scholarly journals Coherent Optical DFT-Spread OFDM

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Fanggang Wang ◽  
Xiaodong Wang
Keyword(s):  
Bandwidth Allocation ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Minimum Mean Square Error ◽  
Sampling Rate ◽  
Average Power ◽  
Low Complexity ◽  
Ofdm System ◽  
Fiber Optic Communications ◽  
Single Carrier

We consider application of the discrete Fourier transform-spread orthogonal frequency-division multiplexing (DFT-spread OFDM) technique to high-speed fiber optic communications. The DFT-spread OFDM is a form of single-carrier technique that possesses almost all advantages of the multicarrier OFDM technique (such as high spectral efficiency, flexible bandwidth allocation, low sampling rate, and low-complexity equalization). In particular, we consider the optical DFT-spread OFDM system with polarization division multiplexing (PDM) that employs a tone-by-tone linear minimum mean square error (MMSE) equalizer. We show that such a system offers a much lower peak-to-average power ratio (PAPR) performance as well as better bit error rate (BER) performance compared with the optical OFDM system that employs amplitude clipping.

scholarly journals Evaluation of Clipping and Filtering-Based PAPR Reduction in OFDM System

2017 ◽  
Vol 1 (2) ◽  
pp. 18
Author(s):  
N. M. A. E. D. Wirastuti ◽  
N. Pramaita ◽  
I M. A. Suyadnya ◽  
D. C. Khrisne
Keyword(s):  
Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Parallel Data ◽  
Serial Data ◽  
Filtering Technique ◽  
Clipping And Filtering

This paper investigates clipping and filtering techniques in reducing peak average power ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) system. The concept of OFDM is to split a high speed serial data into parallel data at a lower speed, then the parallel data carried by mutually orthogonal subcarriers. The high of PAPR is one of disadvantages of OFDM system. The high PAPR can damages the form of OFDM and reduces its performance. The purpose of this study is to reduce PAPR using simulation. OFDM was simulated with and without clipping filtering then compared.  The methods used to reduce PAPR was clipping and filtering technique. Clipping and filtering technique operates by clipping the output of inverse Fourier transform that exceed the threshold. Graphics PAPR vs. CCDF was used to evaluate the performance of OFDM systems. PAPR for OFDM system using Fourier transform when CCDF = 10-3 is 11,2 dB, with classical clipping PAPR was 4,1 dB and PAPR 4,6 dB when with deep clipping.

scholarly journals Performance analysis of OFDMA and SC-FDMA

2017 ◽  
Vol 8 (2) ◽  
pp. 113-116 ◽  
Author(s):  
M. Al-Rawi
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
High Speed ◽  
Minimum Mean Square Error ◽  
Frequency Division ◽  
International Telecommunication Union ◽  
Single Carrier ◽  
Main Challenge ◽  
Better Than

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying (QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used.

scholarly journals Three Term Weighted Type Fractional Fourier Transform Based Generalized Hybrid Carrier and Its Application into PAPR Suppression

2021 ◽  
Author(s):  
Yong Li ◽  
Zhiqun Song ◽  
Teng Sun ◽  
Bin Wang
Keyword(s):  
Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Fractional Fourier Transform ◽  
Average Power ◽  
The Novel ◽  
Cumulative Density Function ◽  
Ofdm System ◽  
Single Carrier ◽  
Definition Of ◽  
Weighted Type

To suppress the peak to average power ratio (PAPR) of wireless communication based upon multi-carrier system. We, in this paper, proposed the three term weighted type fractional Fourier transform (3-WFRFT) based generalized hybrid carrier (GHC) system. We first provide the definition of 3-WFRFT. Moreover, some useful properties of 3-WFRFT have been presented, in this paper, which will helpful to comprehend the novel 3-WFRFT transform. Furthermore, we take PAPR of the proposed algorithm, in comparison with orthogonal frequency division multiplexing (OFDM) system and single carrier modulation (SC) system under typical complementary cumulative density function (CCDF) level. It would be demonstrated that, from some numerical simulations, the proposed 3-WFRFT based GHC performs better than OFDM system and will be useful to reduce the PAPR level.

scholarly journals OFDM PAPR reduction for image transmission using improved tone reservation

2021 ◽  
Vol 11 (1) ◽  
pp. 416
Author(s):  
Zainab Noori Ghanim ◽  
Buthaina M. Omran
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Image Transmission ◽  
Low Complexity ◽  
Papr Reduction ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
Tone Reservation ◽  
The Cost

High peak to average power ration (PAPR) in orthogonal frequency division multiplexing (OFDM) is an important problem, which increase the cost and complexity of high power amplifiers. One of the techniques used to reduce the PAPR in OFDM system is the tone reservation method (TR). In our work we propose a modified tone reservation method to decrease the PAPR with low complexity compared with the conventional TR method by process the high and low amplitudes at the same time. An image of size 128×128 is used as a source of data that transmitted using OFDM system. The proposed method decrease the PAPR by 2dB compared with conventional method with keeping the performance unchanged. The performance of the proposed method is tested with several numbers of subcarriers; we found that the PAPR is reduced as the number of subcarriers decreased.

Partial transmit sequence to improve OFDM using BFO & PSO algorithm

2019 ◽  
Vol 18 (01) ◽  
pp. 1941018
Author(s):  
P. Ravi Kumar ◽  
P. V. Naganjaneyulu ◽  
K. Satya Prasad
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Computational Cost ◽  
Pso Algorithm ◽  
Ofdm System ◽  
Bacterial Foraging Optimization ◽  
Partial Transmit Sequence ◽  
Practical Applications ◽  
High Speed Data

The Peak to Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) system can be decreased effectively through Partial Transmit Sequence (PTS) scheme. In optimum phase factors searches of the PTM scheme, there is a very high computational cost involved and this restricts its ability to be applied in practical applications, more so in the case of high speed data transmissions. A combination of Particle Swarm Optimization (PSO), Bacterial Foraging Optimization (BFO) and Genetic Algorithm (GA) with the PTS scheme in the OFDM system has been proposed in this work which is a PAPR reduction technique with lesser computational complexity. By performing a set of simulations with different PTS schemes, the performance of the PSO–PTS, BFO–PTS and GA–PTS scheme is comparatively investigated in terms of PAPR and computational cost reductions.

A Novel LMMSE-EM Channel Estimator for High Mobility STBC-OFDM System

2019 ◽  
Vol 28 (13) ◽  
pp. 1950223 ◽  
Author(s):  
Jyoti Prasanna Patra ◽  
Poonam Singh
Keyword(s):  
Computational Complexity ◽  
Signal Detection ◽  
Orthogonal Frequency Division Multiplexing ◽  
Minimum Mean Square Error ◽  
A Priori ◽  
High Mobility ◽  
Low Complexity ◽  
Least Square ◽  
Accurate Estimation ◽  
Ofdm System

In time-selective fading channel, the Alamouti orthogonality principle is lost due to the variation of channel from symbol-to-symbol in space–time block-coded orthogonal frequency division multiplexing (STBC-OFDM) system and causes co-channel interference (CCI) effects. To combat the CCI effects, various signal detection schemes have been proposed earlier by assuming that a priori channel state information (CSI) is known to the receiver. However, in practice, the CSI is unknown and therefore accurate estimation of channel is required for efficient signal detection. In this paper, by exploiting circulant properties of the channel frequency response (CFR) autocorrelation matrix [Formula: see text], we propose an efficient low complexity linear-minimum-mean-square-error (LMMSE) estimator. This estimator applies an expectation–maximization (EM) iterative process to reduce the computational complexity significantly. Finally, we compare the proposed LMMSE-EM estimator with conventional least square (LS) and LMMSE estimator in terms of performance and computational complexity. The simulation results show that the proposed LMMSE-EM estimator achieves exactly the same performance as the optimal LMMSE estimator with much lower computational complexity.

DPD with PAPR Suppression for F-OFDM Systems

2021 ◽  
Author(s):  
Xiao Liao ◽  
Zhinian Luo
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Nonlinear Distortion ◽  
Average Power ◽  
Low Complexity ◽  
Papr Reduction ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Joint Structure ◽  
Saturation Region

Abstract A combined digital pre-distortion (DPD) and peak to average power ratio (PAPR) reduction for Filtered Orthogonal Frequency Division Multiplexing (F-OFDM) systems is proposed where F-OFDM is one of the candidates for 5G waveform technology. In the system, the power amplifier (PA) will produce nonlinear distortion because it works in the saturation region and the high PAPR. DPD based on PAPR reduction structure may be adopted to compensate the nonlinear resulting from PAs. Firstly, in order to reduce the PAPR, a low complexity iterative partial transmission sequence (IPTS) algorithm combined with iterative clipping revision (ICR) is introduced. And then, the joint structure of DPD and IPTS-ICR is proposed. Simulation results show that the proposed structure can improve the PAPR suppression performance of F-OFDM system compared to low complexity IPTS algorithm or ICR algorithm alone. The proposed structure can also effectively improve the nonlinear distortion of the F-OFDM system.

scholarly journals A Novel Hybrid Precoding-Companding Technique for Peak-to-Average Power Ratio Reduction in 5G and beyond

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1410
Author(s):  
Mohamed Mounir ◽  
Mohamed B. El_Mashade ◽  
Salah Berra ◽  
Gurjot Singh Gaba ◽  
Mehedi Masud
Keyword(s):  
Computational Complexity ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Papr Reduction ◽  
Power Ratio ◽  
Error Vector Magnitude ◽  
Hybrid Precoding ◽  
High Power Amplifier ◽  
Reduction Techniques

Several high-speed wireless systems use Orthogonal Frequency Division Multiplexing (OFDM) due to its advantages. 5G has adopted OFDM and is expected to be considered beyond 5G (B5G). Meanwhile, OFDM has a high Peak-to-Average Power Ratio (PAPR) problem. Hybridization between two PAPR reduction techniques gains the two techniques’ advantages. Hybrid precoding-companding techniques are attractive as they require small computational complexity to achieve high PAPR reduction gain. Many precoding-companding techniques were introduced to increasing the PAPR reduction gain. However, reducing Bit Error Rate (BER) and out-of-band (OOB) radiation are more significant than increasing PAPR reduction gain. This paper proposes a new precoding-companding technique to better reduce the BER and OOB radiation than previous precoding-companding techniques. Results showed that the proposed technique outperforms all previous precoding-companding techniques in BER enhancement and OOB radiation reduction. The proposed technique reduces the Error Vector Magnitude (EVM) by 15 dB compared with 10 dB for the best previous technique. Additionally, the proposed technique increases high power amplifier efficiency (HPA) by 11.4%, while the best previous technique increased HPA efficiency by 9.8%. Moreover, our proposal achieves PAPR reduction gain better than the most known powerful PAPR reduction technique with a 99% reduction in required computational complexity.

scholarly journals An Efficient DWT-DAPM Technique for PAPR Reduction in OFDM System

2020 ◽  
Vol 9 (3) ◽  
pp. 1691-1696 ◽  
Keyword(s):  
Amplitude Modulation ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Gaussian Model ◽  
Channel Noise ◽  
Discrete Wavelet ◽  
Ofdm System ◽  
Flat Fading ◽  
Frequency Selective

In this paper, Discrete Wavelet Transform (DWT) Orthogonal Frequency Division Multiplexing (OFDM) system is compared with Discrete Cosine Transform (DCT) and Discrete Fourier Transform (DFT) OFDM systems. The channel noise is modelled with A white Gaussian Model (AWGN), the fading is the impairment in the channel and modelled by Rayleigh fading which is frequency selective fading channel and flat fading channel. The comparisons of Peak to Average Power Ratio (PAPR) and Bit Error Rate (BER) are made using modulation techniques such as Differential Amplitude and Phase Modulation (DAPM), Quadrature Amplitude Modulation (QAM) and Pulse Amplitude Modulation (PAM). Simulation results shows that PAPR is 4.497 dB for DWT-DAPM combination, 4.684 dB for DWT-QAM combination and 6.211 dB for DWT- PAM combination at 10-3 Complementary Cumulative Distributive Function (CCDF).The performance Analysis with the combination of DFT, DCT with DAPM, QAM and PAM are also compared. The BER is 0.01816, 0.01806 at 20 dB SNR in frequency selective channel, flat fading channel for DWT-DAPM and for DWT- QAM, AWGN channel BER is 0.01765 at 20dB SNR.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo
Keyword(s):  
Time Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
High Mobility ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Frequency Space ◽  
Time Frequency ◽  
Single Carrier ◽  
The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

Sign in / Sign up

Export Citation Format

Share Document