This question can be answered in a number of ways. In theory, you can simply answer the exact bit rate, assuming ideal conditions. For practical scenarios the exact bit rate or let me say the capability in terms of capacity and cell coverage varies depending on a number of factors such as

  • the amount of available spectrum ,
  • the size of radio channels
  • Urban or rural areas
  • Number of subscribers sharing the capacity in the cell
  • Interference from neighboring cells
  • Line of Sight (LOS)
  • Non Line of Sight (NLOS)
  • Non Line of Sight (NLOS) indoor
  • Etc

3GPP targeted for LTE to provide mobile subscribers with a data channel of at least 100 Mbps in the downlink and 50 Mbps in the uplink with a 20 MHz FDD bandwidth. This is in theory.

Some vendors like Ericsson has shown speeds over 300 Mbps for LTE with 4×4 MIMO .

So before you answer the exact question in an interview. You need to understand or even ask the interviewer about the following:

  • what are the inherent presumptions in the question ?
  • What type of RF conditions are available
  • How many users are available etc.

Of course adding too many constraints the bit rate available will reduce from theoretical bit rate achievable.