Combined Envelope Scaling with Modified SLM Method for PAPR Reduction in OFDM-Based VLC Systems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ridha Touhami ◽  
Djamal Slimani ◽  
Ayad Atiyah Abdulkafi ◽  
Yaseein Soubhi Hussein ◽  
Mohamad Yusoff Alias
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Visible Light Communication ◽  
Low Complexity ◽  
Optical Communication Systems ◽  
High Spectral Efficiency ◽  
Low Complexity Implementation ◽  
Scaling Process ◽  
Selective Mapping

AbstractOrthogonal frequency-division multiplexing technique (OFDM) has been adopted widely as a modulation technique for radio frequency (RF) and optical communication systems such as visible-light communication (VLC) due to its high spectral efficiency and low-complexity implementation. VLC-OFDM is recommended in 5 G mobile communication. However, VLC-OFDM suffer from the high peak to-average power ratio (PAPR). In this paper, a modified selective mapping (MSLM) method is applied to the proposed system followed by a new envelope scaling process for further reductions in PAPR of VLC-OFDM system. Simulation results show that the proposed method reduces the PAPR by about 6.8 and 1.7 dB comparing with the original signal and the traditional SLM with a number of rotation vector U = 8, respectively.

scholarly journals Pilot-Aided Frame Synchronization in Optical OFDM Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 4034 ◽  
Author(s):  
Funmilayo B. Offiong ◽  
Sinan Sinanović ◽  
Wasiu O. Popoola
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Visible Light Communication ◽  
Low Complexity ◽  
Frame Synchronization ◽  
Ofdm Systems ◽  
Pilot Symbol ◽  
Pilot Signal ◽  
Symmetric Property

Efficient frame synchronization is essential for data recovery in communication systems. In this study, a single pilot sequence is used to achieve both frame synchronization and peak-to-average power ratio (PAPR) reduction. The two systems considered are direct-current biased optical orthogonal frequency division multiplexing (DCO-OFDM) and asymmetrically clipped O-OFDM (ACO-OFDM). The pilot symbol is allocated to odd indexed subcarriers only. Thus, the synchronization algorithm leverages the mirror symmetric property of the pilot symbol within a frame to detect the start of the pilot signal at the receiver. This scheme has low complexity and gives precise frame synchronization at signal-to-noise ratios as low as 4 dB in an indoor visible light communication (VLC) channel.

scholarly journals Low-Complexity Distortionless Techniques for Peak Power Reduction in OFDM Communication Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-13
Author(s):  
A. Ghassemi ◽  
T. A. Gulliver
Keyword(s):  
Computational Complexity ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Low Complexity ◽  
Inverse Discrete Fourier Transform ◽  
Peak Power Reduction ◽  
And Performance ◽  
Selective Mapping ◽  
Papr Performance

A high peak-to-average power ratio (PAPR) is one of the major drawbacks to using orthogonal frequency division multiplexing (OFDM) modulation. The three most effective distortionless techniques for PAPR reduction are partial transmit sequence (PTS), selective mapping (SLM), and tone reservation (TR). However, the high computational complexity due to the inverse discrete Fourier transform (IDFT) is a problem with these approaches. Implementation of these techniques typically employ direct computation of the IDFT, which is not the most efficient solution. In this paper, we consider the development and performance analysis of these distortionless techniques in conjunction with low-complexity IFFT algorithms to reduce the PAPR of the OFDM signal. Recently, proposed IFFT-based techniques are shown to substantially reduce the computational complexity and improve PAPR performance.

scholarly journals An Efficient Adaptive Technique with Low Complexity for Reducing PAPR in OFDM-Based Cognitive Radio

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hefdhallah Sakran ◽  
Omar Nasr ◽  
Mona Shokair
Keyword(s):  
Cognitive Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Low Complexity ◽  
Papr Reduction ◽  
Modulation Scheme ◽  
Ofdm Systems ◽  
Cpu Time ◽  
Reduction Techniques ◽  
Selective Mapping

Cognitive radio (CR) is considered nowadays as a strong candidate solution for the spectrum scarcity problem. On standards level, many cognitive radio standards have chosen Non-Contiguous Orthogonal Frequency Division Multiplexing (NC-OFDM) as their modulation scheme. Similar to OFDM, NC-OFDM suffers from the problem of having a high Peak to Average Power Ratio (PAPR). If not solved, either the transmitted signal will be distorted, which will cause interference to primary (licensed) users, or the effeciency of the power amplifier will be seriously degraded. The effect of the PAPR problem in NC-OFDM based cognitive radio networks is worse than normal OFDM systems. In this paper, we propose enhanced techniques to reduce the PAPR in NC-OFDM systems. We start by showing that combining two standard PAPR reduction techniques (interleaver-based and selective mapping) results in a lower PAPR than using them individually. Then, an “adaptive number of interleavers” will be proposed that achieves the same performance of conventional interleaver-based PAPR reduction while reducing the CPU time by 41.3%. Finally, adaptive joint interleaver with selective mapping is presented, and we show that it gives the same performance as conventional interleaver-based technique, with reduction in CPU time by a factor of 50.1%.

scholarly journals A Multi-Carrier Waveform Design for 5G and beyond Communication Systems

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1466
Author(s):  
Imran Baig ◽  
Umer Farooq ◽  
Najam Ul Hasan ◽  
Manaf Zghaibeh ◽  
Varun Jeoti
Keyword(s):  
Communication Networks ◽  
Spectral Efficiency ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Research Problem ◽  
Cumulative Distribution ◽  
Fourth Generation ◽  
Power Domain ◽  
Selective Mapping

The next generation communication network (NGCN) is expected to provide higher spectral efficiency, low latency, large throughput and massive machine-to-machine type communications. In this regard, the design of the multi-carrier waveform (MCW) is posing a major research problem for the NGCN. To overcome the stated problem, a lot of state-of-the-art work exists that proposes various MCW alternative to the standard orthogonal frequency division multiplexing (OFDM) waveform. It is true that OFDM was used in a number of real-time communication systems of fourth generation (4G) networks. However, their use in the upcoming fifth generation (5G) network is not very feasible. This is because of the strict requirements of 5G communication systems, which also extend beyond 5G systems; hence rendering the use of OFDM infeasible for newer communication standards. To satisfy the requirements of upcoming communication networks, there is a dire need for MCWs with better flexibility. In this regard, a precoding-based MCW has been proposed. The proposed MCW fulfills the requirements of the NGCN in terms of low peak-to-average power ratio (PAPR), high spectral efficiency and throughput. The MCW proposed in this work uses power-domain multiplexing such as non-orthogonal multiple access (NOMA) and phase rotation by using the selective mapping (SLM) and generalized chirp-like (GCL) precoding of the input signal to the universal filtered multi-carriers (UFMC) modulations. Statistical analysis of the PAPR is presented by using the complementary cumulative distribution function (CCDF). The MATLAB® simulations have been carried out to implement the CCDF of PAPR and results show that a PAPR gain of 5.4 dB is obtained when the proposed waveform is compared with the standard NOMA-UFMC waveform at clip rate of 10−3, using 4-QAM.

scholarly journals PAPR Performance Analysis of low Complexity SLM for Various Phase Sequences in MIMO-OFDM System

2019 ◽  
Vol 8 (2) ◽  
pp. 4347-4353
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Multipath Fading ◽  
Low Complexity ◽  
Superior Performance ◽  
Ofdm Systems ◽  
Phase Sequence ◽  
Mimo Ofdm ◽  
Papr Performance

Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO OFDM) is a key technology for contemporary communication systems due to its spectral efficiency, higher data rates, better diversity gain, good link reliability and both inter symbol interference (ISI) and multipath fading free transmission. However, due to the presence of OFDM, MIMO-OFDM suffers from high peak to average power ratio (PAPR). Even though, several schemes are available to mitigate PAPR, there is no standard solution. Selective Mapping (SLM) significantly reduces the PAPR in OFDM systems at the cost of computational complexity (CC). The CC of SLM can be reduced by proper design of SLM. This paper considers a low complexity SLM (LC SLM) scheme in which both the CC and length of the index of selected phase sequence are significantly reduced. The PAPR of an SLM-OFDM depends on the number of subcarriers in OFDM, the number of candidate blocks in SLM and selected phase sequence and this paper investigate various phase sequences and analyses their PAPR performance. Simulation results show the superior performance of Riemann sequence over the other phase sequences.

Peak-to-Average Power Ratio Distribution of OFDM Visible Light Communication Systems

2014 ◽  
Vol 519-520 ◽  
pp. 987-990
Author(s):  
Bing Yan Yu ◽  
Hong Ming Zhang
Keyword(s):  
Visible Light ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Average Power ◽  
Visible Light Communication ◽  
Closed Form Expression ◽  
Power Ratio ◽  
Ratio Distribution ◽  
Ofdm Signal

This paper studies the Peak-to-Average Power Ratio (PAPR) distribution in orthogonal frequency division multiplexing (OFDM) signal of visible light communication (VLC) systems with intensity modulation direct detection (IM/DD). In this paper, a closed form expression of PAPR distribution in OFDM-VLC signals is derived, with unequal power allocation to subcarriers is considered. Simulation with different number of subcarriers is conducted. The numerical results show the proposed distribution expression matches well with the result obtained by simulation.

New Hybrid PAPR Reduction Techniques for OFDM-Based Visible Light Communication Systems

2018 ◽  
Vol 39 (4) ◽  
pp. 427-435 ◽  
Author(s):  
Haitham Freag ◽  
Emad S. Hassan ◽  
Sami A. El-Dolil ◽  
Moawad I. Dessouky
Keyword(s):  
Visible Light ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Visible Light Communication ◽  
Cumulative Distribution ◽  
Papr Reduction ◽  
Reduction Techniques ◽  
Ber Performance

Abstract Orthogonal frequency division multiplexing (OFDM) is used with visible light communication (VLC) systems to reduce the effects of inter-symbol interference (ISI) and to achieve communication with high speed of data transmission and huge bandwidth. However, OFDM-based VLC systems suffer from high peak-to-average power ratios (PAPRs). This paper proposes a new hybrid PAPR reduction technique based on signal transformation combined with clipping. The Hadamard transform is used in the proposed technique due to its advantages in reducing the PAPR without affecting the bit error rate (BER) of VLC systems. The optimum clipping threshold at which we can simultaneously reduce the PAPR and improve the BER of VLC systems is also determined. In this paper, we also propose a new OFDM structure based on using discrete cosine transform (DCT) precoding before inverse fast Fourier transform (IFFT) stage to further improve the PAPR reduction capability and BER performance. Several experiments are carried out to test the performance of the proposed technique in terms of complementary cumulative distribution function (CCDF) and the BER. The obtained results show that the proposed technique can simultaneously reduce the PAPR and achieve good BER performance when compared to the original OFDM-based VLC system.

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