802.11 Wireless Network Site Surveying and Installation

188 Chapter 8: Discovering Site-Specific Requirements

Most WLAN devices are designed to be located in a “friendly climate,” meaning areas

where the temperature ranges from 0 and 60 degrees Celsius. In addition, a friendly envi-

ronment is one in which the AP stays dry and clean and vibrations are minimal. If you are

putting an AP into a retail store or office building, a friendly climate might very well exist.

In many scenarios, however, such as a food distribution center with a large freezer that

might reach temperatures of –20 Celsius, or for outdoor installations in climates with

extremely cold or hot weather, you need to design the WLAN based on the worst-case

conditions.

WLANs are deployed in a wide range of locations, from climate-controlled offices to truck

loading docks, outdoor rental car lots, airport tarmacs, shipyards and railyards, and even on

board luxury cruise liners, locomotives, and passenger trains. Each location entails slightly

different circumstances and therefore requires different survey tactics and installation

techniques.

For applications that require the AP to be mounted outdoors, use an AP that has an appro-

priate National Electrical Manufacturer Association (NEMA) rating, or place the AP inside

a NEMA type of enclosure. This provides proper weatherproofing to prevent moisture

damage and corrosion. Salt water is extremely damaging to most APs, so consider this fact

if your WLAN installation area is anywhere near an ocean or sea.

Some WLANs are even used in hazardous areas, including industrial facilities where chem-

icals are manufactured or stored, locations where painting is occurring (for example, auto-

motive factories), or sites where explosives might be used (mines, for example). At such a

hazardous site, use products that meet the site’s intrinsic requirements or find suitable

enclosures. Check with the customer to determine the level of safety necessary and the

degree of isolation required.

Using Cookie Cutter Designs

Although every site differs and a survey for each site should be considered, you might be

able to use a cookie cutter approach in some cases. Consider, for example, a chain of small

auto-parts stores (see Figure 8-8). These stores are built in a very similar manner and are all

about the same size. They also contain very similar products, arranged in a similar way. A

single AP positioned in almost any location provides adequate coverage for a store. After

you have determined this fact (by a survey), you can establish specific guidelines regarding

AP placement and make deployment much simpler.