I would rather even try a focused radio over the concrete walls
before that..
They are concrete floors, like 5 floors of them, and the concrete underground carpark extends beyond the building perimeter, plus various metal shielding, the building is practially faraday cage.
Forget any RF solution.
I would not say that in the 2020s ...
Any folk here aged enough to actually have the experience before the 90s..
pretty much can put things in a rather different way.
You probably lived the time BEFORE "The Internet" like me. And you know
how things were done before forums.. links ... fupedias and downloads..
Spoiled newbies post 90s have no idea of that.
I my case I started being a TOTAL TV junkie in the 70s.
By 80s I had a daily activity repairing TVs, VHS etc..
But also as part of the junkie stuff I was an avid collector
of the stuff from these folks here
http://www.antennaeletronica.com.brhttps://translate.google.com/translate?sl=auto&tl=en&u=http://www.antennaeletronica.com.brThey are/were in the HAM and TV buz since 1926.. and I have a TON
of their publications .. mostly articles for TV junk repairman and
Antenna widely important tips.. FLYBACK converters tons of important
things in the TUBE and all discrete days.. impossible to understand
wo such help..
Invaluable and absolute impossible to describe.
Nothing compares to post 90s as the Internet took over all things.
One thing I have learned from the time (70/80s) I was deeply
doing hard Antenna stuff (like weak VHF and UHF signals impossible
analog reflections.. crappy boosters):
- NEVER never ever gave up before trying
- NEVER ever gave up on the first or second assemble
- Always consult folks w/experience in the area..
Typical in your case
* 4 or 5 walls of concrete can be easily done with highly directional dish antenna
* Signal attenuation for typical concrete is around 12-15 dB in the 2.4 GHz band
* Yagi antennas can provide gain around 12-15 dB just that...
So.. without directional antenna you can hit two walls.
But with a proper focused directional dish you can have more than
25 dB of gain around two concrete walls... or more transparently
Modern small dishes in 2.4 GHz band with boosters
can put you above the 4 concrete wall easily w/a decent
noise floor..
Should be not that expensive today.
Main problem is to ask permission to install that whole crappy hardware.
https://www.ui.com/airmax/litebeam-ac-gen2/will give you straight 26dB of gain without the radio booster.
We are no longer in the 80s or 90s .. and ALL STUFF IS DIGITAL.
so expect highly efficient dedicated signal processors in which
this case are required..
Your solution is a MULTI PATH BOOSTED DISH setup..
the lower range the better.. above 2.4 GHz attenuation is too high..
https://mikrotik.com/product/RBLHG-5HPnD-XL27 dB out of the box per less than 100 bucks..
BONUS.. the stuff is all yours and removable any time..
not the case spending in CAT6 or fibre stuff on walls..
By 90s ahead I was totally spoiled by The Internet and
stopped all CRT TV stuff dedicated myself since then
full time to PCs and network gear.. including that kind
of setups.. repairman became a hobby..
But stuff remains in the blood..
Paul