This article describes some of the important PAPR reduction techniques for multicarrier transmission system including amplitude clipping , filtering, coding, partial transmit sequence, selected mapping, interleaving, tone reservation, tone injection and active constellation extension. The authors then present two new techniques based on selective Mapping (SLM) and selective scrambling combined with Hadamard matrix to reduce peak-to-average power ratio (PAPR) in OFDM systems.

The high Peak to Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) and MIMO-OFDM systems reduces the system efficiency. In this paper, an extension of Tone Reservation (TR) method is introduced for PAPR reduction in Space Frequency Block Coded OFDM (SFBC-OFDM) systems. The proposed algorithm is based on a time domain kernel which is added to the signal of the antenna with maximum PAPR to reduce its peak power. The time domain kernel has been designed such that the location of the reserved tones is compatible with the structure of the space frequency code. Simulation results show that the proposed method has a very close PAPR reduction performance to that of the well-known RC-PII (Reduced Complexity-Polyphase Interleaving and Inversion) method, but its complexity is much less than of RC-PII.

High peak-to-average power ratio (PAPR) has been a major drawback of Filter bank Multicarrier (FBMC) in the 5G system. This research aims to calculate the PAPR reduction associated with the FBMC system. This research uses four techniques to reduce PAPR. They are classical tone reservation (TR). It combines tone reservation with sliding window (SW-TR). It also combines them with active constellation extension (TRACE) and with deep learning (TR-Net). TR-net decreases the greatest PAPR reduction by around 8.6 dB compared to the original value. This work significantly advances PAPR reduction in FBMC systems by proposing three hybrid methods, emphasizing the deep learning-based TRNet technique as a groundbreaking solution for efficient, distortion-free signal processing.

Orthogonal frequency division multiplexing (OFDM) is an attractive approach for multi-channel transmission. Due to some advantages such as high spectral efficiency, simplicity in channel equalization, and robustness to the fading channel, the OFDM technique has been generally used in many wireless communication devices. Besides these advantages, the OFDM systems usually experience a high peak-to-average power ratio (PAPR). As a result of the high PAPR, the OFDM signal is clipped during the passing via a non-linear power amplifier. The precoding techniques decrease the autocorrelation of the input data symbols to mitigate the high PAPR. In this paper, we compare WHMT, VLMT, DCMT, DHMT, DFMT, ZCMT, and CVMT precoding approaches in terms of autocorrelation and PAPR reduction performance. We demonstrate that the serial combinations of both ZCMT and CVMT precoding matrices with the IFFT matrix cancel the impact of each other when their dimensions are the same. In this case, a sparse matrix is produced and hence the PAPR of the OFDM signal is remarkably reduced. This issue is proved by the mathematical calculations and verified by the simulation results. It is also presented that DFMT, ZCMT, and CVMT precoding schemes have almost the same PAPR reduction performance and they are the best among their counterparts.

Tone Reservation (TR) is one of the well-known methods for PAPR reduction of Orthogonal Frequency Division Multiplexing (OFDM) systems. In this method some sub-carriers are reserved for PAPR reduction and the symbols in these sub-carriers are selected such that the PAPR of the OFDM frame is minimized. In this paper, the iterative algorithm introduced earlier for TR method in single antenna OFDM systems is extended to multiple antenna Spatially Multiplexed OFDM (SM-OFDM) systems. In the proposed method, which is called selective TR, in each iteration the peak reduction symbols of the antenna with maximum PAPR are updated. Simulation results show that using this approach leads to the performance improvement in comparison to the case where TR method is applied independently to all of antennas.

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.

In this paper, the Active Constellation Extension (ACE) technique is applied to Space Frequency Block Coded (SFBC) OFDM systems to reduce the Peak to Average Power Ratio (PAPR). For the extension of this technique to SFBC systems, it will be shown that the space frequency coded signals are the combination of several sub frames and that the ACE method may be applied to these sub frames. Using this model, an iterative ACE method, based on Projection Onto Convex Sets (POCS), is introduced. At each iteration, the time domain samples of the sub frames are clipped based on their effect on the samples of all antennas. Then, the clipped sub frames are filtered and the signals of the antennas are constructed from the modified sub frames. The simulation results show that the performance of the proposed method is very close to the performance of the ACE method in the single antenna OFDM system.