Firmware source codes of a wlan chipset ( 802.11a/g/n )

Hi everyone,

Does anyone know a wlan chipset which codes, firmware and driver are
free access to the public? for any of (802.11a/g/n)
All of the works I’m gonna to do is doing some channel estimation and
monitoring the channel on the receiver side and changing some parameters
on the Phy layer (Layer 1) of the transmitter side.
The parameters which I like to play with are the type of preamble,
modulation, transmit power and etc.
I’d appreciate it if anybody knows.

Thanks a lot,