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) technology is proposed through comprehensive numerical analysis for detection of numerous biological and biochemical analytes. The proposed sensor is designed with a simplified hexagonal geometrical structure for ease of fabrication process. Also, to facilitate the ease of sensing and real-time detection capability, the external sensing approach is employed. To investigate the performance of the proposed sensor, both the amplitude and wavelength interrogation methods are utilized. For analyte RI of 1.33 to 1.37, the sensor offers a wavelength sensitivity of 3000 nm/RIU to 13,000 nm/RIU with a maximum spectral resolution of 7.69 × 10 - 6 RIU. The proposed sensor also provides a maximum possible amplitude sensitivity of 953.23 RIU−1. In addition, the sensor provides an excellent figure of merit (FOM) with a maximum value of 228.01 RIU−1. Furthermore, the influence of the structural parameters on the sensor performance is analyzed by tuning the thickness of the gold layer, pitch, and diameter of air holes of the PCF. The proposed sensor reveals a promise to sense and detect different liquid analytes of refractive index (RI) ranging from 1.33 to 1.37 having enhanced performance characteristics.

Two-dimensional (2D) materials, which are confined in one direction, have attracted great interest in surface plasmon resonance (SPR) biosensors owing to its excellent properties like high mobility, conductivity, and mechanical strength. Monolayers of alpha Tin Selenide (α-SnSe) having analogous structure as graphene and phosphorene, additionally exhibit amazing properties of optoelectronic that have taken a lot of attention as a 2D-material beyond former 2D material family members. In this paper, we present simple prism- based SPR biosensors with hybrid structures of Au-SnSe- graphene, Au-SnSe-Mos2, and Au-SnSe- WS2. The performance parameters of the raised biosensors are numerically studied in terms of sensitivity(S), quality factor (Q.F.) and detection accuracy (D.A.) through angular interrogation approach. Results reveal that the determined sensitivity is improved to 101.42 °/RIU, whereas D.A. and Q.F. are decreased a bit than the conventional SPR biosensors. Therefore, the proposed biosensors raise a new platform for its higher sensitive characteristics in many sensing applications.

In this paper, Kretschmann configuration based SPR biosensor with a simple architecture is proposed where a shared plasmonic materials (Ag-Au) is employed. In order to enhance the sensing performance, an optimized graphene layer is used. To evaluate the sensing performance of the proposed sensor, an angular interrogation method is utilized where the performance measuring parameters i.e. sensitivity and detection accuracy (DA) are considered. From the analysis, it can be shown that the sensor exhibits maximum possible sensitivity of 180 °/RIU with lower DA which are highest than that of the conventional prism based sensors. In application to detect myriad of biological and biochemical analytes, the proposed biosensor can be an alternative considering its sensitivity level and DA.

Obesity is a cluster of non-transmissible diseases creating a massive socioeconomic and civil health burden in both developed and developing countries. The prevalence of obesity is increased in an alarming rate and one-third of the world’s population carrying obesity. Phenolic compounds from plant sources play a great role on obesity. Green tea or herbal tea that contains four types of catechins reduced cholesterol level through the modulation of bile acid absorption and metabolism. Objectives: the aim of this study was to monitor the effects of green tea and nutritional education about dietary habit on obese persons. Methods: A randomized control trial (n=20) of obese persons were selected as baseline study and a sliming herbal tea (green tea) with nutritional counseling was prescribed for 12 weeks to take regularly for twice in a day. Results: This study showed a positive impact on obese individuals. After 12 weeks intervention, BMI was decreased from 30.94 to 30.57, body weight, body fat and body fat mass were reduced from 72.50 to 71.36 kg, 32.06 to 30.18% and 27.38 to 25.52 kg respectively. Moreover, a dietary practice of high protein diet with low calorie and low fat diet was developed through nutrition counseling at the baseline study. Conclusion: Obesity management is a combined process. So, green tea with planned diet might be a fruitful effort to reduce body weight, body fat and overall BMI of an obese person.

This paper derives a state-space model of wireless power transfer (WPT) systems to be used for the purpose of state estimation and controller design considering the internet of things (IoT) communication networks. After expressing the WPT systems into a state-space linear equation, the elements of IoT, such as sensors are deployed to obtain the state information. Then, an innovative IoT based communication infrastructure is proposed for sensing, actuating, and transmitting the information to the control center. In order to know the operating condition of the WPT systems, the Kalman filter based dynamic state estimation algorithm is proposed considering the IoT infrastructure. Afterwards, the optimal controller is designed to regulate the system states. Simulation results indicate that the proposed approaches can accurately estimate and stabilise the WPT states. Therefore, the developed frameworks are valuable in designing the IoT based smart control center for WPT systems.

In this paper, a simple finite difference time domain (FDTD) approach is presented for the analysis and design of graphene based optical devices. Here, Maxwell’s curl equations are expressed in normalized flux density. Then, the FDTD method is incorporated with that expression. As the flux density is considered, graphene conductivity which depends on frequency is easily incorporated with the method. The proposed method is used to investigate properties of single and multilayer graphene sheets. To probe the transmission, reflection and surface plasmon polariton (SPP) mode characteristics of graphene in terahertz and far infared frequency regime, numerical examples are demonstrated. Validation of the method has been demonostrated comparing with existing methods and results available in the literature. The accuracy, stability and benefits of proposed method are also presented.

Purpose This review paper aims to focus on recent advances of carbon nanotubes (CNTs) to produce gas sensors. Gas sensors are widely used for monitoring hazardous gas leakages and emissions in the industry, households and other areas. For better safety and a healthy environment, it is highly desirable to have gas sensors with higher accuracy and enhanced sensing features. Design/methodology/approach In this review, the authors focus on recent contributions of CNTs to the technology for developing different types of gas sensors. The design, fabrication process and sensing mechanism of each gas sensor are summarized, together with their advantages and disadvantages. Findings Nowadays, CNTs are well-known materials which have attracted a significant amount of attention owing to their excellent electrical, electronic and mechanical properties. On exposure to various gases, their properties allow the detection of gases using different methods. Therefore, over recent years, researchers have developed several different types of gas sensors along with other types of sensors for temperature, strain, pressure, etc. Originality/value The main purpose of this review is to introduce CNTs as candidates for future research in the field of gas sensing applications and to focus on current technical challenges associated with CNT-based gas sensors.

In this paper, a graphene coated optical fiber surface plasmon resonance (SPR) biosensor is presented for the detection of DNA Hybridization. For the proposed sensor, a four layer model (fiber core /metal /sensing layer /sample) where a sheet of graphene (biomolecular recognition elements ( BRE)) acting as a sensing layer is coated around the gold film because graphene enhances the sensitivity of fiber optic SPR biosensor. Numerical analysis shows the variation of resonance wavelength and spectrum of transmitted power for mismatched DNA strands and for complementary DNA strands. For mismatched DNA strands variation is negligible whereas for complementary DNA strands is considerably countable. Proposed sensor successfully distinguishes hybridization and single nucleotide polymorphisms (SNP) by observing the variation level of resonance wavelength and spectrum of transmitted power.

In this paper, a Surface Plasmon Resonance (SPR) biosensor has been numerically developed that used Graphene–MoS2–Au–TiO2–SiO2 hybrid structure for the detection of formalin. This developed sensor has been sensed the presence the formalin based on attenuated total reflection (ATR) method by observing the change of “surface plasmon resonance angle-the change of minimum reflectance attributor” and “the resonance frequency characteristics (RFC)-maximum transmittance attributor”. Chitosan has been used as probe sensing medium to accelerate particular reaction with the formalin. Here, graphene is used as biomolecular recognition element because of its high adsorption ability and optical characteristics which helps to improve sensor sensitivity, MoS2 used for it has larger band gap, high fluroscence quenching ability, higher optical absorption efficiency, TiO2–SiO2 bilayer as the improvement of sensitivity and Gold (Au) as the sharp SPR curve. Numerical results give the impression that the variation of RFC and SPR angle for improper sensing of formalin is quiet negligible that confirms no formalin is detected whereas for proper sensing these change are considerably countable that confirms the detection of formalin. From the sensor sensitivity analysis, owing to add TiO2–SiO2 bilayer with Graphene–MoS2 Hybrid layer, maximum sensitivity of 85.375% has been numerically resulted. This high sensor performance is for taking advantages of Graphene surface high selectively which detect bio molecular compounds through pi-stacking force, larger work function (5.1 eV) of MoS2 which allows the high sensitive detection of bio targets and Rich plasmon happens at the TiO2–SiO2 interface.

As a perovskite material, methylammonium lead iodide has become more popular for its flexibility, low-cost, lightweight, thin film and high power conversion capability in photovoltaic research community. In this work, we have explored the effect of solar concentration on PV performance for methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell computationally. To calculate the band structure, bandgap and density of states (DOS) of CH3NH3PbI3, density functional theory (DFT) is used here. The detailed balance method is employed to figure out the effect of concentration on performance of perovskite solar cell. We have calculated performance parameters of CH3NH3PbI3 solar cell for two solar spectra AM 1.5 G and AM 1.5 D. All calculations have been performed at different solar concentrations ranging from no concentration to full concentration for both types solar spectra. It is found that the solar cell efficiency at 1.5 G spectrum is higher than 1.5 D solar spectrum at any solar concentration. These results may impact future research on perovskite solar cell.

In this paper, we demonstrate a highly sensitive Kretschmann configuration based surface plasmon resonance (SPR) biosensor with high detection accuracy (DA) and quality factor (QF). Five layers of biosensor model is proposed using numerical simulation and graphical analysis. In this model, graphene and heterostructures of black phosphorus improve the sensitivity of biosensor. Silver (Ag) is coupled with prism CaF2 for better reflectivity, since CaF2 has the less refractive index (RI). The mentioned model gives the highest sensitivity for 633 nm wavelength p-polarized light is 263.51 o/RIU with higher detection accuracy (DA) 2.14 and quality factor (QF) 57.915 RIU-1.

A structure for AlxGa1-xAs/InP multi-junction solar cell is proposed by using numerical simulation and the simulation is done with the help of Analysis of Microelectronic and Photonic Structures (AMPS-1D) simulator. The thickness of p-layer of AlxGa1-xAs top cell is varied from 20 nm to 150 nm keeping the n-layer thickness at a constant value of 800 nm. The thickness of n-layer of InP bottom cell is varied from 100 nm to 7000 nm and p-layer thickness is fixed at 200 nm. The band gap of AlxGa1-xAs top cell absorber layer is varied from 1.42 eV to 1.79 eV. The highest power conversion efficiency (PCE) obtained is 35.643% (Voc=2.385 V, Jsc = 15.789 mA/cm2, FF = 0.88). The operating temperature is also varied from 0 °C to 70 °C. We observed that with the increase in operating temperature, the normalized open circuit voltage decreased almost linearly which shows better stability of this proposed multi-junction solar cell.

The photovoltaic cells are the most ideal approaches to utilize the solar spectrum by absorbing the photons radiation. Perovskite materials have a remarkable role in the photovoltaic (PV) technology. Recently Perovskite material have gained tremendous attention in high performance solar cells for their application. Mixed halide perovskites possess a unique property for bandgap engineering, of which the band gap can be varied from 1.51 eV to 3.0 eV. The absorption coefficient is high for mixed halide perovskite due to its tunable band gap range. The tandem approach is a refined solution to improve the efficiency of Si solar cell as this allows a larger portion of the solar spectrum to be converted to electricity. This work focuses on designing a model for Silicon-mixed halide perovskite tandem solar cell by using SCAPS-1D simulation. Dopant concentration, absorption coefficient, thickness of absorber layer and dopant concentration of ETM have affected the solar cell performance. After simulating the cell structure using SCAPS-1D, the obtained power conversion efficiency of 26.99% for Si-mixed halide perovskite tandem solar cell with short circuit current of 43.0069 mA/cm2, open circuit voltage of 0.7370V and fill factor of 85.14%.

In this paper, multi-structural optical devices are designed based on graphene tri-layer sheets using finite deference time domain (FDTD) method with surface boundary condition (SBC). The perfectly matched layer (PML) absorbing boundary condition is also used with FDTD SBC to terminate the computational space. Numerical demonstration of plasmon polaritons (SPPs) wave propagating along variety shaped tri-layer graphene sheets is presented of the proposed method by means of utilizing the gate voltage dependent property of graphene. Finally, the theoretical fabrication of a straight line interferometer, L-shaped optical waveguide and T-shaped optical splitter based on the proposed model is presented. The paper provides an effective technique in modeling multi-layer graphene based high-speed and ultra-compact optical devices.

This paper demonstrates a numerical modeling of surface plasmon resonance (SPR) biosensor for detecting DNA hybridization by recording the resonance frequency characteristics (RFC). The proposed sensor is designed based on graphene material as biomolecular recognition elements (BRE) and the sharp SPR curve of gold (Au). Numerical analysis shows that the variation of RFC for mismatched DNA strands is quiet negligible whereas that for complementary DNA strands is considerably countable. Here, graphene is used to perform faster immobilization between target DNA and probe DNA. The usage of graphene also changes the RFC that ensure hybridization of DNA event by utilizing its optochemical property. In addition, proposed sensor successfully distinguishes between hybridization and single-nucleotide polymorphisms (SNP) by observing the variation level of RFC and maximum transmittance. Therefore, the proposed frequency readout based SPR sensor could potentially open a new window of detection for biomolecular interactions. We also highlight the advantage of using graphene sublayer by performing the sensitivity analysis. Sandwiching of each graphene sublayer enhances 95% sensitivity comparing with conventional SPR sensor.

Probiotic bacteria with anti-inflammatory properties have the potential to be of therapeutic benefit in inflammatory bowel diseases. The present study was designed to evaluate the effect of feeding low-fat probiotic yogurt containing L. acidophilus and L. bulgaricus on acetic acid-induced inflammation in mouse colon. Inflammatory model that mimics various features of IBDs was induced by a single application of 100µl of 4.5% acetic acid in Swiss Albino mice. Mice were pretreated orally by 200µl yogurt containing both L. acidophilus and L. bulgaricus for 3 days before induction of inflammation and 200µl yogurt was given orally for a period of 7 days after acetic-acid induction. The body weight, food and water intakes, serum biomarkers, macroscopic and histopathological studies of colon tissues were performed to evaluate the anti-inflammatory effect. Combined administration of both strains prevented the damages of villous and crypts in colon epithelial cells and thus provides unique mucosal protective effects in experimental colitis. In conclusion, feeding low-fat probiotic yogurt containing L. acidophilus and L. bulgaricus prevented or ameliorated the inflammatory conditions that can be beneficial to prevent or lower risks of IBDs and its complications.

In this paper, a highly sensitive surface plasmon resonance biosensor is presented using angular interrogation. Due to low sensitivity of conventional biosensor, graphene/two-dimensional transition metal are used in surface plasmon resonance biosensor to improve the sensitivity. Here, we propose a seven layer model of biosensor which shows by incorporating silicon layer in addition of transition metal dichalcogenides MoS2 and graphene, the sensitivity of the proposed SPR biosensor can be greatly enhanced than the conventional gold film SPR sensors. It is observed that the highest sensitivity can be obtained by optimizing the structure with 8 nm thickness of silicon layer, one layer of MoS2 and one layer of graphene. The highest sensitivity of our proposed sensor is 210°/RIU.

This paper presents an analysis of the reactive power and voltage stability of the Northern region of Bangladesh Power System Network (BPSN) in EDSA Paladin Design Base Software. In order to prevent unacceptable voltage collapses and to reduce losses to ensure sufficient reactive power during normal and emergency conditions, voltage level at different points has been analyzed and determining those nodes which are allowing to exceed the permitted range or weak points in BPSN through simulation results. Handling this situation, the voltage and reactive power control in distribution system can be properly controlled by coordinating transformer tap changing and shunt capacitors. Simulation results show that by providing shunt capacitor among the buses to the collapse point results in improved voltage stability within positive consequence limit as an acceptable voltage level in the system.

In this paper a theoretical porous silicon surface based plasmon resonance (SPR) sensor has been presented consisting graphene-Melybdenum sulphide (MoS 2 ) hybrid structure for enhancing sensor detection sensitivity. The biosensor uses perfectly matched layer (PML) boundary condition incorporating on its computational domain to improve its surface plasmon resonance characteristics. Here, graphene-MoS 2 hybrid sheet is used to detect the refractive index change of the sensor surface, which is cause of the reaction of biomolecules. Our calculations show that the graphene-MoS 2 hybrid structure on silicon porous sensor has 25% more sensitivity than the conventional silicon resonant sensor. The enhanced sensitivity is for increasing SPR angle about 25% by adding graphene-MoS 2 hybrid structure.

The design of a graphene based nano dipole antenna on stacked substrate is reported. A stack of substrate is formed from two different dielectric substrate materials, each of equal height. The performance of the designed antenna is investigated for three different substrate stacks such as Quartz-Silicon, GaAs-Silicon Nitride, and Polyimide-Glass. For each stack, total substrate height is varied from 80 μm to 120 μm, taking 20 μm as step size. The considered performance parameters of the designed antenna are return loss, bandwidth, radiation efficiency, gain, and directivity at a targeted resonance frequency of 1.02 THz. The simulation results confirm that Quartz-Silicon substrate pair with a height of 100 μm provides the best antenna performance. The enhanced outcomes are compared with other similar graphene antennas to ensure the effectiveness of the proposed design. The attractive properties and significant performances of the proposed graphene antenna make it a potential candidate to be used in wireless communication in nanosystems and THz sensing applications.

In the present paper, surface plasmon resonance based two graphene coated fiber optic biosensors are analyzed using a four layer model. Graphene is used as third layer of a four layer model. Gold or silver is used as second layer and graphene is coated around the silver or gold. A theoretical study has been carried out for two sensors using gold and silver. Two biosensors have been studied separately and then a comparison has been made. Sensitivity has been studied for different number of graphene layers.

This paper investigates the modeling of graphene interband conductivity in near infared frequency range. First, the interband graphene conductivity is incorporated in surface boundary condition (SBC). Then, SBC is applied in finite-difference time domain (FDTD) method for modeling graphene sheet. Moreover, auxiliary differential equation (ADE) is used to characterize frequency dependent graphene conductivity in FDTD method. Advantages, accuracy, applicability and stability of the proposed method are analyzed by numerical examples. The method is validated by comparing the existing analytical results. This method can be easily implemented to model the graphene interband conductivity for optical device applications.

The demand for increased capacity in wireless communication networks has motivated recent research activities toward wireless systems that exploit the concept of smart antenna and space selectivity. Efficient utilization of limited radio frequency spectrum is only possible to use smart/adaptive antenna system. Smart antenna radiates not only narrow beam towards desired users exploiting signal processing capability but also places null towards interferers, thus optimizing the signal quality and enhancing capacity. We analysis the performance of adaptive (LMS) algorithm for smart antenna systems which is very important for smart antenna design. The SA incorporates this algorithm in coded form which calculates complex weights according to the signal environment. The performance of LMS algorithm is compared on the basis of normalized array factor and Mean Square Error (MSE) for SA systems. It is observed that an LMS algorithm is converging after 50 iteration.

In this paper we have proposed modified optical conductivity model of graphene and simulated surface-plasmon polariton (SPP) mode propagation for different chemical potentials. We have approximated the critical value of chemical potentials which is responsible for (SPP) propagation in Single layer straight and double layer 90 Degree sharp bending using Finite Difference Time Domain method (FDTD) with SBC-Perfectly Matched Layer (PML) technique. The possible application of SPP for the plasmonic devices is discussed.

This paper demonstrates a competent rational polynomial method for efficient computational modelling of graphene surface conductivity using compact framework in the finite-difference time domain (FDTD) method that shape out graphene conductivity. The update equations of graphene surface conductivity using the proposed model in compact-FDTD (CFDTD) method are developed. Numerical identity is presented to show the accuracy of the proposed approach and validation is obtained by comparing with exact formulism.

This paper proposes a modified mathematical model of graphene interband conductivity. The proposed modified model is similar to Drude model that can be easily applied for wideband modelling up to optical frequency range. This model can easily be superimposed with various computational methods especially in the finite difference time domain method (FDTD) for wideband applications. The effect of biasing chemical potential on the performance of modified conductivity model is analyzed. Validation of modified approach is also presented comparing with other existing interband conductivity models.

Single carrier-frequency division multiple access (SC-FDMA) utilizes single carrier modulation at the transmitter and frequency domain equalization at the receiver. It has almost similar performance and essentially the same overall structure of an orthogonal frequency division multiple access (OFDMA) system with low peak to average power ratio (PAPR). Recently, the SC-FDMA has drawn great attention as an attractive alternative to OFDMA, in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of manufacturing cost as well as transmit power efficiency. Such power efficiency can provide considerable performance improvements in future wireless communication networks. This article outlines the basic principles of SC-FDMA systems with different types of sub-carrier mapping schemes. Simulation results demonstrate the performance of different sub-carrier mapping schemes under ideal and pedestrian channel condition.