WN Podcast 013 – WiFi Design for Warehouse

Welcome to our new WiFi Ninjas Podcast episode!

In this episode Mac and Matt discuss at a high level how they design WiFi for the warehouse as they look to share their personal experience and tips with you.

Design recap (see episode 12):

  • Understand the purpose (data, high density, voice, scanners, etc.)
  • Capture success criteria (capacity, coverage, other RF elements, roaming)
  • Always go on site before and after (attenuation, RF condition, interferers, DFS, visual check)

Warehouse design challenges:

  • Often very high ceilings
  • Moving forklift trucks knocking off APs and antennas
  • Changing stock
    • Amazing WiFi during holidays season can go ‘tits up’ before Christmas
  • Changing racks layout
    • Matt can say something about it 😉
  • Changing requirements and purpose
    • Those scanners from 1999 might now be upgraded and need to support voice
  • Tons of obstructions
  • Legacy devices
    • Tendency to use old scanners forever
  • Weird devices (especially true for legacy ones)
    • Using specific channels only
      • 2.4 or 5GHz only
      • Limited 5GHz channels, in most cases UNII-1 only
    • Using specific data rates only
      • AP tries 54, fails, tries 48, fails, (…), settles on 2 Mbps – difficult to tshoot
    • Battery operated devices with failed implementation of battery saving mechanisms
      • Drops off
      • Doesn’t roam properly or quickly enough
  • Preferred authentication is often not supported
    • Security team crying about having to use PSK
  • Can be difficult to get to the AP or antenna if needed

Warehouse design essentials:

  • Choose the right antenna type for the job
    • Cover what needs to be covered
      • Coverage on the ground level, 15m up where the forklifts operate or both?
      • Propagation pattern
    • Reduce overlapping
      • Use the environment
      • Position antennas wisely
    • Environment can dictate antenna type
      • Omnidirectional won’t be great at 20m
      • Overlapping can be substantial with omnis in vast open spaces
      • Not always possible to put omni in the middle of the rack
  • Pick your AP wisely:
    • Cold or hot? Dust?
    • Internal or external?
    • Needs more ruggedness?
  • Think about the config:
    • Normally you’d have a different SSID for WH offices and WH packing / production / shifting
    • For WH offices design, listen to our previous episode
    • For WH production, keep it simple
    • Get to know the devices you design for – sometimes warehouses use very capable tablets or a mix or modern tablets and very old scanners
    • Roaming (quick one!) is extremely important
    • Can you / should you stick to PSK?
    • Can you / should you use just UNII1 and UNII2 channels?
    • Watch the Tx power and data rates
    • Will you survive on 20MHz? Normally WH capacity needs are low
    • Do you really need those bells and whistles for often very limited number of devices?
      • Bonded channels = more interference = lower SNR
      • RX-SOP can mean drop offs mid roam for stickier
      • Devices might not like 802.11v – clients don’t like to be disassociated and v sends client a proposition to associate with other best AP, followed by a threat of disassociation if STA doesn’t jump on its own and a big chunk of clients don’t support it
      • Devices might not like 802.11r at all or some flavour of it
    • Even old scanners normally support 802.11a and 2.4GHz is often noisy from both WiFi and non-WiFi interference; stick to 5GHz whenever possible
  • Mounting and positioning
    • Often very high
    • Few examples:
      • Patch or sector on the walls, covering entire or most of the aisle, tilted down, pointing towards the aisle’s end
        • Sometimes one AP per aisle is enough (up to 80-100m), sometimes two at both ends (more than 100m)
      • Patch or sector cone of coverage with antenna pointing down, antenna mounted to the ceiling, duct or suspended
      • Omni with external antennas pointed up or down, mounted to the wall, beam or column, away from the metal surfaces
      • AP/antenna placed in a heated or cooled Nema enclosure
    • Ensure basic AP redundancy – it’s not easy nor quick to replace one
    • Most important after coverage is no CCI / ACI and fast roaming
    • Ensure speeding clients, both human on forklifts and robots (have you seen automated warehouses yet?), are associated with the AP you want them to be associated with and that they roam where and when we want

Other standard considerations

  • Distance to the switch
  • PoE
  • Mounting restrictions
  • Obstructions, metal
  • Other networks
  • Interferers
  • Vendor choice
  • Architecture

Thanks for listening and please don’t hesitate to leave a comment, feedback, subscribe or follow us on social media.

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