Accidental IT: Boosting Your WiFi Signal

Like many technical innovations, WiFi connections are no longer optional. But with the increase in use, you've noticed an increase in grumbles when users can't connect. Here are some tips

March 1, 2005

11 Min Read
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Accidental IT is a series of technical how-tos for people whose job descriptions don't necessarily include tech support but who often find themselves doing just that for their co-workers.

Once upon a time, someone in the office (maybe you?) came back from the computer store with a brand new box and a great idea. You plugged in the office's first 802.11 WiFi router, and everyone was delighted when a few lucky laptop users were able to carry their computers into the meeting room and stay online.

Like many technical innovations, WiFi connections are no longer optional. A growing portion of the office relies on WiFi for their full-time connection to the company's servers and the Internet. But with the increase in use, you've noticed an increase in the frequency and volume of grumbles when users find spots in the office where they can't connect, or worse, when they simply lose their connection while sitting at their desks. Equipment that was originally put in place for use by a single user just doesn't cut it when mission-critical tasks are performed on WiFi-connected PCs.

Intermittent Connections

Your installation probably consists of a single 802.11b or 802.11g access point (AP). When it was installed, location was based on convenience rather than research. So, it was plugged into an available Ethernet port and powered up. When it was configured for LAN access, we hope the security features were turned on, but that's a topic for another story altogether. For now, be sure that the SSID is something other than "Default" and that WPA security is turned on.

As your WiFi network changed from novelty to necessity, more users started to rely on the WiFi connection for their laptops, PDAs, and some desktop units. The lucky ones simply signed on and started working. The unlucky ones got weak signals, or no connection at all. And as the user population grew still more, even users who could normally work without a problem began to lose their connections.

These are all symptoms of an unplanned WiFi installation. But now it's time to plan, even if it's after the fact.

Surveying The Landscape

A site survey is a requirement for any large WiFi installation where coverage is critical, because the improper placement of access points can get expensive. The good news is that for the typical small office, you don't need any fancy gear, or even special software. What you're trying to accomplish is to discover those areas that don't get a signal, then try to position your access point to provide a signal to the "blind" spots.

Take the simple approach. Pick up your laptop and walk around with it. Most WiFi card drivers include a power meter or some other indicator that shows the strength of the radio signal it's receiving. Turn that on, and watch it as you move through your office. There are more sophisticated programs like NetStumbler that provide lots of detail. But all that really matters is whether you can get a decent connection.

While you're walking around, take a map of your office (a photocopy of the fire exit floor map will do) and mark the areas you visit with the relative strength of the connection at each point. Once you've made a basic map and identified the problem spots, look at the building to see if there are obvious signal-blocking structural components like stairwells or elevator shafts.

The WiFi (802.11b/g) radio signal is a line-of-sight signal, meaning it doesn't bounce off things like walls, ceilings, or even the atmosphere, as some radio signals do. But it can get through some opaque objects like walls, ceilings, and floors under certain conditions.

Those certain conditions depend on how electrically dense the barriers are. A typical drywall wall between offices isn't normally a problem, but conduit, plumbing, or steel studs can increase the density. Going through several of these walls can defeat the signal quickly.

Radio power is measured in decibels (db), and a typical WiFi access point will produce about 110db. You can make a rough estimate of the area you can cover with an access point by simply adding up the value of the obstacles between the access point and the computer. The average office wall will eat up about 30db, an average human soaks up 15db. If you add a reinforced stairwell or elevator shaft, you can see that your 110db doesn't last long.

Now that you have your building's target dead spots identified, you need to pick your solution. The choices fall into five categories:

  • Remove interference

  • Increase the number of access points

  • Increase the efficiency of the transmissions

  • Increase the power of the transmissions

  • Increase the number of radios in the AP


WiFi signals share radio space with wireless telephones. Fortunately, these are more typically found in homes rather than offices, but don't rule them out. If one of your co-workers complains that she sometimes simply loses her network connection, see if there's a wireless handset (not a cell phone) nearby. Microwave ovens can also cause the same interference.

Also, WiFi LANs in the office next door can interfere with your network. Most wireless routers are preconfigured to use channel 6. Try changing your router to channel 1 or 11 to avoid your neighbor's signal.

More APs

To simply increase your coverage area, the simplest method is to add access points in those areas that have weak or no signal. If you already have Ethernet cable, or can run a cable to the area, do that and plug in an access point. For the price of an AP you can eliminate the problem area. Proxim's Orinoco AP-700 unit can be mounted on ceilings or walls because of its internal antenna, and supports a/b/g versions of the 802.11 spec.

If you don't have Ethernet cable in the location you need to cover, you can add a range extender (also known as a repeater) like Linksys' Wireless-G Range Expander. Extenders receive a WiFi signal and then rebroadcast it. This means the extender needs to be located where it can get a signal from an existing AP.

Keep in mind that because these repeaters are doing double duty, their overall throughput is reduced. This may not matter if your primary use is to connect to the Internet, since even 802.11b transport speeds are faster than the typical broadband connection speed. However, the speed hit may cause problems if you intend to use the remote connection for intensive file transfer work.

Proxim's Orinoco AP-4000 unit has two radios. One supports 802.11a, and the other supports 'b/g'. This unit can be used as a repeater without taking a hit on speed because it can use the 'a' radio for the repeater role and the 'b/g' radio to support the client computers.

More Efficient Transmission

Access point manufacturers have developed various ways to increase the efficiency of sending and receiving radio signals. One of the simplest and least expensive methods is to replace the standard antenna on the AP with a high-gain antenna. The Linksys HGA7T replacement antenna set for its wireless routers and access points provides a 7db increase.

Hawking Technology's Hi-Gain 24 series attaches through a cable rather than directly to the router, can be mounted on walls, ceilings, or even outside, and delivers an extra 6db of strength. On average, every increase of 3db doubles the connection range of the AP.

These antennas can be helpful and inexpensive if you are simply trying to increase the signal strength in marginal reception areas. High-gain antennas focus the radio signal so, for example, any signal that was directed up or down is redirected to the horizontal plane. This makes good sense for increasing coverage on a single floor of an office, but will actually reduce the coverage from one floor to another.

More Power

If repositioning your APs doesn't get around some of your office obstacles, you might want to try boosting your AP's signal strength.

WiFi radio waves use an unlicensed portion of the radio spectrum, and that's one reason it's so simple and inexpensive to set up your WiFi network. A condition of the no-license arrangement is a limit of 1 watt on the transmission power an AP can output. The typical computer-store AP is rated at .1 watt, which is low enough to keep bordering networks from interfering with each other.

But sometimes there simply is no substitute for horsepower. Adding a booster, or power amplifier, is simple and quick, and can even be combined with high-gain antenna when needed. Hawking Technology's WiFi Signal Booster can be set to boost an AP's power to .5 watts (500mW) by simply connecting it in place of the antenna on your AP.

More Frequencies

Adding frequency bands and the number of radios in an AP can make better use of the wireless radio band. Belkin's Pre-N router and network cards use Multiple Input, Multiple Output (MIMO) technology to increase range and speed. The label "Pre-N" alludes to the fact the devices are based on the yet-to-be ratified 802.11n WiFi standard. Keep in mind that to get the advertised increases of 8x range and 6x speed, both the AP and the client adapters must be Belkin's Pre-N products.

ParkerVision's SignalMax line applies advanced radio frequency management techniques to improve the effectiveness of the standard WiFi signal. ParkerVision guarantees to deliver connectivity anywhere within a small office, and up to 1 mile outdoors.

One important note here: If you have installed an 802.11g router to take advantage of the increased connection speed of up to 54Mb/sec over 802.11b's 11Mb/sec, you may not be getting all the speed you expect. If there is even one 802.11b client connecting to an 802.11g router, the router's modem decreases its speed to accommodate the slower 'b' client. That means that all the 'g' clients are also running at the slower speed. One advantage of having multiple modems in a router is that each modem can support its own speed. Belkin's Pre-N units can handle 'g' traffic at its full speed even when 'b' clients are connected.

So, Fix It

Armed with the right tools and a modest budget, you should be able to address the groaning coming from your wireless co-workers. Start by mapping your office space to see just how bad the problem is before you start buying equipment. Then make a few changes at a time, and judge your success by the decreasing noise level coming from those who are connected wirelessly.

Do you have a suggestion for an Accidental IT topic? Let us know!

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