Packet socket attached to 802.11 interface?

I'm trying to implement a new comms (network) protocol directly on top
of the MAC layer using "packet sockets" for this purpose. This will
allow me to have the protocol implementation in user space (vs kernel
space). When I attempt to unicast (by specifying a particular MAC
address) I receive it (the transmission) at all nodes which can hear it
- not just the node with the corresponding MAC address. I.e., I cannot
filter by MAC address! Furthermore, based on the RTS/CTS protocol I
would expect to see reattempts to transmit if no node with the
corresponding MAC address could hear it - because of the failure to
receive an ACK. I see NO such reattempts.

Any ideas?

---John