You know how with radio channels, there's a limited amount of channels, and they're all something specific? Like, your 103.6 might be a channel for news, or for classic 80's songs. That radio station has a range, let's say 100 miles. If you drive out of that range, you get a different station for that same 103.6 channel.

Cell phones are like that, too. Cell towers run on channels that have limited bandwidth. If you're in a crowded event, it's like everyone is trying to set up their own radio station, but we're running out of station numbers for that immediate area.

This is what newer technologies in cell towers are trying to address. Imagine if instead of a station's range being 100 miles, it's now being much smaller, and many stations can now exist on 103.6 in that old 100 mile radius. For cell phones, this means more people can make calls and the bandwidth of their channel is more efficiently used.