Packet Data Convergence Protocol (PDCP) is specified by
3GPP in TS 25.323 for
UMTS
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the Inte ...
, TS 36.323 for
LTE and TS 38.323
for
5G. PDCP is located in the Radio Protocol Stack in the UMTS/LTE/5G
air interface
The air interface, or access mode, is the communication link between the two stations in mobile or wireless communication. The air interface involves both the physical and data link layers (layer 1 and 2) of the OSI model for a connection.
Physic ...
on top of the
RLC layer.
PDCP provides its services to the
RRC and user plane upper layers, e.g.
IP at the
UE or to the relay at the base station. The following services are provided by PDCP to upper layers:
* transfer of user plane data;
* transfer of control plane data;
* header compression;
* ciphering;
* integrity protection.
The header compression technique can be based on either IP header compression (
RFC 2507) or
Robust Header Compression
Robust Header Compression (ROHC) is a standardized method to compress the IP, UDP, UDP-Lite, RTP, and TCP headers of Internet packets.
The need for header compression
In streaming applications, the overhead of IP, UDP, and RTP is 40 bytes f ...
(
RFC 3095). If PDCP is configured for ''No Compression'' it will send the IP Packets without compression; otherwise it will compress the packets according to its configuration by upper layer and attach a PDCP header and send the packet.
Different header formats are defined, dependent on the type of data to be transported. In LTE, there are e.g. header formats for Control Plane PDCP Data
PDU with long PDCP SN (12 bits), for User plane PDCP Data PDU with short PDCP SN (7 bits) and others.
References
External links
* IP header compression
* {{IETF RFC, 3095, link=no Robust Header Compression
Mobile telecommunications standards
3GPP standards
UMTS
5G (telecommunication)