wireless between buildings

March 8, 2005 8:50 AM

Have dsl in building 1 with linksys gateway providing a wireless connection. Need to use dsl is building 2. What is the best/cheapest way to accomplish this?

Without going into details, would like to remain completely wireless. Building 2 is a metal building 15 feet from building 1. At the point in building 1 nearest building 2 (still inside), there is a 30% signal, but none inside building 2. Currently using a linksys BEFW11S4. Do I want a larger antenna, another AP, repeater, absolutely must find some way to run cat5, or what is recommended?

posted by striker to computers & internet (6 comments total)

IMO, best results would be had with cat 5. You wouldn't have to worry about interference/signal loss quite so much then.

Your router is part of the issue. It tops out at 802.11b; an 802.11g router might give better results, but for best performance the receiver in building 2 would also need to be 802.11g.
posted by staresbynight at 9:16 AM on March 8, 2005

b + g have the same range; g has a higher capactiy at shorter ranges/better conditions. so going from b to g won't help you much here, i think (intel primer on lan tech).
antennas don't give you more power, in total, but do give more directionality. so you could go with directional antennas (pointing at each other), which might work, but then you'd lower the signal quality in other directions.
posted by andrew cooke at 9:29 AM on March 8, 2005

I'm a bit confused by the description. Do you mean you need to use the Internet in building 2, or that you need to move the DSL connection from building 1 to building 2 while still using the Internet in building 1, or something else?

Running a cable is the best for signal, but not for convenience, since you'll have to meet whatever requirements your area has for outdoor cable runs (grounding, insulation, conduit, etc.) and keep the cable from being damaged. Easier with fiber than with copper, but then you start getting into more expensive equipment and having to bury cable. Of course, outdoor antennas have many of the same problems.

Sticking with wireless, I think the standard way to accomplish this is to set up wlans in both buildings, and then link the two buildings together with their own wireless link via directional antennas, and then route or bridge between the three. (I'd route -- two buildings = two subnets seems natural to me.) If you have devices which have two antenna connectors and let you specify which is used for what you might be able to get away with two instead of four devices, but then you're also limiting yourself in terms of getting coverage in the buildings themselves (unless you can relocate the other antenna to meet your needs, too). Separating the links up also lets you manage each component separately, which depending on scale might lead to fewer or more administrative headaches.

Re 802.11b/g, there's a speed difference between the two, but that doesn't translate to a signal strength difference. Using equipment which lets you push up transmit power to the legal maximums will help too. The best bet for this sort of thing is Linksys's WRT54G with third-party firmware like Sveasoft's. It happens to support G, but the important matter is that it's Linux-based and GPL-licensed and therefore has had third-party firmware available. Then again, the inter-building link will be a bottleneck if there's more than one client on the far end of it, so putting G there is probably worth it for speed alone.
posted by mendel at 9:40 AM on March 8, 2005

Also, the books Wireless Hacks or Building Community Wireless Networks might be of use, as might the following Web resources:

Seattle Wireless community network
NoCat, Sonoma County community network
Bridging 802.11 Networks with Linksys
posted by mendel at 9:54 AM on March 8, 2005

to clarify: I need to use internet in building 2
posted by striker at 11:01 AM on March 8, 2005

striker - If you're tech-savvy, buy a WRT54G like mendel says and flash it over to sveasoft's os. Buy a higher-gain antenna (at least 7 db, preferably directional or with a lobe-shaped signal, which should be shown on the box). Also, put the antenna as close as possible to building 2.

On the other hand, if you have cat5 already strung through building 1, just add an access point on the side of building 1 closest to building 2. Then put the good antenna on the access point, switch the channel and ssid to one you're not using already, and enjoy. You'll have to switch access points if the signal goes bad in building one when you're coming in from building 2, but ... so be it.

Whatever you do, do NOT buy the Linksys repeater. It's a pile of steaming dog crap, and there's no way to troubleshoot it. If it can't get on any network, it's only diagnostic is a blinking light and there's no way to access the hardware at all 'cept via wireless.

Note that you won't get good performance, no matter what, unless only one or two people are using the wireless at once.

I run wireless at my office for my employee and myself. We share a T-1 in the lower part of the building with another business, and my office is in the upper rear part of the building. The antenna that serves the whole office is connected to a simple access point with a 6db comp usa antenna on top of the kitchen cabinets, which is just on the other side of the elevator shaft from my office.

It turns out that the kitchen is a much better location no matter what, because the whole building has good wireless there ... whereas the west side of the building, where most wireless users are, didn't get any access before with the access point in the server closet. So you might find that by adding an access point at a different location, you suddenly get a really good signal. ;)
posted by SpecialK at 1:41 AM on March 9, 2005