About the simple_mac.py in bbn80211

GNU Radio
1

Hi,

I download the bbn80211, and want to use the simple_mac.py to do some
experiment. But this code is not compile with the new version of GNU
Radio,
thus cause many errors. Does anyone do the modification of this script
so
that it can work with the new GNU Radio version?

Thank you very much.

Best,

Chen C.

2

Can you describe what errors you are getting?

  • Miklos
3

I believe this code was never updated to the blks2/hier_block2 API.
At least in the usrp2_branch and my branch on CGRAN it hasn’t been. It
may just take the same work that was done for the transmit and receive
code to port it over (e.g. changing blks → blks2, hier_block →
hier_block2, and the init call to specify the io signature).

On Thu, Oct 15, 2009 at 8:52 PM, Miklos Christine
[email protected] wrote:

experiment. But this code is not compile with the new version of GNU Radio,

Discuss-gnuradio Info Page

–
Doug G.
[email protected]

4

Since I have made changed in the bbn_80211b_rx.py and bbn_80211b_tx.py
(also
some related script such as bbn_80211b.py and bbn_80211b_pkts.py) as you
mention: blks-blks2, hier-block->hier_block2, and the init call.
(modifiy the original version since it is for usrp1). It can run but the
receiver can not show anything.

receiver side:
./bbn_80211b_rx.py -f 2412M -d 24 -S 8 -g 35

transmitter side:
./bbn_80211b_tx.py -f 2412M -i 24 -S 8

So I am wondering if I modified the simple_mac.py, it will cause the
same
problem?

Does anyone make the bbn_80211b_rx.py and bbn_80211b_tx.py work on the
usrp1? and also for simple_mac.py?

Thanks

Chen

On Fri, Oct 16, 2009 at 9:15 AM, Douglas G. <

5

One thing to be aware of: the USRP1 does not have sufficient
bandwidth to the host PC to do real DSSS 802.11b. On the receive side
they were able to get it ‘sort of’ working by simply accepting the
aliasing that results from under-sampling. For transmitting/receiving
between two USRP1’s - I believe the original BBN code simply took the
DPSK-modulated sequence, and ran it through a RRC filter, without any
spreading taking place - so the bandwidth of the USB link is no longer
an issue. This mode allows the USRP1 to do 802.11-like networking -
but it won’t inter-operate with regular 802.11 gear.

I will also note that the original BBN code had a bug in the matched
filter design (in bbn_firdes_barker.cc), it did not reverse the barker
sequence (which makes the FIR filter/convolution operation the same as
multiplying by the [forward] sequence). I have not checked in the fix
to my branch, but the usrp2_version branch achieves the sample thing,
with the addition of a resampling block to make the FIR operation work
on a lower data rate. Since it worked, I assume the error simply made
the effective SNR worse - as it was with the USRP1 it could only
receive very high SNR 1 and 2Mbps packets from commerical 802.11 gear.

On Fri, Oct 16, 2009 at 10:30 AM, Chen C. [email protected]
wrote:

./bbn_80211b_tx.py -f 2412M -i 24 -S 8

–
Doug G.
[email protected]

6

Chen C. wrote:

Hi,

I download the bbn80211, and want to use the simple_mac.py to do some
experiment. But this code is not compile with the new version of GNU
Radio,
thus cause many errors. Does anyone do the modification of this script
so
that it can work with the new GNU Radio version?

Thank you very much.

Best,

Chen C.

hi,Chen C.

would you send bbn80211 code to me,my poor net has problem when
connected to the server.My mail address [email protected].

Thank you very much.

7

Hi,

In your simple_mac.py, do you change these things: flow_graph->top_block
blks->blks2, hier_block->hier_block2?

I think these are some differences between new and old version of GNU
Radio.
And the bbn code is for the old version of GNU Radio

Thanks,

Chen