Question: During Discontinuous Transmission (DTX) in a UTRA network, what triggers a User Equipment (UE) to shut its transmitter off if no data is received from the UTRAN?
Option 1: Failure to receive any signal with a quality above threshold Qout for 320 ms.
Option 2: Not detecting at least one Special Burst with a quality above threshold Qsbout over the last 80 ms period.
Option 3: Not detecting at least one Special Burst with a quality above threshold Qsbout over the last 160 ms period.
Option 4: Receiving a direct command from the UTRAN to power off due to inactivity.
Explanation: During DTX, when the UE receives no data, it relies on Special Bursts from the UTRAN to maintain synchronization. The UE shuts its transmitter off if it doesn't detect at least one Special Burst with a quality above the Qsbout threshold within a specified time frame, which is 160 ms, highlighting the importance of Special Bursts in maintaining connectivity during periods of inactivity.