Question: In a UDC (Uplink Data Compression) packet, under what condition are the FR field and the Checksum field in the UDC header utilized?
Option 1: Always, regardless of the FU field value.
Option 2: Only when the UE: User Equipment decides not to compress PDCP SDUs due to high UL data rates.
Option 3: Only if the FU (Field for specifying type) field in the UDC header is set to 1.
Option 4: Never, as they are reserved for future use.
Explanation: The correct utilization condition for the FR field and the Checksum field in the UDC header is directly tied to the value of the FU field. According to the specifications, these fields are used only when the FU field is set to 1, indicating a specific type of data block (in this context, likely related to compressed blocks generated by the UDC protocol). This conditional use ensures efficient packet structure based on the type of data being transmitted.