Re: [Discuss-gnuradio] Problems with IEEE802-11 Blocks?

[Bastian Bloessl]

Hi,

please keep the conversation on the list.

On 7/9/2017 5:36 PM, Taylor Eisman wrote:
> Hey,
>
> I went ahead and substituted Wifi Hier Phy into my program, and it made 
> no difference; however, I did end up using Packet Pad, and it was able 
> to receive a full frame. Using Packet Pad did not completely solve the 
> problem though because it does not pass the checksum check.

I tested the flowgraph without padding, i.e., frames back to back, and 
also saw the problem mentioned in your previous email. So this was 
really related to padding.

If your frames have a wrong checksum, they were not received correctly. 
That's a different problem. What you want is not disable the checksum, 
but understand why the frames got corrupted.

I don't know what your flowgraph is doing, but check the signal quality 
of the stream that you feed into the WiFi receiver. Also avoid sending 
frames padded with zeros (add a bit of noise).

Best,
Bastian

> Is there any 
> way to quickly pass the checksum?
>
> Thanks,
> Taylor
>
> On Sun, Jul 9, 2017 at 1:57 AM, Bastian Bloessl <address@hidden 
> <mailto:address@hidden>> wrote:
>
>     Hi,
>
>     I recommend to start with the example flow graph and make sure that
>     it works works for you. If that works, just replace the constant
>     message source with the data that you want to transmit.
>     Did you maybe delete the packet pad block and just sent data back to
>     back without any space in between?
>
>     Best,
>     Bastian
>
>
>     On 07/08/2017 09:20 PM, Taylor Eisman wrote:
>
>         I've been trying to use the IEEE802-11 blocks to simulate Wi-Fi
>         environments. I've generated data from the local radio station,
>         tagged it, modulated, etc. It is never able to generate a file
>         at the end and I've tracked it down to an issue in the WiFi
>         Decode block.
>
>         This is the error that the WiFi Decode block generates:
>
>         Decode MAC: frame start -- len 250  symbols 29  encoding 3
>         copy one symbol, copied 0 out of 29
>         copy one symbol, copied 1 out of 29
>         copy one symbol, copied 2 out of 29
>         copy one symbol, copied 3 out of 29
>         copy one symbol, copied 4 out of 29
>         copy one symbol, copied 5 out of 29
>         copy one symbol, copied 6 out of 29
>         copy one symbol, copied 7 out of 29
>         copy one symbol, copied 8 out of 29
>         copy one symbol, copied 9 out of 29
>         copy one symbol, copied 10 out of 29
>         copy one symbol, copied 11 out of 29
>         copy one symbol, copied 12 out of 29
>         copy one symbol, copied 13 out of 29
>         copy one symbol, copied 14 out of 29
>         copy one symbol, copied 15 out of 29
>         copy one symbol, copied 16 out of 29
>         copy one symbol, copied 17 out of 29
>         copy one symbol, copied 18 out of 29
>         copy one symbol, copied 19 out of 29
>         copy one symbol, copied 20 out of 29
>         copy one symbol, copied 21 out of 29
>         copy one symbol, copied 22 out of 29
>         copy one symbol, copied 23 out of 29
>         Decode MAC: input 1
>         copy one symbol, copied 24 out of 29
>         Decode MAC: input 25
>         copy one symbol, copied 25 out of 29
>         Warning: starting to receive new frame before old frame was complete
>         Already copied 26 out of 29 symbols of last frame
>
>         I've tried changing the source file to something else. I've
>         messed with the parameters and noticed that it is always 3
>         symbols short of a full frame, even if there are theoretically
>         3000 symbols, it would only pass 2997 symbols.
>
>         Any ideas on what could be causing this?
>
>         I'm attaching the WiFi Phy Hier graph to give you some idea of
>         the layout
>         .
>
>
>
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>
>
>     -- 
>     Dipl.-Inform. Bastian Bloessl
>     CONNECT Center
>     Trinity College Dublin
>
>     GitHub/Twitter: @bastibl
>     https://www.bastibl.net/
>
>
>
>
> --
> Thanks,
>
> Taylor Eisman
> Graduate Researcher
> University of Texas at San Antonio