Wireless access points in factories / warehouses

[carl_townshend]

Hi Guys

Just a quick question, I noticed in some of our sites the vendor chooses external access points in the factories with omni antennas aiming downwards, the ap is in a sealed box.

What would be the main reason for doing this vs using indoor access points and aiming them downwards? would be be mainly for ap protection in the harsher environment? or do the externally mounted omni antenna provide better coverage?

[Leo Laohoo]

Internal AP are always omni-directional.

Using external antennas is preferred in warehouse deployment because the signal "footprint" can be shaped.  As to why the vendor picked an omni-directional external antenna, I have no idea as to logic and decision behind it.  

[carl_townshend]

Hi Leo. do you mean the external omni's would not make much difference to having an internal ap ?

[Leo Laohoo]

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@carl_townshend wrote:
do you mean the external omni's would not make much difference to having an internal ap ?

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Depends on the design. 

Anyone who knows how to design the placement of the antennas will know whether or not omni-directional is ideal over directionals.  It all depends on the design and the design will determine which specific model of antennas to use base on the "shape" of the signal propagation.

[carl_townshend]

Hi Leo

What would the gain be having an external ap with omnis vs having an internal ap in the same place if only general coverage and not focused is required? would they pretty much cover the same area?

[Leo Laohoo]

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@carl_townshend wrote:
What would the gain be having an external ap with omnis vs having an internal ap in the same place if only general coverage and not focused is required?

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I cannot make any comment in regards to your warehouse. 

Traditionally, warehouses have aisle in them.  Designing with external antennas are used most of the time because the shaping the coverage area to go up and down the aisle is ideal (long and narrow).  Putting an omni-direction between the aisle just do not make any sense because the signal will propagate to the sides. 

Why would anyone want the signal to go to the shelves?  Are there any wireless client(s) on the shelves?  No, the clients are roaming up and down the aisle.

[JPavonM]

I guess this was done by a vendor with some lack of knowledge about wireless design in general, and warehouse in particular.

Using such APs with omnidirectional patterns could make hidden nodes to impact performance.

[Rich R]

The key to this is a proper site survey by a qualified wireless specialist who will select the correct AP/antenna according to the specific environment.  There is no single "right" answer.