Adaptive slope and threshold companding technique for PAPR reduction in OFDM systems

High Peak to Average Power Ratio (PAPR) of transmitted signals is a major drawback for multi-carrier modulation systems such as orthogonal frequency division multiplexing (OFDM) systems. Companding technique has been recently used to reduce PAPR. In this work, an adaptive slope and threshold (AST) companding transform is proposed to increase the reduction in PAPR with minimum degradation of received bit error rate (BER). The key idea is to adaptively vary both the slope of expansion and the threshold for expansion of the input signal amplitude to optimize the PAPR/BER tradeoff. This is implemented by selecting slope and threshold ratios in real-time from a look-up table (LUT) on the basis of the received feedback, making it adaptive.