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A Wi-Fi site survey measures or models how radio signals behave in a specific building so that access points can be placed where they will deliver the coverage and capacity you need. Walls, shelving, glass, elevators, and even stock levels change how Wi-Fi propagates, and those effects are hard to guess from a floor plan. A survey replaces the guess with evidence.
The main types of survey
Predictive survey
A predictive survey is done in software. A designer imports a scaled floor plan, assigns wall and obstruction materials, and models access point placement until the predicted coverage meets the requirements. It is fast and inexpensive, and it is the usual starting point for a new design. Its accuracy depends entirely on the accuracy of the floor plan and the materials entered.
Pre-install survey (AP-on-a-stick)
In an AP-on-a-stick survey, a technician temporarily mounts an access point at a proposed location, usually on a tripod or pole at mounting height, and measures the signal throughout the area. It verifies the predictive design in difficult spaces such as warehouses, hospitals, and buildings with unusual construction. It takes longer than a predictive survey but measures the real building.
Passive and active surveys
A passive survey listens to all access points in range and records signal strength, noise, and channel use without connecting. An active survey connects to the network and measures throughput, latency, and roaming between access points. Passive surveys are used to map coverage and interference. Active surveys show what a client device will actually experience.
Validation (post-install) survey
After installation, a validation survey confirms that the network meets the design requirements. It is the step most often skipped, and the one that proves the project was delivered as designed.
Spectrum analysis
Some problems are caused by non-Wi-Fi interference, such as microwave ovens, wireless cameras, or industrial equipment. A spectrum analyzer shows energy in the band regardless of its source, and is often part of a troubleshooting survey.
What a survey report should include
- The coverage requirements the design was measured against
- Heat maps of signal strength, signal-to-noise ratio, and channel overlap for each band
- Access point locations marked on the floor plan, with names and mounting details
- Cabling and power needs for each location
- Interference sources found and how they were addressed
- Recommendations, and any areas that do not meet the requirements
Requirements should be specific. For example, a common target for voice-grade coverage is a received signal of about -67 dBm or stronger with a signal-to-noise ratio of around 25 dB. The right targets depend on your devices and applications, so agree them before the survey, not after.
When you need a survey
- A new building, a remodel, or a change of use such as offices becoming a warehouse
- Adding devices that depend on Wi-Fi, such as handheld scanners, voice handsets, or tablets for staff
- Moving to Wi-Fi 6E or Wi-Fi 7 and the 6 GHz band, which has shorter range than 5 GHz at comparable power
- Persistent complaints about dead spots, dropped calls, or slow connections
- High-density spaces such as meeting halls, classrooms, and venues
- Warehouses, where racking and inventory levels change signal behavior
When you may not need one
A like-for-like replacement of access points in a small office with no complaints may not justify a full survey. Even then, a quick validation walk after installation is worth doing, because new access points can behave differently from the ones they replace.
What to give the surveyor
- Scaled floor plans, ideally in a vector or high-resolution format
- The devices and applications the network must support, and how many users in each area
- The areas that must be covered, including outdoor or warehouse spaces
- Existing access point locations and models
- Access arrangements for ceilings, closets, and restricted areas
- Site hours and any times the survey cannot happen
From survey to installation
The survey produces an access point plan. The installation team then needs a cabling plan, mounting details, and a naming scheme. Many failed wireless projects have good designs and poor execution: access points mounted in the wrong place, cable runs that exceed the 90-meter permanent link limit, or devices installed above obstructions the design did not include. Give installers the plan, the floor map, and photos of each mounting location, and ask for a photo of every installed AP in return.
How Relion fits in
Relion technicians perform on-site site surveys that document mounting locations, ceiling types, cable paths, and closet conditions, and install access points to your design through our Wi-Fi and access point installation service. When your project needs a specific survey method, such as AP-on-a-stick or post-install validation, tell us in the scope and we will confirm what can be provided before dispatch.