Openwrt Testing Antennas and Disabling Diversity Antenna 2

5/19/2018 Openwrt Testing Antennas and Disabling Diversity Antenna 2

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Testing Antennas and Disabling Diversity Antenna 2

One application for Horst is testing external antennas, for example directional high gain antennas. The Mesh Potato, like many routers, has two antennas, numbered 1 and 2. Antenna 1 is a tx/rx ante

and Antenna 2 is only rx, sometimes called a "diversity" antenna. This helps with multipath issues where the signal received by one antenna may be very weak, but very strong in another antenna jus

few cm away. Multipath effects are especially common during indoor operation.

Now we usually connect external antennas to Antenna 1, as we use external antennas for long range tx/rx operation. However the Mesh Potato Wifi driver tends to favour Antenna 2 for receive. So w

testing antennas you can get confusing results: sometimes packets are received on Antenna 1 and sometimes on Antenna 2. These will usually have different signal strengths and will confuse anten

testing results.

So if you are using Horst to test antennas (or testing antennas with other software), it is useful to disable the receive only Antenna 2. First di sable automatic antenna selection:

root@OpenWrt:~# echo 0 > /proc/sys/dev/wifi0/diversity

Then select just Antenna 1:

root@OpenWrt:~# echo 1 > /proc/sys/dev/wifi0/rxantenna

You can check using athstats:

root@OpenWrt:~# athstats

74 tx management frames

2691 tx failed due to too many retries

361969 long on-chip tx retries

13509527 tx frames with no ack marked

120624 tx frames with an alternate rate

761053 rx failed due to bad CRC

46146 PHY errors

15 transmit override receive

52 OFDM restart

46079 CCK restart

rssi of last ack: 17

rssi of last rcv: 24

739402 switched default/rx antenna

Antenna profile:

[1] tx 7247393 rx 37256094

[2] tx 7769498 rx 9750180

The last two lines from athstats indicate how many packets were received on Antenna 1 and how many on Antenna 2. After Antenna 1 is selected no more packets should be received on antenna 2.

running athstats several times to check.

Note that a reboot is required to re-enable diversity (Antenna 2) operation, this:

root@OpenWrt:~# echo 1 > /proc/sys/dev/wifi0/diversity

doesn't seem to work.

Audio Ping

option diversity 0

option rxantenna 1

option txantenna 1

iw list | grep ntenn check antenna

iwconfig

set country Bolivia = BO , set diversity = 0 ,


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Wifi Devices

The wifi-devicerefer to physical radio devices present on the system. The options present in this section describe properties common across all wireless networks on this radio

interface, such as channel or antenna selection.

In most cases there is only one radio adapter present on the device, so only one such section is defined, however on multi-radio hardware there may be multiplewifi-devicesection

each referring to a different adapter.

A minimal wifi-devicedeclaration may look like the example below. Note that identifiers and options may vary for different chipset types or drivers.

config 'wifi-device' 'wl0'

option 'type' 'broadcom'

option 'channel' '6'

wl0is the internal identifierfor the wireless adapter

broadcomspecifies the chipset/driver type

6is the wireless channelthe device operates onThe possible options for device sections are listed in the table below. Note that not all options are used for all chipset/driver types, refer to the comments for further details.

Common Opt ions

Name TypeRequir

edDefault Description

typestrin

gyes

(autodete

cted)

The typeis determined on firstboot during the initial radio device detection

it is usually not required to change it. Used values are broadcomon brcm47xx,

or mac80211for b43, ath5k and ath9k

phystrin

g

no/

yes

(autodete

cted)

Specifies the radio phy associated to this section. If present, it is usually

autodetected and should not be changed.

macaddr

MAC

addr

ess

yes/

no

(autodete

cted)

Specifies the radio adapter associated to this section, it is notused to chang

the device mac but to identify the underlying interface.

disabledbool

eanno 0

Disables the radio adapter if set to 1. Removing this option or setting it

to 0will enable the adapter

channel

integ

er or

"aut

o"

yes autoSpecifies the wireless channel to use. "auto" defaults to the minimum

channel available

hwmodestrin

gno

(driver

default)

Selects the wireless protocol to use, possible values are 11b, 11g, and 11a(not

that 11ngand 11naare not available options, seeticket 17541)

htmodestrin

gno

(driver

default)

Specifies the channel width in 802.11n and 802.11ac mode, possible values

are:

HT20(single 20MHz channel),

HT40-(2x 20MHz channels, primary/control channel is upper, secondary

channel is below)

HT40+(2x 20MHz channels, primary/control channel is lower, secondary
https://dev.openwrt.org/ticket/17541https://dev.openwrt.org/ticket/17541https://dev.openwrt.org/ticket/17541https://dev.openwrt.org/ticket/17541


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channel is above).

VHT20/ VHT40/ VHT80/ VHT160(channel width in 802.11ac, extra channels are

picked according to the specification)

Cf.why.can.t.i.use.ht40.with.channel.11andhttp://hostap.epitest.fi/cgit/h

tap/tree/hostapd/hostapd.conf(search for HT40) in the web page.

This option is only used for type mac80211

chanbwinteg

erno 20

Specifies a narrow channel width, possible values are: 5(5MHz

channel), 10(10MHz channel) or 20(20MHz channel).

Only supported by the ath9k/ath5kdriver (since Attitude Adjustment)

ht_capabstrin

gno

(driver

default)

Specifies the available capabilities of the radio. The values are autodetecte

Seehttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.conffor

options (search for ht_capab in web page).

This option is only used for type mac80211

txpower integer

no (driverdefault)

Specifies the transmission power in dBm

diversitybool

eanno 1 Enables or disables the automatic antenna selection by the driver

rxantennainteg

erno

(driver

default)

Specifies the antenna for receiving, the value may be driver specific, usually

it is 1for the first and 2for the second antenna. Specifying 0enables

automatic selection by the driver if supported. This option has no effect if

diversity is enabled

txantennainteg

erno

(driver

default)Specifies the antenna for transmitting, values are identical to rxantenna

antennastrin

gno

(driver

default)

Selects the antenna, possible values are verticalfor internal vertical

polarization, horizontalfor internal horizontal polarization or externalto use

the external antenna connector

Only used on theUbiquiti NanoStationdevice family instead of the

rxantenna/txantenna settings.

countryvarie

sno

(driver

default)

Specifies the country code, affects the available channels and transmission

powers. For typebroadcoma two letter country code is used (ENor DE).

The madwifidriver expects a numeric code.

country_i

ebool

eanno

1

if countryis

set,

otherwise

Enables IEEE 802.11d country IE (information element) advertisement in

beacon and probe response frames. This IE contains the country code and

channel/power map. Requires country.
http://wiki.openwrt.org/doc/faq/faq.wireless#why.can.t.i.use.ht40.with.channel.11http://wiki.openwrt.org/doc/faq/faq.wireless#why.can.t.i.use.ht40.with.channel.11http://wiki.openwrt.org/doc/faq/faq.wireless#why.can.t.i.use.ht40.with.channel.11http://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://wiki.openwrt.org/toh/ubiquiti/nanostationhttp://wiki.openwrt.org/toh/ubiquiti/nanostationhttp://wiki.openwrt.org/toh/ubiquiti/nanostationhttp://wiki.openwrt.org/toh/ubiquiti/nanostationhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://hostap.epitest.fi/cgit/hostap/tree/hostapd/hostapd.confhttp://wiki.openwrt.org/doc/faq/faq.wireless#why.can.t.i.use.ht40.with.channel.11


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0

distanceinteg

erno

(driver

default)

Distance between the ap and the furthest client in meters .

Only supported by madwifi, and the mac80211type (in trunk)

noscanbool

eanno 0

Do not scan for overlapping BSSs in HT40+/- mode.

Only supported by mac80211

Turning this on will violate regulatory requirements!

beacon_in

tervalinteg

erno

100

(hostapd

default)

Set the beacon interval. This is the time interval between beacon frames,

measured in units of 1.024 ms. hostapd permits this to be set between 15

and 65535. This option only has an effect on apandadhocwifi-ifaces.

Only supported by mac80211(in trunk)

basic_rat

e list no

(hostapd/

driver

default)

Set the supported basic rates. Each basic_rate is measured in kb/s. This

option only has an effect onapand adhocwifi-ifaces.


require_m

odestrin

gno none

(AP mode) Set the minimum mode that connecting clients need to support

to be allowed to connect. Supported values: g = 802.11g, n = 802.11n, ac =

802.11ac

log_levelinteg

erno 2

Set the log_level. Supported levels are: 0 = verbose debugging, 1 =

debugging, 2 = informational messages, 3 = notification, 4 = warning

Broadcom Opt ions

The options below are only used by the proprietary Broadcom driver (type broadcom).

Name Type Required Default Description

frameburst boolean no 0 Enables Broadcom frame bursting if supported

maxassoc integer no (driver default) Limits the maximum allowed number of associated clients

slottime integer no (driver default) Slot time in milliseconds

Madwif i Options

The following options are only used by the Madwifi driver (type atheros).


softled boolean no 1 Enables software based LED control in the driver

outdoor boolean no 0 Enables outdoor channels in the 5GHz band

regdomain number no (driver default) Overrides the regulatory domain setting


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Wifi NetworksA complete wireless configuration contains at least one wifi-ifacesection per adapter to define a wireless network on top of the hardware. Some drivers support multiple wireless

networks per device:

broadcomif the core revision is greater or equal 9(see dmesg | grep corerev)

madwifialways supports multiple networks

mac80211STA mode supported on trunk. STA and AP at the same time is not yet supported(r22989).A minimal example for a wifi-ifacedeclaration is given below.

config 'wifi-iface'

option 'device' 'wl0'

option 'network' 'lan'

option 'mode' 'ap'

option 'ssid' 'MyWifiAP'

option 'encryption' 'psk2'

option 'key' 'secret passphrase'

wl0is the identifier for the underlyingradio hardware

lanspecifies thenetwork interfacethe wifi is attached to

apis the opetion mode,Access Pointin this example

MyWifiAPis the broadcasted SSID

psk2specifies the wireless encryption method, WPA2 PSK here

secret passphraseis the secret WPA passphraseCommon Opt ions

The most common configuration option for wifi-ifacesections are listed below.


device string yes (first device id)Specifies the used wireless adapter, must refer t

one of the defined wifi-devicesections

mode string yes ap

Selects theoperation modeof the wireless

network interface controller (some are supportesimultaneously by some drivers):

apfor Access Point,

stafor managed (client) mode,

adhocfor Ad-Hoc,

wdsfor static WDS,

monitorfor monitor mode,

meshforIEEE 802.11smesh mode

meshmode only supported by mac80211(in trun

disabled boolean no 1 When set to 1, wireless network is disabled.

ssid string yes OpenWrt

The broadcasted SSID of the wireless network (f

managed mode the SSID of the network you're

connecting to)

bssidBSSID

addressno (driver default)

Override the BSSID of the network, only

applicable in adhocor stamode. In wdsmode

specifies the BSSID of another AP to create WDS
http://wiki.openwrt.org/doc/uci/wireless#wifi.deviceshttp://wiki.openwrt.org/doc/uci/wireless#wifi.deviceshttp://wiki.openwrt.org/doc/uci/wireless#wifi.deviceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wireless.kernel.org/en/users/Documentation/modeshttp://wireless.kernel.org/en/users/Documentation/modeshttp://wireless.kernel.org/en/users/Documentation/modeshttp://en.wikipedia.org/wiki/IEEE%20802.11shttp://en.wikipedia.org/wiki/IEEE%20802.11shttp://en.wikipedia.org/wiki/IEEE%20802.11shttp://en.wikipedia.org/wiki/IEEE%20802.11shttp://wireless.kernel.org/en/users/Documentation/modeshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/wireless#wifi.devices


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with.

mesh_id Mesh ID no none

The Mesh ID as defined in IEEE 802.11s. If set, th

wireless interface will join this mesh network

when brought up. If not, it is necessary to invoke

mesh join to join a mesh after the

interface is brought up.


hidden boolean no 0 Turns off SSID broadcasting if set to 1

isolate boolean no 0

Isolate wireless clients from each other, only

applicable in apmode. May not be supported in

the original Backfire release for mac80211

doth boolean no 0Enables 802.11h support.

Not supported for the mac80211type yet

wmm boolean no 1Enables WMM (802.11e) support. Required for

802.11n support

network string yes lanSpecifies thenetwork interfaceto attach the

wireless to

encryption string no none

Wireless encryption method. nonefor an open

network, wepfor WEP, pskfor WPA-PSK, or psk2foWPA2-PSK. See theWPA modestable for

additional possible values.

For an access point in WEPmode, the default is

"open system" authentication. Usewep+sharedfor

"shared key" authentication (less

secure), wep+opento explicitly use "open system,"

or wep+mixedto allow either. wep+mixedis only

supported by hostapd.

keyinteger or

stringno (none)

In any WPA-PSKmode, this is a string thatspecifies the pre-shared passphrase from which

the pre-shared key will be derived. If a 64-

character hexadecimal string is supplied, it will b

used directly as the pre-shared key instead.

In WEPmode, this can be an integer specifying

which key index to use (key1, key2,key3, or key4.)

Alternatively, it can be a string specifying a

passphrase or key directly, as in key1.
http://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/network#interfaces


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In anyWPA-Enterprise APmode, this option has

different interpretation.

key1 string no (none)

WEP passphrase or key #1 (selected by the inde

in key). This string is treated as a passphrase from

which the WEP key will be derived. If a 10- or 26

character hexadecimal string is supplied, it will b

used directly as the WEP key instead.

key2 string no (none)WEP passphrase or key #2 (selected by the inde

in key), as in key1.





macfilter string no disable

Specifies the mac filter policy, disableto disable

the filter, allowto treat it as whitelist or denyto

treat it as blacklist.

Supported for the mac80211sincer25105

maclistlist of MAC

addressesno (none)

List of MAC addresses (divided by spaces) to put

into the mac filter.

iapp_interface string no (none)Specifies anetwork interfaceto be used for

802.11f (IAPP) - only enabled when defined.

rsn_preauth boolean no 0

Allow preauthentication for WPA2-EAP network

(and advertise it in WLAN beacons). Only works

the specified network interface is a bridge.

ieee80211w integer no 0

Enables MFP (802.11w) support (0 = disabled, 1

optional, 2 = required).

Only supported by the ath9kdriver (in trunk)

ieee80211w_max_timeout integer no(hostapd

default)

Specifies the 802.11w Association SA Query

maximum timeout.


ieee80211w_retry_timeout integer no(hostapd

default)Specifies the 802.11w Association SA Query retr

timeout .
http://wiki.openwrt.org/doc/uci/wireless#wpa.enterprise.access.pointhttp://wiki.openwrt.org/doc/uci/wireless#wpa.enterprise.access.pointhttp://wiki.openwrt.org/doc/uci/wireless#wpa.enterprise.access.pointhttps://dev.openwrt.org/changeset/25105/trunkhttps://dev.openwrt.org/changeset/25105/trunkhttps://dev.openwrt.org/changeset/25105/trunkhttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttp://wiki.openwrt.org/doc/uci/network#interfaceshttps://dev.openwrt.org/changeset/25105/trunkhttp://wiki.openwrt.org/doc/uci/wireless#wpa.enterprise.access.point


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maxassoc integer no(hostapd/driver

default)

Specifies the maximum number of clients to

connect.

macaddrmac

addressno

(hostapd/driver

default)

Overrides the MAC address used for the wifi

interface.

dtim_period integer no2 (hostapd

default)

Set the DTIM (delivery traffic information

message) period. There will be one DTIM per th

many beacon frames. This may be set between 1

and 255. This option only has an effect on apwif

ifaces.


short_preamble boolean no 1Set optional use of short preamble

Supported for the mac80211sincer35565

max_listen_int integer no65535 (hostapd

default)

Set the maximum allowed STA (client) listen

interval. Association will be refused if a STA

attempts to associate with a listen interval great

than this value. This option only has an effect

on apwifi-ifaces.


mcast_rate integer no (driver default)

Sets the fixed multicast rate, measured in kb/s.

Only supported by madwifi, and mac80211(for

type adhocin trunk)

See theWPA tablesbelow for a full listing of WPA related options used for WPA2 Enterprise (802.1x)

See theWPS Optionsbelow for a full listing of Wi-Fi Protected Setupoptions.

wds boolean no 0 This sets4-address mode

Madwif i Options

The options in the table below only work with type atheros.


ar boolean no 0 Enables AR support

bgscan boolean no 0 Enables background scanning
https://dev.openwrt.org/changeset/35565/trunkhttps://dev.openwrt.org/changeset/35565/trunkhttps://dev.openwrt.org/changeset/35565/trunkhttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttp://wiki.openwrt.org/doc/uci/wireless#wps.optionshttp://wiki.openwrt.org/doc/uci/wireless#wps.optionshttp://wiki.openwrt.org/doc/uci/wireless#wps.optionshttp://wireless.kernel.org/en/users/Documentation/iw#Using_4-address_for_AP_and_client_modehttp://wireless.kernel.org/en/users/Documentation/iw#Using_4-address_for_AP_and_client_modehttp://wireless.kernel.org/en/users/Documentation/iw#Using_4-address_for_AP_and_client_modehttp://wireless.kernel.org/en/users/Documentation/iw#Using_4-address_for_AP_and_client_modehttp://wiki.openwrt.org/doc/uci/wireless#wps.optionshttp://wiki.openwrt.org/doc/uci/wireless#wpa.modeshttps://dev.openwrt.org/changeset/35565/trunk


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bursting boolean no 0 Enables frame bursting

compression boolean no 0 Enables hardware compression

ff boolean no 0 Enables fast frames

fraginteger no (none) Fragmentation threshold

minrate integer no(driver

default)Limit the minimum rate used

maxrate integer no(driver

default)Limit the maximum rate used

nosbeacon boolean no 0Disables the hardware beacon timer, only applicable in Managed

mode

sw_merge boolean no 0 Disables the hardware beacon timer, only applicable in IBSS mod

probereq boolean no 1Enables probe responses (AP will not appear in wifi scans if

disabled)

rate integer no(driver

default)Use a fixed rate

rts integer no (driverdefault)

Override the RTS/CTS threshold

turbo boolean no 0 Enables turbo mode

uapsd boolean no 0 Enables Unscheduled Automatic Power Save Delivery (UAPSD)

wds boolean no 0Enables Lazy-WDS, only applicable in Access Point or Managed

mode

wdssep boolean no 0 Separates WDS clients from each other

xr boolean no 0 Enables XR support, only applicable in Managed mode

Documents

Openwrt Testing Antennas and Disabling Diversity Antenna 2