One more thing I need to mention here that I got a reply from expert regarding this topic that is “Ideally we can remove, because there is no channel involved where maximum noise are encompassed. Well, in photo-detector some inherent noise cannot that we have to tolerate.
Please try to correct the Direct Current (DC) shift, because of that there is shift in coordinates of constellation.”
I am not getting how to achieve this. Please let me know how to correct the DC shift as mentioned in the above context.
Thanks
Regards