Constant envelope multicarrier modulation: performance evaluation AWGN and fading channels

In this paper we study the suitability of constant envelope multi-carrier modulation technique for the implementation of 1 Gbps wireless link at 60 GHz. This technique combines orthogonal frequency division multiplexing (OFDM) and phase modulation (PM) where: (1) PM creates a constant envelope signal which allows high power amplifier to operate near saturation levels thus maximizing power efficiency, (2) OFDM increases robustness to multipath fading. Since OFDM-PM symbols satisfy symmetry property, maximum-ratio combiner (MRC) can be used at the receiver. Our simulations show that in an AWGN channel at bit error level 10^-3, the OFDM-PM with MRC has about 0.8 dB performance loss compared to OFDM or single carrier minimum shift keying (MSK). For Rician fading channels, we find that OFDM-PM performs comparably to MSK and outperforms uncoded OFDM. Furthermore, we show that both OFDM and OFDM-PM have similar bit error distribution characteristics, and thus the performance of OFDM-PM can be improved by the use of water-filling or coding techniques