Reading raw packets from a wireless card in Linux (kernel 2.6.4)

Hi all,

I just need someone to point me in the right direction. I am planning
to do some research on RSSI using two wireless adapters over a network.
The basic idea is to run a client server model on the two machines and
find out approximate distance between them using the Received Signal
Strengths on either of them (cards).

Now I figure I would need to read the headers for the packets arriving
at the wireless cards to find out the signal strengths. I haven't yet
set up the experimental procedures yet, and therefore, do not know what
cards I might use (Should be D-Link or LinkSys on each) but I am
assuming there must be some modular way of reading packets in a WiFi
scenario (like the sk_buff structure in TCP/IP). Is there a parallel
structure I can use in Wireless situation too?

If not, how do I go about it? Any pointers, resources, books are most
welcome.

Thanks,
Hemant