Parsing a packet

Hello all,
I am trying to use the USRP to capture 802.11 packets and
have a few questions.

Looking at the archives, I understand that I can receive 1 Mbps
probe/beacon packets with code developed by BBN. I use their code and
see packets at 1 Mbps from different nodes.
However, I don’t know of a way to have the USRP as a destination for a
flow using standard packet generation tools like Iperf. So I setup a
UDP flow between a conventional 802.11bg AP and a Laptop. I capture
the packets on air with the USRP and determine how many of the packets
of this flow I am able to receive. But here, out of 1000 packets (1500
bytes each) sent at 1 Mbps, the laptop is able to receive around 900
packets but the USRP captures somewhere between 100 to 550 packets. I
am wondering whether this makes sense. I thought that the BBN code
would capture most of the packets provided the rate is 1 Mbps
(disregarding probe packets from other APs). But this does not seem to

I use gnuradio-3.1.2 on Ubuntu Dapper with a 2 GHz Intel core duo
processor and 2 GB RAM.

I would be grateful for any directions/pointers on the above and how I
could get the USRP to receive a continuous 1 Mbps 802.11 stream.