Hi Yasir,
In OptiSystem OFDM demodulator component help section, some explanations have been provided. But unfortunately, an image which seems very informative is illegible due to being very small. That image explains the steps in which equalization is done. Please see the following:
Symbol Rotation in OFDM
I think if someone helps in this regard, you would get your answer. However, the papers used for equalization are listed at the end of help section.
Regards