Question: What happens when a Downlink (DL) data frame arrives at the Node B after the specified Time of Arrival Window Endpoint (TOAWE)?
Option 1: The Node B sends an acknowledgement (ACK) for the received frame, and no further action is taken.
Option 2: A Timing Adjustment Control frame response is triggered to adjust the transmission timing.
Option 3: The Node B discards the late-arriving DL data frame to maintain synchronization.
Option 4: The TOAWE is automatically adjusted to accommodate the late arrival of the DL data frame.
Explanation: According to the NBAP signalling protocol, if a DL data frame arrives after the specified Time of Arrival Window Endpoint (TOAWE), it indicates a timing mismatch. To correct this, a Timing Adjustment Control frame response is sent, which helps in adjusting the transmission timing to ensure proper synchronization between the nodes in the UTRAN network. This mechanism is crucial for maintaining the integrity and efficiency of wireless communications.