Communications
B. Norsabbaghi; G. Baghersalimi; A. Pouralizadeh; O. Mohammadian
Abstract
Background and Objectives: High peak-to-average power ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM)-based Underwater Optical Wireless Communication (UOWC) systems is one of the most important reasons for out-of-band power and in-band distortion leading to the declination of system ...
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Background and Objectives: High peak-to-average power ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM)-based Underwater Optical Wireless Communication (UOWC) systems is one of the most important reasons for out-of-band power and in-band distortion leading to the declination of system performance. Therefore, different approaches have been suggested and implemented for decreasing high PAPR of OFDM signals in UOWC systems that is the main aim of this paper.Methods: In this research, the performance of an OFDM-based UOWC system is investigated by employing Repetitive Clipping and Filtering (RCF) technique in clear open ocean water. The Monte Carlo Modeling of Light (MCML) approach with the Henyey Greenstein (HG) model of the scattering phase function is used to simulate the UOWC channel. Results: First, the CCDF performance of the suggested system with RCF method for different CR values is investigated. Also, the proposed system performance is examined in terms of bit error rate (BER) and error vector magnitude (EVM) at two different depths for link lengths of 1m and 5 m.Conclusion: The results showed that the system performance is limited by increasing the link length, the number of subcarriers, and depth. Also, it is shown that the RCF method significantly leads to reduction of the PAPR in the DCO-OFDM UWOC system and enhance BER performance up to 10 dB.
M.B. Noori Shirazi; A. Golestani; H. Ahmadian Yazdi; A. Habibi Daronkola
Abstract
The destructive impact of fading environments and also bandwidth limitations are two main challenges which communication is dealing with them. These challenges can affect on the growth of wireless communication and even cause reliable communications and high data rate to be prevented. Thus, OFDM (Orthogonal ...
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The destructive impact of fading environments and also bandwidth limitations are two main challenges which communication is dealing with them. These challenges can affect on the growth of wireless communication and even cause reliable communications and high data rate to be prevented. Thus, OFDM (Orthogonal Frequency Division Multiplexing) modulation by using of fast calculation hardwares such as FFT, high ability for combating multipath fading and appropriate spectral efficiency has taken into consideration. However, we should know that OFDM systems potentially have high Peak to Average Power Ratio (PAPR). This drawback drives the power amplifier into saturation leading to higher distortions and also degrades BER performance. Since increasing the dynamic range of power amplifier is not affordable, reduction of the PAPR is so important. In this paper, we investigate the PAPR and its reduction methods by using the theoretical and numerical analysis. These techniques can be classified into two main categories, signal distortion techniques, multiple signaling and probabilistic techniques. The advantages and disadvantages of each technique are derived from different prospectives. Moreover, we compare the numerical results of the techniques in the first classification from BER prospective which demonstrates that for changing the parameters corresponding to each technique, its performance can be changed greatly. Hence, we are sure that a technique can not outperform the other ones in all cases. Finally, the computational complexity of the techniques in the second classification are compared to each other which their results show that TR and TI techniques are much more complex than the other ones.
