Depending on your cell company, like others have said, many will provide a cell boaster for your home or you can buy your own.
They are pretty expensive, but it is what it is.
Just google best home cell signal boasters.
They do work, we use them in the security business but its not often and I cant remember the brand.
Your best bet by far, if you have one of the major cell providers is to call them and complain, see what they offer you.