Question: What is a prerequisite for a User Equipment (UE) to support 16QAM in a concerned band for UL unicast?
Option 1: The UE must operate exclusively in TDD mode.
Option 2: The UE must support category NB2.
Option 3: The UE has to be capable of DL MIMO (Multiple Input Multiple Output).
Option 4: The UE needs to have a specific CA (Carrier Aggregation) configuration.
Explanation: According to E-UTRA specifications, for a User Equipment (UE) to support 16QAM in a particular band for uplink (UL) unicast transmissions, it is mandatory that the UE supports category NB2. This prerequisite ensures the UE has the necessary capabilities to handle the more complex modulation scheme of 16QAM efficiently.