Power Ratio Reduction Research Articles

Peak-To-Average Power Ratio Reduction in Polar Coded OFDM Signal in WiMAX Architecture

Peak to Average Power Ratio (PAPR) reduction technique for polar coded Orthogonal Frequency Division Multiplexing (OFDM) is introduced in WiMax Architecture was analyzed using Matlab Simulation Tool. The main idea is to use polar encoder in WiMax architecture which is one of the best encoder to choose the lowermost PAPR as a transmitted signal. This algorithm better showed efficiently reduced the peak to average power in the transmitted signal. It is suggested that the advised technique efficiently reduce the peak to average power distortion and as well as better bit error rate performance of the OFDM Signal. The simulation outputs are compared with various modulation techniques in relations to PAPR without degrading BER performance.

The peak-to-average power ratio reduction using hybrid scheme with companding and discrete Hartley transform for orthogonal frequency division multiplexing system

The peak-to-average power ratio reduction using hybrid scheme with companding and discrete Hartley transform for orthogonal frequency division multiplexing system

Selected‐Mapping Peak‐to‐Average Power Reduction Method with Orthogonal Pilot Sequences in Underwater Acoustic OFDM System Without Side Information

A novel Selected-mapping (SLM) Peak-to-average power ratio (PAPR) reduction scheme requires no Side information (SI) in Underwater acoustic (UWA) OFDM system is proposed. In the proposed scheme, every distinct phase sequence is represented by a unique Orthogonal comb pilot sequence (OPS), and the orthogonal properties of the OPSs are used to distinguish the index of phase sequences at the receiver. Therefore, the proposed scheme does not need to reserve bits for transmitting SI, so that the data rate can be raised. Simulation results show that the PAPR reduction performance has almost 0.5dB gains comparing to the Conventional SLM (C-SLM) scheme and the Bit error ratio (BER) performance is approximately the same as the SLM scheme with perfect SI. Field experimental results also demonstrate that the proposed scheme can differentiate phase sequences, therefore significantly enhance the quality of the UWA OFDM communication system.

Transceiver Design for Full-Duplex UAV Based Zero-Padded OFDM System With Physical Layer Security

In this paper, multi-antenna transceiver for zero-padded orthogonal frequency division multiplexing (OFDM) system is designed at mmWave by integrating full-duplex unmanned aerial vehicle (UAV) into the terrestrial cellular networks. Assuming that there exist no direct communication links between the ground base station (GBS) and the mobile users due to unexpected blockages from high storied buildings in urban area, the UAV applies decode-and-forward cooperative strategy on the received OFDM signals transmitted from GBS and re-transmits to the ground mobile users and passive eavesdropper. In this proposed system, intertwining logistic map (ILM)-cosine transform aided encryption algorithm combined with artificial noise enhancing physical layer security (PLS) is introduced. Also walsh-hadamard transform technique integrated with QR-decomposition based zero forcing (ZF) block diagonalization (QR-ZF-BD) precoding for multi-user interference reduction and non-iterative clipping and filtering technique for peak to average power ratio (PAPR) reduction are utilized. In addition, Low density parity check (LDPC) and repeat and accumulate (RA) channel coding with cholesky decomposition based ZF and minimum mean square error signal detection schemes for improved bit error rate (BER) are also introduced. Numerical results demonstrate the effectiveness of the proposed system in terms of PLS for color image transmission at high order digital modulation (16-PSK and 16-QAM). At the complementary cumulative distribution function of probability level 1-6%, the estimated PAPR is found to have value of 6 dB.The three users achieve BER <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$= 1\times {10}^{-4}$ </tex-math></inline-formula> at signal-to-noise ratio of 1.5 dB, 4 dB and 6 dB under RA channel coding and 16-QAM digital modulation.

Performance Analysis of WOFDM‐WiMAX Integrating Diverse Wavelets for 5G Applications

In the 5th generation (5G) and 6th generation (6G) of wireless mobile telecommunication networks, the requests for an elevated data rate with access to stationary as well as portable customers are going to be overwhelming. Mobile worldwide interoperability for microwave access (WiMAX) comes out as a favourable alternative that is intelligibly developed and more matured than wireless fidelity (Wi‐Fi). Mobile WiMAX makes use of the orthogonal frequency division multiple access (OFDMA) technology for its two‐way communication to enhance the system performance in fading environments making it more suitable for 5G applications. The diverse OFDM forms deliberated here are the fast Fourier transform‐ (FFT‐) based WiMAX and discrete wavelet transform‐ (DWT‐) based WiMAX. The suggested study exhibits the bit error rate (BER) and peak to average power ratio (PAPR) reduction by integrating different wavelet families, i.e., Haar, symlet, coiflet, and reverse biorthogonal over Rayleigh fading channel. The simulation results obtained by MATLAB depicts an improvement in PAPR reduction, and signal to noise ratio (SNR) requirement is also reduced by 6‐12 dB by using DWT‐incorporated WiMAX at a BER of 10-4.

A Novel DFT-Based Scheme for PAPR Reduction in FBMC/OQAM Systems

In this letter, a novel discrete Fourier transform (DFT)-based scheme is proposed for peak to average power ratio (PAPR) reduction in filter-bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) systems. The key idea is the combination of DFT and the concept of block repetition. Different from the conventional DFT-based PAPR reduction method, the output complex-valued signal of the DFT module is directly transmitted in the proposed DFT-based PAPR reduction method, instead of separating and transmitting the real and imaginary parts of the output signal, respectively. The proposed method can provide a solution to the low PAPR without the cost of high complexity, signal distortion or side information. To validate the performance of the proposed method, simulation results are provided in terms of complementary cumulative distribution function (CCDF) and bit error ratio (BER).

PAPR reduction using selective mapping scheme in universal filtered multicarrier waveform

In this paper, the selective mapping (SLM) technique possessing the powerful and distortionless peak to average power ratio (PAPR) reduction capability was employed in universal filtered multicarrier (UFMC) waveform that is considered as one of the most promising fifth generation (5G) waveform candidates in order to provide a solution to the PAPR issue encountered in the related waveform. Owing to our SLM-based PAPR reduction implementation performed by employing the SLM scheme between the quadrate amplitude modulation (QAM) mapping and bandwidth-subdivision operations at the transmitter side, successful PAPR reduction results were achieved in a straightforward and effective manner. In the simulations, the effect of the related way of SLM application on alleviating the PAPR and spectral leakages of the UFMC signal amplified via the solid state power amplifier (SSPA) was investigated for various number of phase factor combinations. Besides, the impact of SLM on the bit error rate (BER) of the UFMC waveform was analyzed for varied values of SSPA parameters called smoothness (p) and input back off (IBO) controlling the linearity and operation point of the SSPA, respectively.

A SLM Scheme for PAPR Reduction in Polar Coded OFDM-IM Systems Without Using Side Information

In the present article, we propose a novel selected mapping (SLM) scheme based on a Polar coding technique for peak to average power ratio (PAPR) reduction in orthogonal frequency division multiplexing with index modulation (OFDM-IM) systems. The proposed scheme by utilizing random frozen bits in polar codes generates different number of candidate sequences. Then the candidate sequence with the smallest PAPR is selected for transmission. The proposed scheme can be considered as one block in an OFDM-IM system that performs both PAPR reduction and error correction. For a fair comparison, the performance of an OFDM-IM system based on the proposed scheme is compared with a system that carries out the same operations with two separate blocks where a Polar encoder is cascaded with the one for PAPR reduction (such as conventional SLM or PTS), and a Polar coded OFDM-IM system without any PAPR reduction scheme. Moreover, based on our proposed SLM scheme, a novel receiver without using side information (SI) is proposed. This SI free receiver is based on the successive cancellation list (SCL) polar decoding scheme. Simulation results show that as the Polar code can bring both error correction and PAPR reduction capabilities by using our proposed scheme. Also, the proposed SI free receiver can achieve similar bit error rate (BER) performance as that of the ideal case in both additive Gaussian white noise (AWGN) and frequency selective channels.

Peak-to-Average Power Ratio Reduction for High-Mobility Massive MIMO With Angle-Domain Doppler Suppression

Doppler suppression techniques with angle-domain Doppler compensation target reducing the time fluctuations of time-varying channel for high-mobility massive MIMO communications. However, the existing Doppler suppression solutions suffer from high peak-to-average power ratio (PAPR). In this letter, we propose a PAPR reduction scheme for Doppler suppression, where an optimization problem is formulated to minimize the Doppler spread under a constraint of tolerable PAPR level. We further develop a suboptimal solution which decomposes the original joint optimization problem into two steps. First, an iterative Fourier technique is employed and the idea of basis expansion model (BEM) is proposed to reduce the computational complexity. Then, the antenna weighting vector is optimized which takes into consideration both Doppler spread and PAPR. Simulation results are provided to demonstrate that the proposed scheme can substantially outperform the existing schemes.

Machine Learning-Assisted PAPR Reduction in Massive MIMO

In this letter, we propose a machine learning (ML) approach to peak-to-average power ratio (PAPR) reduction in the downlink channel of the digital Massive Multiple Input Multiple Output (MIMO) system with orthogonal frequency division multiplexing (OFDM) signal. Naturally, substantial PAPR reduction is achieved when the noise after PAPR reduction is distributed in both frequency and spatial domains following the maximum allowed error vector magnitude (EVM). However, such an approach requires time-consuming manual tuning of hyperparameters for each scenario. To overcome this problem, we propose to compute an optimal hyperparameter function. Then we propose an efficient approximation for this function to enable the PAPR reduction based on the classical ML approaches.

Non-linear companding scheme for peak-to-average power ratio (PAPR) reduction in generalized frequency division multiplexing

Abstract Due to the evolution of mobile phone technology which enables the use of Internet, the demand for data rates has increased tremendously. Therefore, current 4G-LTE (long-term evolution) technology needs to be replaced in near future. Hence, currently possible solutions for 5G technology are heavily investigated. Generalized frequency division multiplexing (GFDM) is one such technique which is based on multi-carrier filters and uses time-frequency structure to optimize delay and out-of-band emission (OOB). Still GFDM is very much similar to orthogonal frequency division multiplexing (OFDM) with much improved spectral and peak-to-average power ratio (PAPR) performance. This paper presents a detailed description of GFDM technique, along-with its comparison to OFDM method. This paper further investigates the non-linear companding scheme which can be used to further reduce PAPR. Simulation results are presented to obtain (Power Spectral Density) PSD and PAPR performance.

An Improved GreenOFDM Scheme for PAPR Reduction

In this paper, we propose an improvement to a recent Peak-to-Average Power Ratio (PAPR) reduction technique for Orthogonal Frequency Division Multiplexing (OFDM), the GreenOFDM. This technique, which is inspired by SeLected Mapping (SLM), generates several waveform candidates using a given number of Inverse Fast Fourier Transforms (IFFT), and selects the one with the lowest PAPR for the transmission of the OFDM symbol. For U IFFTs, GreenOFDM provides better PAPR reduction capabilities than SLM-OFDM as it increases the number of waveform candidates from U (for SLM-OFDM) to U2/4. In this work, we propose an extension of the GreenOFDM that further increases the number of waveform candidates by a factor of 4 (from U2/4 to U2), or equivalently reduces by a factor of 2 the number of IFFTs for a same PAPR performance. Compared to SLM-OFDM, the improved GreenOFDM technique reduces the complexity by requiring only the square-root of the number of IFFTs for a same PAPR reduction performance. Furthermore, exciting methods for additional complexity reduction are also implemented and discussed.

Demonstrating the Effect of Using Goppa Coding with Hybrid Selective Mapping and Partial Transmit Sequence Technique for PAPR Reduction in OFDM Systems

Orthogonal Frequency Division Multiplexing is a multi-carrier modulation technique which provides numerous advantages like high spectral efficiency, minimal interference, low multipath fading, etc. But Peak-to-average Power Ratio is a severe challenge in using such multiplexing technique as it introduces distortions in nonlinear devices. Various Peak-to-average Power Ratio reduction techniques have been investigated in the literature to improve the performance of Orthogonal Frequency Division Multiplexing systems. But, each of them suffers either from high complexity or degraded bit error rate or less spectral efficiency. For reducing Peak-to-average Power Ratio more effectively, a hybrid combination of Partial Transmit Sequence with Selective Mapping is detected to show better performance. In this paper, we have combined Goppa coding technique with this hybrid Selective Mapping and Partial Transmit Sequence for further improving the performance. Along with Peak-to-average Power Ratio reduction capability, the proposed technique also has inherent error control mechanism due to the use of coding. Based on the simulation results, we have concluded that the proposed technique provides good amount of Peak-to-average Power Ratio reduction than conventional techniques. The proposed technique is analyzed for different number of Orthogonal Frequency Division Multiplexing symbol candidates for Selective Mapping and different number of block divisions for Partial Transmit Sequence. Further, this technique is simulated for different number of subcarriers and modulation order and the simulation results are compared with each other. The proposed technique also shows better Bit error rate values for high Signal-to-Noise ratio.

PAPR reduction of MIMO-OFDM system with reduced computational complexity SLM scheme

Multiple input and multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is a prominent technology for fourth generation mobile radio communication. OFDM is a special case of multi-carrier-modulation (MCM) technique that divides the high data rate input bit streams into large number of lower rate sub streams and each sub stream is transmitted over orthogonal subcarriers. The main advantage of MIMO-OFDM system is the efficient utilization of band width, multipath delay spread tolerance and mitigation of inter symbol interference (ISI) in frequency selective fading channels. However, the main drawback of MIMO-OFDM system is high peak to average power ratio (PAPR) for large number of sub carriers which causes serious degradation in performance. One of the well-known peak to average power ratio (PAPR) reduction schemes for MIMO-OFDM systems is selected mapping (SLM) scheme. In this work computational complexity of MIMO-OFDM system is reduced by adding mapping signal sequences to the OFDM signal sequences. It also increases the PAPR reduction performance of the MIMO-OFDM system.

A low complex peak‐to‐average power ratio reduction in orthogonal frequency division multiplexing systems using a two‐dimensional interleaving strategy

SummaryOne of the effective peak‐to‐average power ratio (PAPR) reduction methods in orthogonal frequency division multiplexing (OFDM) systems is the partial transmit sequence (PTS) method in which the input data stream is divided into disjoint subblocks and the subcarriers in each subblock multiplied by predefined phase factors. Consecutive data symbols corresponding to a source/user are often more correlated, so when the corresponding subcarriers are weighted by the same phase factor, a sufficient reduction in PAPR cannot be attained by the PTS algorithm in common subblocks. To solve this problem, in this paper, we propose a new systematic PAPR reduction method based on a two‐dimensional subcarrier mapping. Specifically, we scramble/interleave each OFDM symbol based on T‐transform to obtain a new set of subblocks which will be multiplied by predefined phase factors. In the proposed method, each one‐dimensional symbol sequence is converted to a two‐dimensional matrix, and the partitions are formed starting from the main diagonal diameters in the matrix. We present the permutation matrix and reformulate the T‐transform technique based on the permutation matrix. Through numerical experimentations, it is shown that the proposed PAPR reduction technique outperforms the previous counterparts. Also, we analyzed our proposed results by aperiodic autocorrelation function (ACF); reducing of ACF side lobes shows that our proposed method cause considerable PAPR parameter reduction respected to other methods.

Peak-to-Average Power Ratio Reduction in Pilot-Embedded OTFS Modulation Through Iterative Clipping and Filtering

In this letter, the method to reduce peak-to-average power ratio (PAPR) is studied in the pilot-embedded orthogonal time frequency space modulation where guard symbols with zero padding are introduced to avoid the interference between data and pilot symbols. By permitting the guard symbols to be padded with signals of small magnitudes, an efficient PAPR reduction method based on the iterative clipping and filtering (ICF) framework is proposed. In the proposed method, first, the clipping noise other than the clipped signal is filtered; second, the filtering coefficients for the clipping noises in the data-plus-pilot region and guard region are set to be different values to achieve good tradeoff between PAPR and bit error rate (BER) performance. Simulation results show that the proposed method can reduce the PAPR efficiently with mild BER performance loss.

Peak to average power ratio (PAPR) reduction in filter bank multicarrier (FBMC) and orthogonal frequency division multicarrier (OFDM) based visible light communication systems

Abstract Filter bank multicarrier (FBMC) is a new waveform candidate in the visible light communication system (VLC). FBMC is a particular sort of multi-carrier modulation that can be viewed as an option in contrast to orthogonal frequency division multicarrier (OFDM) with CP (cyclic prefix). The point is to defeat some innate disadvantages of the normally utilized optical OFDM schemes. The principles of key transceiver should be intended to suit the necessities of the channel of IM/DD. Peak to average power ratio (PAPR) and bit error rate (BER) performance of FBMC based VLC are discussed and compared with scheme of optical OFDM. FBMC based VLC system with clipping technique has the lowest PAPR and good BER performance compared to conventional system in this paper. This paper recommends that FBMC based VLC has an incredible potential for optical wireless communication systems with high-speed. Matlab program simulations confirm the analysis. The results may shed light into potential research line on FBMC based VLC systems.

Extreme Learning Machine-Based Tone Reservation Scheme for OFDM Systems

One of the limitations of the Neural Network-based peak-to-average power ratio (PAPR) reduction methods lies in the long-term training process through a large amount of training data. To address this issue, an extreme learning machine-based (ELM) tone reservation scheme is proposed, which could achieve comparable PAPR performance with low complexity compared to other Neural Network-based algorithms. An ELM-based mapper, trained on the clipping control tone reservation (CC-TR) signals, is designed to reduce the PAPR of orthogonal frequency division multiplexing (OFDM) system. Simulation results indicate that the proposed algorithm owns the advantages of fast learning capability and short training length.

A Novel Transceiver Model for Polar Transform Optical (PTO --) OFDM for V isible L ight C ommunication (VLC) Based on Peak to Average Power Ratio Reduction u sing Precoding

Indoor visible light communication (VLC) has the potential of providing high data rates for short-range wireless communication with a relative spatial elevated security in contrast to a radiofrequency wireless one. To support that high data stream, Orthogonal Frequency Division Multiplexing (OFDM) is used; however, due to the limited operational bandwidth of the commercial white light-emitting diode (LED), signal processing techniques are used to increase the efficiency of the OFDM and to adapt OFDM to VLC systems. As a major concern, the intensity modulation direct detection necessary for VLC requires positive real signal, this is dealt with by imposing Hermitian pre-possessing or Cartesian to polar conversion post-processing to the OFDM. The use of the Cartesian to polar converter allows the transmission of complex OFDM symbols through the intensity modulation channel. A polar transform optical (PTO-) OFDM presented here as an improvement and simplification of previous polar optical OFDM schemes gives an efficient transceiver architecture. Nevertheless, both OFDM transmission techniques for Visible optical links, similar to radiofrequency (RF), suffer greatly from irregular excessive Peak-to-Average power ratio (PAPR). Higher PAPR reduces the power efficiency of the On-Off Keying (OOK) based on pulse amplitude modulation (PAM). Furthermore, it also is recommendable to reduce the PAPR for conformity with eye safety. A precoding technique is proposed to reduce the PAPR of intensity-modulated for direct detectability of the OFDM signal destined for the wireless optical link using Cartesian-to-Polar conversion. Based on the enhanced processing at the front ends and using MATLAB simulation, it is proven that the presented model can improve the link parameters including the bit error rate (BER) and signal to noise ratio (SNR) and bandwidth efficient compared to Hermitian modified ones.

Massive MIMO With Downlink Energy Efficiency Operation in Industrial Internet of Things

In this article, we present high energy-efficiency (EE) operation schemes for downlink orthogonal frequency division multiplexing (OFDM)-based massive multiple-input multiple-output (MIMO) systems in industrial Internet of Things (IIoT) networks. We derive the exact closed-form expressions for some important downlink operation parameters, and based on the parameters, we propose the methods of systematic operation to satisfy the required EE metric with low latency. The operation parameters include the number of service antennas, downlink transmission power, and related coverage. To increase the EE of downlink OFDM signal transmission, it is also well known that peak-to-average power ratio (PAPR) reduction is particularly important, and we apply the clipping PAPR reduction technique for the purpose to increase the power amplifier efficiency, and thus we also determine the level of clipping to satisfy the EE requirement. We use two representative linear precoding schemes for massive MIMO, such as maximum ratio (MR) precoding and zero-forcing (ZF) precoding, and show that the amount of clipping distortion of both MR precoding and ZF precoding is proportional to the distortion from the corresponding IIoT device's signal and distortions from other IIoT devices' signals. Simulation results are provided to validate the analysis and related schemes.