For a given received SNR of 8 dB, Figure 3 shows the relationship of the Q factor between clipping ratio in clipped QPSK OFDM with and without normalization after 100 km fiber transmission.
From the experiment results in Figures 2 and 3, it can be seen that data normalization can improve the quality of the clipped OFDM signals over AWGN and fiber channel.
Figure 4 shows the BER comparison for different clipping ratios for clipped OFDM without the normalization case.
We evaluated the BER performance of clipped OFDM over the fiber channel with and without normalization.
Figure 6 shows the simulation results for clipped optical OFDM without normalization over the fiber channel.
Figure 7 shows simulation results of the clipped and normalized OFDM over the fiber channel.
All different clipped and amplified OFDM signals are amplified to the same maximum amplitude, which is the maximum allowable amplitude of DAC in the transmitter end.
In this section, we will measure the performance of the clipped QPSK OFDM signal of 4 Gs/s with and without normalization after 100 km standard SMF transmission in our transmission experiment platform.
From Figure 9, it can be seen that the clipped and amplified OFDM with clipping ratio of 4 can obtain the Q factor improvement of 2.9 dB when compared to that of the original OFDM under launch optical power of 6 dB case.