You are not logged in.
Hi,
Is there any particular reason that in the reference design (ofdm_trrx_mimo/OFDM Rx MIMO/FFT & Chan Est/Input Buffers) input buffers take 80 downsampled values in the buffer and then gives out the middle 64 samples (index 8-72) for the FFT? Why it uses those middle values?
-B-
Offline
That's how the receiver removes the cyclic prefix from the incoming OFDM symbols. The transmitter adds a 16-sample cyclic prefix to each OFDM symbol (i.e. for each 64 IFFT outputs, 80 samples are actually sent over-the-air). The choice of offset (8 in the example you gave) can be controlled in software. An offset of 16 corresponds to taking the FFT of the final 64 samples of each 80 (i.e. no cyclic prefix samples are fed into the FFT). We use an offset of 8 by default, to give a large margin to symbol synchronization errors. The tradeoff here is between synchronization tolerance and delay spread tolerance. The more cyclic prefix fed into the FFT (smaller offset) leads to less tolerance to multipath.
Offline
Ok. Thank you. I started a new topic concerning the actual problems that we are having and with a more describing title.
Offline