What a Proper Wi-Fi Site Survey Actually Involves
Most poor Wi-Fi we are called to fix was installed without a survey. Here is what one should include.
When a client tells us their Wi-Fi is unreliable, the first question we ask is whether a site survey was carried out before installation. The answer is almost always no.
Why guessing does not work
Radio signals interact with buildings in ways that are not intuitive. Concrete walls, metal shelving, lift shafts, water tanks and even large aquariums all attenuate signal differently. Two rooms of identical dimensions can require completely different access point placement.
What a survey involves
A proper survey has three phases. First, we walk the site with measurement equipment, recording actual signal behaviour and identifying interference sources — including neighbouring networks you have no control over.
Second, we build a predictive model of the space, accounting for construction materials and how the rooms are used. Coverage requirements differ between a quiet office and a lecture hall holding two hundred devices.
Third, we validate after installation. Predicted coverage and actual coverage rarely match perfectly, and adjustment is part of the job rather than an admission of error.
Capacity, not just coverage
The most common design error we encounter is planning for coverage while ignoring capacity. A single access point may cover a large hall comfortably — and then collapse when eighty people connect at once.
Modern design places more access points at lower power, which sounds counterintuitive but produces far better results in dense environments.
The cost of skipping it
A survey typically adds a small fraction to project cost. Retrofitting a badly placed deployment — running new cable, patching ceilings, buying additional hardware — costs considerably more, and that is before counting the months of frustration in between.