?????? Why the ofdm data packet is not fully received ?

[????????]

Hi,

Thank you very much for your detailed explanation. I understand now, but when I use the equalizer, I no longer use "simpledfe()" but use "static()". I assume that the receiving end does not know the modulation method. At this time, something as expected occurred. The received text file was garbled. I have tried measures such as increasing the transmission power\using cable, etc., but the problem still occurs. I want to know what factors are related to this, and I should continue to adjust Is the parameter configuration of "USRP Source/sink"? Or should it be adjusted from other locations in the GRC flow chart? (I used two USRPb210)

Sincerely

------------------ ???????? ------------------

??????: "Marcus M??ller" <mueller@kit.edu>;

????????: 2021??10??28??(??????) ????8:31

??????: "discuss-gnuradio"<discuss-gnuradio@gnu.org>;

????: Re: Why the ofdm data packet is not fully received ?

Hi!

A single OFDM symbol has 64 carriers. I can only guess you're using the
configuration of OFDM Carrier Aggregator that gives you 48 carriers
dedicated to data.
On each of these carriers, you do QPSK, so 2 bit per symbol.
That makes for a total of 96 bits, in a single OFDM symbol.

96 bits are 12 Bytes. "hello world" has 11 Bytes. So, you're not even
filling a single OFDM symbol with data!

But you're even setting a frame length of 96 bytes. So, this can't work;
you need to give the transmitter enough data to fill a frame.

Best regards,
Marcus



On 28/10/2021 10.59, ???????? wrote:
> Hello everyone,
> I am using ofdm_tx/rx.grc to transfer text file data, and there is a
> "hello world" character in the text. I use two usrpb210 for transmission
> .When I set the "repeat" in the "file sink" to no, the receiving end
> cannot receive the correct "hello world" word, and the open file is
> blank; but when I set the "repeat" to yes, the receiving file is opened
> , Which contains a lot of repeated "hello world" words, I want to know
> why this happens? How can I solve this problem? (It can still be
> received correctly when my "repeat" is set to no)
> The flowchart is in the attachment.
> Thanks to anyone for the relevant information, thank you!
> Sincerely