ofdm cyclic prefix doubt?

[Dub01]

alzomor
Than processing of the CP signal differs from the ZP signal? How works reciever in CP signal and ZP signal?

 

[rag_perfect]

Intrasymbol interference
The guard interval is not used in practical systems because it does not
prevent an OFDM symbol from interfering with itself. This type of interference
is called intrasymbol interference.
The solution to the problem of intrasymbol interference involves a
discrete-time property. Recall that in continuous-time, a convolution in time
is equivalent to a multiplication in the frequency-domain. This property is
true in discrete-time only if the signals are of infinite length or if at least one
of the signals is periodic over the range of the convolution. It is not practical
to have an infinite-length OFDM symbol, however, it is possible to make
the OFDM symbol appear periodic.This periodic form is achieved by
replacing the guard interval with something known as a cyclic prefix of
length LP samples. The cyclic prefix is a replica of the last LP samples of the
OFDM symbol where LP > LC. Since it contains redundant information, the
cyclic prefix is discarded at the receiver.
Like the case of the guard interval,
this step removes the effects of intersymbol
interference. Because of the
way in which the cyclic prefix was
formed, the cyclically-extended OFDM
symbol now appears periodic when
convolved with the channel. An important
result is that the effect of the
channel becomes multiplicative.

 

[Dub01]

Thanks alzomor, rag_perfect.
But please help me, can you answered me about this question?:

1)What advantages and disadvantages at cyclic prefix(CP)?
2)What advantages and disadvantages at zero-prefix(ZP)?
3)Why cyclic prefix used widely?
4)How process a signal with cyclic prefix(CP)? How works reciever? Who can present a code in MathLab?
5)How process a signal with zero-prefix(ZP)? How works reciever? Who can present a code in MathLab?

 

[rag_perfect]

Hi dub01..
ur doubts are geniune....
though i have no idea abt zero prefix but for cp prefix i m sending a doc 4 u..
it will give u answer of most ques..

see this:

 

[alzomor]

Hi Dub01

I am sorry I don't know about ZP but CP processing is straight forwared

Salam
Hossam Alzomor
www(.)i-g(.)org