What I was saying about the radios are that lte signals have a tower time penetrating walls, this is true to whichever carriers lte. 3G is lower bandwidth and has better penetration. I wish I had a good article to throw up handy but google it. It's why you had 5 bars 3G pre lte and then saw worse coverage indoors.
TMI moment my htc thunderbolt never got a signal in my last company's bathroom. Yeah yeah shaddup lol it was just my work phone haha.