What is a wireless site survey, and what are the different types of site surveys used when planning an enterprise Wi-Fi deployment?

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A wireless site survey is the process of evaluating a physical environment to design, validate, or troubleshoot a Wi-Fi network. It involves measuring radio frequency characteristics of the space to determine optimal access point placement, channel assignments, and power levels. Site surveys are essential because wireless performance depends heavily on the physical environment, including building materials, floor plans, interference sources, and user density.

There are three primary types of site surveys: predictive, active, and passive. Each serves a different purpose in the wireless network lifecycle.

A predictive site survey is performed before any hardware is installed. It uses specialized software to create a virtual model of the environment based on floor plans and building material characteristics. The engineer imports the floor plan, defines wall types and their RF attenuation properties, and places virtual access points. The software then simulates RF propagation to predict signal strength, channel overlap, and coverage gaps. Predictive surveys are cost-effective for initial planning because they do not require physical access to the site or actual hardware. However, their accuracy depends on how well the building materials and environment are modeled. They work best as a starting point that is later validated with a physical survey.

An active site survey involves walking through the environment with a survey device that is connected to the Wi-Fi network. The survey tool measures real-world metrics from the client perspective, including signal strength, signal-to-noise ratio, data rates, packet loss, and roaming behavior. Active surveys capture the actual client experience and can identify problems that predictive surveys miss, such as interference from microwave ovens, Bluetooth devices, or neighboring Wi-Fi networks. The surveyor walks a predefined path through the facility while the software records measurements and maps them to the floor plan, producing heat maps of coverage and performance.

A passive site survey also involves walking the environment, but the survey device only listens to RF signals without connecting to any network. It captures all wireless activity in the area, including signals from neighboring networks, rogue access points, and non-Wi-Fi interference sources. Passive surveys are useful for understanding the RF environment before deploying a network and for identifying sources of interference that could affect performance.

In practice, a thorough enterprise deployment uses all three types in sequence. A predictive survey guides the initial design, an active survey validates the deployment, and periodic passive surveys help identify environmental changes or new interference sources over time. Post-deployment validation surveys are critical because real-world conditions often differ from predictions, and adjustments to power levels, channel assignments, or AP placement may be needed.