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Filling in a Network’s Dead Spots, Part 1

Wifi-logo Face it, every school wireless network has its share of dead zones, where no signal penetrates. Either it’s an office that’s surrounded by brick or stone walls or one at the end of a hallway or even a basement room that was never meant to be a classroom. While teachers, administrators and IT people throw up their arms in exasperation, there are a few things you can do to bring those dead spots back to life.

It may sound simplistic, but the reason for a dead spot is that the WiFi signal is that the signal that carries the data is just too weak to sustain an Internet connection or access to local server resources. In other words, the signal strength meter has no bars filled in, and it is essentially unconnected.

It’s actually easy and inexpensive to raise that to one or two bars and plug most of those holes in your network. The first step is to perform a site survey. In a systematic manner walk the floor, taking signal strength or throughput readings every few feet with a notebook. If you record the numbers on a floor plan of the building you can create a crude, but effective, contour map of your wireless network’s reach, and where it dies.

Wireless mon Getting Passmark’s Wireless Mon can help with all the info you need as well as a way to log the data. It’s free for 30-days and costs $50 to use forever. On the other hand, if you listen to the complaints of teachers long enough, you’ll hear where all the dead spots are, generally with an expletive or two attached.

Once you’ve identified dead areas, it’s time to get down to work. My preferred method to get rid of dead spots is to use special antennas that either boost the signal or can aim it to where it’s needed – or both.

This technique attacks a key flaw in most routers and access points: they come with the cheapest antennas available. The stubby antennas that come with most WiFi transmitters are omnidirectional and typically rated at 2-, 3- or 3.5dBi, which is a measure of their sensitivity to grabbing and signal.

That’s why tLinksys_WRT54GShe typical piece of WiFi equipment has a range of only between 75- and 100 feet, when a school’s walls are taken into account. If your equipment has removeable antennas, it takes just a few minutes to do the trick and there’s no software to load. If your gear has internal antennas, you’re out of luck, but in two weeks I’ll show you a different way to plug WiFi holes.

I used a Linksys WRT54GS router in a small building that is nearly 90 years old and has many thick walls. To gauge the connection and test how well each approach worked, I used an HP Mini 100e.

For the dead spot that has a near-by access point, Linksys’s 7dBi  Hi Gain Antenna can help get the signal to where it needs to be. Like the stub antennas that came with the router, it is an omnidirectional antenna. This means that its signal is transmitted in roughly a sphere around the antenna. The difference with the Linksys antenna is that it is much more powerful and three-times bigger. It screws right onto the router and spreads its signal out evenly in all directions.

Linksys 7dBi antenna The antennas were able to increase the range of my router from 75- to 100-feet. More to the point, the antennas were able to fill in a dead spot with a signal strength of 21 percent, up from essentially zero. This was perfect for viewing videos, grabbing files and having a live Web connection. It costs about $60 for a pair of antennas with a clip that holds them together.

TEW-AI77OB_d1_2 Another approach is to use Trendnet’s TEW AI77OB Omnidirectional antenna set. Like the Linksys antennas, it includes two long stalk antennas, you can screw them right into a router. But, they come with a stand that has a 3-foot cable so they can be set up away from the router. Just put the stand anywhere or screw it into a wall and then point the antennas where you want the signal to go.

The antenna pair was able to send a 10 percent signal to the former dead spot, giving it access to files and the Internet, but video was choppy and some Web pages took a long time to load. It increased the router’s range to 105-feet.

When that doesn’t work, it’s time to call in the heavy artillery and start using a directional antenna. Rather than sending the signal out in a sphere, directional antennas create a zone of connectivity along a straight line from the antenna. It’s not perfect, but a great way to aim where you want the signal to go.

Resize.php A white metal rectangle that’s 8.5-inches long, Hawking Technology’s Hi-Gain Corner Antenna couldn’t be more different than the router’s stock stub antennas. The $50 antenna lacks mounting hardware, but it can be attached to a wall or ceiling with adhesive Velcro tape, and as the name implies, it’s perfect for fitting into the corner where two walls meet.

Happily, it comes with adapters for most routers in use. It outdid the Linksys omnidirectional antennas by boosting the router’s range to 125-feet, a two-thirds increase. The former dead spot now has a signal strength of 21-percent, plenty for a variety of online uses.

By contrast, Trendnet’s TEW AI86DB antenna is smaller and not as powerful but it has a base that includes mounting hardware on the back. Just put a small screw in a wall and hang it there. A bonus is that it is on an articulated arm that lets it be aimed.

Tew-ai86db_d2_2 The key is the device’s 3.5 by 4-inch active antenna that is rated at 8dBi. Not as powerful as the Hawking antenna, it still does much better than stock antennas. It was able to raise the router’s range to 120-feet, but in the area that was previously a dead spot it provided an ample 23 percent signal. This is a big step up and more than enough for Web browsing, downloads and video. In other words, it’s a big step forward from no connection.

Using these antennas is a great way to turn a dead spot into a vibrant zone of connectivity and digital education. But some dead zones don’t respond to antennas. For them, I use a repeater or extender that is like an access point that re-broadcasts the WiFi signal to new areas of the school. I’ll show you how to set one up in two weeks.



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I prefer using a 75-100 feet range router since our home is not that big. This would be perfect to use especially in apartments or condo units.

That seems about right. The typical access point or router can handle two, maybe three classrooms, but that can be stretching it if the walls are thick and dense (which absorbs some of the signal). The beauty of these extenders is that they don't need a wired connection to the network to work.

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