Zadoff-Chu sequences in LTE

Rigoberto Juarez

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Jul 23, 2009, 4:18:01 AM7/23/09

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This is my first message in the forum. :)
I'm studying the propierties of Zadoff-Chu sequences in LTE. These sequences for the synchronization channel have the expression that you can find in
http://en.wikipedia.org/wiki/Zadoff%E2%80%93Chu_sequence
with Nzc=63 and roots u=25,29,34. So there are defined 3 different sequences.
These sequences have these propierties:
1)- Cyclic autocorrelation is ideal
2)- Cyclic cross-correlation is constant and equal to 1/sqrt(Nzc) (=0.126 because Nzc=63)

Ok, let's chech this with the cyclic correlation function of http://www.mathworks.com/matlabcentral/fileexchange/4810

Results: "1)" is true for the 3 sequences
"2)" is only true for the pairs of sequences with roots 25-29 and 29-34. With the roots 29-34 the function is not constant and its maximum value its exactly 3 times 0.126.

Can you help me with this? Do you know where the problem is?
Thank you very much!

Regards,

Rigoberto

Rigoberto Juarez

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Jul 23, 2009, 4:26:02 AM7/23/09

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I forgot! I put my code to generate the sequences!

function seq = zadoff(root)
for n=0:62
seq(n+1)=exp(-j*(pi*root*n*(n+1))/63);
end
end

"Rigoberto Juarez" <jmaz...@gmail.com> wrote in message <h496bp$87l$1...@fred.mathworks.com>...

Rigoberto Juarez

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Jul 23, 2009, 9:14:01 AM7/23/09

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Up!
Any help? :(

"Rigoberto Juarez" <jmaz...@gmail.com> wrote in message <h496qq$5om$1...@fred.mathworks.com>...

Miguel Vazquez

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Jul 23, 2009, 12:52:02 PM7/23/09

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"Rigoberto Juarez" <jmaz...@gmail.com> wrote in message <h49nmp$gv4$1...@fred.mathworks.com>...

Hey Rigoberto,

Help me out there:

Results: "1)" is true for the 3 sequences
> > > "2)" is only true for the pairs of sequences with roots 25-29 and 29-34. With the roots 29-34 the function is not constant and its maximum value its exactly 3 times 0.126.

What are you talking about?

Cheers,

Miguel

Rigoberto Juarez

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Jul 24, 2009, 5:50:03 AM7/24/09

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Thanks for your response.
I mean:

The propierty 1 (ideal CYCLIC autocorrelation) is fulfilled for the three sequences.
The propierty 2 (cylic crosscorrelation constant=0.126) is only fulfilled for the pair of sequences 25-29 and the pair 29-34, BUT NOT for the pair 25-34. Why not?

That's the question.
Cheers,
Rigoberto ;)

"Miguel Vazquez" <mavazqu...@gmail.com> wrote in message <h4a4fi$kj2$1...@fred.mathworks.com>...

KAIST ?

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Jan 28, 2010, 1:48:04 PM1/28/10

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Because 34 - 25 = 8 is not prime with 63.
Refer to this paper : Branislav M, Popovic, “Generalized Chirp-Like polyphase sequences with optimum correlaiton properties”, IEEE tran. Infom. Theory, vol. 38, no. 4, 1992

"Rigoberto Juarez" <jmaz...@gmail.com> wrote in message <h496bp$87l$1...@fred.mathworks.com>...

Irine

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Feb 11, 2012, 10:28:34 AM2/11/12

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Hi! I'm also intersted in LTE and especially in Zadoff-Chu sequences, can you tell me how did you get the ideal correlation and a cross-correlation with constant amplitude?
Can you show an example of the matlab script

With respect, Irine