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Contributor I

Questions about using VisualRF to model APs in a large Warehouse

Greetings,

 

I am trying to create a design for installing APs in a large warehouse.  I have never tried to do this for a warehouse before.  I see that the true downtilt APs are 105s, 135s, and 225s.  I am modeling 105s and 135s.

 

In this location the ceiling is 10 meters high, and the dimensions of the space are approximately 400' x 1,000'.  We are able to run Cat5/6 cabling to all APs so we don't need to Mesh.  I need to provide support for a/g/n clients, including the motorola handhelds which have a max output of about 20 dBm. 

 

In practicing with VisualRF, there is a dramatic affect in moving the Environmental Slider back and forth.  I am unsure whether to place it farther to the left for more open space, or farther to the right for more walled space to account for the shelving and stored items.  Dependig on which way I go, it changes from predicting maybe 26 APs for this space, to maybe 340 total APs ( all when designing around a -70 signal strength.)

 

I have read the VRDs, the stuff by Chuck Lukaszewski, and that Barcelona report.

 

So I guess my questions are,

1)  Is there a Best Practice for where to set the slider bar for space allocation for VisualRF warehouse design?

2)  Is there a Best Practice for designing around coverage speed vs signal?

3)  Should I scrap VisualRF and just put an AP 105 every 75-80 feet down the first row, then skip a rows while alternating or staggering the AP locations on the remaining rows till done?

 

Thank you in advance,

William

 

Re: Questions about using VisualRF to model APs in a large Warehouse

Have you drawn concrete walls down the aisles?  The warehouse design suggestions from Chuck are spot on.  

 

I will let others comment about the slider...but I have had good luck with drawing this wall to show predictive coverage...

 

I would also recommend the APs mounted in the aisles, not at the ends. I would use an alternating pattern of every other aisle.

Seth R. Fiermonti
Consulting Systems Engineer - ACCX, ACDX, ACMX
Email: seth@hpe.com
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Contributor I

Re: Questions about using VisualRF to model APs in a large Warehouse

Adding concrete walls to simulate the shelves/aisle is a good idea.  That was helpful.  VisualRF still does not reliably predict correct AP placements, even with the walls drawn in.  I got an eval copy of another modeling platform and it does a slightly different job, and does account for the walls, but one has to tweak it a bit to arrive at even roughly similar AP counts as VisualRF resolves (still predicts over twice as many APs as VisualRF for the same environment  with the same variables.)

 

The design guides do a good job of offering hints for avoiding some common pitfalls, choosing the right APs/Antennas, etc., but no real insight into AP placement. 

 

 

What I got from the guide is:

Assuming a 20 db loss, coverage radius is typically 60-80 meters best case.

Coverage at the top of a 10 meter shelf will be lost likely prior to the 4th row over.

Coverage at the bottom of a 10 meter high shelf will be lost likely prior to the 2nd row over.

Use a lower gain downtilt Omni to limit AP-AP Arm conflicts causing tx power reduction resulting in reduced RF coverage at floor level.

Use a lower gain downtilt Omni can limit ground coverage range to a predicable area, but without a site survey there is no way to predict what that predictable area will be.

Basically go WAG it, and maybe over-saturate APs, and just let Arm work out the problems the lack of design fundamentals caused.

 

Or:

|-------------------------------------------------------------------------------|                                                                                             

|           AP              AP                                                          AP       |

|       ||       ||        ||                                                                             |

|AP  ||       ||  AP ||                              AP                                          |

|       ||       ||        ||                                                                             |

|       ||       ||        ||                                                                             |

|       ||  AP||        ||  AP                                              AP                   |

|       ||       ||        ||                                                                             |

|       ||       ||        ||                                                                             |

|AP  ||       ||  AP ||                             AP                                           |

|       ||       ||        ||                                                                             |

|           AP              AP                                                              AP   |

|-------------------------------------------------------------------------------|

Re: Questions about using VisualRF to model APs in a large Warehouse

With are warehouse, you have a lot to take into considerations. For example, if there are aisles, how high is the shelving? Are the shelves metal and what is on them? These questions pertain to reflecting RF and causing gaps in coverage. 

 

To try and answer your questions, I would do the following:

 

1. Draw concrete walls on the shelving in each aisle to simulate RF interference.

2. Set slider around 3, technically it is open space, but you will have interference due to shelving and other stuff in the warehouse

3. Regarding signal vs coverage, I would try to have all green coverage (-65) with no yellow (-55) touching in order to prevent ARM from adjusting signal strength or AP power. 

4. As a best practice, I would not put more than 1 AP per aisle, and I would try to keep the APs from being in a straight line.

 

I would say that is going to be a relatively accurate and well covered RF plan for a warehouse. 


Thank you.

Michael Haring | AIS Consultant
Architecture and Implementation Solutions
Optiv Security Inc. | www.optiv.com
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