Question: What is the purpose of the `PhysCellIdUTRA-FDD` Information Element in E-UTRA Radio Resource Control (RRC) protocol?
Option 1: To identify the UE's (User Equipment) unique identifier within a cell.
Option 2: To specify the downlink transmission power of the cell.
Option 3: To indicate the physical layer identity of the cell, specifically the primary scrambling code.
Option 4: To determine the handover criteria between different radio access technologies.
Explanation: The correct answer is Option 3 because `PhysCellIdUTRA-FDD` identifies the physical layer characteristics of a cell, pertaining to the primary scrambling code. This is crucial for distinguishing between cells and managing radio resources efficiently in a UTRA-FDD system. The primary scrambling code aids in cell detection and synchronization processes.