Fortunately, for LTE, the minimum receive sensitivity is in one of the specifications, and so all you really need to do is figure out the required gain between the antenna connector (Which is specified in dBm, making life easy) and the ADC, probably 1 or 2 Volts peak to peak. Make sure you pay attention to the impedance levels to get your calculations correct. You probably need 30 to 40 dB of gain. Make sure you pay attention to the specified large signal performance to look at your AGC requirements.