Question: After receiving an RRC message indicating an HS-DSCH cell change with an immediate activation time, how soon must a UE (User Equipment) be ready to receive the HS-SCCH channel from the new cell?
Option 1: Immediately after the last TTI (Transmission Time Interval) containing the RRC command
Option 2: Within Dcell_change seconds from the end of the last TTI containing the RRC command
Option 3: After RRC procedure delay seconds plus one second from the end of the last TTI containing the RRC command
Option 4: Only after completing a full RRC connection re-establishment with the new cell
Explanation: According to telecom protocol for FDD UEs supporting HSDPA, when an HS-DSCH cell change is commanded with immediate activation, the UE must prepare to switch its HS-SCCH reception within a defined timeframe, specifically Dcell_change seconds after the last TTI of the RRC command, ensuring seamless handover and service continuity.