Question: In a UTRAN cell, after changing parameters from T1 to T2, if the UE fails to respond with a PRACH (URA UPDATE message cause "change of URA") within the allowed time, what action is taken by the SS after waiting for a total of 15s from the beginning of T2?
Option 1: The SS immediately transmits a URA UPDATE CONFIRM message and proceeds to step g)
Option 2: The UE is switched off, and the procedure returns to step a) without further action.
Option 3: The SS waits for additional responses; if none are received, the UE is switched off, and the procedure returns to step a), otherwise, it transmits a URA UPDATE CONFIRM message and continues with step g)
Option 4: The parameters are reverted back to T1 without waiting for the UE's response.
Explanation: This option correctly reflects the procedure. After the UE fails to respond within the allowed time, and after an additional wait (totaling 15s from T2's start), if still no response is received, the UE is switched off, and the process restarts. If any response is received during this extended wait, the SS responds with a URA UPDATE CONFIRM message and proceeds, covering both scenarios.