NOVEL OFDM SYSTEM BASED ON DUAL-TREE COMPLEX WAVELET TRANSFORM

The demand for higher and higher capacity in wireless networks, such as cellular, mobile and local area network etc, is driving the development of new signaling techniques with improved spectral and power efficiencies. At all stages of a transceiver, from the bandwidth efficiency of the modulation schemes through highly nonlinear power amplifier of the transmitters to the channel sharing between different users, the problems relating to power usage and spectrum are aplenty. In the coming future, orthogonal frequency division multiplexing (OFDM) technology promises to be a ready solution to achieving the high data capacity and better spectral efficiency in wireless communication systems by virtue of its well-known and desirable characteristics. Towards these ends, this dissertation investigates a novel OFDM system based on dual-tree complex wavelet transform (D

Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

Visible Light Communication (VLC) is a data communication technology that modulates the intensity of the light to transmit the information mostly by means of Light Emitting Diodes (LEDs). The data rate is mainly throttled by the limited bandwidth of the LEDs. To combat, Multi-carrier Code Division Multiple Access (MC-CDMA) is a favorable technique for achieving higher data rates along with reduced Inter-Symbol Interference (ISI) and easy access to multi-users at the cost of slightly reduced compromised spectral efficiency and Multiple Access Interference (MAI). In this article, a multi-user VLC system is designed using a Discrete Wavelet Transform (DWT) that eradicates the use of cyclic prefix due to the good orthogonality and time-frequency localization properties of wavelets. Moreover, the design also comprises suitable signature codes, which are generated by employing double orthogonality depending upon Walsh codes and Wavelet Packets. The proposed multi-user system is simulated in MATLAB software and its overall performance is assessed using line-of-sight (LoS) and non-line-of-sight (NLoS) configurations. Furthermore, two sub-optimum multi-users detection schemes such as zero forcing (ZF) and minimum-mean-square-error (MMSE) are also used at the receiver. The simulated results illustrate that the doubly orthogonal signature waveform-based DWT-MC-CDMA with MMSE detection scheme outperforms the Walsh code-based multi-user system

Intelligent OFDM telecommunication system. Part 1. Model of complex and quaternion systems

In this paper, we aim to investigate the superiority and practicability of many-parameter transforms (MPTs) from the physical layer security (PHY-LS) perspective. We propose novel Intelligent OFDM-telecommunication systems based on complex and quaternion MPTs. The new systems use inverse MPT (IMPT) for modulation at the transmitter and MPT for demodulation at the receiver. The purpose of employing the MPT is to improve: 1) the PHY-LS of wireless transmissions against to the wide-band anti-jamming and anti-eavesdropping communication; 2) the bit error rate (BER) performance with respect to the conventional OFDM-TCS; 3) the peak to average power ratio (PAPR). Each MPT depends on finite set of independent parameters (angles). When parameters are changed, many-parametric transform is also changed taking form of a set known (and unknown) orthogonal (or unitary) transforms. For this reason, the concrete values of parameters are specific "key" for entry into OFDM-TCS. Vector of parameters belong to multi-dimension torus space. Scanning of this space for find out the "key" (the concrete values of parameters) is hard problem. MPT has the form of the product of the Jacobi rotation matrixes and it describes a fast algorithm for MPT. The main advantage of using MPT in OFDM TCS is that it is a very flexible anti-eavesdropping and anti-jamming Intelligent OFDM TCS. To the best of our knowledge, this is the first work that utilizes the MPT theory to facilitate the PHY-LS through parameterization of unitary transforms. © 2019 IOP Publishing Ltd. All rights reserved

Wavelet Theory

The wavelet is a powerful mathematical tool that plays an important role in science and technology. This book looks at some of the most creative and popular applications of wavelets including biomedical signal processing, image processing, communication signal processing, Internet of Things (IoT), acoustical signal processing, financial market data analysis, energy and power management, and COVID-19 pandemic measurements and calculations. The editor’s personal interest is the application of wavelet transform to identify time domain changes on signals and corresponding frequency components and in improving power amplifier behavior

Cognitive Radio Systems

Cognitive radio is a hot research area for future wireless communications in the recent years. In order to increase the spectrum utilization, cognitive radio makes it possible for unlicensed users to access the spectrum unoccupied by licensed users. Cognitive radio let the equipments more intelligent to communicate with each other in a spectrum-aware manner and provide a new approach for the co-existence of multiple wireless systems. The goal of this book is to provide highlights of the current research topics in the field of cognitive radio systems. The book consists of 17 chapters, addressing various problems in cognitive radio systems

OFDM comparison with FFT and DWT processing for DVB-T2 wireless channels

Introduction− Recent studies on the FFT processing (Fast Fourier Transform) or DWT (Discrete Wavelet Transform) of the OFDM signal (Orthogonal Frequency Division Multiplexing) have shown pros and cons for DVB-T2 (Digital Video Broadcasting-Second Generation Terrestrial) radio communications; however, the benefits of both types of processing have yet to be compared for the same scenario. Objective− The objective of this research is to compare the response of the wireless channel with AWGN noise (Additive White Gaussian Noise Channel) and Rayleigh and Rician fading in the UHF (Ultra High Frequency) bandMethodology−The transmission of DVB-T2 information with OFDM modulation and FFT and DWT processing was simulated in Matlab®, specifically in Simulink. Results− The results of the study proved to be more ef-ficient for DWT system than FFT system, due to the low rate of erroneous bits, spectral efficiency and reduction of the Peak-to-Average Power Ratio (PAPR), for Eb / No relations greater than 10dB. Conclusions−In this article, we present the designs of both systems and the results of the research experience; likewise, the practical applicability of these systems is discussed, and improvements are suggested for future work.Introducción− Recientes estudios sobre el procesado FFT (Fast Fourier Transform) o DWT (Discrete Wavelet Transform) de la señal OFDM (Orthogonal Frequency Di-vision Multiplexing) han demostrado pros y contras para comunicaciones de radio DVB-T2 (Digital Video Broad-casting – Second Generation Terrestrial); sin embargo, aún falta comparar las prestaciones de ambos tipos de procesamiento para el mismo escenario. Objetivo− El objetivo de esta investigación es comparar la respuesta del canal inalámbrico con ruido AWGN (Ad-ditive White Gaussian Noise Channel) y desvanecimiento Rayleigh y Rician en la banda de UHF (Ultra High Fre-quency).Metodología− Se simuló en Matlab®, específicamente en Simulink, la transmisión de información DVB-T2 con modulación OFDM y procesado FFT y DWT. Resultados− Los resultados del estudio demostraron ser más eficientes para el sistema DWT en comparación con el Sistema FFT, por la baja tasa de bits errados, eficiencia espectral y reducción del cociente entre la potencia pico a promedio (PAPR: Peak-to-Average Power Ratio), para relaciones Eb/No mayores a 10dB. Conclusiones− En este artículo se presentan los diseños de ambos sistemas y los resultados de la experiencia de investigación; así mismo, se discute la aplicabilidad práctica de estos sistemas y se sugieren mejoras para trabajos futuros

Comparación OFDM con procesado FFT y DWT para canales inalámbricos DVB-T2

Introduction: Recent studies on the FFT processing (Fast Fourier Transform) or DWT (Discrete Wavelet Transform) of the OFDM signal (Orthogonal Frequency Division Multiplexing) have shown pros and cons for DVB-T2 (Digital Video Broadcasting-Second Generation Terrestrial) radio communications; however, the benefits of both types of processing have yet to be compared for the same scenario. Objective: The objective of this research is to compare the response of the wireless channel with AWGN noise (Additive White Gaussian Noise Channel) and Rayleigh and Rician fading in the UHF (Ultra High Frequency) band. Methodology: The transmission of DVB-T2 information with OFDM modulation and FFT and DWT processing was simulated in Matlab®, specifically in Simulink. Results: The results of the study proved to be more efficient for DWT system than FFT system, due to the low rate of erroneous bits, spectral efficiency and reduction of the Peak-to-Average Power Ratio (PAPR), for Eb / No relations greater than 10dB. Conclusions: In this article, we present the designs of both systems and the results of the research experience; likewise, the practical applicability of these systems is discussed, and improvements are suggested for future work.Introducción: Recientes estudios sobre el procesado FFT (Fast Fourier Transform) o DWT (Discrete Wavelet Transform) de la señal OFDM (Orthogonal Frequency Division Multiplexing) han demostrado pros y contras para comunicaciones de radio DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial); sin embargo, aún falta comparar las prestaciones de ambos tipos de procesamiento para el mismo escenario. Objetivo: El objetivo de esta investigación es comparar la respuesta del canal inalámbrico con ruido AWGN (Additive White Gaussian Noise Channel) y desvanecimiento Rayleigh y Rician en la banda de UHF (Ultra High Frequency). Metodología: Se simuló en Matlab®, específicamente en Simulink, la transmisión de información DVB-T2 con modulación OFDM y procesado FFT y DWT. Resultados: Los resultados del estudio demostraron ser más eficientes para el sistema DWT en comparación con el Sistema FFT, por la baja tasa de bits errados, eficiencia espectral y reducción del cociente entre la potencia pico a promedio (PAPR: Peak-to-Average Power Ratio), para relaciones Eb/No mayores a 10dB. Conclusiones: En este artículo se presentan los diseños de ambos sistemas y los resultados de la experiencia de investigación; así mismo, se discute la aplicabilidad práctica de estos sistemas y se sugieren mejoras para trabajos futuros

PAPR FOR OFDM SYSTEM BASED ON FAST DISCRETE CURVELET TRANSFORM

Orthogonal Frequency-Division Multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. However, high Peak to Average Power Ratio (PAPR) of transmitted signals is a major shortcoming for Multi-Carrier Modulation (MCM) system such as the OFDM system. Traditional OFDM implementations use common Fourier filters for data modulation and demodulation via the Inverse Fast Fourier Transform (IFFT) and the FFT operations respectively, in this paper the Fast Discrete Curvelet Transform (FDCT) is proposed for OFDM in order to reduce the PAPR. The software CurveLab, used in this work is available at http://www.curvelet.org. The proposed system used FDCT via both Unequispaced Fast Fourier Transform (USFFT) and Wrapping. In terms of PAPR, the results show that both transforms used in this work gives better PAPR results, FDCT via USFFT and FDCT via Wrapping are given approximately about 7.7 dB reduction compared to traditional OFDM. Moreover, the results show that the BER performance of the considered system nearly matches the theoretical BPSK BER performance in an Additive White Gaussian Noise (AWGN) channel