Multiple-subcarrier optical communication systems with peak reduction carriers

We propose a multiple-subcarrier (MS) optical communication system with peak reduction carriers (PRCs) to reduce the optical power requirement on an additive white Gaussian noise (AWGN) channel. The proposed system transmits L subcarriers referred to as PRCs among N subcarriers for the d.c. bias reduction so that the optical power is reduced. Since information bits are mapped onto each subcarrier independently, the information bits of each subcarrier can be detected independently and the error rate of the proposed system is unaffected by PRCs. We show that with the fixed bias, the normalized power requirements of MS-PRC are smaller than those of the MS system with the normal block coding (MS-normal) and the MS system with the reserved-subcarrier block coding (MS-reserved) for all the total number of transmitted bits, and smaller than that of the MS system with the minimum-power block coding (MS-min.power) for four transmitted bits and below, respectively. We also show that with the time-varying bias, the normalized power requirements of MS-PRC are smaller than those of the conventional MS systems for all the total number of transmitted bits.