Question: After receiving an RRC message for HS-DSCH cell change with an activation time of "now", how soon must a UE (User Equipment) be ready to receive the HS-SCCH channel from the new cell, considering the specified delay?
Option 1: Immediately at the end of the last TTI (Transmission Time Interval) containing the RRC command.
Option 2: Within the RRC procedure delay seconds from the end of the last TTI containing the RRC command.
Option 3: Within Tcell_change seconds from the end of the last TTI containing the RRC command.
Option 4: After the completion of the current radio frame.
Explanation: According to the specifications for handling HS-DSCH cell changes, when a UE receives an RRC message with an immediate or near-immediate activation time ("now" or earlier than the RRC procedure delay), it must be prepared to switch to receiving the HS-SCCH channel from the new cell within a defined timeframe. This timeframe is specifically outlined as Tcell_change seconds from the end of the last TTI containing the RRC command, ensuring seamless handover and minimizing service interruption. This requirement highlights the importance of timely resource reallocation in maintaining continuous connectivity during cell changes in HSDPA (High-Speed Downlink Packet Access) supported networks.