Ann Arbor Business to Business
Small Business and the Internet

Wireless in a Big Way

July 2002

By Mike Gould

Those of us with laptops are coming to appreciate more and more the delightfulness of wireless networking. You walk into a properly-configured work site, open your laptop, and boom, you're on the Internet, surfing and emailing your fingers off. In a boring meeting (if that's not an oxymoron) you can whip out your laptop and, with a flip of the lid, check your email or order concert tickets online. Just tell your boss you are taking notes, and be sure to position yourself so she or he can't see your screen. (If you are a boss: Just Kidding! Nobody really ever does this. Honest.)

In a previous article (1/01 B2B, available online at: I've discussed the simplicity of plugging a single Airport or other base station into your home or office. Here we cover a bigger job: equipping an entire facility for WiFi.

Background Music
To review, a bit of background. WiFi ("Wide Fidelity", AKA 802.11b) is an emerging standard for wireless Internet behaviors. The Internet arrives at your laptop courtesy of suitably-massaged radio waves, provided by a base station access point (AP) talking to a receiver card in your laptop. The card is also a broadcaster, sending requests and outgoing emails to the base station. The AP and the card behave sort of like geeked walkie-talkies, muttering inscrutable info packets at each other. The result is that your laptop behaves the same way your desktop, wired-to-the-wall computer does, only without the wires. This is Cool Stuff.

So a household or small office can install a single AP and enjoy wireless-ness within a defined area, usually around 150 to 200 feet. The trick is to scale this to a larger facility, enabling users to roam the entire area without dropping the signal.

Let's say you have a large warehouse next to your office complex. You would like to check something in the warehouse but still be within range of email because of that memo you are expecting any moment now from your boss. With a suitably-equipped warehouse and office, you would be able to plunk down your laptop on any surface in the warehouse and continue communications while you wait for your forklift operator to show up.

Now you could scatter a bunch of low-cost broadcasters around and hope for the best. Or you can hire a company that specializes in this sort of thing to do an analysis and design you a pro system.

I have recently encountered such a company. Wireless Resources, Inc. (WRI), based out of Troy, has been doing this sort of thing at the UM and elsewhere for some time now. They just finished an installation at a large UM facility, and are working on North Campus to wire (un-wire?) the School of Engineering and others out there. We are investigating having them help us where I work at the UM School of Ed (SoE).

We talked with Eric Vahlbusch, a very knowledgeable rep for WRI, who shared a number of insights with us. We currently have around 24 AP's scattered around the SoE, mostly Apple Airport units. These cover our classrooms and some of our offices. We are interested in planning how to expand the system to cover the entire building, and turned to WRI for advice. Here are some of the tips we learned:

Coverage Area
The key to doing this smoothly is to overlap your coverage between the different APs. What you want is to be able to roam such that as you move around, your laptop sees a consistent broadcast strength no matter where you are. You also have to tweak things so the overlapping fields from the APs don't interfere with each other; this involves setting them on different channels.

Broadcast strength
This was a new one on me. It turns out that newer APs can have higher power ratings than older ones. Most broadcast Access Points, such as those from Apple, LinkSys and other manufacturers send out their radio waves at a power of 30mw. More bodacious systems, such as those from Cisco, broadcast at 100mw. This translates into wider coverage area and faster data throughput.

Survey cost
WRI will come to your facility and do an evaluation of the number of APs needed, complete with floorplan coverage maps and the like. They wheel a little cart with an antenna around the place, tracking on a laptop how the coverage area varies. This can be all over the map (so to speak) depending on wall composition, other radio-emitting devices (such as wireless phones), etc.. Here at the SoE, this will be a real challenge because, being in an older building, the plaster walls are built around wire mesh, which is a great insulator of radio waves. Generally speaking, the newer the building, the more transparent the walls are to radio, and the easier it is to set up for multiple APs.

Recommended hardware
The University of Michigan is moving towards standardizing on Cisco equipment; APs, laptop cards, and the like. We already have a lot of Cisco routers in our equipment closets, so integration will be easier for us. I am looking into getting one of the 100mw cards for my laptop, a Mac G4 Titanium. Being sheathed in titanium, the internal AirPort card has a limited range, as well as being power-limited to the wimpier 30mw.

This is a biggie if you don't want your competitors parking in your parking lot and snooping through your network. There are a variety of encryption schemes out there, with differing levels of security. WEP, or Wireless Encryption Protocol, is available in varying strengths, but this can be compromised. A scheme in use at many UM sites (including the SoE) involves registering all laptops that need to use the system. This involves a secure database with the hardware addresses of the laptops involved; if your laptop isn't in the database, you don't get access.

So that's a quick overview of the conniptions involved in enterprise-wide wireless networking. For most of you, a single AP in a single office will serve. For you bigger organizations, look to a more robust, professionally-designed system.

You can reach Wireless Resources, Inc. at 248 740 1345.

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