January 06, 2004

Extending Wi-Fi Wireless Range

How Can I Extend the Range of my Wi-Fi network?

Best option is probably for antenna extenders. Something like the HyperGain Range Extender 14 dBi Flat Patch Antenna versus the HyperDirectTM HG-XT11P 11 dBi Smart Directional Diversity Antenna. Tessco makes units to 6dB.

These have drawbacks as they are "directional". This means the signal is focused over a smaller sector, and thus gets better distance. You need to be sure the coverage sector is appropriate for your location. The HyperGains above both show a 30 degree coverage sector. The XT11 is a bit weaker (each 3db doubles the mW power, each 10db increases power by a factor of 10). So I would pick the stronger antenna. They look pretty similar otherwise.

Then there are repeaters. The DLink DWL-900AP+ has a repeater mode. You enter in the MAC address of the AP to repeat. Problem here is that it has limited compatibility.

Other Issues to consider:

Repeater mode is not the best approach, because it uses a lot of frequency space, and typically slows down the throughput. While it can work in some situations, it should not be the first choice. And if you want to get into wireless networks with more complexity than a single access point like the WSG, be prepared to support them.

In client mode, the Dlink product works fine (I use several of DWL-810+ devices to deliver WiFi to my neighbours). But it does not really extend the range of the network, rather, it provides a RJ-45 wall jack with no cable behind it. Good to connect a wired device (say a desktop computer) to a wireless network.

A more powerful antenna, situated in a good location (i.e. separate from the AP, in an obstruction free spot), is probably the simplest approach for improving signal coverage. For 1000 feet (indoors I presume), multiple access points would be the only reasonable approach. This would require some cabling efforts and a site survey of sorts to determine optimal cable paths and access point locations.

There are FCC limitations with respect to power levels. (1 Watt for point to multi-point). The WSG 100 is 30mW I believe. Add a 15db antenna and you will be very close to this limit (16 db antenna will push 30mW to 1200mW or 1.2W, just over the limit). Antenna cabling introduces loss, and its always fun to get the connectors right, as there is no prevalent standard interconnects.

In summary, extending the range of a wireless network beyond a hotspot is not trivial, and will vary with the attributes of each location. Its really outside of our core mission, but with the right engineering, its very do-able. I have designed and installed hotel installations with more than 60 access points in the network. But the design and installation fee, separate from equipment, usually fell between $10,000 and $20,000 USD. Then you have to consider ongoing support, equipment warranties etc.

Posted by Craig at January 6, 2004 10:27 PM