Light Fidelity (LiFi) technology has gained attention and is growing rapidly today. Utilizing light as a propagation medium allows LiFi to promise a wider bandwidth than existing Wireless Fidelity (WiFi) technology and enables the implementation of cellular technology to improve bandwidth utilization. In addition, LiFi is very attractive because it can utilize lighting facilities consisting of light-emitting diodes (LEDs). A LiFi system that uses intensity modulation and direct detection requires the signal of orthogonal frequency division multiplexing (OFDM) to have a real and non-negative value; therefore, certain adjustments must be made. The proposed methods for generating unipolar signals vary from adding a direct current, clipping the signal, superposing several unipolar signals, and hybrid methods as in DC-biased optical (DCO)-OFDM, asymmetrically clipped optical (ACO)-OFDM, layered ACO (LACO)-OFDM, and asymmetrically clipped DC-biased optical (ADO)-OFDM, respectively. In this paper, we review and compare various modulation techniques to support the implementation of LiFi systems using commercial LEDs. The main objective is to obtain a modulation technique with good energy efficiency, efficient spectrum utilization, and low computational complexity so that it is easy for us to apply it in experiments on a laboratory scale.

A custom lithium-Ion battery was built for the payload system on a single-engine two-seaters glider. The stages of software development in forming the Battery Management System as a way to provide security in the charging and discharging processes need some parameters to indicate the conditions of the battery. Therefore, in this study, the process of the State of Charge estimation which used in the Electrical Equivalent Circuit Methods and Adaptive Extended Kalman Filter was carried out in a 42 Ah Li-ion battery. As the results, a Mean Absolute Error, and a Root Mean Square Error in which the value of less than 1%. In the actual process, the real error value has never been discovered. The noise is given to determine the adaptive ability between the extended Kalman Filter and the Adaptive Extended Kalman Filter (AEKF) algorithms. In addition, the primary SoC is set at a certain value to see the estimation accuracy. The investigation shows that this method is possible to be applied in the development of the BMS software for payload systems.

In this study, we perform an analytical investigation of the electro-optic (EO), Mach-Zehnder modulator (MZM) transmission boundary area with a nonlinear model. We propose a nonlinear model that represents the allowable RF input amplitude within the MZM transmission boundary area. We investigate the maximum RF input amplitude and confine its harmonics using nonlinear model theory, RoF simulation, and MZM characteristic experiments. The maximum RF input amplitude in the MZM transmission boundary area is a convenient technique that can confine harmonics without an optical amplifier, optical filter, or other optical devices in RoF links. We select several RF input amplitudes within the MZM boundary area and account for harmonic distortion in the investigation. The RF input amplitude is 0.8 times of the EO modulator switching voltages. The boundary areas show that near the switching voltage value, the harmonics-to-main RF ratio (HMR) is less than 10%. Furthermore, the maximum RF inputs are still appropriate for QPSK modulation. We evaluate the nonlinear model of these modulation signals in terms of the error vector magnitude and constellation diagram. After considering the optical fiber impairment, thermal noise, and harmonics distortion in the nonlinear model with the modulation signal of QPSK, the ACLR and EVMs satisfy the 3GPP specification. The nonlinear models are appropriate for a small or medium sized of radio-over-fiber links.

Supercapacitors are a new technology that promises to be an electrical energy storage device in the future. Supercapacitor electrodes derived from activated carbon have high power and energy capabilities because they have a high surface area, high conductivity, and the ability of activated carbon to optimize the properties of supercapacitors. This paper also describes the manufacture of supercapacitor electrode materials by utilizing activated carbon from various biomass and supercapacitor performance compared to batteries. The effect of the activation method, type of activator, type of electrolyte, carbonation or pyrolysis process used will determine the energy and density of energy produced by the supercapacitor. In this case the process of forming an electric double layer on the surface of the electrode was also reviewed and the effect of the type of electrolyte used on the performance of supercapacitors. The use of organic electrolytes can improve the performance of supercapacitors but in the ecological terms the use of acetonitrile solvents is not good for the environment. In this paper we recommend the simplest and lowest-cost fabrication technology but has better performance than the technology of poets such as lithium and alkaline batteries.

During the Covid-19 pandemic, the impact on internet demand is very high throughout the world. In Indonesia, through a survey conducted, broadband users recorded 175 million people or equivalent to 64 % of the population. Based on field observations, the Passive Optical Network (PON) port utility in the Optical Line Terminal (OLT) is presently below 75 %, as opposed to the initial value, which was more than 95 % [1]. Furthermore, it was also found that more than 80 % of IndiHome customers use a maximum bandwidth of 20 Mbps with majority using 10 Mbps, which is very ineffective, especially related to network capacity. Generally, passive Optical Distribution Network (ODN) devices are not optimally used, therefore this research aims to determine the optimization level of the FTTH network by maximizing the available infrastructure capacity. This process was carried out by increasing the associate ratio of 1:32 to 1:64 while taking into account the Optical Line Terminal (OLT) capacity factor and the standard link budget with schemas A, B and C used to obtain adequate efficiency. Scheme A consists of a 1:2 passive splitter in the Optical Distribution Cabinet (ODC) & 1:32 at the Optical Distribution Point (ODP). Scheme B consists of a 1:4 (ODC) & 1:16 (ODP) passive splitter, while scheme C consists of a 1:8 (ODC) & 1:8 (ODP) passive splitter intended for the use of different customer area types. The result showed an increase in network capacity from 32 to 64 per PON port while taking into account the technical quality of the Link Budget. In conclusion, to ensure this solution functions properly, both simulation and direct measurement tests are carried out using the existing network

Human body tissue disease diagnosis will become more accurate if transmittance images, such as X-ray images, are separated according to each constituent tissue. This research proposes a new image decomposition technique based on the matrix inverse method for biological tissue images. The fundamental idea of this research is based on the fact that when k different monochromatic lights penetrate a biological tissue, they will experience different attenuation coefficients. Furthermore, the same happens when monochromatic light penetrates k different biological tissues, as they will also experience different attenuation coefficients. The various attenuation coefficients are arranged into a unique $k\times k$-dimensional square matrix. $k$-many images taken by $k$-many different monochromatic lights are then merged into an image vector entity; further, a matrix inverse operation is performed on the merged image, producing N-many tissue thickness images of the constituent tissues. This research demonstrates that the proposed method effectively decomposes images of biological objects into separate images, each showing the thickness distributions of different constituent tissues. In the future, this proposed new technique is expected to contribute to supporting medical imaging analysis.