The Packet Data Convergence Protocol (PDCP) acts as a workhorse within the 5G User Plane (UP), ensuring efficient and reliable data transmission. Its core responsibilities involve:

1. Data Transfer: PDCP is responsible for transporting user plane data (both control plane and user plane) across the air interface.
2. Maintaining Sequence Numbers: PDCP assigns sequence numbers to data packets, enabling the receiving party to identify and reorder packets if necessary.
3. Header Compression (Optional): PDCP can optionally compress packet headers to reduce overhead and improve bandwidth utilization.
4. Data Protection (Control Plane Only): For control plane data, PDCP offers integrity protection to ensure data hasn’t been tampered with during transmission.
5. Interaction with Higher Layers: PDCP interacts with the upper layers (e.g., SDAP) to receive data packets and with the lower layers (e.g., Radio Link Control – RLC) to transmit them over the air interface.