Predictive Wireless Site Survey Prerequisites
To successfully perform a predictive site survey, it’s necessary to provide certain basic information:
- Floor plan or area map: A predictive wireless site survey simulates how radio waves would propagate through the survey area from individual access points, overlaying the results on a floor plan or area map. A plan or map that doesn’t represent the real location can jeopardize the entire survey.
- Construction materials: Wireless signals are absorbed by different building materials at various rates. For example, a 2.4 GHz WiFi signal passing through heavy concrete can experience a transmission loss of around 23 dB, while a 5 GHz WiFi signal passing through the same wall can lose up to 45 dB. Brick and lumber don’t affect wireless signals nearly as much, but their effect is still not negligible and should be accounted for during every predictive wireless site survey.
- Appliances and other sources of RF interference: In addition to walls and other solid obstacles, wireless signals are also affected by various sources of radio frequency interference, such as Bluetooth devices, cordless phones, remote mice and slide advancers, wireless doorbells, baby monitors, microwave ovens, and electronics with a switching load above 2 A.
- The number of wireless users: When conducting any kind of WiFi survey, it’s important to realistically estimate how many wireless clients will be accessing the WiFi network simultaneously and provide sufficient capacity by ensuring a sufficient density of wireless access points. There are many places, such as schools and hospitals, where the concentration of wireless devices is much higher compared with the average building.
- Desired coverage: It’s not always necessary or even desirable to cover the entire surveyed area with a strong signal. A business may want to limit its main WiFi network to its premises for security reasons or set up multiple wireless networks for different departments, minimizing their overlap to reduce co-channel and adjacent-channel interference.
