wireless modem to router

I have a Mac Pro 3.1 without wireless capability, i.e. no Airport card. I am considering a 4G modem which has no physical connections. I ma considering this because my ADSL connection is hopelessly slow. I am trailling a prepaid 4G modem and it is very fast. Can I use a wireless router to pick up the signal of the 4G modem. If so, I can connect to the WR via ethernet. Possible? This would be much easier than installing an Airport card.