Different Types Of Modulation Schemes Research Articles

MULTIPLE ACCESS TECHNIQUES FOR 5G NETWORKS

Fifth generation (5G) wireless networks face various challenges in order to support largescale heterogeneous traffic and users, therefore new modulation and multiple access (MA) schemes are being developed to meet the changing demands. As this research space is ever increasing, it becomes more important to analyze the various approaches, therefore, in this article we present a comprehensive overview of the most promising Multiple Access schemes for 5G networks. Our article focuses on various types of non-orthogonal multiple access (NOMA) techniques. Specifically, we first introduce different types of modulation schemes, potential for OMA. We then pay close attention to various types of NOMA candidates, including power-domain NOMA, code-domain NOMA, and NOMA multiplexing in multiple domains. From this exploration, we can identify the opportunities and challenges that will have the most significant impacts on modulation and MA designs for 5G networks.

An Enhanced Two Stage MMSE Equalizer for Coded FBMC/OQAM Systems

In this article, the authors investigate the enhanced two stage MMSE (TS-MMSE) equalizer in bit-interleaved coded FBMC/OQAM system which gives a tradeoff between complexity and performance, since error correcting codes limits error propagation, so this allows the equalizer to remove not only ICI but also ISI in the second stage. The proposed equalizer has shown less design complexity compared to the other MMSE equalizers. The obtained results show that the probability of error is improved where SNR gain reaches 2 dB measured at BER compared with ICI cancellation for different types of modulation schemes and ITU Vehicular B channel model. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.

Multiplexed free-space optical system design using Manchester coding

Free space optics (FSO) has been considered as the alternative to wireless radio communication system because of the inherent advantages such as huge data rate, license-free operation, easy and quick deployability. Nevertheless, the performance of the FSO system is greatly influenced by atmospheric temperature, pressure, humidity etc. To overcome these challenges various techniques have been proposed in the literature, not only in the physical layer but also in the transport layer. Generally, the average bit error rate (BER) and quality factor (Q-factor) are prime parameters to measure the performance of the FSO systems. To improve the average BER and Q-factor, different types of modulation schemes have been analyzed for different weather conditions. In this paper, for the first time, to improve the performance of the system, differential phase shift keying (DPSK) modulation technique with Manchester coding is used. Manchester encoding synchronizes the signal itself; hence, it minimizes the error rate and optimizes the reliability of the proposed system. In addition, a 16-channel wavelength division multiplexing (WDM) FSO system is considered for improving the spectral efficiency of the system. For analyzing, the low to high turbulence level of atmosphere Gamma-Gamma type channel model is preferred.

Minimization of Filter Capacitor for Medium-Voltage Current-Source Converters Based on Natural Sampling SVM

Current-source converters (CSCs) used in high-power (megawatt level) medium-voltage (MV) (2.3–6.6 kV) drives require three-phase capacitors to assist the commutation of switching devices and to filter out harmonics of the converter output PWM current. Different types of modulation schemes with different harmonic performance lead to different capacitor selections. Conventional space vector modulation (SVM) featuring high dynamic performance cannot be used in practice even with the help of active damping, which can effectively damp the possible LC resonance introduced by conventional SVM. Recently, a natural-sampling SVM (NS-SVM) is proposed for MV CSC drives. It features superior low-order harmonics and has been highly considered for MV CSCs in practice. This study, therefore, focuses on two issues. One is why conventional SVM cannot be used in practice even with the help of active damping. On this basis, the second is capacitor minimization based on NS-SVM. Finally, experimental verification is provided.

Modulation and Multiple Access for 5G Networks

Fifth generation (5G) wireless networks face various challenges in order to support large-scale heterogeneous traffic and users, therefore new modulation and multiple access (MA) schemes are being developed to meet the changing demands. As this research space is ever increasing, it becomes more important to analyze the various approaches, therefore, in this paper we present a comprehensive overview of the most promising modulation and MA schemes for 5G networks. Unlike other surreys of 5G networks, this paper focuses on multiplexing techniques, including modulation techniques in orthogonal MA (OMA) and various types of non-OMA (NOMA) techniques. Specifically, we first introduce different types of modulation schemes, potential for OMA, and compare their performance in terms of spectral efficiency, out-of-band leakage, and bit-error rate. We then pay close attention to various types of NOMA candidates, including power-domain NOMA, code-domain NOMA, and NOMA multiplexing in multiple domains. From this exploration, we can identify the opportunities and challenges that will have the most significant impacts on modulation and MA designs for 5G networks.

Performance analysis of different modulation schemes using OFDM techniques in Rayleigh fading channel

This paper deals with the communication system that uses M-ary Phase-Shift-Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) to transmit information using OFDM technique over Rayleigh communication channel. In terms of Symbol Error Rate (SER), the performance of different modulation schemes using OFDM techniques in Rayleigh channel is analyzed. For different types of modulation schemes (QPSK, 16-QAM, 16-PSK, 64-QAM, 64-PSK) gray coded bit mapping has been used with OFDM techniques. So, better performance is shown in different modulation scheme by using gray coded bit mapping. Here in this paper, it is our goal to show the way through which the SNR result varies between M-PSK and M-QAM.

Comprehensive Relationship Between Carrier-Based PWM and Space Vector PWM in a Five-Phase VSI

Multiphase machines are nowadays considered for high-power variable-speed drive applications due to numerous advantages that they offer when compared to their three-phase counterparts. Multiphase voltage source inverters are invariably used to provide multiphase variable voltage and variable frequency supply with appropriate pulsewidth modulation (PWM) control. Carrier-based PWM and space vector PWM (SVPWM) are the most common options. This paper is aimed at providing a comprehensive relationship between carrier-based PWM and SVPWM techniques. The relationship is determined in terms of modulation signals and space vectors, modulation signals and space vector sectors, and switching pattern of space vector and type of carrier. Distribution of zero vector is discussed, leading to different types of modulation schemes. The practical implementation issues of carrier-based PWM and SVPWM are discussed. Simulation results and their experimental validation are provided to support the analytical findings.