So I've been working a little bit more on the problem of the USB wifi chip dropping packets particular when there is a large amount of traffic going through the air (such as when someone is streaming Netflix, which happens more than you'd think). Even when there isn't a whole lot of network traffic, it's easy to miss a packet. Obviously if this is going to replace my need to carry keys then this can't not work. If it drops the authentication packet, then there is no way to send a new one unless I turn off the wifi on my phone off and on. The idea is that I can just walk up to the door and it's open.

I've thought about a few other options such as a FPGA solution that analyzes the packets but it would have to do so at a fairly high level. In order to get a decent sample, the sampling rate would be 4.8 GHZ which I don't think would be possible in an cheap FPGA and would likely require serious cooling in an expensive high end one.

I've given it some thought and decided that the bluetooth low energy spec is actually pretty decent and since all of us have phones that support it, it does make a good choice. The only problems I've thought of is authentication. I think the idea would be that the micro controller would just sense when a phone came in range so it would unlock the door. It would likely do this through MAC address authentication. While I live in a wonderful community that is very crime free, the security of this isn't as robust as I would like. All it would take is someone to sniff out the bluetooth mac address of one of our phones and then spoof it. Of course, if someone was putting this much effort to get in our house, they might as well just break the large and very thin front window of the apartment.

The other problem with this approach is the reduction of novelty. Without wifi, it simply becomes another bluetooth doorknob like everyone else. At what point is it simply more convenient to just buy one for a hundred bucks?

Any thoughts or suggestions?