cross correlation of OFDM

hey thank you for your reply one confusion as when we do cross correlation i need a fixed input too with which correlation will be done of the coefficients i read papers and it suggests as OFDM is my application i will get that input from there is it?

and i m willing to design a multiplierless correlator using shift and add how could that be done. i am planning on designing a correlator using binary bits which gives better performance and computation and uses less area. so i am planning to do it by correlating two binary inputs and getting the putput using shift and add do you have any idea how should i proceed with it

and yes with your idea what should be my other input for correlation .i am quite new to this