Constant Envelope OFDM

TLDR

The paper proposes a transformation technique to reduce the peak‑to‑average power ratio in OFDM. CE‑OFDM converts the OFDM signal into a constant‑envelope waveform through phase modulation, enabling efficient power amplification, and reverts it at the receiver via phase demodulation before standard demodulation, with performance evaluated in AWGN and fading channels. Simulations and hardware tests show CE‑OFDM performs well in dense multipath with cyclic prefix and frequency‑domain equalization, outperforming conventional OFDM.

Abstract

This paper describes a transformation technique aimed at solving the peak-to-average power ratio (PAPR) problem associated with OFDM (orthogonal frequency-division multiplexing). Constant envelope OFDM (CE-OFDM) transforms the OFDM signal, by way of phase modulation, to a signal designed for efficient power amplification. At the receiver, the inverse transformation - phase demodulation - is applied prior to the conventional OFDM demodulator. The performance of CE-OFDM is analyzed in additive white Gaussian noise (AWGN) and fading channels. CE-OFDM is shown to achieve good performance in dense multipath with the use of cyclic prefix transmission in conjunction with a frequency- domain equalizer (FDE). By way of computer simulation and hardware realization, CE-OFDM is shown to compare favorably to conventional OFDM.