Showing papers on "Modulation published in 2022"

A Direct Carrier-Based Modulation Scheme With Full Index Range for DC-Link Current Ripple Mitigation of a Current Source Converter

Abstract: This article presents a direct carrier-based modulation scheme to mitigate the dc-link current ripple for a current source converter (CSC) Excessive dc-link current ripple increases system losses, causes current distortion, and leads to more electromagnetic interference, so, it should be mitigated Compared with increasing dc-link inductor or switching frequency, it is more attractive to mitigate dc-link current ripple with modulation schemes However, existing modulation schemes suffer from either high dc-link current ripple or shrink of modulation index range To address this issue, this article analyzes the mechanism of mitigating the dc-link current ripple and proposes a new modulation scheme for a CSC By employing two kinds of non-nearest three vectors to synthesize the reference current, the proposed scheme successfully extends the index range from [ $\sqrt 3 /3$ , 1] to [0, 1] For easier implementation, its carrier-based modulation, which can automatically select the desired vectors and last predetermined dwell times, is also presented Theoretical analyses show that the proposed scheme can mitigate the dc-link current ripple over the full index range for a CSC The effectiveness of the proposed modulation scheme is verified experimentally with a CSC operating as a rectifier

A High-Efficiency ASK-Modulated Class-E Power and Data Transmitter for Medical Implants

Abstract: In this article, we propose an amplitude-shift keying (ASK) modulation technique for Class-E power transmitters used in the inductive power and data transfer links. The proposed modulation circuit consists of a capacitor and a transistor, which switch the load network of the Class-E transmitter between two states; in one state, the drain waveform of the Class-E transistor satisfies both zero-voltage switching (ZVS) and zero-voltage-derivative switching conditions, while in the other one, the waveform approximately satisfies the ZVS condition. Therefore, at both states, the dc-to-ac power conversion efficiency is high, but the transmitted power is different, which allows the implementation of ASK data modulation in the transmitter. We also present an analytical procedure to design the circuit for the desired output power and data modulation index (MI). We have verified the design procedure in both simulation and measurement. The implemented inductive link consists of a 2.4- $\mu$ H transmitter coil and a 1.1- $\mu$ H receiver coil, separated by a 10-mm air gap. With a carrier frequency of 10 MHz, the power transfer efficiency and the power delivered to load were measured to be 64.6% and 35 mW, respectively. With MI = 10%, the bit error rate for the data rates of 1 and 2 Mb/s was measured to be less than 10–8 and 10–6, respectively.

Current Ripple Prediction and DPWM Based Variable Switching Frequency Control for Full ZVS Range Two Parallel Interleaved Three-Phase Inverters

Abstract: In this article, an improved variable switching frequency zero-voltage switching (ZVS) control strategy is proposed for two parallel interleaved three-phase inverters. Discontinuous pulsewidth modulation is adopted and full-range ZVS can be achieved at any load or modulation ratio. The critical switching frequency can be easily calculated in a digital controller based on current ripple prediction instead of current zero-crossing detection. No additional high-frequency sensor or auxiliary circuit is needed. Compared with the continuous pulsewidth modulation, the switching frequency variation range is narrower and the frequency calculation equation is simplified. In addition, lower peak current ripple leads to lower current stress. Owing to the high switching frequency and the low inductance, the size and the cost of the inverter can be significantly reduced. A 6.6-kW experimental prototype with SiC MOSFETs interfacing 400-V dc with three-phase 110-V ac grid is developed to verify the effectiveness of the proposed control strategy.

Investigation of Jervol Water Types Properties Effects on Underwater Optical Wireless OCDMA System Performances for Different Modulation Techniques

Abstract: In this paper, an analytical evaluation of direct detection OCDMA system using zero cross correlation codes is presented in an underwater wireless optical channel (UWOC). Performances were evaluated by varying the main simulation parameters (range,transmitted power,number of users and inclination angle) considering different modulation techniques for different water types (categorized according to Jerlov classification).

5G Modulation Techniques—A Systematic Literature Survey

Abstract: In the recent trend, data consumption goes on increasing day by day. In this way, the present 3G and 4G advancements cannot bolster those expansions in data usage, and the speed should be improved to accomplish better experience while at the same time accessing the data services. 5G technologies have a higher information rate and a better coverage area. It expends less power and has greater security, better spectral efficiency and energy efficiency. The speed of 5G technology reaches from roughly 50 mbps to 2G and even to 1000 Gbps which is much quicker than the 4G technology. Modulation is a process of influencing the data to a signal transmitted over radio carrier, which is the backbone of wireless communication system. Most remote transmissions today are computerized, and with the restricted range accessible, the modulation is more critical than it has ever been. We live in a digital era where wires are not needed to connect with loved ones. Messages, information and signals are sent across the globe within minutes. The modulation process is an important technique in the fast transmission of signals. The fundamental objective of modulation process is squeezing as much of data into a smaller possible spectrum is known as the spectral efficiency. It is used to measures how rapidly the information is transmitted in a single bandwidth. Its unit is b/s/Hz (bits per second per Hz). Various methods have risen to accomplish high spectral efficiency in different modulation techniques. Thus, in this paper, the various methods for modulation techniques are utilized for the development of the next generation communication system are contemplated.

Effect of Code and Frequency Index Modulation in MIMO-OFDM-FSO System

Abstract: This paper analyses the MIMO-OFDM-FSO system using code and frequency index modulation. In this scheme, a joint code and frequency index modulation (CFIM) is used that enhances spectral and energy efficiencies. In weak turbulence condition for a particular spectral efficiency value, a comparative analysis is done by taking conventional OFDM, CFIM scheme with OFDM and MIMO-OFDM system in free space. The CFIM-MIMO-FSO scheme exhibits the lowest BER as compared to conventional OFDM and CFIM-OFDM scheme. Additionally, the PAPR reduction is observed by using CFIM-MIMO-OFDM-FSO scheme in free space.

BER Performance Evaluation of M-PSK and M-QAM Schemes in AWGN, Rayleigh and Rician Fading Channels

Abstract: Wireless communication systems with their vast development rely greatly on the modulation schemes and channel environments. Given the proper channel condition and modulation technique, information can be transmitted with ease and with negligible or no error. Thus, it is necessary to develop an efficient communication system to minimize errors during data transmission. The modulation techniques in communication systems have various performance characteristics such as power efficiency, bandwidth efficiency, and error rate. Some of the common modulation schemes are the M-ary Phase-Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM). These techniques are used in the field of communication notably in wireless communication to test and evaluate the performance in fading channels. In this chapter, the Bit Error Rate (BER) performance of both M-PSK and M-QAM modulation schemes under the Additive White Gaussian Noise (AWGN), Rayleigh, and Rician fading channels has been compared. It was found M-QAM modulation scheme gives better performance in terms of data transmission rates and communication reliability when compared to M-PSK modulation scheme.

Gain-Coupled 4×56 Gb/s EML Array with Optimized Bonding-Wire Inductance

Abstract: Gain-coupled 4 × 56 Gb/s electroabsorption modulated laser (EML) arrays are implemented by identical epitaxial layer (IEL) integration scheme. On-chip coplanar waveguide (CPW) electrodes are incorporated to reduce the parasitic capacitance and facilitate direct microwave probing of the device. Based on the circuit parameters extracted from the S11 data, the influence of bonding-wire inductance on the modulation performance of the EML is investigated. It is found that the modulation bandwidth can be enhanced by taking advantage of the bonding-wire induced resonance. Modulation bandwidth over 40 GHz as well as low microwave reflection has been experimentally confirmed by optimizing the bonding-wire inductance. Clear eye opening under 56 Gb/s nonreturn-to-zero (NRZ) modulation is demonstrated for the EML array with optimized bonding-wire length, and transmission through 10 km single-mode fiber (SMF) has been carried out.

Photonic Techniques for Generating a Single RF Sideband With No Second Order Sidebands

Abstract: Two structures that can realise optical single sideband modulation without generating both second order upper and lower sidebands are presented. They are based on a dual-parallel Mach Zehnder modulator (DP-MZM) with an optical filter and a dual-polarisation dual-parallel Mach Zehnder modulator (DPol-DPMZM) with a 90° hybrid coupler. The former is an all-optical structure and hence it has a very wide bandwidth. The latter uses one DP-MZM to realise single sideband suppressed carrier modulation while the other DP-MZM simply passes the optical carrier. It also suppresses the third order sideband on the same side as the wanted fundamental RF modulation sideband. Hence, in an ideal situation, there is no second order harmonic component generated after photodetection. Experimental results are presented for the novel structures, which demonstrate the realisation of optical single sideband modulation without second order sidebands. The results also show large fundamental to second order harmonic power ratio over a wide input RF signal frequency range even after inserting a long single mode fibre into the system for signal transmission. The new optical single sideband modulators find applications in improving the multioctave spurious free dynamic range in a long-haul fibre optic link and reducing measurement errors in an optical vector analyser.

Analysis of FSO-OFDM System Performance for Different Bit Rates and Link Ranges

Abstract: With advancements in technology, optical communication has become a necessity for the world. The need for advancements in this field has increased more than ever. Free space optics (FSO) technology allows communication to be achieved wirelessly in free space, i.e. air, space, vacuum, etc. It allows the use of high bandwidth, security and good power transmission. The main disadvantage is that it requires line of sight, so any obstruction or turns in between the channel can lead to loss of data. It has been used for both, terrestrial and satellite applications in the past. The model that has been implemented in this work uses Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme in an FSO channel employing 4-QAM (Quadrature Amplitude Modulation). The performance of FSO-OFDM model has been analyzed for varying bit rates and link ranges on Optisystem software. The system supports a data rate of 15 Gbps up to a link range of 13 km for clear weather conditions.

Hardware Realization of DPSK-Based Bluetooth Modem

Abstract: In this chapter, we will discuss DPSK Transceiver hardware design which is based on π/4-DQPSK and 8-DPSK modulation-demodulation techniques, physical layer specifications for it, SIMULINK model for it, effect of using timing and carrier recovery on the transceiver performance, and finally synthesizable HDL model for the Bluetooth DPSK transceiver. The radio part of Bluetooth uses three kinds of digital modulation to transmit data, GFSK, π/4-DQPSK and 8-DPSK. Initially, the Bluetooth standard chose GFSK modulation due to its robustness against signal fading and interference, maintaining a good spectral efficiency, the maximum bit rate that can be obtained using GFSK is limited to 1Mbps. Two new modulation schemes were introduced to increase this. In the other version of Bluetooth a bit rate value of up to 2 Mbps can be achieved for π /4-DQPSK and up to 3 Mbps for 8-DPSK. However, the advantage of constant envelope is now lost and this behavior introduces some non-linear effects during modulation and transmission.

In-band intermodulation induced by transient response of erbium-doped fiber amplifier

Abstract: Transient response of an erbium-doped fiber amplifier (EDFA) is studied in an externally-modulated analog link. Double tones represented as transmitted radio frequency and dither signals are introduced. Extra modulation is generated owing to the EDFA’s transient response caused by a low-frequency dither signal. Therefore, the parasitic modulation is superposed to the output signals and may significantly affect in-band electrical spectra. Analytical and numerical solutions are both given, which agree well with experimental results. This work indicates that a suitable dither signal should be selected to maximize the carrier to intermodulation ratio. In-band spurious free dynamic range is optimized in the meantime.

Performance Assessment of Waveform Modulation Methods for Fifth-Generation Wireless Systems

Abstract: The 5G cellular network systems feature several innovative strategies such as cognitive radio, large scale antenna arrays installed on macro base stations, extensive adoption of small cells, use of mm-wave communications for short-range links, cloud-based radio access network, etc. In addition to this, 5G cellular networks have more stringent requirements than LTE in terms of data rates, energy efficiency, and latency. However, all these strategies are impacted by the modulation format used at the physical layer. In spite of their success in LTE, the existing modulation scheme such as orthogonal frequency division multiplexing (OFDM) cannot fulfill all the requirements of 5G wireless networks. Hence, the choice of efficient waveform modulation scheme is crucial to meet the requirements of the new 5G cellular network systems. In this paper, we analyze and compare the performance of OFDM, Universal filtered multicarrier (UFMC), and Filter bank multicarrier (FBMC) in terms of peak-to-average power ratio (PAPR) and bit error rate (BER). A detail performance analysis is done by varying the parameters that affect the performance of these the modulation techniques such as number of subcarriers, number of FFT, guard bands, and mapping schemes. The simulation results show that FBMC outperforms both OFDM and UFMC in terms of BER, which makes it more suitable in noisy wireless channels. In terms of PAPR, UFMC gives best performance among the three modulation schemes. Hence, it is a preferable modulation scheme in applications where the power consumption of transmitter power amplifier is critical. The contribution of this work is significant in supporting the selection of efficient modulation technique for the upcoming 5G wireless system standards.

Channel Characterization and CE-OFDM Modulation for Terahertz System

Abstract: In wireless communication systems, the transmission channel constitutes the medium separating the transmitter from the receiver. Due to the growing demand for wireless systems in terms of data rate, it is necessary to look for new technology to support this need. Nowadays, The interest of Terahertz (THz) technology is growing increasingly. Indeed, THz technology indeed has the potential to provide ultra-fast data rate of Terabit-per-second (Tbps), Reliable Low Latency Communications and multimedia applications for wireless communication systems. However, the transmission channel at Terahertz bands poses more complexity than the currently used sub-30 GHz bands. The increase in the carrier frequency led to a high path loss. In this direction, Constant envelope Orthogonal Frequency Division Multiplexing (CE-OFMD) modulation is used in this work to increase the quality of transmission in terms of the Bit Error Rate (BER). Thus, In order to develop the THz system and effectively exploit the advantages of this technology, it is essential to know the properties of the radio channel in THz Band than to implement the THz channel in the transmission chain based on CE-OFDM. To do that, an accurate model for THz channel have to be expected by taking into account the effect of both the scattering loss and atmospheric attenuation which are the main characteristics of THz channels. The proposed model in this chapter is based on the Saleh-Valenzuela (S-V) statistical model which combines the concepts of “clusters” and AOA (Angle Of Arrival). In order to validate the proposed model, simulations of frequency channel response and time domain channel are carried out. It has been demonstrated from simulation that the performance of the THz system depends on the transmission windows. For this reason, we used CE-OFDM over these transmission windows to improve the performance of THz system.

Simultaneous Frequency and SSB Modulation for Ultrasonic Speakers

Abstract: Due to the high directivity of ultrasonic speakers, they are used a lot. AM is the proposed modulation for them but FM is used even though there have not been much research done on the use of FM for such speakers. These modulated waves can be demodulated by exposing them no linearly with air. In this paper, we will try to a devise modulation technique that works on simultaneous FM and AM demodulation. The proposed method should provide a higher sound quality on comparatively low frequency, and we are also trying to reduce the power consumption of the suggested method. We are hoping to achieve that by modifying our original method with SSB instead of AM DSB. We will check the effectiveness using various parameters.