I did a quick search and many of those model Dells are equipped with a Broadcom chipset. You can verify what chipset you have with the lspci command. You may find this link useful if your laptop is equipped with one of the BCM43xx chipsets.
On public yum there are packages that support the BCM43xx series
b43-fwcutter.x86_64 : Firmware extraction tool for Broadcom wireless driver
b43-openfwwf.noarch : Open firmware for some Broadcom 43xx series WLAN chips
b43-tools.x86_64 : Tools for the Broadcom 43xx series WLAN chip