Re: [Discuss-gnuradio] BBN 80211b Transmitter with GNURadio 3.2.2 and USRP1

[Colby Boyer]

Cool to hear about the OFDM 802.11 project.

When I was working with the USRP2 version, I was only able to get two USRP2s to talk to each other. I can't remember if I was able to get it to decode packets from a chipset, that was a year ago.....

I do remember that sometime ago, there was further discussion on getting the spreading waveform correct since it was not matching the 802.11 roll off specs. My first guess is to check the match filter being used (if you can capture the chipset's waveform).

On Thu, May 20, 2010 at 1:08 PM, George Nychis <address@hidden> wrote:

On Thu, May 20, 2010 at 3:14 PM, Smith L. <address@hidden> wrote:

Thanks for the help, Doug.

I do have two USRP2s and hence was also working on the usrp2_version code. I
have both the transmitter and receiver code individually working correctly
with USRP2. However, the receiver is not able to receive the packets
correctly from the transmitter (i.e in case of USRP2). I always get bad CRC
message.

I have looked up the forum and everybody seem to stuck with the same
problem. Is there any work around to solve this problem?

>From the forum discussion, it seems that one of the issues is the preamble.

Any idea how to make synchronize the receiver so that it can receive the
packets from USRP2 transmitter using bbn code.

I struggled with this for quite a while.  I never understood exactly where a standard card was not able to decode it.  Large frequency offset maybe?  I never got a single packet through.

Can I suggest something?  Try out this 802.11 project:
https://www.cgran.org/wiki/ftw80211ofdmtx

They definitely claim that a standard NIC can decode the packets, but I never personally got around to trying it.  The code seemed pretty clean, and I was able to use it to generate proper packet signatures... so the modulation is definitely correct.

- George

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