Patch to Disable Clear-Channel-Assessment
   -----------------------------------------


INTRODUCTION:
-------------

This software consists of a set of changes to the MadWifi driver which
disable clear-channel assessment and other backoff mechanisms in
Atheros 5212 and 5213-based wireless cards.  It is based in large part
on the "txcont" regulatory testing functionality.  The actions
performed to disable backoff can be grouped as:

0. Disable carrier sense and "virtual carrier sense" (NAV)
   functionality.  This includes abusing the gain control registers,
   so successful packet reception is unlikely.

1. Set the DFS control unit (DCU) to backoff or wait as little as
   possible.

2. For each queue, configure to send as many frames as possible in a
   burst, and do not do post-frame backoff.

USAGE:
------

CCA suppression is controlled with the "dev.wifiX.disable_cca"
sysctl. A value of 0 means "do not perform any CCA suppression."
Non-zero values are interpreted as a bit-mask: Bits 0, 1 and 2 each
enable the function groups described above.  Bit 3 disables interrupts
for beacons and missed beacons.  This is largely unrelated
functionality; if you don't know why you want it, then you don't.  The
mask is stored as seven bits, but only the bottom four are
significant.


MISC:
-----

The most recent version of this software, along with related
information and tools, can be found at the following URL:
http://systems.cs.colorado.edu/mediawiki/index.php?title=Downloads 

If you use this software in your research, please cite it as:

@TechReport{Anderson2008Commodity,
  author = 	 {Eric Anderson and Gary Yee and Caleb Phillips and
                  Douglas Sicker and Dirk Grunwald},
  title = 	 {Commodity AR52XX-Based Wireless Adapters as a Research Platform},
  institution =  {University of Colorado at Boulder},
  year = 	 {2008},
  month =	 {April},
  type =	 {Technical Report},
  number =	 {CU-CS-XXXX-08},
  address =	 {Department of Computer Science, Campus Box 430},
}


COPYRIGHT:
----------

This patch and accompanying text are Copyright (c) 2008, Regents of
the University of Colorado.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.

    * Neither the name of the University of Colorado nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.  

THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY OF COLORADO ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OF COLORADO BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.