Reducing the guard-band of a DDO-OFDM system by Multi-objective optimization

A Multi-objective optimization on the parameters of direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems in short-range links is proposed. Based on Genetic Algorithms (GA), the optimization process takes into account the influence of optical power in the guard-band reduction of such multicarrier systems with 4 and 16-QAM subcarrier mapping and for propagation in 40 km of standard single-mode fiber (SSMF). Simulation results show that the parameters optimization is responsible for a gain of ≈ 2.5 dB [≈ 1.8 dB] in the required optical power for a bit-error-rate of 10-3, for DDO-OFDM system transmission over 40 km of uncompensated SSMF, with a guard band (BG) equals to 50% of the signal bandwidth (Bw) and 16-QAM [4-QAM] subcarrier mapping. For a extremely reduced guard-band of only 1% of Bw, the gain reduced to ≈ 0.5 dB and ≈ 1.5 dB for 16-QAM and 4-QAM mapping, respectively.