https://wiki.archlinux.org/index.php/Broadcom_wireless#b43
contains the next note, suggesting to use b43-firmware-classic for BCM4311 and other named cards.
Package b43-firmware-classic uses old firmware version 5.100.138. *Note:* * BCM4306 rev.3, BCM4311, BCM4312 and BCM4318 rev.2 have been noticed to experience problems with *b43-firmware*. Use b43-firmware-classic <https://aur.archlinux.org/packages/b43-firmware-classic/>^AUR for these cards instead. * BCM4331 noticed to have problems with *b43-firmware-classic*. Use b43-firmware <https://aur.archlinux.org/packages/b43-firmware/>^AUR for this card instead.
