Is there any correlation between bandwidth and subcarriers-tounes in ofdm?

GNU Radio
1

Hi guys,

I wonder if there is any correlation between baseband bandwidth of
receiver side and fft-subcarriers-tounes of sender sider in OFDM? When
I set the bandwidth to 20Mhz in sender side, the spectrum analyzer of
receiver side shows only half of bandwidth（10Mhz). Does the reason
that I use 128fft and 64 subcarriers account for this phenomenon?

Sent from my iPhone

2

The fraction of the Nyquist zone occupied is equal to the number of
active tones divided by the FFT length. The actual bandwidth then
depends on your sampling rate.

MB

On Wed, Mar 27, 2013 at 05:54:46PM +0800, Yingjie C. wrote:

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–
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin B.
Research Associate

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Building 05.01
76131 Karlsruhe

Phone: +49 721 608-43790
Fax: +49 721 608-46071
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KIT – University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

3

Thanks for your reply. You mean the bandwidth in receiver side(spectrum
analyser) is only half of that of sender side if the active tones is
half
of the FFT length, is that right? Can you provide the explicit formula
for
helping me better understand.

2013/3/27 Martin B. (CEL) [email protected]