Effect of sampling frequency change in OFDM

thavamaran

Hi guys, I have this question, I know in OFDM system, when you upconvert the signal with certain carrier frequency with certain sampling frequency and when you downconvert it, if the carrier frequency is same, but the sampling is not, then you will have a sampling frequency offset and that will cause unsyncronized problem, like you will get a phase rotation or shifted constellation.

But how actually this sampling difference causes the intermixing in subcarrier or even changes the phase of the signal? In theoretical perspective, I dont really get it. Please someone explain it to me, I went through books, and still I dont get the idea. thank you very much!