An unusual design challenge
We design wireless networks in-house using more than 15 years of engineering experience. Wi‑Fi now serves far more than offices and cafés, and some sites present unusual challenges.
Integrators such as CROC or Jet can design office Wi‑Fi using Cisco or HPE Aruba, which remain available, or alternatives such as Eltex and TP-Link. Established approaches include selecting 4×4 rather than 2×2 MIMO access points for high-density areas and installing two controllers in a 1+1 redundancy arrangement. Planning seamless coverage for a mine with complex terrain and a large mobile equipment fleet presents a different engineering challenge.
Our latest task is a Wi‑Fi network for a robotic warehouse at a large dairy processing plant. Its client devices are 3D shuttles, each carrying one pallet. Unlike shuttles limited to one horizontal path, they travel along racks, enter storage channels, and use lifts to reach other mezzanine levels.
Shuttle movement must remain continuous. Because the warehouse robots are coordinated over Wi‑Fi, the operational network is critical to production continuity.
Why milk is a challenge for Wi‑Fi
The network must account for several requirements:
- Client devices are constantly moving;
- They exchange data continuously with the warehouse management system (WMS), which assigns pallet retrieval and transport tasks;
- Coverage must reach every storage tier and channel, not only the aisles, regardless of stock levels;
- The network should provide seamless roaming for shuttles.
We are familiar with proprietary roaming algorithms in specialized equipment from Moxa, Altai, Doublecom, and other manufacturers. We have tested them repeatedly when building Wi‑Fi networks with mobility support.
Coverage requires particular attention. For a Wi‑Fi signal, a warehouse full of milk is more than a collection of racks: it is a continuous wall of obstacles. Milk is 87-90% water, which strongly absorbs radio waves at 2.4 GHz and 5 GHz by converting their energy into heat — the same principle used by microwave ovens. Passing through tightly packed milk cartons on pallets, a radio wave loses substantial energy and experiences significant attenuation: it effectively “sinks” into them. Dense product storage and high water content create a shielding effect an order of magnitude stronger than dry goods such as electronics or clothing. We know this from theory, but it must always be tested.
Laboratory approach: 100 packs of milk for planning accuracy
Even brief disconnections can stop logistics operations when 3D shuttles move across mezzanine levels. Standard obstacle models in Ekahau RF planning software are insufficient for this environment. AP-on-a-stick measurements are also unavailable at this stage because the racks are not yet stocked.
We bought 100 cartons of milk for laboratory tests to estimate signal attenuation through the actual product.
This is a practical engineering test rather than a scientific study. We cannot fill the laboratory with dairy products, and precise measurements would require an anechoic chamber with walls absorbing 100% of RF energy to eliminate reflections, as used for antenna pattern measurements. Even in an office environment, however, we can obtain an estimate suitable for Ekahau modeling.
We used a narrow-beam antenna with no sidelobes to minimize wall reflections and assess attenuation through a wall of milk cartons. The measurements enabled a custom obstacle model in Ekahau based on the actual absorption of a milk pallet.
We will share results after deployment, subject to the NDA and a post-installation audit. Coverage will be measured from the shuttles’ perspective, rather than only with an Ekahau Sidekick, alongside roaming and connection stability tests. Findings will enter our internal wiki and practical knowledge base for future projects.
Connectum designs and validates Wi‑Fi for offices, factories, and warehouses with a wide range of stored products.
Contact a Connectum engineer to discuss Wi‑Fi design for your warehouse.