Constant-envelope orthogonal frequency division multiplexing modulation

A constant-envelope signaling approach for orthogonal frequency division multiplexing (OFDM) modulation is proposed. By splitting the standard OFDM complex signals into real and imaginary sections, the proposed approach employs phase modulation in conjunction with signal clipping to endow the transmitted signal with a constant envelope, without destroying the required transmission characteristic associated with OFDM. The resultant constant-envelope signal enables the operation of the transmitter´s power amplifier at the saturation point and thus maximizes the achievable power efficiency. Despite the constant-envelope advantage, half the bandwidth efficiency is traded off by the approach. It is shown by simulation that the bit error performance of the proposed system is only slightly degraded from the conventional OFDM system.