[Discuss-gnuradio] Carrier sense MAC / realtime / etc

[Eric Blossom]

I've just finished checking in a bunch of modifications to
gnuradio-core and gnuradio-examples.  These are the culmination of
work with Matt over the past few days.

Summary:  If you're tracking CVS+SVN, now's a good time to update:

  gnuradio-core
  usrp
  gr-usrp
  gnuradio-examples

We now have a workable carrier sense MAC.
The old tunnel_ip_null_mac.py has been removed, and is replaced
by gnuradio-examples/python/gmsk2/tunnel.py

tunnel.py enables real time scheduling if possible, and implements the
carrier sense MAC.  Running with a raw bitrate of 500k, I've been able
to scp files across the air at aggregate throughput of about 50KB/sec.
This was tested by using scp to simultaneously pull large files from
the other node.

There was a bug in tunnel_ip_null_mac that was silently truncating
large packets, causing TCP throughput to approach zero.  That's fixed
in tunnel.py

The gmsk2_pkt.py code is now deprecated, and has been replaced by the
modulation independent pkt.py.  Likewise, all the examples and support
code in gnuradio-examples/python/gmsk2 have been updated to use this.

If you've built similar examples, and they used the receive_path and
transmit_path.py files, your code will need a bit of work.  Take a
look at the new examples to note the changes in the constructor
arguments.

The README in gnuradio-examples/python/gmsk2 has also be updated to
reflect the new reality, and to emphasize that the Linux 2.6 kernel
ships with the tun/tap driver.

Have fun!

Eric