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Interference due to Metal walls for Wifi signals

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  • 1.  Interference due to Metal walls for Wifi signals

    Posted 2 days ago

    HI, I am doing the wifi coverage simulation for offshore facility where all walls are made from metal. I would like to know what are the main things I should consider to avoid interference and reflection due to metal walls as wifi signal may get reflect due to metal walls. As this is the new offshore project, I cant do real simulation so I am using wifi coverage tool Ekahau for this.



  • 2.  RE: Interference due to Metal walls for Wifi signals

    EMPLOYEE
    Posted 2 days ago

    Don't rely on APs in hallways/corridors to service users inside rooms on other side of metal walls. Put APs where your users expect service.




  • 3.  RE: Interference due to Metal walls for Wifi signals

    Posted 2 days ago

    Thanks but We cant place the access point in each room as there are many room in the offshore facility.

    What about the refractions due to metal walls? How to consider them during simulation?




  • 4.  RE: Interference due to Metal walls for Wifi signals

    EMPLOYEE
    Posted 2 days ago

    Unless you've tested the behavior and/or are planning on doing an actual survey, then plan on the walls providing zero RF penetration.

    Which is just another way of saying what Josh already did: "put APs where your users expect service".



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    Carson Hulcher, ACEX#110
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  • 5.  RE: Interference due to Metal walls for Wifi signals

    EMPLOYEE
    Posted 19 hours ago

    You cannot expect Wi-Fi signals to penetrate metal walls, particularly thick steel, which I expect is used in an offshore/rig type facility.There is no 'magic wand' to break the laws of physics; each room in the facility will essentially be a faraday cage, so you will need to deploy many more access points due to the metal construction and resulting signal attenuation.

    I'd suggest using the 'elevator shaft' wall setting in your Ekahau simulated design, I believe this has an attenuation factor of 30dBm. If possible, and you have access to a similar facility, I would recommend measuring the actual wall attenuation, as per Ekahau best practice:  https://www.ekahau.com/blog/how-to-measure-wall-attenuation-for-spotless-wi-fi-network-designs/

    It is now standard practice in hospitality to install an AP in each room in a hotel and this is certainly the approach you will need to take. We deploy large networks in Cruise ships and this is the same scenario. Consider using the Aruba AP503H and/or AP505H, these are specifically designed for in-room deployments. https://www.arubanetworks.com/en-gb/products/wireless/access-points/remote-hospitality-access-points/500h-series/

    The good news is that you will encounter very little co-channel interference, as each room will be isolated from other Wi-Fi signals! :-)




  • 6.  RE: Interference due to Metal walls for Wifi signals

    Posted 18 hours ago

    Hello Derrel, Thanks for this detailed explanation and for enhancing my knowledge about AP implementation. 

    One thing I would like to know about the reflection of RF signal due to metal walls. Which parameters I should consider while performing predicate coverage as there will be chances that wifi signal may bounce back due to metal walls and degrade the wifi services in specially in offshore or rig facility. 




  • 7.  RE: Interference due to Metal walls for Wifi signals

    Posted 16 hours ago

    If you could share (a part) of a floorplan, with dimensions, it may help to get a better idea what you are looking for.

    In most cases, reflection is not the primary problem in ships/offshore, more the blocking of the metal. Consider no or very limited coverage behind a solid metal wall, for other metal object like pilars, engines, the walls may even help to reflect around such objects. For small rooms, with all metal walls, the idea is really simple: one AP per room; and add corridor coverage if you need roaming from room to room/outside where in case of metal hallways/corridors, I would put the APs at corners and crossings probably to avoid a sudden drop in signal when you move around a corner. Note that this is specific for the corridors and in addition to the rooms. For larger spaces the approach may be somewhat different, but as signals bounce back instead (metal) of being absorbed (normal walls), you may need the same or fewer APs, but take into account shielding of objects in that area.

    Also the requirements on capacity, reliability, performance, all should be considered. If the WLAN system is used for emergency alarming (typical application on rigs), or push-to-talk/voice (as cellular may not work offshore), the design may be completely different.

    Sounds to me like a pretty advanced design, where you may try to find someone with proven experience in these types of environments. If you are experienced, understand RF signal propagation (physics, theory and/or practical), and just the metal is new, you may be good with the information shared already.



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    Herman Robers
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    If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
    ------------------------------



  • 8.  RE: Interference due to Metal walls for Wifi signals

    EMPLOYEE
    Posted 14 hours ago

    Hi Harsh, I wouldn't be concerned with the high-level of signal reflections you will most certainly encounter. Firstly signal reflection/refraction is actually used to the benefit of the wireless connections by MIMO technology (introduced in Wi-Fi 4/802.11n). 

    Also, you will be deploying APs with very-low user density and very-low co-channel interference, due to the isolated nature of the metal rooms, and therefore any adverse effect of the signal reflections will be minimal. 

    I don't believe you need to take any special measures or precaution in your network design to account for the high-level of reflections inevitable with your deployment. Wi-Fi deployments are commonplace on large ships, oil-rigs and similar structures, with no issues.