Cisco 1242_AP + Patch antenna's for warehouse?

[johnny_5]

Hi there,

I’m looking for some input/recommendations for upgrading/improving my current wireless system in the warehouse. I have attached a building outline with dimensions to give you a better understanding.

We currently have 2 Cisco Aironet 1240 AP(1242’s) that each have 2 AIRNET 1728 Omni-directional antenna attached(2.4 Ghz, 5.2 dBi) to each. I have been receiving a lot of complaints lately from the warehouse staff. We use RF scanning guns (ground only) that authenticate to the AP’s for our Oracle applications. Complaints range from guns freezing, having to re-connect, and moving to another location to get a signal.

I’m guessing the initial install of AP’s worked fine because there wasn’t as much stock – currently all the racks are full to the top on the daily basis.

I don’t believe the Omni directional antenna is a suitable solution to the problem. I was thinking of using 5-6dBi patch antenna’s placed on wall (marked X on the diagram) with similar Cisco 1242’s and utilizing their directional antenna gain down the isles on different channels. Unfortunately due to budget constraints the 1242’s are what I have on hand right now.

Has anyone had any similar experience with designing a solution for “pushing” signal gain down warehouse isles(metal)? Thanks in advance.

[Scott Fella]

The better solution might be to use both sides and have AP's 2 on one side and the other 2 on the other alternating.

Thanks,

Scott

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[Scott Fella]

Like this

Thanks,

Scott

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[johnny_5]

Scott Fella,

Thanks for the quick response. In the revised document you sent back, would you suggest leaving the current 2 AP's in the their place or remove them completely?

Also what is reasoning behind staggering the AP's? 2 on one side and 2 on the other? I was going to manually set the channels to 1,6,11 & 1 with them on the same wall.

[Scott Fella]

You still need to move those others to a location that can provide additional coverage. The reason to stagger is that you don't wan time end to have the strongest signal. If you stagger the AP's, you can provide good coverage on both ends. This is typical of how I would deploy with patches and works good. I can take a look at the other two AP's and suggest where I would put them, but is the top the only section with racks?

Sent from Cisco Technical Support iPhone App

[johnny_5]

Got ya...I figured myself that re-using at least one of the existing AP(aisle AP) on the wall and maybe leaving AP1 at its current location - that open area is almost 35' X 150' and works quite well(no complaints). Although I have heard that the 1242 I have with the omni directional antennas get approximately 100'- maybe I should add a second one here in this location?

My primary concern though is the isles as this is where the problems lie. The racks themselves are made of metal and go from the ground up 8' wide X 25" High. A typical fork lift can remove inventory from either side of the rack.

Do I need to be taking into account Horizontal and Vertical Beamwidth? The RF guns are only used on the ground to read barcodes, so I'm guessing 10 feet off the ground should suffice?

[johnny_5]

Scott Fella,

I thought I would give you a more up to date diagram. Your staggering would have worked only we ran out of wall on the right hand side! The most we could get is one unless we decide to take them back further (another 30 Feet). However as you can see from the the diagram shaded in orange, the extra 30 feet is open (no walls, small ops) and is being rented by another company that uses an Aruba 105 AP. We can still place our AP's on the that back wall as we own the building, the Aruba hasn't being installed yet and I don't know off hand what their using  a/b/g/n.

Its never easy!

[Scott Fella · Accepted solution]

This is what I would do.... the other AP can be dropped down to a small board that the AP and the patch can be mounted on.  Installers do this all the time, this way you can have the staggered patch setup.  I would also move the other two into the open area.

Thanks,

Scott

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[johnny_5]

Thanks for the suggestions. I am in the process of completing a proposal for my department...Would you have any recommendation about setting the height on these AP's or is there a way to calculate the antenna placement based on dBi or bandwidth?

[Scott Fella]

Every warehouse/manufacturing has a minimum height above finish floor.  On the wall's, I would put them 15' - 20' depending if there are any obstructions.  The ones that you can drop from the ceiling, will have to be at the height that is allowed for that area.  There is no calculator to calculate the bandwidth, but usually you can determine the signal by a survey.  You should be okay though with the 1242 and the antennas that you use.

Thanks,

Scott

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