Efficient data transmission in 5G relies on a layered protocol structure. Each layer performs specific tasks to ensure smooth communication. Here’s a quick look at the key functions within the main NR Radio Protocol layers, focusing on three important aspects for each layer.

A breakdown of the main functions within each NR Radio Protocol layer:

Physical Layer (PHY):

• PDSCH & PUSCH: Handles downlink/uplink data transmission: segmentation, coding, modulation.
• PDCCH & PUCCH: Manages control information exchange: scheduling, power control, HARQ feedback.

Control Plane (MAC):

• Maps logical channels to transport channels.
• Multiplexes/demultiplexes data units.
• Performs error correction (HARQ) and prioritization.

Radio Link Control (RLC):

• Supports Transparent, Unacknowledged, and Acknowledged modes.
• Provides reliable data transfer with retransmissions (AM mode).
• Handles data unit segmentation, reassembly, and error detection.

Packet Data Convergence Protocol (PDCP):

• Control Plane (CP): Performs basic processing like sequence numbering.
• User Plane (UP): Handles additional tasks like header compression, reordering, security, and retransmissions.

Service Data Adaptation Protocol (SDAP) (Control Plane Only):

• Introduced in 5G, present only with the 5G Core Network (5GC).
• Main function: Maps between QoS flows and radio bearers.

Radio Resource Control (RRC):

• Manages overall radio resource allocation and connection setup/teardown.
• Broadcasts system information, controls UE access, and performs paging.
• Establishes, maintains, and releases connections, handles security, and manages UE mobility