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Nick Lowe 81ff23fc91 hostapd: Add cell_density data rates option 
Add a cell_density option to configure data rates for normal, high and
very high cell density wireless deployments.

The purpose of using a minimum basic/mandatory data rate that is higher
than 6 Mb/s, or 5.5 Mb/s (802.11b compatible), in high cell density
environments is to transmit broadcast/multicast data frames using less
airtime or to reduce management overheads where significant co-channel
interference (CCI) exists and cannot be avoided.

Caution: Without careful design and validation, configuration of a too
high minimum basic/mandatory data rate can sacrifice connection stability
or disrupt the ability to reliably connect and authenticate for little to
no capacity benefit. This is because this configuration affects the
ability of clients to hear and demodulate management, control and
broadcast/multicast data frames.

Deployments that have not been specifically designed and validated are
usually best suited to use 6, 12 and 24 Mb/s as basic/mandatory data
rates.

Only usually seek to configure a 12 Mb/s, or 11 Mb/s (802.11b
compatible), minimum basic/mandatory rate in high cell density
deployments that have been designed and validated for this.

For many deployments, the minimum basic/mandatory data rate should not be
configured above 12 Mb/s to 18 Mb/s, 24 Mb/s or higher. Such a
configuration is only appropriate for use in very high cell density
deployment scenarios.

A cell_density of Very High (3) should only be used where a deployment
has a valid use case and has been designed and validated specifically for
this use, nearly always with highly directional antennas - an example
would be stadium deployments. For example, with a 24 Mb/s OFDM minimum
basic/mandatory data rate, approximately a -73 dBm RSSI is required to
decode frames. Many clients will not have roamed elsewhere by the time
that they experience -73 dBm and, where they do, they frequently may not
hear and be able to demodulate beacon, control or broadcast/multicast
data frames causing connectivity issues.

There is a myth that disabling lower basic/mandatory data rates will
improve roaming and avoid sticky clients. For 802.11n, 802.11ac and
802.11ax clients this is not correct as clients will shift to and use
lower MCS rates and not to the 802.11b or 802.11g/802.11a rates that are
able to be used as basic/mandatory data rates.

There is a myth that disabling lower basic/mandatory data rates will
ensure that clients only use higher data rates and that better
performance is assured. For 802.11n, 802.11ac and 802.11ax clients this
is not correct as clients will shift around and use MCS rates and not the
802.11b or 802.11g/802.11a rates that able to be used as basic/mandatory
data rates.

Cell Density

0 - Disabled (Default)
Setting cell_density to 0 does not configure data rates. This is the
default.

1 - Normal Cell Density
Setting cell_density to 1 configures the basic/mandatory rates to 6, 12
and 24 Mb/s OFDM rates where legacy_rates is 0. Supported rates lower
than the minimum basic/mandatory rate are not offered.
Setting cell_density to 1 configures the basic/mandatory rates to the 5.5
and 11 Mb/s DSSS rates where legacy_rates is 1. Supported rates lower
than the minimum basic/mandatory rate are not offered.

2 - High Cell Density
Setting the cell_density to 2 configures the basic/mandatory rates to the
12 and 24 Mb/s OFDM rates where legacy_rates is 0. Supported rates lower
than the minimum basic/mandatory rate are not offered.
Setting the cell_density to 2 configures the basic/mandatory rates to the
11 Mb/s DSSS rate where legacy_rates is 1. Supported rates lower than the
minimum basic/mandatory rate are not offered.

3 - Very High Cell Density
Setting the cell_density to 3 configures the basic/mandatory rates to the
24 Mb/s OFDM rate where legacy_rates is 0. Supported rates lower than the
minimum basic/mandatory rate are not offered.
Setting the cell_density to 3 only has effect where legacy_rates is 0,
else this has the same effect as being configured with a cell_density of 2.

Where specified, the basic_rate and supported_rates options continue to
override both the cell_density and legacy_rates options.

Signed-off-by: Nick Lowe <nick.lowe@gmail.com>
2020-11-30 09:31:15 +01:00
.github build: Update README & github help 2018-07-08 09:41:53 +01:00
config toolchain: kernel-headers: kernel Git tree mirror hash 2020-11-27 14:46:13 +01:00
include cmake.mk,rules.mk: fix host builds using CMake and ccache 2020-11-28 16:17:58 +01:00
package hostapd: Add cell_density data rates option 2020-11-30 09:31:15 +01:00
scripts build: mkhash on FreeBSD 2020-11-27 18:01:22 -10:00
target lantiq: fix build of squashfs images 2020-11-29 00:53:44 +01:00
toolchain toolchain: kernel-headers: kernel Git tree mirror hash 2020-11-27 14:46:13 +01:00
tools tools: always create $STAGING_DIR/usr/{include,lib} 2020-11-27 14:46:13 +01:00
.gitattributes
.gitignore build: improve ccache support 2020-07-11 15:19:53 +02:00
BSDmakefile
Config.in
feeds.conf.default feeds: add freifunk feed 2020-06-24 14:58:17 +02:00
LICENSE LICENSE: use updated GNU copy 2020-08-02 15:54:43 +02:00
logo.svg README: port to 21st century 2020-08-02 15:44:40 +02:00
Makefile build: improve ccache support 2020-07-11 15:19:53 +02:00
README.md README: port to 21st century 2020-08-02 15:44:40 +02:00
rules.mk cmake.mk,rules.mk: fix host builds using CMake and ccache 2020-11-28 16:17:58 +01:00

README.md

OpenWrt logo

OpenWrt Project is a Linux operating system targeting embedded devices. Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application. For developers, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.

Sunshine!

Development

To build your own firmware you need a GNU/Linux, BSD or MacOSX system (case sensitive filesystem required). Cygwin is unsupported because of the lack of a case sensitive file system.

Requirements

You need the following tools to compile OpenWrt, the package names vary between distributions. A complete list with distribution specific packages is found in the Build System Setup documentation.

gcc binutils bzip2 flex python3 perl make find grep diff unzip gawk getopt
subversion libz-dev libc-dev

Quickstart

  1. Run ./scripts/feeds update -a to obtain all the latest package definitions defined in feeds.conf / feeds.conf.default

  2. Run ./scripts/feeds install -a to install symlinks for all obtained packages into package/feeds/

  3. Run make menuconfig to select your preferred configuration for the toolchain, target system & firmware packages.

  4. Run make to build your firmware. This will download all sources, build the cross-compile toolchain and then cross-compile the GNU/Linux kernel & all chosen applications for your target system.

Related Repositories

The main repository uses multiple sub-repositories to manage packages of different categories. All packages are installed via the OpenWrt package manager called opkg. If you're looking to develop the web interface or port packages to OpenWrt, please find the fitting repository below.

Support Information

For a list of supported devices see the OpenWrt Hardware Database

Documentation

Support Community

  • Forum: For usage, projects, discussions and hardware advise.
  • Support Chat: Channel #openwrt on freenode.net.

Developer Community

License

OpenWrt is licensed under GPL-2.0