WAN over WiFi with public IP

[Michael Durham]

A design question...

We have one main building and four close remote buildings at our location.  At the main building will be getting AT&T business fiber optic 50Mbps connection with 24 static IP addresses. One of the remote buildings is close enough that we can run an Ethernet cable to it.  However, the three other remote buildings are too far for Ethernet but well within WiFi range.

Here is the problem, we need each remote building to have a public IP address that will be provided by AT&T delivered to the remote building's router.  Most likely the remote building's router will be a LinkSys or other store bought router.

AT&T provided Cisco 1941 router --> Our Cisco 3750v2 switch ---> 3750v2 Switch --> user equipment
                                                                                                  ---> WiFi bridge/router --> WiFi bridge/router -->LinkSys -->user equipment.
                                                                                                  ---> WiFi bridge/router --> WiFi bridge/router -->LinkSys -->user equipment.
                                                                                                  ---> WiFi bridge/router --> WiFi bridge/router -->LinkSys -->user equipment.

We are planning on using two WiFi bridge/routers for each location and a mix of 2.4Ghz and 5Ghz so they do not step on each other too bad.  All WiFi bridge/routers will be located outdoors.

Remember, the LinkSys MUST have a public IP address on its WAN side.

What equipment, Cisco or non Cisco, do you suggest to meet our needs?  We do not need more than 50Mbps transmission speed as ONLY internet access will be on the WAN WiFi network.

Also, we prefer to stay with older equipment to save on costs.

[Haydn Andrews]

you can look at a WGB to do the backhall between the sites.

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/service-set-identifier-ssid/211293-Configure-Work-Group-Bridge-WGB-Multip.html

[patoberli]

Use a fiber cable between the buildings, not a copper based one, or your destroy the network equipment!
The rest should work with WGB if the distance is fairly short. Otherwise I'd use specialized outdoor wireless (not Wi-Fi) equipment to bridge the sites. This always requires a free line of sight!

[Michael Durham]

I have a Cisco 3945 router with IOS 15.2 and want to know if these items will meet my needs or do I need different models. 
     NME-AIR-WLC1-K9 and the SM to NME adapter
     AIR CAP3502E-A-K9
If they will work, what else will I need?  Antenna recommendations?  One connection must go a half mile but there is no obstructions between the two sites.  No trees or buildings.

If these will not work for me, what models will?  Keeping costs to a minimum.

[patoberli]

Half a mile is a very long range for Wi-Fi. I don't have experiences with "long ranges" and can't really say if that would work or not.
As far as I know, Cisco doesn't really have specialized equipment for this (which would work when it rains or snows, something where Wi-Fi typically has big issues), so I list a few alternative products for "Wireless Bridges":
https://www.ui.com/products/#airfiber
http://www.tw-wireless.com/Outdoor-MIMO-WiTDM.html
https://wifigear.co.uk/blog/linking-buildings-point-to-point-wireless-guide/
Please note that I don't have any experience with any of those products. From friends I hear that specialized bridges are MUCH more reliable than Wi-Fi site-to-site links. Of course it should also work over Wi-Fi, but it's simply not designed for that.

Maybe somebody else will also chime in, with more experiences in this are.

Regarding your listed products, I would probably convert the 3502 to Autonomous, then you don't need a WLC, but must configure every AP directly. I think this might be better for this setup.
Oh and you should have a laser(pointer) ready to setup the antennas, they need to be pointed very exactly. Also because it's outdoor, make sure you use correct lightning protected mounting materials, better yet, use an electrician to do the whole installation.