Re: [Discuss-gnuradio] gr_ieee-80211 receiver

[Bastian Bloessl]

Hi,

LiLi <address@hidden> writes:

> Hi, everyone
>
> I am using gr-ieee-80211 to recieve wifi packets on 2.4G.
> The operating system is Ubuntu.The version of GNU RADIO is 3.7.5, and we use
> USRP N210 with SBX daughterboard.
> Our purpose:
> Capture packets of 802.11 protocol on 2.4G or the other band SBX
> daughterboard
> Our problems:
> When the Wireshark Connector was connected to 'WIFI Decode MAC', it can't
> receive any frame but an empty file. I want to figure out the cause, but it
> may consume a long time for a beginner. I think the main cause may exist in
> the 'WIFI Decode MAC' or the Wireshark Connector in the view that the latter
> can receive frames before the former.

I don't believe it's a problem with the Wireshark or 'Decode MAC'
block. It's more likely that something goes wrong earlier. This can have
a lot of reasons (gain setting, wrong sample rate, wrong channel,
overruns, ...). You might find something useful here:

https://www.wime-project.net/installation/

If you still have problems, it would be helpful if you could provide
some more details on what happens and what you did to debug. Something
like are frames detected? Are only frames detected or is frame detection
triggered all the time? Did you try the setup with other transceivers?
Does the constellation diagram look good, etc.

> Another tricky problem which I want to make clear is that whether the
> surroundings contains pure 802.11g frame. Could you show me the possible
> reasons? As I target to captured frames on 2.4GHz , how should the
> parameters of the Wireshark be recomposed?

There is nothing you can do in the receiver. You have to make sure that
the device that you want to monitor sends 11a/g/p frames. Others are at
the moment not supported.

How to configure the mode depends on your device. (If you open a network
with a MacBook it works for me. Maybe that could be a simple test.)

Best,
Bastian