An Adaptive Clipping and Filtering Technique for PAPR Reduction of OFDM Signals
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An Adaptive Clipping and Filtering Technique for PAPR Reduction of OFDM Signals Byung Moo Lee · Youngok Kim
Received: 6 February 2012 / Revised: 11 October 2012 / Published online: 9 November 2012 © Springer Science+Business Media New York 2012
Abstract In recent years, many peak-to-average power ratio (PAPR) reduction techniques have been proposed for orthogonal frequency division multiplexing (OFDM) signals. Among various techniques, the iterative clipping and filtering (ICAF) technique has been considered as a practical scheme, and widely used owing to its nonexpansion of bandwidth, low computational complexity, and simplicity in implementation without receiver-side cooperation. However, the performance of conventional ICAF technique is degraded, because the same signals are iteratively clipped with a fixed clipping threshold (CT) in every clipping operation. In this paper, we analyze the performance of conventional ICAF technique, and then propose an adaptive ICAF scheme, which clips the signal with an adaptively modified CT in every clipping operation to achieve enhanced PAPR reduction of OFDM signals. Simulation results show that the proposed scheme significantly outperforms the conventional scheme, in PAPR reduction of OFDM signals at the same number of iterations. Keywords Peak-to-average power ratio · Iterative clipping and filtering · OFDM 1 Introduction Since orthogonal frequency division multiplexing (OFDM) has high spectral efficiency and is robust against inter-symbol interference and frequency-selective fading channel, it is widely chosen for European digital audio/video broadcasting (DAV/DVB), and wireless local/metropolitan area network standards (WLAN/ B.M. Lee Central R&D Laboratory, Korea Telecom (KT), Seoul 137-792, Korea e-mail: [email protected] Y. Kim () Department of Electronic Engineering, Kwangwoon University, Seoul 139-701, Korea e-mail: [email protected]
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Circuits Syst Signal Process (2013) 32:1335–1349
WMAN). It is now a strong candidate for future broadband wireless communication systems. However, one of the major problems of an OFDM-based system is its high peakto-average-power ratio (PAPR), which causes a distortion of signal at the nonlinear high power amplifier (HPA) of the transmitter. Thus, the power efficiency of HPA is seriously limited to avoid nonlinear distortion, otherwise, high PAPR results in significant performance degradation. To reduce the high PAPR, a number of algorithms have been introduced, such as clipping [1, 10, 15, 16], companding [5, 7, 8, 20], block coding [9, 17, 22, 23], active constellation extension [11], tone reservation/injection [18, 24], partial transmit sequence [2, 3, 13], and selective mapping [4, 21, 25]. The clipping technique indicates simply clipping the signal that is beyond a predefined threshold. Due to possible spectrum leakage, filtering is used after the clipping process. The companding technique indicates compressing the signal amplitude at the transmitter, using a kind of nonlinear function, and recovering the signal at the receiv
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