ZeroMQ

What’s the Current Status?

Despite its uncomfortable role as enterprise technology that somehow escaped into the wild, WiFi is already useful for more than making a free Skype call. It’s not ideal, but it works well enough to let us solve some interesting problems. Let me give you a rapid status report.

First, point-to-point versus AP-to-client. Traditional WiFi is all AP-client. Every packet has to go from client A to AP, then to client B. You cut your bandwidth by 50%—but that’s only half the problem. I explained about the inverse power law. If A and B are very close together but both are far from the AP, they’ll both be using a low bit rate. Imagine your AP is in the garage, and you’re in the living room trying to stream video from your phone to your TV. Good luck!

There is an old “ad hoc” mode that lets A and B talk to each other, but it’s way too slow for anything fun, and of course, it’s disabled on all mobile chipsets. Actually, it’s disabled in the top-secret drivers that the chipset makers kindly provide to hardware makers. There is also a new Tunneled Direct Link Setup (TDLS) protocol that lets two devices create a direct link, using an AP for discovery but not for traffic. And there’s a “5G” WiFi standard (it’s a marketing term, so it goes in quotes) that boosts link speeds to a gigabit. TDLS and 5G together make HD movie streaming from your phone to your TV a plausible reality. I assume TDLS will be restricted in various ways so as to placate ...