Comreg have produced a national ourdoor mobile coverage map

https://coveragemap.comreg.ie/map

What is the Mobile Coverage Map?
The map currently shows ComReg’s predicted mobile outdoor coverage across Ireland and at specific addresses and/or Eircodes selected by consumers for all Mobile Service Providers - 48, Eir, Lycamobile, Postmobile, Three, Tesco Mobile, Virgin Media and Vodafone.

https://coveragemap.comreg.ie/faq

The evolution of mobile technology and what is 5G?

Comreg have put together information 'ABOUT 5G' and the evolution of mobile technology 

https://www.comreg.ie/industry/radio-spectrum/about-5g/