WiFi designs can be established theoretically from simulations, or from survey work, or a combination of the two. For example, a theoretical design can used to plan a survey that will ratify it or help establish required design changes.
WiFi simulations have become quite sophisticated, they consider building structure, variations in the ability of different type of WiFi equipment, and requirements for specific use cases. These simulations calculate many properties of the design, among them are coverage, how many connected devices can be supported, speeds achievable, interference, channel reuse, and spectrum use. Nonetheless, some things are inherently difficult or impossible to simulate; they require surveys.
WiFi surveys measure the WiFi currently present, any test WiFi used, and can capture WiFi traffic and interference in the radio spectrum used by WiFi. They also document important relevant site features, such as dimensions and wall types, wired data networks to connect to, usable power sources, possible install locations, and obstacles for WiFi and installation. Survey results can be used to identify actual and potential problems with a current WiFi network.
WiFi surveys can take four main forms:
Passive site survey
This survey discovers WiFi currently visible across a site, including WiFi from neighbours and rogue WiFi equipment within the site. As a result, this kind of survey allows us to detect some current and potential problems. Prior to deploying a WiFi design, a passive site survey with test WiFi equipment is advisable. This is called a pre-deployment survey. It helps ensure the WiFi design more accurately meets requirements.
Active site survey
This survey measures the data transfer performance that is achieved by a WiFi system, as opposed to what is theoretically possible. It can be used to check a WiFi system conforms to performance requirements, to track down suspected performance problems, and to proactively detect as yet unrecognised problems. If WiFi data transfer performance is important this is an essential survey.
WiFi traffic analysis
This survey captures WiFi traffic which is then analysed to track down the cause of difficult to understand problems, such as intermittent throughput problems. The behaviour of WiFi is due as much to the devices that use it as the equipment that provides the network. So, a WiFi client can degrade the behaviour of an access point it connects to for all clients. WiFi traffic analysis can be the only decisive way to address difficult to understand problems with WiFi.
This survey captures data about WiFi and non-WiFi based emissions across the radio spectrum used by WiFi. This can highlight if current or planned WiFi is likely to suffer from interference or contention. This kind of survey is becoming more important as the spectrum used by WiFi is increasingly crowded with emissions from many kinds of equipment.
Whatever combination of survey design and planning is used, experience and specialised equipment and software are all essential.