Peak-To-Average Power Ratio Reduction by CB-ACE and Adaptive Ace Algorithms

Orthogonal Frequency Division Multiplexing (OFDM) is a method of Digital Modulation in which a signal is split into several narrowband channels at different frequencies. The OFDM technology was first conceived in the 1960s and 1970s during the research into minimizing interference among the channels near each other in the frequency [5]. The main idea behind OFDM is that since lowrate modulations are less sensitive to multipath, the better way is to send a number of low rate streams in parallel than sending one high rate waveform [8].The OFDM signal has a noise like amplitude with a very large dynamic range; therefore it requires RF power amplifiers with a high Peak-toAverage Power Ratio (PAPR) or Peak-to-Average Ratio (PAR) [1]. The high PAPR increases the complexity of Analog-toDigital (A/D) and Digital-to-Analog (D/A) converters and also lowers the efficiency of power amplifiers [1]. The ClippingBased Active Constellation Extension (CB-ACE) Algorithm and Adaptive Active Constellation Extension (Adaptive ACE) Algorithm can be efficiently used to reduce the high PAPR in OFDM systems.