Planning UniFi Wi-Fi: coverage, channels and roaming

1. Plan capacity, not just floor area

Floor area is only one input. A nearly empty warehouse aisle and a full training room can be the same size but impose entirely different requirements. Wi-Fi shares airtime: the more active devices, slow transmissions, broadcasts and interferers occupy a channel, the less airtime remains for each participant. Planning therefore starts with usage zones and applications.

2. Materials and obstacles determine the radio path

Radio does not spread through an office as a neat circle. Concrete, fire walls, coated glass, lifts, steel shelving, machinery, water and even changing stock attenuate or reflect signals. Openings and corridors can carry radio unexpectedly far. Higher frequencies behave differently from lower ones, so a floor plan alone is not yet a radio model.

• Draw wall and ceiling types, and inspect them on site where the construction is uncertain.
• Mark metal surfaces, cold rooms, lift cores, service shafts and movable shelving as special radio zones.
• Measure neighbouring networks and non-Wi-Fi interferers during real operating hours, not only in an empty building at the weekend.
• Include weaker or business-critical client types. A high-end survey laptop does not represent a scanner with a small antenna.

Ubiquiti publishes antenna radiation patterns for its access points. They show the direction and shape of radiation, measured in a fully anechoic chamber. The vendor itself notes that interference, materials and building geometry change shape and gain in real installations, and recommends measuring before installation with mock positioning, during installation and afterwards.

3. Place access points around the intended radio cell

Mount an access point where its antenna behaviour serves the intended usage zone and a sound cable route is possible. The geometric centre of a floor is not automatically correct. With several APs, cells should overlap in a controlled way: enough to support transition, but not so much that many clients and APs unnecessarily share the same airtime.

• Install ceiling and wall models in their intended orientation. Arbitrary rotation changes the radiation pattern.
• Keep APs clear of metal, service channels, lights, cupboards and other direct obstructions where possible.
• Provide capacity locally in busy rooms instead of covering them from a distant cell at high transmit power.
• Do not raise transmit power as a substitute for a missing cell. The client still has to complete the return path to the AP.
• Make mounting points accessible, clearly labelled and photographed so replacement does not require redesign.

4. 2.4, 5 and 6 GHz serve different purposes

6 GHz is not an automatic range booster. It provides additional spectrum for suitable clients but requires closer attention to usage zones and compatible security configuration; Ubiquiti advises placing APs closer together for 6 GHz than for 5 GHz. In Germany, Wi-Fi may use 5,945–6,425 MHz under the Federal Network Agency’s general authorisation (Vfg. 76/2025). Fixed access points count as LPI devices there: indoors only and at no more than 23 dBm EIRP. Outdoors, only portable very-low-power devices (VLP, 14 dBm) are permitted, so Ubiquiti enables 6 GHz in Germany for indoor use only. The upper 6 GHz range above 6,425 MHz is not assigned to Wi-Fi. Some IoT and legacy endpoints still need 2.4 GHz, but it should not carry the entire high-performance fleet. In many SMEs, 5 GHz is the practical main band, yet it still needs planning around actual interference.

5. Channel plan and width: distribute airtime deliberately

Wider channels can deliver more peak throughput in good conditions, but they also occupy more spectrum. In a dense environment this reduces the number of independently usable channels and makes neighbouring cells compete sooner. The correct width follows density, interference, client capabilities and application targets, not the largest selectable value.

• Start 2.4 GHz planning at 20 MHz, as Ubiquiti also recommends, and avoid overlapping channel use. Wider settings aggravate an already constrained spectrum.
• On 5 GHz, balance channel width against cell density and neighbouring occupation. More width per cell leaves fewer separate channels for adjacent cells; for dense office environments Ubiquiti suggests 40 MHz as the starting point.
• Wide channels are possible on 6 GHz, but spectrum is tight in Germany: 480 MHz yields 24 channels at 20 MHz, six at 80 MHz, three at 160 MHz and only one non-overlapping 320 MHz channel. Wide channels make sense only when clients, capacity targets and channel reuse support them.
• Avoid assigning the same channel to directly adjacent APs where possible. Your own Wi-Fi can be the strongest source of interference.
• DFS channels (in Germany 5,250–5,350 and 5,470–5,725 MHz) expand the 5 GHz options, but must be vacated when radar is detected. An affected channel stays blocked for at least 30 minutes, and before transmitting on a DFS channel the AP checks for radar for 1–10 minutes depending on country and channel. Include that behaviour in acceptance testing.
• Use Channel AI as a tool: according to Ubiquiti it only optimises channel selection, while channel width and transmit power stay unchanged. Review its recommendations against the floor plan, measurements and critical applications.

6. Site survey: connect prediction, measurement and acceptance

A professional workflow combines three perspectives. Predictive design models the floor plan, materials, AP models and expected cells. An on-site survey checks assumptions and captures neighbouring use or interferers. Post-installation validation shows whether the built network meets the agreed objectives under real conditions.

Measure at different times with representative devices. Alongside signal level, where Ubiquiti cites at least −70 dBm and preferably −65 dBm at the client, capture signal-to-noise ratio, channel and airtime utilisation, retries, packet loss, latency and usable throughput. A green heatmap cell does not prove a stable video meeting or a clean scanner handoff between warehouse areas.

7. Cabling and PoE are part of radio design

Every AP is limited by its uplink and power supply. The intended model determines port speed, IEEE PoE class and maximum draw. The switch must meet those requirements per port and in total. Cable run, patching and certification must support the expected data rate.

• Cable every AP in normal business installations. Mesh is a justified exception, not the default substitute for data cabling.
• Assess AP port, switch port and uplink speeds together so the bottleneck does not sit immediately behind the radio.
• Check PoE mode and maximum draw in current data sheets instead of relying on the generic PoE label.
• Plan total PoE availability with headroom, and assess the effect of switch or power loss on critical radio cells.
• Test and label cables and outlets after installation. A faulty pair can present as an apparent Wi-Fi fault.

8. Roaming is assisted, but the client decides

The client fundamentally decides when to leave an access point and which one to join. UniFi can assist through BSS Transition (802.11v), Fast Roaming (802.11r) and, since UniFi Network 9.2, the Roaming Assistant, which uses BSS transition frames to prompt clients with a weak signal to move before they are disconnected. This is reliable only when cells overlap sensibly, security settings are compatible and the endpoints implement the mechanisms correctly.

• Test roaming along real movement paths: corridors, stairs, warehouse aisles, outdoor transitions and lift lobbies.
• For voice and real-time applications, record packet loss, latency spikes and audible interruption while moving.
• Respect client differences. Operating system, driver, power saving and antenna affect the decision.
• Do not maximise transmit power everywhere. Oversized cells can keep clients attached to a poor AP for too long.
• Use Minimum RSSI only per AP after measurement, not as a global supposed roaming switch. Ubiquiti recommends it only for high-density deployments; the Roaming Assistant is the gentler alternative.

9. Validation: sign off applications, not just measurements

Agree acceptance criteria before installation. They apply to defined areas, operating conditions and client classes. Measurements provide diagnosis, while acceptance also follows the business workflow: the scanner posts the goods movement, the call remains intelligible while walking, and the video meeting works in a full room.

10. Common mistakes that are avoidable

• Buying access points from an area estimate and considering capacity or cable routes only after mounting.
• Running every radio at maximum transmit power and maximum channel width, causing your own cells to compete more heavily.
• Surveying only with a high-end laptop and never testing scanners, phones or older IoT devices.
• Broadcasting too many SSIDs. Ubiquiti cites four SSIDs per band and AP as the normal limit (eight with wireless meshing disabled) and advises against large numbers; every extra SSID adds management traffic and complexity to VLANs and policies.
• Accepting automatic values without review, or changing several settings at once whenever a problem appears.
• Using mesh as a convenient substitute for missing cabling and overlooking that, according to Ubiquiti, every wireless hop at least halves throughput.
• Treating a one-off heatmap as permanent even though neighbouring networks, furniture, stock and endpoints change.

11. Connect Wi-Fi to the wider architecture and operations

SSID, VLAN, firewall, switch port, PoE and radio cell form one chain, so Wi-Fi is not accepted in isolation. Guests, employees and IoT devices must land in the right networks, reach only intended services and remain traceable when changes occur. After go-live, monitor utilisation, interference, abnormal clients and channel changes. Make tuning changes individually, document them and measure again.

The companion guide Planning a UniFi network: gateways, VLANs and Wi-Fi for SMEs covers gateway sizing, switching, PoE budget and segmentation. Whether UniFi suits your business in principle is covered in the article on UniFi’s suitability for businesses. If cameras share the infrastructure, also see UniFi Protect and the GDPR: video surveillance at work. Design, surveying and installation are available through my UniFi networks for businesses service.