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

Hadamard Coded Modulation for Wavelet based Radio Over Fiber Networks

With the advancements in the technology of communication, there has been an increase in demand of higher data rates for the services such as voice, multimedia and data over both wired and wireless links. Therefore there is the requirement of new modulation schemes to transfer the large amount of data that existing techniques may not be capable of supporting in future. OFDM so far has resulted in good performance on the implementation level but, these techniques must be able to provide high data rate, allowable Bit Error Rate (BER), and minimum delay. In this paper, PAPR, CCDF of OFDM is implemented using wavelet transform based Hadamard Coded Modulation (HCM) and discusses relationship between them for RoF networks. This paper also presents comparison of OFDM and DWT-HCM BER performance for different SNR values

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

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

A Unique Wavelet-based Multicarrier System with and without MIMO over Multipath Channels with AWGN

yesRecent studies suggest that multicarrier systems using wavelets outperform conventional OFDM systems using the FFT, in that they have well-contained side lobes, improved spectral efficiency and BER performance, and they do not require a cyclic prefix. Here we study the wavelet packet and discrete wavelet transforms, comparing the BER performance of wavelet transform-based multicarrier systems and Fourier based OFDM systems, for multipath Rayleigh channels with AWGN. In the proposed system zero-forcing channel estimation in the frequency domain has been used. Results confirm that discrete wavelet-based systems using Daubechies wavelets outperform both wavelet packet transform- based systems and FFT-OFDM systems in terms of BER. Finally, Alamouti coding and maximal ratio combining schemes were employed in MIMO environments, where results show that the effects of multipath fading were greatly reduced by the antenna diversity

On The Analysis Of Mcm Systems Papr Profiles And The Wp-Ofdm System Papr Reduction Techniques

Orthogonal frequency division multiplexing (OFDM) is a prominent system in transmitting multicarrier modulation (MCM) signals over selective fading channel. It has several magnificent properties such as attaining a higher degree of bandwidth efficiency, higher data transmission, robust to narrowband frequency interference and low-complexity implementation. However, the system has its shortage which needs improvement; high peak-to-average power ratio (PAPR) where the signals work in the nonlinear region of the high power amplifier (HPA) results in poor performance and other signal property impairments. Apart from that, an attractive dynamic tool which is wavelet analysis is utilized, and its derivatives such as wavelet packet transform (WPT) possesses almost the same criteria of the orthogonal Fourier base MCM system. Wavelet base analysis surpasses Fourier base by inherent flexibility in terms of windows function for non-stationary signal analysis. The subset base of WPT known as discrete wavelet transforms (DWT). In MCM system, these two base functions construct the orthogonal modulation signal system as the fast Fourier transform (FFT) do in the conventional OFDM (COFDM) system. Applying both WPT and DWT in the MCM system, produces orthogonal signals known as the wavelet packet-based OFDM (WP-OFDM) and wavelet-based OFDM (WOFDM) signals respectively. With no cyclic prefix (CP) need to be applied, these orthogonal signals hold higher bandwidth efficiency. Hence, a comprehensive study is established by performing manipulation on specified parameters using WP-OFDM, WOFDM and C-OFDM signals under the additive white Gaussian noise (AWGN) channel. Furthermore, Partial Transmit Sequence (PTS) is an efficient technique to mitigate the large PAPR in WP-OFDM signals

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

Wavelet Based Multicarrier Modulation (MCM) Systems: PAPR Analysis

Orthogonal frequency division multiplexing (OFDM) is a prominent system in transmitting multicarrier modulation (MCM) signals over selective fading channel. The system offers to attain a higher degree of bandwidth efficiency, higher data transmission, and robust to narrowband frequency interference. However, it incurs a high peak-to-average power ratio (PAPR) where the signals work in the nonlinear region of the high-power amplifier (HPA) results in poor performance. Besides, an attractive dynamic wavelet analysis and its derivatives such as wavelet packet transform (WPT) demonstrates almost the same criteria as the OFDM in MCM system. Wavelet surpasses Fourier based analysis by inherent flexibility in terms of windows function for non-stationary signal. In wavelet-based MCM systems (wavelet OFDM (WOFDM) and Wavelet packet OFDM (WP-OFDM)), the constructed orthogonal modulation signals behaves similar to the fast Fourier transform (FFT) does in the conventional OFDM (C-OFDM) system. With no cyclic prefix (CP) need to be applied, these orthogonal signals hold higher bandwidth efficiency. Hence, this chapter presents a comprehensive study on the manipulation of specified parameters using WP-OFDM, WOFDM and C-OFDM signals together with various wavelets under the additive white Gaussian noise (AWGN) channel