5G Protocol Stack - User Plane/Control Plane

NR 5G Protocol Stack - User Plane/Control Plane

NR User Plane Protocol Stack  is shown in below figures,

User Plane

NR Control Plane Protocol Stack  is shown in below figures

Control Plane 

SDAP (Service Data Adaptation Protocol)

RRC(Radio Resource control)

PDCP (Packet Data Convergence Protocol)

RLC (Radio Link Control )

MAC (Media Access Control)

Functions :-

SDAP functions:-

• transfer of user plane data
• mapping between a QoS flow and a DRB for both DL and UL 
• marking QoS flow ID in both DL and UL packets
• reflective QoS flow to DRB mapping for the UL SDAP data PDUs.

PDCP  functions: -

• transfer of data (user plane or control plane)
• maintenance of PDCP SNs
• header compression and decompression using the ROHC
• ciphering and deciphering
• integrity protection and integrity verification
• timer based SDU discard
• reordering and in-order delivery
• duplicate discarding.

RLC functions:-

• transfer of upper layer PDUs
• error correction through ARQ (only for AM data transfer) segmentation and reassembly of RLC SDUs
• re-segmentation of RLC SDU segments
• duplicate detection (only for AM data transfer)
• RLC SDU discard (only for UM and AM data transfer)
• RLC re-establishment
• Protocol error detection (only for AM data transfer). 

MAC functions: -

• mapping between logical channels and transport channels.
• multiplexing/ de-multiplexing of MAC SDUs.
• scheduling information reporting.
• error correction through HARQ.
• logical channel prioritisation.

RRC functions: -

• Broadcast of system information.
• RRC connection control.
• Paging.
• Establishment/modification/suspension/resumption/release of RRC connection, establishment/modification/suspension/resumption/release of SRBs/ DRBs (except for SRB0).
• Access barring.
• Initial security activation.
• mobility control.
• Radio configuration control including e.g. assignment/modification of ARQ. configuration, HARQ configuration, DRX configuration.
• QoS management functions.
• Recovery from radio link failure.
• Establishment/modification/release of measurement configuration.
• Setup and release of measurement gaps; - Measurement reporting. 

3GPP references : 38.331 V15.3.0 (2018-10)

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