Orthogonal frequency division multiplexing with phase modulation and constant envelope design

Abstract

Constant envelope OFDM with phase modulation (CE-OFDM-PM) was proposed. The motivation of the CE-OFDM-PM system is to alleviate the high peak-to-average power ratio of conventional OFDM systems. In this paper, we explore more details of CE-OFDM-PM systems regarding bandwidth efficiency and performance under AWGN and multipath channels. A theoretical approach instead of Carson's rule to analyze bandwidth is proposed. It indicates that bandwidth requirement is determined by factors such as input data variance and modulation index. The analytical results show that the CE-OFDM-PM systems require the same bandwidth as conventional OFDM system when appropriate (low) modulation index is applied in CE-OFDM-PM system. Under the same multipath channel and bandwidth, the performance of CE-OFDM-PM systems is compared to conventional OFDM system with one tap equalizer. The uncoded BER performance of CE-OFDM-PM is getting close when OFDM applies clipping, but power efficiency of CE-OFDM-PM still outperforms OFDM since clipping cannot eliminate PAPR issue