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OFDM synchronization question

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Full Member level 2
Jun 21, 2005
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ofdm sync

Guys, i have a doubt which i hope u guys can help me.

I've read & studied about OFDM symbol synchronization, either through the use of cyclic prefix or preamble sequences.

However there is 1 part i do not understand. My OFDM simulation in Simulink produces a real valued output before transmission (Complex symmetry at IFFT). Thus my transmitting signal is real. But at synchronization, after a certain delay of T i'm suppose to perform complex conjugate before correlation with the original signal. How do i perform the conjugation when the incoming signal is real? Am i suppose to perform some IQ demodulation to turn it into complex?

simulink ofdm synchronization

yes, you need to take the complex conjugate before correlating with the original signal.
Well, you might be thinking why should one take complex conjugate of a real signal. Think in this way: Your signal is real at the Tx end, this signal is multiplied by a complex phasor when it passes through a channel, this will result in reception of a complex signal at the receiver end.

Now, if you are not introducing a channel between your Tx and Rx you can safely ignore the complex conjugation operation.

hope this answers your Q

ofdm synchronization 2009

Haven't seen in you quite a while Gandharva :) Good to see you again...

Ok, so do i just perform simple conjugation then? or none? Coz to perform correlation i need to have conjugation right?

To give you an idea of what i'm trying to do with the synchronization. HomePlug, the standard for power line communications uses preambles for synchronization 6 SYNCP symbols and 1 SYNCM symbols (which is the reverse of SYNCP). However, i do not know what is SYNCP and SYNCM thus i'm using the PN sequence generator in Simulink.

I'm trying to implement a double correlation system, where:
1) coarse sync forms a plateau where the incoming signal is autocorrelated with a delayed version of itself and
2) fine sync produces peaks when crosscorrelated with the known preamble

Then the result of the 2 is compared and synchronization is obtained.

Added after 23 minutes:

Another thing, for autocorrelation before the conjugation there is a delay. How much should i set for this delay/lag?

ofdm synchronization matlab

Please refer "Robust Frequency and timing synchronizatrion for OFdm " By Schmidle and c.cox IEEE paper for clearing your concepts regarding your problem.

matlab ofdm sync

you could download the papers to see,it's easy!

ofdm synchonisation

Check this link, it contains a very good dissertation in OFDM synchronization.

ofdm synchronization

I have the same problem too, but deos anyone can tell me how to find Matlab codeing for OFDM synchronization?

ofdm synchronization correlation

hello every one
m new member of edaboard
can any one help me regarding cyclic prefix
how i will add it to my data in matlab???

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