Wireless Survey Research
With wireless systems, it’s very difficult to predict the propagation of radio waves and detect the presence of interfering signals without the use of test equipment. Walls, doors, elevator shafts, people, and other obstacles offer varying degrees of attenuation, causing the RF radiation pattern to be irregular and unpredictable. As a result, it’s absolutely necessary to perform a wireless site survey to fully understand the behavior of radio waves within the operating environment before installing access points. The goal of a wireless site survey is to determine the number and placement of access points that provides adequate signal coverage throughout a facility. A wireless site survey also detects the presence of RF interference coming from other sources that could degrade the performance of the wireless LAN. Also keep in mind that the facility of the WLAN is highly impactful on the whether it requires a survey. For example a small room office may not require a site survey. With the given example a small office might only require an access point or a router located within the office to require adequate coverage. A larger facility is going to require a well scoped survey to be able to provide sufficient coverage to all areas, and if a larger facility isn’t properly surveyed other areas in the facility might be affected by poor coverage or no coverage. Example of these areas would be airports, hospitals, colleges.
When conducting a site survey keep in mind what type of coverage is going to be needed or be provided, and also what technology is going to be implemented. Locating a set of building blueprints before doing the site survey is very helpful. Walk through the facility before performing any testing to verify the accuracy of the facility diagram. This is a good time to note any potential interference with RF signals. Determine the capacity of any existing wired networks that can interface the access points. Most buildings already have Ethernet, but also check on how much of the existing networks can be made available for supporting the wireless network. On the facility diagram, indicate all areas where coverage is needed, such as offices, hallways, break rooms, etc. It also very important in identifying where users will not need wireless coverage is important to avoid wasting time surveying unnecessary areas. By considering the location of wireless users and range estimations of the wireless LAN products you’re using, approximate the locations of access points that will provide adequate coverage throughout the user areas. Be certain to consider mounting locations, which could be vertical posts or metal supports above ceiling tiles. Recognize suitable locations for installing the access point, antenna, and data / PoE cable. Verify access point locations. Most wireless LAN vendors provide wireless site survey software that identifies the associated access point, data rate, signal strength, and signal quality. You can load this software on a laptop and test the coverage of each preliminary access point location. Alternately, you can use a third party site survey tool available from several different companies, such as AirMagnet, Berkeley Varitronics Systems, and Ekahau. Install an access point at each preliminary location, and monitor the site survey tool readings by walking varying distances away from the access point. Also take notes of signal readings and performance, and also keep channels in consideration and the interferences that they’re affected by. Based on the results of the testing, you might need to reconsider the location of some access points and redo testing for the affected locations. Testing just one once won’t be sufficient you have to be able to provide sufficient coverage so that necessary areas are covered as well. Once you’re satisfied that the location of access points you’ve identified will provide adequate signal coverage, document your findings on the facility diagrams by depicting the location of each access point.

This video was very helpful in understanding the survey.
https://www.youtube.com/watch?v=OfPC3ziuEiE