WiFi Coverage for Bus Garage

[rharms]

I’ve got a challenging environment that I’m looking to improve Wifi coverage and capacity in.  It’s a parking garage for city transit buses.  The building is somewhere in the neighborhood of 240 feet across and around 600 feet long, but the flat roof is only maybe 16 feet high.  It’s basically a big, open space except for a concrete block dividing wall about 50 feet in from one end.  The 2 or 3 feet immediately below the roof are a jungle of steel roof trusses and ventilation ducts and such as that.  Buses park nose-to-tail in columns of four running down the center of this building.

Current WIFi coverage is seven MR45 access points which are arranged in essentially a horseshoe shape over top of the bus parking area.  It works, but that’s about all you can say for it.  Recently the vendor for another project did a rudimentary scan of the wifi coverage and pointed out some weak areas, so we are looking at options for improvement. 

Obviously MR45s were not the optimal choice for this environment to start with, so we’re looking at something more along the lines of the MR86 for replacement.  The primary users of the WiFi are the buses themselves.  They each have an onboard router with an 802.11ax 4x4 MIMO WiFi radio and a rooftop antenna.  Rooftop antennas means we need the best coverage in the 2-3 feet between the building roof structure and the tops of the buses.  Coverage down to the floor is good, but not really the priority.

Appreciate any suggestions.

[DarrenOC]

I would encourage you to utilise the services of a wireless consultant to carry out a wireless survey.  Simply changing the specification of the AP isn’t going to address your issues.

[rharms]

Yes, I know.  I'd love to bring in a consultant to properly study the situation and plan out a solution, but, at present, that's not really an option that is available.  I just have to try and do the best that I can.  

[PhilipDAth]

As a rough guide, and assuming you are using omni antennas, I would allow for an AP per 400 m^2 to get "good" solid reliable "fast" coverage.  You have 13,104 m^2 of space to cover - so I would allow 32 access points.

I would be looking at APs with a coverage pattern that you would use in an office (coverage goes out horizontally, but not much vertically).

In your case, I would rather have twice as many lower spec APs (because of the HUGE area) rather than a smaller number of high spec APs.

I particularly like the sound of the MR78.

https://documentation.meraki.com/MR/MR_Overview_and_Specifications/MR78_Datasheet 

If has nothing sticking out (antennas are internal), IP67 rated, but it is only 2x2.  I bet you would get higher throughout by having a lot more of these, as opposed to half the number of 4x4 APs.  I like the idea of "nothing sticking out" in such a public space (less likely to be vandalised).

Otherwise, if the budget permits, the MR86 would be excellent.  I would probably go with the cheap omni antennas, MA-ANT-20.

https://meraki.cisco.com/product-collateral/dual-band-omni-antennas-4-7-dbi-datasheet/?file 

However many APs you think you need, I would get more.