Scanners dropping out halfway down an aisle, forklift terminals that freeze at the dock door, and a heatmap that looked fine on paper. If that sounds familiar, the problem usually isn't the access points themselves — it's where they are and how they're aimed. In this blog, we'll walk through how to find and fix Wi-Fi coverage problems in warehouses and other large sites.
Most of the warehouse networks we're asked to look at were designed like an office: ceiling omnidirectional APs in a neat grid. That works over an open floor. Down a 40-metre aisle of full pallet racking, the signal from the AP two aisles over simply doesn't make it to the scanner.
The other surprise is seasonal. A site surveyed in a quiet month, with half-empty racking, can look healthy. Come peak season the shelves are full, the attenuation goes up and the same network starts dropping out.
Start with evidence, not opinions. Collect the device models and their transmit power, ask where and when drops happen, and walk the site with a survey tool and the actual device your staff use. A ticket that says "Wi-Fi is bad in aisle 12 after lunch" is far more useful than "the Wi-Fi is slow".
We think like the client device. The least-capable, most-important device sets the standard, and in a warehouse that's usually a handheld scanner or vehicle-mounted terminal. Find out what it supports (2.4GHz only? which 5GHz channels?) and how loud it can transmit.
Then compare what you measure against what the design intended. An active survey walked along every aisle shows primary and secondary coverage at device height, not at the ceiling where it was modelled.
Pro-Tip: Ask for drop times as well as locations. Drops that line up with deliveries or shift changes often point to doors, vehicles or stock movements rather than the APs.
The most reliable fix for aisle coverage is to stop shining omnidirectional APs down from the roof and instead aim directional patch antennas down the aisles. Mount an AP at the end of an aisle, tilted down around 15 degrees, and alternate ends on neighbouring aisles so each one gets a clean signal.
Long aisles need more. On 5GHz, aisles longer than about 30 metres usually need an AP at both ends, or back-to-back APs mid-aisle on alternate aisles (watch for a hole directly underneath).
Placement matters as much as the antenna. Stand APs off two to three metres from the aisle entry so forklifts coming out with forks raised don't hit them, and mount on the front of girders with a stand-off rather than behind them, where the steel blocks the signal.
Low-level pick areas and open floor are different again. Omnis on drop poles, or wall-mounted patches about 20 metres apart, generally beat a high ceiling grid there.
Roaming drops happen when a device moving between aisles loses its current AP before it finds the next one. The fix is overlap at device height in the areas people move through, a short list of channels for the device to scan, and power levels that match the device rather than the maximum the AP can manage.
The AP should transmit at least 3dB quieter than the client. If the AP shouts and the scanner whispers, the scanner hears the network but the network can't hear the scanner — that's the classic "full bars but nothing works" complaint.
Channel scan lists help too. Many handhelds scan DFS channels slowly, so restricting the device to the channels you actually use speeds up roaming. Our post on DFS channels explains the trade-off.
A fix isn't finished until it's tested with the real devices, in real conditions. That means an onsite survey before cabling (we call it an AP-on-a-stick survey), then a validation survey after install, ideally with the racking as full as it gets.
In a warehouse the onsite survey is close to mandatory. Mounting heights, girders, lights and stock all change the result, and moving an AP after it's cabled at 15 metres means an elevated work platform and a second visit. Adding one AP after install typically costs far more than planning it in.
Record mounting height and downtilt for every AP so whoever maintains the site later knows what "right" looks like.
Survey with the actual scanners at working height, then replace high ceiling omnis in the aisles with directional patch antennas aimed down each aisle, add APs at both ends of long aisles, set AP power below the client's, and validate with stock in the racking.
Stock absorbs and reflects radio signal. Full racking adds a lot of attenuation compared with empty shelves, so a network surveyed in a quiet month can fall short at peak. Design and validate for the fullest racking you expect.
Not everywhere. Omnis on drop poles work well over open floor and low-level pick areas. They struggle down long, full aisles, where directional antennas mounted at the aisle ends give much more even coverage.
Warehouse APs are commonly mounted between 11 and 19 metres, but what matters is coverage between the floor and about four metres, where devices are used. Lower mounting on drop poles or racking ends often gives better results than the roof.
Warehouse Wi-Fi problems come from racking, height and a changing environment, so the fix is a design built around the device and the aisle: directional antennas where stock blocks the signal, power that matches the client, overlap where people move, and a survey with the racking full. Get those right and the scanners stop being the bottleneck in your operation.
Our Wi-Fi survey and design team has designed and validated wireless for warehouses and distribution centres around Australia — see our warehousing Wi-Fi page or run the free AP Estimator. If that would be useful, get in touch with the IPTel team or email sales@iptel.com.au.