Locationg mobile phones with a radar

Hi guys

I’m working on a project where i need to determine the distance from my
USRP B210 to mobile phones nearby.

For my understanding there is a way to do so by sending a pulse, and
studying the reflection from mobile devices which contain SAW filters.

Since i’m new to the SDR world, could you help me get started?
do i have to use GNU Radio for this (unfamiliar with the software) or
can i use matlab?

Any help will be really appreciated,
Thanks in advance,