Stanford Team Tries For Better Wi-Fi In Crowded Buildings

alphadogg writes "Having lots of Wi-Fi networks packed into a condominium or apartment building can hurt everyone's wireless performance, but Stanford University researchers say they've found a way to turn crowding into an advantage. In a dorm on the Stanford campus, they're building a single, dense Wi-Fi infrastructure that each resident can use and manage like their own private network. That means the shared system, called BeHop, can be centrally managed for maximum performance and efficiency while users still assign their own SSIDs, passwords and other settings. The Stanford project is making this happen with inexpensive, consumer-grade access points and SDN (software-defined networking)."

Comments

and how do they track users across muilt units?

[Joe_Dragon]

also what about stuff like file shearing and other stuff that the cops only look at the IP and not that real end user.

Re:and how do they track users across muilt units?

[grcumb]

also what about stuff like file shearing...

Well, typically, you start by grabbing the file by its strings, give 'em a twist and get it on its back. Then you lift the tail[*] such that all the loose bits run off onto the floor as you make your first pass. Some prefer Occam's Razor when shearing data, but I find Hanlon's Razor works, too.

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[*] I find that tail -n 100 is enough to get a decent grip, but it really depends on the size of the RAM....

Re:and how do they track users across muilt units?

[Schrockwell]

On a university network, every networked device is usually registered by its MAC address, which is tied to that student's school-wide login for tracking purposes. The university already knows everything you do. I assume the same would be true over this public WiFi architecture.

I tried to get around this one time by spoofing my MAC with one from a library computer. THAT didn't go over so well. Since I was using the personal WiFi in my dorm room (stupid, I know), they knew exactly which network spigot it was coming from. Alarms went off all over their monitoring tools. Luckily I had a friend in IT who saw it, laughed, and told me to not do it again.

Software Defined Networking = Telephony

[Animats]

"Software Defined Networking", as Stanford uses the term, means a centrally controlled virtual circuit switching system. Every time someone makes a "call" (a new IP/port IP/port tuple), the first packet is routed to Master Control, which decides if they get to make the call, logs the call, decides whether the call gets wiretapped or filtered, and chooses the priority given to the call. All the routers involved are then issued instructions from Master Control on how to route that call.

(Yeah, they don't use the term "call". But that's what it is, really.) Goodbye, "net neutrality". Goodbye, flat rate billing. Goodbye, distributed control. This puts everything you do on the Internet under central control and makes it billable.

Re:Software Defined Networking = Telephony

[Anonymous Coward]

Your upstream provider can already do all of those things to you. They don't control where your packet goes upstream from you, but if your local ISP chooses to shut you out, the upstream folks will never see your packet in the first place. (The only difficult one is choosing the priority of the packet. Your local ISP can't raise the priority of your packet, but you bet they can lower it as much as they want by simply not sending it.)

The fact that ISPs don't do that is based on tradition and the threats of competition and regulation, not on any technical limitations.

Re:How efficient is WiFi when crowded?

[Guspaz]

2.4ghz is still usable with 16 networks in the same area, but it's not a great experience. There are only three non-overlapping bands in the 2.4 GHz band, so you can see how there can be a rather lot of congestion.

The 5.8 GHz band, on the other hand, wouldn't have nearly as much of an issue. 802.11n in the 5.8GHz band devices can use 8 non-overlapping channels, significantly reducing the amount of interference.

802.11ac is kind of in a wierd spot. It's really 40MHz per channel minimum (twice the minimum for 802.11g or 802.11n), but many devices also support a whole whack of new frequencies that require the use of DFS to avoid interfering with radar (basically if the router detects radar on the channel, it blacklists the channel for a set amount of time and switches to another channel). That brings the total up to a possible 12 channels, even though they're twice as wide...

802.11ac also supports beam forming, which enables multiple simultaneous transmissions to happen on the same frequency at the same time without interfering. I believe that's more targeted at handling more users on a single network rather than letting multiple networks co-exist, though.

Re:How efficient is WiFi when crowded?

[niftymitch]

Let's say you live in an apartment building and you can see 16 different SSIDs. Is it slow because .....snip...

Someone needs to make a reference to the Aloha Protocol (http://en.wikipedia.org/wiki/ALOHAnet).
Multiple routers and multiple end points sharing a limited bandwidth shared commons
is just darn difficult.

I do hope Stanford makes this work because dense living just happens.

More and more work places are getting to be "dorm living" on caffeine.
Old folks homes and retirement communities are just around the corner
for lots of us and the bandwidth needed for Gramps and Gma to browse
all the photos and videos of kids and food boggles the mind.

Re:Dorms

[Voyager529]

It's a shame the kids these days can't be bothered to plug a computer into the Ethernet drops that were installed in their rooms 20 years ago.

To be fair, plenty of the anorexic laptops being sold these days have shed the ethernet port (obnoxiously, most of the sub-$500 laptops only have 10/100 NICs...), and phones and tablets are wi-fi or cellular only; wired isn't even an option for them.