Beamflex causing roaming problems with warehouse devices

[jeff_roback]

We’re having a really tough time getting 25 R610’s working in a warehouse environment with Vocollect (Honeywell) T5 devices that are used by the warehouse personnel. After a lot of investigation, review of logs, and packet captures it appears that the issue is around the T5 devices misreading the signal strength of the AP’s and staying on ap’s with poor coverage. The T5 devices are deigned to be used by operators that are driving forklifts around a warehouse so they are extremely sensitive to changes in the RF environment, always looking for a better ap.
Unfortunately they are using the AP beacons to read signal strength, so even if they are connected to an AP with great coverage, when they see a beacon from that ap with a weak signal, so when they see a beacon from an AP that physically does have good coverage but shows as having a weak signal, they assume the operator has moved from that AP and they imediately scan and jump to another ap. This process seems to repeat over and over again, resulting in a terrible experience for the client devices. These T5 devices do use older 802.11 b/g radios, and the newer devices like ipads, iphones, androids and laptops work great. Unfortunately the T5 devices are mission critical so I need a way to get them working reliably. Before Ruckus was in place, the warehouse was using Ubiquity access points, which worked great for the t5’s, just not for anything else... So we’re kind of stuck now... overall it seems like both the Ruckus and the T5 devices are trying to independently solve the same problem but they’re conflicting with each other resulting in terrible device experience. We’ve tried just about every configuration change possible including adjusting signal strength up and down, changes to power management mode on the devices, forcing b, forcing g, bss minrate, smartroam, changing roam thresholds on the device, etc.... but nothing seems to get the devices to believe the rucks signal is as strong as it actually iis because the beacons show lower strength. Does anyone have any experience with client devices that are using beacons to identify signal strength, and have any strategies to prevent them from getting confused by beamflex? Vocollect/Honeywell has asked if we can turn off beamflex, but it seems like that’s built in to the hardware and not changable. I have opened a case with Ruckus tech support but haven’t been able to get past the “Just reboot It” stage... I don’t think they understand we have a fundamental problem with the interaction of the devices and beamflex. Thanks for any thoughts....

[tom_pisacic]

Hi Michael,

thanks for the fast response. U I have been looking before, unfortunately there is no place to put APs anywhere but to the ceiling.

How does 7782 omni works in this kind of environment? Does it work fine in the way we do not need APs with directional antennas?

Aisles are approx. 6-7ft wide and the metal racking is around 40ft high.

[michael_brado]

40 feet high is not close for your wifi clients.  I think you would benefit if you could bring any APs down to, or install a couple new APs, at floor level, at alternating opposite ends of your rows of racks.  This is our typical approach for improved warehouse coverage.  And yes, sectional antenna APs that focus energy just down the aisles might provide somewhat better coverage, than an indoor omni (ie 7982) alternative. [ You may find the EoL 7982s for sale at very low prices, to add to APs over bringing any down from your ceiling. ]

[tom_pisacic]

What about the tx power on 7782 APs? I have been trying to find some useful documentation which would help me to configure my controller and APs specifically for this kind of environment but could find anything. 

Before I had all channels and TX power set to Auto and was experiencing more issues than now. Are there any options on the controller which I should turn off/on, tweak them?


I was told that this type of APs are not just an omni antenna but 'smart" omni antenna, and there is no need for sector deployment as these APs can focus their signal in the direction of the client. (told by sells person). 

thanks for your reply!

[michael_brado]

Leave TX power at Auto, which will be 100% of AP radio + antenna gain.  We use BeamFlex to direct energy back to connected clients, instead of radiating in all directions, which helps improve customer signal strength and reduce co-channel interference.

You need to Site Survey your current environment to really see what coverage you have, or where you might need more.
It is recommended to have some APs at ground level, at alternate ends of different rows, to augment your ceiling AP coverage.

[tom_pisacic]

I have done site survey with Ekahau and Sidekick, and so far SNR (not lower then 20), signal strength looks to be in specs (not lower then -67dBm).

We had TX power set to auto, and had a lot of channel overlap in most of the warehouse. That's why I have been playing around with TX power. Channels were set to auto as well (channelization to 40 by default on both bands).
At that point, WiFi card on the Citadel would loose connection, RED X showed up on the WiFi icon and only fix was to reboot the unit.

After I have done changes and configure channels, channelization set to 20, tx power manually set, there is no issue with the RED X but during a day, operations would experience issue with 'page cannot be found' in the web tool.

Recently, I ran a script to see what happens with the signal from the cilent side, and noticed my cleints would roam to an AP with lower signal. For instance, it would be connected to the AP with signal of -55dBm and it would roam to an AP with signal of -77dBm.

why would a client do that? the Roam Aggressiveness on a client is set to Medium.

thanks,

Tom