BCM43xx wireless range

This weekend, I'm at the annual Debian BBQ in Cambridge, and it's very nice weather. All the cool people are sitting outside with their laptops, a good 10-20 meters from the indoor wireless access point, happily using the internet. The problem is, by default, my wireless card just doesn't work at that range. So, today I had a look at the Broadcom bcm43xx driver code, to see what was going on....