Efficient Algorithms for PAPR Reduction in OFDM Transmitters Implemented using Fixed-Point DSPs

OFDM has a very high peak-to-average power ratio. This imposes stringent dynamic range requirements on the analog front-ends of the transmitter and receiver and, if a fixed-point processor is used, on the digital sections of the system, particularly the FFT/IFFT. OFDM systems often use digital peak reduction techniques such as clipping and filtering but these require several FFT/IFFT operations. In this paper results are presented for the combination of a novel FFT algorithm which allows numeric overflow to occur with low probability, and several computationally efficient clipping techniques. Results are presented for the mean-square error of the clipped and filtered OFDM signal and for the computational complexity of the system in terms of cycle counts. These show that the technique causes negligible signal degradation and can be very efficiently implemented on low cost processors