Thanks… i wasn’t too sure about the parameters. My matlab implementation is based on 256 subcarriers by 200 symbols used in the ofdm tranceivers. Symbol size is basically the number of ofdm symbols used in its implementation. I dont know how it works on optisystem.. below is my matlab implementation based on subcarriers and sysmbol size. Hopefully this helps because am going to implement this system design with the matlab attached below.