Wireless Standards
This article lists common standards and basic features that are relevant to OpenWrt.
802.11a
Old standard that operates in 5GHz frequency band
802.11b
IEEE_802.11b-1999 Operates in 2.4GHz Band Old standard.
802.11g
IEEE_802.11g-2003 Operates in 2.4GHz Band Old standard.
802.11n
802.11ac
IEEE_802.11ac Also called “Wifi 5”
802.11ad
IEEE_802.11ad Not very common in OpenWrt.
802.11ax
Also called “Wifi 6”
Features in Drivers
Each hardware has certain features that can be queried in OpenWrt by using
iw phy <phy interface> info
Mismatching features result in compatibility problems and possibly reduced data transfer rates.
example:
RX LDPC HT20/HT40 SM Power Save disabled RX HT20 SGI RX HT40 SGI TX STBC RX STBC 1-stream Max AMSDU length: 3839 bytes DSSS/CCK HT40
MIMO multiple-input and multiple-output
Technology that uses multiple antennas to increase data transfer rates. see also MCS tables
STBC is part of MIMO.
HT, VHT, HE
Required for higher throughput - 802.11n, 802.11ac, 802.11ax standards. HT ... 802.11n , VHT ... 802.11ac, HE ... 802.11ax
HT20 : 20 MHz wide channels HT40: 40 MHz VHT80 : 80 MHz VHT160: 160MHz
see also MCS table
MCS Modulation and Coding Scheme
often visualized as a table. The MCS Index is a value that the hardware supports and uses when communicating.
Low data rates mean the higher indexes are not used. Reasons might be configuration or interference.
RSDB DBDC
Acronym for Radio Simultan Dual Band, Dual Band Dual Concurrent
Use two frequency bands at the same time by one endpoint.
Supported by: mt76 and potentially brcmfmac ( BCM4359 )
Normally radios operate in Single Band Single Concurrent (SBSC) (OpenWrt: 802.11an, 802.11bgn) or are capable of Dual Band Single Concurrent (DBSC): having 2 frequency bands selectable (OpenWrt: 802.11abgn capable).