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

[Rupak Paul]

Hello there,

Thanks for your explanation. As this discussion is going on, I want to add my questions here too.

- Should I redesign Occupied Carrier size or Packet length every time depending on my data size? It seems if I set the packet length to 1 then it transfers all data regardless of any data size. 

- What is the purpose of that Delay block at the beginning of the receiver? Is it related to cycle prefix removal? 

Thank you.

BR,

Rupak

On Thu, Oct 28, 2021 at 2:33 PM Marcus Müller <mueller@kit.edu> wrote:

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, 能书能言 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

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Regards,

Rupak Paul