Married Student Housing wireless network

[Adcadet]

hey crew,
so I'm a student at a large university (University of Minnesota-Twin Cities). My wife and I live in married student housing, about 2 miles off the main campus (Minneapolis) and a mile from the "other" campus (St. Paul). Our housing is a coop so we own "shares," vote, control rent, etc. Very cool. Anyway, the University is installing a sprinkler system for us which is controlled from the Minneapolis campus. Along with the control wires, they laid some sort of internet cable (T1 perhaps? T3?) so our office can connect to the University backbone. Connecting all of our buildings would be prohibitively expensive (to spread out, too many), but the idea of going wireless was recently brought up and our President asked if anybody knew anything about this or would look into it. And like the volunteer I am, I agreed. So....what do you guys think? How would we do this? Would we get repeating routers in every building? Directional antennas and off-the-shelf wireless access points? Would the connection to the University be fast enough to support that many users? Anybody have some good info on this, or know of where I can find some?

Thanks!
Adcadet

 

[ddrueding]

It's important to know a few things:

1. What is the connection between you and the campus? T-1 would be nice, but a fractional T-1 is likely and an ISDN is possible. The quality of the connection makes the other costs more justifiable.

2. How many buildings and how far apart? Depending on the distance and number, either directional or omni antennas would make sense. If they are close, these antennas can be attached to standard wifi gear. If they are further away, higher powered equipment like that from alvarion could be used.

3. What kind of budget is allowed? If it's substantial, routers hooked to high-end gear would provide high uptime and long warranties. If it's shoe-string, home-made antennas and USB adapters could be made to work.


It does sound like a fun project, though.

 

[ddrueding]

Oh, also try to find a convenient building with LOS to the rest to make your measurements from.

 

[blakerwry]

how many buildings, how far apart are each building and what is the total area to be covered? (an overlay of a zooomed in street map would be uber cool and would probably be necessary in order to do a proper site survey)

 

[Adcadet]

we've got 360 units, which I'm thinking equates to 60 "coreways" which equates to perhaps 10 or so buildings, plus the administrative office. We're 2 city blocks long and one city block long. No cool areal maps (yet).

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[Adcadet]

we've got 360 units, which I'm thinking equates to 60 "coreways" which equates to perhaps 10 or so buildings, plus the administrative office. We're 2 city blocks long and one city block long. No cool areal maps (yet).

here's a USGS/TerraServer image

and another one zoomed out. From what I can tell, we're the 2 block tall by one block wide complex. I count about 12 buildings. The red pin marks the edge of the office building

 

[blakerwry]

wow, it looks like battleship.

200m by 400m.... pretty big area

I think you might be able to cover the entire area if you used 3 access points with good antennas and signal boosters.

http://netgear.com/pdf_docs/Antennas_Datasheet_26Mar2004.pdf

I wouldnt want to put more than 100 people on a single wifi network.. and that's pushing it.

Personally, i'd rather see something like this done with wired network to each building using burried cable (either copper or fiber look like it'd work) and have a W-LAN in each building. Each W-LAN using a seperate channel to segment the network.

It'd be a good idea to talk with somebody with professional history to get some insight as to the best route.

 

[ddrueding]

Wow, that place is huge. It appears that the buildings are paired. One AP might make it to each pair, but I'll second blake about wanting a cable to each AP. Trying a directional to each broadcasting AP is possible, but the air around your buildings will be saturated enough without having to troubleshoot these.

I'll also second Blake on talking to an expert before spending some cash. I found the technical pre-sales people at alvarion to be very helpful.

 

[Adcadet]

oh, and the walls, at least subjectively, are very thick. We've got two infant twins upstairs. Every now and then I'll be in the hallway and hear them crying, but as soon as I go into my appartment I can't. It's very nice, but I wonder how that will affect wireless.

 

[blakerwry]

I assume standard construction of sheetrock and studs.. do you know if they are metal studs (bad for wireless) or wood?

btw, that's been my experience with every apartment I've been in.. the hallways is noisey, but once you're in the apartment it's pretty quiet.

 

[Adcadet]

not sure about the contruction. I've been in many apparetments where you can hear some sound from outside. In mine you can't hear the neighbor's loud rap music. I'm very impressed.

 

[sechs]

I'd guess that the walls are metal lathe with plaster, plaster on block, or just solid cement.

Any ideas about floors/ceilings?

 

[Adcadet]

nope. No idea about floors.

 

[sechs]

Do people have any trouble getting radio signals on the interrior of the building?

 

[Mercutio]

100 people on an AP is *way* too many, Blake. Remember that 802.11 is shared bandwidth to the AP. If you're doing 11Mbit wireless then you're talking about splitting ~7.5Mbps (actual wireless throughput) among however many people happen to fall into the same AP's coverage area.
Hopefully you'll get something better than a T1 back to your main campus. It'd really suck to have all your bandwidth sapped by one or two people running Kazaa.

If the walls are thick concrete, you have a substantially less than ideal environment for wireless - figure maybe 50 feet of coverage per AP. If lots of people have baby monitors and 2.4GHz cordless phones, it's even worse.

There's probably some kind of wireless networking class or program on campus. You might try asking the Computer Technology or EE types on campus for a hand.

 

[blakerwry]

yeah, I realize it's alot. But, it's well within the maximum allowed and it is still faster than dialup.

I know with dialup, most providers had 1 line for every 3 customers (at best).. for high speed everybody can be connected at once, but actual usage will probably be like 1 out of every 3 actually using the connection during peak...

so 1/3 * 100 = 33; 7,500kbps/33 users = 227kbps per user typical speed, still better than ISDN.



You would have to be very careful about somebody with a virus or kazaa/p2p etc as a wireless network could easily be brought to its knees under that kind of situation. Not to mention the legal problems that may be associated with running p2p applications on your network.

 

[Adcadet]

of course, many people here have cable internet or DSL...we could always set up an informal sharing system. In fact, I'm pretty sure I've accidently connected to somebody else's wireless network before (since it's really hard to connect to yours after you've disabled the wireless portion).