Which sampling rate in LTE?

Hello everyone,

Im studying with the SDR items, especially with the Ettus B210 (its a NI-USRP 2901, but it is considered an equivalent). I executed the LTE code given in https://es.mathworks.com/help/supportpkg/usrpradio/examples/lte-cell-search-mib-and-sib1-recovery-with-two-antennas.html using two SDR , one aas a transmitter and the other one as a receiver, and it worked.

But now i would wanted to study how to receive the LTE downlink signals from mobile companies. I was recommended to use 30.72 MHz as sampling rate instead of 1.96 MHz used in the code of the link above. My question is : Why do i have to use this sampling rate (if it is correct)? And which equation i must use to get the sampling rate of a signal? I guess it should be a little higher than the signal bandwidth.

Thank you for the help in advance,