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Author Orthogonal issues after IFFT
Edwin

2006-09-29, 4:13 am

Hi,

I am a student doing my final year project, which is on OFDM wireless
communications. Currently, I'm using Matlab to construct the
transmitter.

I have some queries about orthogonal.
Assuming I have 2 subcarriers and I placed them in a matrix of 100 by
2. The 2 columns indicates the 2 subcarriers and I perform a IFFT on
it.

y = ifft(x);

The ifft function will return IDFT of each column of the matrix.

Are these 2 subcarries orthogonal now? because I read up that IFFT
not only produce complex outputs in frequency domain and
orthogonality.

Lastly, how to I test for othogonality in Matlab?

Thanks.

Edwin
Ken Davis

2006-09-29, 8:05 am

"Edwin" <edwintan82@gmail.com> wrote in message
news:ef42711.-1@webcrossing.raydaftYaTP...
> Hi,
>
> I am a student doing my final year project, which is on OFDM wireless
> communications. Currently, I'm using Matlab to construct the
> transmitter.
>
> I have some queries about orthogonal.
> Assuming I have 2 subcarriers and I placed them in a matrix of 100 by
> 2. The 2 columns indicates the 2 subcarriers and I perform a IFFT on
> it.
>
> y = ifft(x);
>
> The ifft function will return IDFT of each column of the matrix.
>
> Are these 2 subcarries orthogonal now? because I read up that IFFT
> not only produce complex outputs in frequency domain and
> orthogonality.
>
> Lastly, how to I test for othogonality in Matlab?
>
> Thanks.
>
> Edwin


Your posting indicates that you do not understand OFDM. Since it would take
too much effort to teach you here, I suggest that review your textbooks on
this subject and you will see how to do what you want. Hint: your IFFT
should only apply to ONE column.


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