Question: What is a prerequisite for a User Equipment (UE) to mandatorily support transmission of discovery announcements based on UE autonomous resource selection, as per E-UTRA specifications?
Option 1: The UE must operate exclusively in TDD (Time Division Duplexing) mode.
Option 2: Sidelink discovery must be supported on at least one band by the UE.
Option 3: The UE has to be capable of transmitting in multiple frequency bands simultaneously.
Option 4: Autonomous resource selection is only mandatory for UEs supporting Voice over LTE (VoLTE).
Explanation: This option is correct because, according to the E-UTRA specifications, if a UE supports sidelink discovery on at least one band, it is mandatory for that UE to also support transmission of discovery announcements based on UE autonomous resource selection, ensuring seamless functionality when sidelink capabilities are utilized.