A warehouse looks like a large empty space. In radio terms it's one of the most difficult environments there is, which is why an office Wi-Fi design almost always disappoints when moved into one.
The symptoms are distinctive: scanners work fine near the doors, then stop responding in the middle aisles. Or everything runs well for a month, then starts failing with nothing having changed.
Why warehouses are different
Four things separate them from offices, and all four act at once.
| Office | Warehouse and factory | |
|---|---|---|
| Ceiling | 2.5–3 m | 8–12 m |
| Obstacles | Plasterboard, glass | Metal racking, stock, machinery |
| Users | Seated at desks | Moving, some on forklifts |
| Environment | Fixed | Changes with every delivery |
That last row surprises people most. A warehouse surveyed while empty gives results that simply don't hold once the racks fill. Stock absorbs signal, and metal racking reflects it in directions nobody wanted.
The practical consequence: survey while the warehouse is stocked as it is on a normal working day, not just after it's built. If that's already been missed, repeat the measurements once the racks are full, simple tools are enough, as covered in the guide to Wi-Fi analyser apps.
The most expensive placement mistake
The first instinct is nearly always: mount it on the ceiling, as high as possible, for maximum reach.
In a warehouse this works against you. An access point at 10 metres radiates mainly across the tops of the racks. What reaches the aisles, where people and forklifts actually work, is leftover reflection.
Two approaches work better:
- Bring it down to aisle height. Mount on the racking itself at 4–6 metres, facing down the aisle. The signal then travels along the aisle instead of trying to pass through racking.
- Use directional antennas. Patch or sector antennas concentrate the transmission into one aisle. The omnidirectional antennas built into most access points radiate everywhere, and most of it is wasted into metal. This same radiation-pattern difference governs placement in ordinary rooms too, see the guide to router placement.
The working rule: map aisles, not floor area. One access point per two or three aisles, mounted at the end and facing in, usually beats anything laid out by square metres.
Moving between access points
This problem doesn't exist in offices, and it's most often what the complaint is really about.
A forklift at 10 km/h crosses the coverage of several access points within a minute. Each handover introduces a gap. If the gap runs long, the scanner's session drops and the operator has to scan again.
What improves it:
- One network name across the whole site. Different names per zone force devices to be re-selected by hand.
- Fast roaming support (802.11r/k/v). Devices are told where to move before the signal runs out, rather than searching once already dropped.
- Transmit power that isn't cranked up. Counterintuitive, but full-power access points make devices cling to one they've long since moved away from, the classic symptom being a strong signal reading with no data flowing.
- Enough overlap. Around 15–20 percent between coverage areas, so there's always a next destination before the current one disappears.
Old devices dictate the design
Handheld scanners and warehouse terminals live a long time, ten years is unremarkable. Many support only 2.4 GHz and older Wi-Fi standards.
That means the network must keep offering 2.4 GHz, even though the band is narrower and more crowded. The differences are covered in the guide to 2.4, 5, and 6 GHz.
What to avoid is letting everything share one network. A single old device running at low speed holds up the queue for everything else on that band. The usual split:
| Network | Band | For |
|---|---|---|
| Operations | 2.4 GHz | Scanners, terminals, scales |
| Office | 5 GHz | Staff laptops, admin, cameras |
| Guest | 5 GHz | Drivers, couriers, visitors |
This split isn't only about speed. Warehouse devices rarely receive security updates, so they are better kept off the same network as administrative computers, see the guide to VLANs and the guide to separating guest networks.
Interference peculiar to industry
A few things rarely met in offices but routine in factories:
- Large electric motors and welding produce broad noise that never appears as another network in a scanner app, it shows up only as inexplicably poor signal.
- Cold rooms require access points rated for the temperature range, mounted to avoid condensation. Ordinary office units don't last long in them.
- Conveyors and moving machinery change reflections cyclically, making problems appear only during certain production hours.
- Thick concrete walls and metal doors between zones effectively cut the signal. Treat each zone as its own area rather than a continuation of the last.
Cable, not repeaters
The temptation to add wireless repeaters across a large warehouse is strong, because pulling 80 metres of cable is genuinely inconvenient.
But repeaters roughly halve capacity at every hop and add delay, precisely what makes scanners fail. For a warehouse, cabling every access point is worth the fight.
- The practical limit for LAN cable is 100 metres. A large warehouse therefore needs intermediate equipment cabinets rather than one central point, see the guide to choosing LAN cable.
- Use a switch with PoE so access points need no socket at height, see the guide to choosing a network switch.
- Provide backup power for switches and router. Power flickers are more frequent in a factory than an office, see the guide to a UPS for your router.
A sensible order to work in
Inventory the devices first
How many scanners, which bands they support, how many are active at once. This drives nearly every decision that follows, and it's often skipped.
Measure while stocked
Walk every aisle recording signal strength, on a normal working day. The weakest points define the design, not the average.
Design per aisle
Place access points according to the aisles that must be covered, with overlap at the ends for handover.
Test while moving
Standing-still tests prove nothing in a warehouse. Run real scans from a moving forklift, crossing the boundaries between access points.
Re-measure after layout changes
Racks get moved, stock turns over seasonally, new machinery arrives. An annual re-measure catches degradation before it becomes a complaint.
Closing notes
A warehouse isn't a larger office. Metal racking, high ceilings, and moving users make placement and handover far more decisive than the speed printed on the box.
Design along the aisles, mount lower than feels natural, cable every access point, and measure while the racks are full. For the office area itself, the ordinary approach is fine, covered in the guide to small office Wi-Fi. If the work is going to a contractor, the guide to choosing an installer lists what to ask.
