Adaptive peak power reduction scheme controlling peak level based on adaptive algorithm

In this paper, based on an adaptive algorithm, an adaptive peak power reduction scheme (APPR) is proposed that can reduce the peak power and suppress radiated power outside the bandwidth. In the proposed method, no sudden nonlinear processing such as clipping is used, but the gain calculated by the adaptive algorithm is multiplied by the modulation signal. Hence, reduction of the peak power of the modulation signal and decreased radiation outside the bandwidth can be realized simultaneously. Further, since the proposed method can reduce the peak without dependence on the spectral shape of the modulation signal, the method can be applied to various wireless communications systems that have modulation signals with a large peak power. In order to evaluate the effectiveness of the proposed scheme, numerical simulations are performed with OFDM signals having a large peak power as the modulation signals in order to demonstrate the excellent peak reduction effects. (C) 2006 Wiley Periodicals, Inc.