Yes SER is zero also whenever BER is zero.
1- what is the best bitrate to configure and evaluate the OFDM QAM4 system based on?
because when I increase the bitrate the BER is increasing with SMF distance (take the symbol rate half of the bitrate because I am using QAM 4)
2- if I took the one span (10km SMF, 2km DCF) should I include the length of the DCF in the OFDM demodulator or just the SMF?
if NO, then if I increase the span to 20 the DCF will be 40km is it ok to not include its length?!