Question: When transmitting an RRC (Radio Resource Control) PDU as a PDCP (Packet Data Convergence Protocol) SDU to the PDCP layer, how is the bit ordering preserved?
Option 1: The last bit of the RRC PDU is represented as the first bit in the PDCP SDU.
Option 2: The bits of the RRC PDU are interleaved with padding bits before being mapped to the PDCP SDU.
Option 3: The first bit of the RRC PDU is represented as the first bit in the PDCP SDU, and this ordering continues sequentially.
Option 4: The RRC PDU is encrypted before transmission, altering its original bit order in the PDCP SDU.
Explanation: This correct answer reflects the specified protocol behavior for maintaining bit order integrity when transmitting RRC PDUs via PDCP. By ensuring the first bit of the RRC PDU is always represented as the first bit in the PDCP SDU (and onwards), the original message structure and meaning are preserved across the radio interface, which is crucial for accurate communication between peer entities in a telecom network.