[Discuss-gnuradio] Successful transmission in gr-ieee802-11 with adding extra samples (before OFDM preamble)

[Isen I-Chun Chao]

Hi,

I am using gr-ieee-802-11 and putting a custom block, which is responsible for adding a 90-sample preamble at the head of incoming sample stream, right after the output of WiFi PHY Hier, as attached figure, generator.png. So the sample stream is changed as attached figure, adding_preamble.png. 

However, in the case of use of transceiver.grc, I can still successfully decode received data, which is keep printing out "Hello World!".

Does anyone know why adding extra samples at the head of transmission samples does not affect the receiving results? Does it because somewhere in Rx side detect the OFDM preamble so the payload can be normally processed without being affecting by the extra samples placed before OFDM preamble?

Thanks.

Best Regards,
Isen I-Chun Chao

generator.png
Description: PNG image

adding_preamble.png
Description: PNG image