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# A new PAPR reduction in OFDM systems using PTS combined with APPR for TWTA nonlinear HPA

Songklanakarin Journal of Science and Technology 01/2008;

Source: DOAJ

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**ABSTRACT:**An orthogonal frequency division multiplexing (OFDM) system has a number of orthogonally modulated subcarriers, which can give a large peak-to average power (PAPR). The PAPR reduces the efficiency of RF power amplifier in OFDM systems. In this paper, we propose a new PAPR reduction method, which pre-scrambles data sequence for high speed data processing in OFDM. The proposed method uses a correlator for the reduction of PAPR value and calculations. We have compared the new method with a partial transmit sequences (PTS) method. As a result, the new method has shown that it permits a considerable improvement in the computational complexity with achieving a reasonable PAPR reduction.IEEE Transactions on Consumer Electronics 12/2004; · 1.16 Impact Factor - IEEE Communications Letters. 01/2000; 4:86-88.
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**ABSTRACT:**Presents a hybrid analytical-simulation procedure for performance evaluation in M-ary quadrature amplitude modulation (M-QAM) orthogonal frequency-division multiplexing (OFDM) digital radio systems in the presence of nonlinear distortions caused by high-power amplifiers (HPAs). The present analysis is carried out considering an additive white Gaussian noise (AWGN) transmission channel. It is shown that, in the case of an OFDM system with a large number of subcarriers, the distortion on the received symbol caused by the amplifier can be modeled, with good approximation, as a “Gaussian nonlinear noise” added to the received symbol. This important result allows a hybrid analytical-simulation approach to solve the problem of performance evaluation. In practice, the simulation aspect is only used to estimate means and variances of the “nonlinear noise”. Such estimated parameters are subsequently used to evaluate analytically the system bit-error rate (BER) using an expression, which takes into account both AWGN and “nonlinear noise” effects. The advantage of the proposed method lies in the strongly reduced computational time. In fact, an accurate estimate of the “nonlinear noise” parameters requires only few iterations when compared with a classical semianalytical approach. This is especially true when low BER values (<10<sup>-4</sup>) have to be estimated. The proposed procedure is applied to evaluate M-QAM-OFDM performance in the presence of nonlinear distortions caused by traveling-wave tube (TWT) and solid-state-power (SSP) amplifiersIEEE Transactions on Vehicular Technology 03/1998; · 2.64 Impact Factor

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