Error Rate Analysis of Phase-Modulated OFDM (OFDM-PM) in Awgn Channels

QAM transmission of OFDM signals achieves good spectral efficiency while greatly simplifying the equalization process. However, RF transmitters must be operated in their linear region and highly stable oscillators (low phase-noise) are a necessity or the BER will degrade significantly. If angle-modulation is instead used, then the RF signal has constant envelope and phase-noise has an additive effect, the result being more efficient power transmission and orthogonality is maintained with a noisy oscillator. Angle-modulation has lower spectral efficiency then QAM and angle-demodulators suffer a threshold effect: the receiver output SNR degrades, significantly once below a certain input SNR. To apply angle-modulated OFDM systems in practice this threshold effect and ifs impact on the BER (for a given spectral efficiency) must be analyzed. This paper is the first to present such an analysis for phase-modulation (OFDM-PM) in AWGN channels