Post Deployment Wireless Site Survey
A few days ago I conducted a wireless site survey for a Warehouse for a coffee trading company in Auckland. The motivation behind this was due to the some poor signal reports and coverage in some aisles.
The list below summarises the key findings:
- Good overall coverage of signal especially around the corners and in the small office areas.
- Survey revealed a few coverage holes on both the radios.
- FortiAP-U421EV 4×4 MU-MIMO with dual radio with 802.11ac wave 2 APs installed.
- The warehouse environment will rarely be same everyday (items in the rack are stacked and unstacked regularly). This amount of variation needs to be taken into consideration.
- The survey highlighted several aspects that requires improvement. There were areas where the signal strength needs to be improved by adding new APs or directional antenna’s. There are internal Wi-Fi interference’s, issues with devices roaming between access points and low data rates due to older protocols (2.4GHz) being supported by the handheld devices.
- Challenging and dynamic environment with high ceilings (Approx. 14 meters), high racks (9meters) and various stocks with different attenuation characteristics makes usage of omni directional antenna not practical.
- Existing JDE Wi-Fi deployment utilises both 2.4 and 5 GHz bands but the APs operating on 2.4 GHz are configured with low power levels (6mw) that can provide insufficient coverage to the clients as the wireless scanners are operating on 2.4GHz. On the contrary the AP operating on the 5 GHz band have high power level set to25mw which might help for 5GHz clients but could also lead to co-channel interference.
- Clients have reported wireless signal drop outs moving between the aisles especially between AD and AE. AE aisle only has one AP in the far corner leaving the clients in the aisle,which may have roamed from other aisle to stick to the previous AP before handing over the connection to AP3 in the aisle. Racks in this aisle are tall and sometimes could prove difficult for the signal to penetrate through other aisle AP.
Recommendations for the Warehouse:
- Increase transmit power levels on AP on 2.4 GHz radios to 11/13mW for better coverage
- As the Handhelds use2.4 GHz, it is suggested to install additional AP in aisle AE, which will boost the overall, signal strength and help with issues.
- Consider installing directional antenna AP. FortiAP-U421EV does not come with external antenna so will need to upgrade to FAP-U422EV.Directional antenna help focus the signals especially in an environment likethis.
- Check firmware version to be latest/known good for scanners/WLAN controllers and AP.
The site survey was conducted using the following tools:
- Ekahau Site Survey Pro 9.2.2
- Ekahau Sidekick
- Dell Rugged Latitude 720.
Learning from this site survey
- FortiAP do not share the AP name in their beacon which did not show up on the ekahau site survey.
- I had to merge the 2.4GHz and 5GHz radio on the AP as they were seperately placed by Ekahau on the map. Ekahau have confirmed that their future release will improve this.
- Speak to the client, understand their issues. Most of the times understanding the client’s point of view can help provide better conclusions on the reports created for them.
- Omni Directional antenna are not suggested for high ceiling warehouse type environment.
- Always highlight what is good about the site first before jumping on the improvements.