No description
f0d0a5d23b
When noise floor measurements are not available, compute SNR
using default values for the noise floor. This helps steer us
towards 5 GHz BSSes in high signal strength environments.
In more detail...
Existing code prefers a 5 GHz BSS when the 5 GHz BSS's signal
strength is "close" to that of the 2.4 GHz BSS, or when both SNRs
are large. However, the mwifiex driver does not provide noise
floor measurements, so we can't compute SNRs.
Because mwifiex doesn't provide NF measurements, the "large SNR"
code wasn't effective. By using default values for the noise floor,
we can again compute SNRs, and decide that the SNR is high enough
that we shouldn't worry about the exact difference in SNR.
The default noise floor values (one for 2.4 GHz, and one for 5 GHz)
were chosen by measurement in a noisy environment, so they should be
conservative.
Note that while this patch is motivated by mwifiex, it affects
ath9k as well. Although ath9k provides noise floor measurements
in general, it will sometimes fail to provide a measurement for
one or more specific channels.
As a result of this patch, we'll always compare BSSes based on SNR
(either measured or estimated), rather than sometimes comparing
based on signal strength. ("Always" assumes that the
WPA_SCAN_LEVEL_DBM flag is set. It is for mwifiex and ath9k.)
While there:
- fix a whitespace issue (spaces -> tab)
- clean up existing comments
- update dump_scan_res to indicate whether the noise floor is
measured, or default
Signed-hostap: mukesh agrawal <quiche@chromium.org>
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| doc | ||
| eap_example | ||
| hostapd | ||
| hs20 | ||
| mac80211_hwsim | ||
| patches | ||
| radius_example | ||
| src | ||
| tests | ||
| wlantest | ||
| wpa_supplicant | ||
| wpadebug | ||
| wpaspy | ||
| .gitignore | ||
| Android.mk | ||
| build_release | ||
| CONTRIBUTIONS | ||
| COPYING | ||
| README | ||
wpa_supplicant and hostapd -------------------------- Copyright (c) 2002-2015, Jouni Malinen <j@w1.fi> and contributors All Rights Reserved. These programs are licensed under the BSD license (the one with advertisement clause removed). If you are submitting changes to the project, please see CONTRIBUTIONS file for more instructions. This package may include either wpa_supplicant, hostapd, or both. See README file respective subdirectories (wpa_supplicant/README or hostapd/README) for more details. Source code files were moved around in v0.6.x releases and compared to earlier releases, the programs are now built by first going to a subdirectory (wpa_supplicant or hostapd) and creating build configuration (.config) and running 'make' there (for Linux/BSD/cygwin builds). License ------- This software may be distributed, used, and modified under the terms of BSD license: Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. 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. 3. Neither the name(s) of the above-listed copyright holder(s) 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 COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.