How can i verify how many samples have i skipped (OFDM QUESTION)

hi all DSP giants and experts,
                                          i am struggling on one
problem..lemme share with you people..

Thanks in advance for all answers

its like this

i  have OFDM Symbols say 256 ifft which has a cylic prefix of 32

say a system is taking fft at some sample offset..i need to know..at
what sample offset from start.

the FLOW is like this

step1-==========================================

assume there are 5 OFDM symbols (so overall 5*288 complex samples)
-----------------------------------------------------------------------------------------
|  CP  SYM |  CP  SYM |  CP  SYM |  CP  SYM |  CP  SYM |
|   32    256 |   32    256 |   32    256 |   32    256 |   32    256
|
----------------------------------------------------------------------------------------

step2 =========================================

assume a front end is picking up fft at say X samples before the
actual start of the SYM

example...if X = 11 so the fft window will take fft[11(CP)+245(SYM)]
(means it is picking up 11 samples from CP and remaining 245 samples
from OFDM SYMbol making it overall 256 and then it will take FFT
window on the extracted 256 complex samples)

step3==========================================
now if i want to find out what is that X

options which i have are, go for phaseramp stuff to decode what is
that X..

QUESTION======================================

is there any ROBUST method apart from PHASERAMP related Estimation
method which will give me answer..lemme clarify again..i dont
want ..any phaseramp..related method to find out that..

thanks in advance again
particlereddy

onemore small clarification..
                                       plz understand that the
frontend is like blackbox to me..donno what is happening inside

thanks again
particlereddy

On Dec 4, 8:09 pm, "PARTICLEREDDY (STRAYDOG)"
<particlere...@gmail.com> wrote:
> hi all DSP giants and experts,
>                                           i am struggling on one
> problem..lemme share with you people..
>
> Thanks in advance for all answers
>
> its like this
>
> i  have OFDM Symbols say 256 ifft which has a cylic prefix of 32
>
> say a system is taking fft at some sample offset..i need to know..at
> what sample offset from start.
>
> the FLOW is like this
>
> step1-==========================================
>
> assume there are 5 OFDM symbols (so overall 5*288 complex samples)
> ------------------------------------------------------------------------------------------
> |  CP  SYM |  CP  SYM |  CP  SYM |  CP  SYM |  CP  SYM |
> |   32    256 |   32    256 |   32    256 |   32    256 |   32    256
> |
> -----------------------------------------------------------------------------------------
>
> step2 =========================================
>
> assume a front end is picking up fft at say X samples before the
> actual start of the SYM
>
> example...if X = 11 so the fft window will take fft[11(CP)+245(SYM)]
> (means it is picking up 11 samples from CP and remaining 245 samples
> from OFDM SYMbol making it overall 256 and then it will take FFT
> window on the extracted 256 complex samples)
>
> step3==========================================
> now if i want to find out what is that X
>
> options which i have are, go for phaseramp stuff to decode what is
> that X..
>
> QUESTION======================================
>
> is there any ROBUST method apart from PHASERAMP related Estimation
> method which will give me answer..lemme clarify again..i dont
> want ..any phaseramp..related method to find out that..
>
> thanks in advance again
> particlereddy