• ETRI Journal
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• v.37 no.2
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• pp.338-347
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• 2015

The multi-carrier transmission signal in Multi-Carrier Code Division Multiple Access (MC-CDMA) has a high peak-to-average power ratio (PAPR), which results in nonlinear distortion and deteriorative system performance. An n-tuple selective mapping method is proposed to reduce the PAPR, in this paper. This method generates $2^n$ sequences of an original data sequence by adding n-tuple of n PAPR control bits to it followed by an interleaver and error-control code (ECC) to reduce its PAPR. The convolutional, Golay, and Hamming codes are used as ECCs in the proposed scheme. The proposed method uses different numbers of the n PAPR control bits to accomplish a noteworthy PAPR reduction and also avoids the need for a side-information transmission. The simulation results authenticate the effectiveness of the proposed method.

• The Journal of the Korea Contents Association
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• v.8 no.3
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• pp.41-46
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• 2008

Many methods have been developed to overcome the PAPR(peak-to-average power ratio) problem. Selective mapping(SLM), partial transmit sequence(PTS), subblock phase weighting(SPW) and gradient descent(GD) are used widely to reduce the PAPR. In this paper, we present an effective PAPR reduction method that decreases the number of calculations through Radix-2 DIF IFFT procedure and GD method that transmits selected data sequence. The data sequence is constructed by choosing elements that satisfy threshold value as one part of the sequence and the rest elements of each sequence are chosen to have the lower papr operating, which yields performance improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.401-407
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• 2010

In this paper, we consider a low-complex companding technique for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems. For the technique, we propose a novel companding function to compensate the problem of the conventional companding functions which are difficult to design complying with system requirements and deteriorate the bit error rate (BER) performance significantly. The proposed scalable companding function can provide an arbitrary value of the maximum PAPR with which the BER performance changes gracefully. In addition, the proposed companding function can be designed readily according to the PAPR and BER performance required by the system and is observed to provide better BER performance than the conventional clipping and $\mu$-low companding schemes under the similar PAPR condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.340-343
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• 2007

OFDM (Orthogonal Frequency Division Multiplexing) system is robust to frequency selective fading and narrowband interference in high-speed data communications. However, an OFDM signal consists of a number of independently modulated subcarriers, which can give a large PAPR (peak-to-Average Power Ratio) when added up coherently. In this paper, we propose a new PAPR reduction method using Adaptive Sine Soft Clipping (ASS Clipping) to solve the PAPR problem. The proposed method reduce the PAPR and out-of-band spectrum by cutting down high frequency components. From computer simulation results, we analyze the PSD (Power Spectral Density) and BER (Bit Error Rate) performance as well as PAPR reduction performance when the ASS Clipping method is applied to OFDM system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1320-1325
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• 2000

A very simple and effective peak power reduction scheme for a downlink OFDM-CDMA system is proposed using the relationship between peak-to-average power ratio (PAPR) and out-of-phase autocorrelation. Since power spectrum and autocorrelation function are Fourier transform pair, the PAPR property of the sequences can be estimated by the out-of-phase autocorrelation function of the spreading sequences. Thus, by scrambling the spread data in the frequency domain, we can reduce the sidelobe energy of autocorrelation, and at last, suppress PAPR in the proposed OFDM-CDMA system.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.17-20
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• 2002

We propose in this paper a companding scheme for PAPR (Peak-to-Average Power Ratio) reduction in OFBM (Orthogonal Frequency Division Multiplexing) systems. By exploiting statical distribution of OFDM transmit signals, the proposed scheme effectively reduces the PAPR by compressing the peak signals, while maintaining the average power unchanged. Simulation results are provided to show good performance of the proposed scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.889-897
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• 2002

In this paper, we propose an improved block coding scheme for PAPR reduction in the OFDM communication system. Unlike the conventional block coding scheme which uses one block encoder of subcarrier N, two block encoders of subcarrier N/2 is used for the proposed block coding scheme. This not only improves the coding gain, but enhances the spectral efficiency by twice due to the increment of code rate. PAPR Reduction performance is the same as the conventional block coding. When BER is $10^{-4}$, the proposed block coding scheme has coding gain of 0.5 dB than the conventional scheme.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.15-16
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• 2006

In this paper, we propose an adaptive SLM scheme based on peak observation for PAPR reduction of OFDM signals. The proposed scheme is composed of three steps: peak scaling, sequence selection, and SLM procedures. In the first step, the peak signal samples in the IFFT outputs of the original input sequence are scaled down. In the second step, the sub-carrier positions where power difference between the original input sequence and the FFT outputs of the scaled signal is large, are identified. Then, the phase sequences which have the maximum number of phase-reversed sequence words only for these positions, are selected. Finally, only using the selected phase sequences, the generic SLM procedure is performed for the original input sequence. Simulation results reveal that the proposed adaptive SLM remarkably reduces the complexity in terms of IFFT and PAPR calculations than the conventional SLM, while maintaining the PAPR reduction performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10C
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• pp.1010-1018
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• 2007

In this paper, we propose a companding scheme to effectively reduce PAPR (Peak-to-Average Power Ratio) of the OFDM (Orthogonal frequency Division Multiplexing) signals. The proposed scheme is basically based on the companding scheme to consider both complexity and Bit Error Rate (BER) performance, and composed of the clipping followed by the companding scheme. In the first step of the proposed scheme, some of peak signals which do not influence the BER even without them, are clipped. In the second step, the proposed scheme utilizes the ${\mu}-law$ companding to effectively reduce the PAPR. Simulation results show that the proposed clipped companding scheme can provide more PAPR reduction without degradation of the BER performance, as compare to the conventional ${\mu}-law$ companding.

• ETRI Journal
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• v.29 no.2
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• pp.231-233
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• 2007

One of the drawbacks in an OFDM system is the high peak-to-average power ratio (PAPR). Among a number of techniques to reduce the high PAPR, simple amplitude predistortion (SAP), a form of active constellation extension, has been proposed to effectively achieve the desired PAPR. In this letter, a novel scheme, simple amplitude and phase predistortion (SAPP), is proposed. In SAP the carriers' amplitude is utilized to combat the peak signal. Each amplitude is amplified according to its degree of contribution as a metric. In addition to amplitude, SAPP also utilizes the phase. Simulation results indicate that the proposed scheme provides better PAPR reduction than SAP.