COMPANY CONFIDENTIAL
49
shortgi
#iwpriv ath
N
shortgi
1|0
This command will enable/disable the short Gating Interval (shortgi) when transmitting HT 40 frames. This
effectively increases the PHY rate by 25%. This is a manual control typically used for testing. This command
has a corresponding get command, and its default value is 1.
#iwpriv ath0 shortgi 1
#iwpriv ath0 get_shortgi
ath0 get_shortgi:1
tx_chainmask
rx_chainmask
#iwpriv ath
N
tx_chainmask mask
#iwpriv ath
N
rx_chainmask mask
These commands are identical to those commands in the radio layer, and have the same effect. These
parameters set the transmit and receive chainmask values. For MIMO devices, the chainmask indicates how
many streams are transmitted/received, and which chains are used. For some Atheros devices up to 3 chains
can be used, while others are restricted to 2 or 1 chain. It’s important to note that the maximum number of
chains available for the device being used. For dual chain devices, chain 2 is not available. Similarly, single
chain devices will only support chain 0. The chains are represented in the bit mask as follows:
Chain 0 0x01
Chain 1 0x02
Chain 2 0x04
Selection of chainmask can affect several performance factors. For a 3 chain device, most of the time an RX
chainmask of 0x05 (or 0x03 for two chain devices) is used for 2x2 stream reception. For near range operations,
a TX chainmask of 0x05 (or 0x03 for two chain devices) is used to minimize near range effects. For far range,
a mask of 0x07 is used for transmit.
It is recommended to use the radio version of these commands, since they may become deprecated in the future
through this interface.
These setting affect ALL VAPS, not just the VAP that is being set.
The default chainmask values are stored in EEPROM. This iwpriv command will override the current
chainmask settings. These commands have corresponding get commands.
#iwpriv ath0 tx_chainmask 0x05
#iwpriv ath0 rx_chainmask 0x05
#iwpriv ath0 get_tx_chainmask
ath0 get_tx_chainmask:5
#iwpriv ath0 get_rx_chainmask mask
ath0 get_rx_chainmask:5
