• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1548-1553
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• 2000

In this paper, an effective peak power reduction scheme for a downlink OFDM-CDMA system is proposed. Using the partial parallel transform(PPT) structure, peak-to-average power ratio(PAPR) can be reduced. The patterns of inputs of Inverse Fast Fourier Transform(IFFT) are more randomized in this structure by allotting the subcarriers to each users. At the cost of complexity we can obtain reduced PAPR and multiple access interference(MA) Computer simulations are carried out from the viewpoint of PAPR and demonstrated the improved PAPR performance.

• 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 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3117-3130
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• 2016

High peak-to-average power ratio (PAPR) of transmitted signals is a major drawback in Multicarrier modulation (MCM) systems. Companding transform is a well-known method to reduce the PAPR without restrictions on system parameters such as the number of subcarriers, frame format and constellation type. In this paper, a novel adaptive companding scheme, mainly focuses on compressing the large signals into the desirable distribution, is proposed to reduce the PAPR with low implementation complexity. In addition, formulas to calculate its PAPR and bit error rate (BER) performance are also derived. Simulation results confirm that the proposed scheme can achieve an effective tradeoff between PAPR reduction and BER performance by carefully choosing the companding parameter.

• ETRI Journal
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• v.28 no.2
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• pp.235-238
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• 2006

In this letter, a block code that minimizes the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals is proposed. It is shown that peak envelope power is invariant to cyclic shift and codeword inversion. The systematic encoding rule for the proposed code is composed of searching for a seed codeword, shifting the register elements, and determining codeword inversion. This eliminates the look-up table for one-to-one correspondence between the source and the coded data. Computer simulation confirms that OFDM systems with the proposed code always have the minimum PAPR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7C
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• pp.554-561
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• 2008

For the tone reservation (TR) scheme in orthogonal frequency division multiplexing (OFDM), there exists a trade-off between peak to average power ration (PAPR) reduction performance and data transmission rate. While PRT set is fixed in the conventional TR scheme, the proposed scheme adaptively select the PRT set according to the PAPR of the input OFDM symbol. It is shown that the PAPR reduction performance of the proposed scheme is better than that of the conventional scheme when the data transmission rate is the same.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.7-8
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• 2008

It is well-known that one of the most serious problems of Orthogonal Frequency Divison Multiplexing (OFDM) is its high Peak-to-Average Power Ratio (PAPR) which seriously limits the power efficiency of High Power Amplifier (HPA). This paper introduces various methodologies to cope with this problem.

• ETRI Journal
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• v.29 no.3
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• pp.402-404
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• 2007

One of the major disadvantages of the orthogonal frequency division multiplexing system is high peak-to-average power ratio (PAPR). Selected mapping (SLM) is an efficient distortionless PAPR reduction scheme which selects the minimum PAPR sequence from a group of independent phase rotated sequences. However, the SLM requires explicit side information and a large number of IFFT operations. In this letter we investigate a novel PAPR reduction method based on the radial basis function network and SLM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.806-808
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• 2015

In this paper, we suggest the method of pilot tone design for a compressed channel sensing in order to decrease the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems.