Radio Resource Control

OSI model
by layer
7.  Application layer
6.  Presentation layer
5.  Session layer
4.  Transport layer
3.  Network layer
2.  Data link layer
1.  Physical layer

The Radio Resource Control (RRC) protocol is used in UMTS, LTE and 5G on the Air interface. It is a layer 3 (Network Layer) protocol used between UE and Base Station. This protocol is specified by 3GPP in TS 25.331[2] for UMTS, in TS 36.331 [3] for LTE and in TS 38.331[4] for 5G New Radio. RRC messages are transported via the PDCP-Protocol.

The major functions of the RRC protocol include connection establishment and release functions, broadcast of system information, radio bearer establishment, reconfiguration and release, RRC connection mobility procedures, paging notification and release and outer loop power control.[5] By means of the signalling functions the RRC configures the user and control planes according to the network status and allows for Radio Resource Management strategies to be implemented.[6]

The operation of the RRC is guided by a state machine which defines certain specific states that a UE may be present in. The different states in this state machine have different amounts of radio resources associated with them and these are the resources that the UE may use when it is present in a given specific state.[6][7] Since different amounts of resources are available at different states the quality of the service that the user experiences and the energy consumption of the UE are influenced by this state machine.[7]

  1. ^ "X.225 : Information technology – Open Systems Interconnection – Connection-oriented Session protocol: Protocol specification". Archived from the original on 1 February 2021. Retrieved 10 March 2023.
  2. ^ 3GPP TS 25.331 Radio Resource Control (RRC); Protocol specification
  3. ^ 3GPP TS 36.331 Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification
  4. ^ 3GPP TS 38.331 NR; Radio Resource Control (RRC); Protocol specification
  5. ^ UMTS RRC Protocol specification (version 12.4.0 Release 12) (PDF), European Telecommunications Standards Institute, February 2015
  6. ^ a b Pe´rez-Romero, Jordi (2005). Radio Resource Management Strategies in UMTS. John Wiley & Sons Ltd. p. 103. ISBN 0470022779. Retrieved 10 April 2015.
  7. ^ a b Qian, Feng (November 2010). "Characterizing Radio Resource Allocation for 3G Networks" (PDF). Proceedings of the 10th ACM SIGCOMM conference on Internet measurement. Melbourne, Australia: ACM. pp. 137–150.