Question: In a 5G NR network, as per the RRC protocol specification, what is the significance of the value '0' for the ServCellIndex information element in identifying a serving cell across cell groups?
Option 1: It indicates an SCell that has not been assigned an SCellIndex.
Option 2: It signifies the PSCell (Primary Secondary Cell) in a cell group.
Option 3: It uniquely identifies the PCell (Primary Cell) within a cell group.
Option 4: It represents an invalid or reserved ServCellIndex value.
Explanation: According to the RRC protocol specification, a ServCellIndex value of '0' is specifically assigned to identify the PCell (Primary Cell) across different cell groups. This unique identification is crucial for efficient communication and resource allocation between the UE (User Equipment) and the network, especially in scenarios involving multiple serving cells.