Fedora 21 (kernel-3.19.3) comes with kernel mod brcmsmac, the opensource driver from broadcom.
Problem wifi slow and lost connection
Wait till next update.
sudo su modprobe iiwlwifi 11n_disable=1 echo "options iwlwifi 11n_disable=1" > /etc/modprobe.d/iwlwifi.conf
http://www.cyberciti.biz/faq/fedora-linux-install-broadcom-wl-sta-wireless-driver-for-bcm43228/