Don't confuse me for an expert, but I have been dealing with Broadcom issue on a recycled dell laptop.
According to the wiki, Broadcom devices have been historically difficult for Linux developers to work with. Replacement hardware could be a better option, but in the meantime wireless seems to work in my case using the "dkms" package.
If Installing this you should read the following:
Adding a dkms package will change your update procedure, sometimes making additional work for pacman.
In case you didn't find the MacBook-specific wiki page, which also mentions Broadcom issues, try looking around here:
Also, this topic is on numerous BBS threads, so you may want to try a google search, such as: "broadcom macbook 4331 site:bbs.archlinux.org" .
Hope this helps,
Post by Maykel Franco via arch-general
Broadcom Limited BCM4331 802.11a/b/g/n
BCM4331 noticed to have problems with b43-firmware-classic. Use
b43-firmware for this card instead.
I probed with b43-firmware-classic community and b43-firmware yaourt
and both poor performance... 900k bandwith and microcuts.
Too I see broadcom-wl-dkms but I have the default kernel no dkms.
Somebody with the same problem??