Radio Resource Control (RRC)

Services

• Routing Function Entity (RFE)
  - Routing of higher layer messages to different MM/CM entities (UE side) or different core network domains (UTRAN side)
• Broadcast control function entity (BCFE)
  - Used to deliver RRC services, which are required at GC-SAP
  - Uses lower layer services provided by Tr-SAP and UM-SAP
• Paging and notification control function entity (PNFE)
  - Paging of idle mode UE(s)
  - Used to deliver RRC services required at Nt-SAP
  - Uses lower layer services provided by Tr-SAP and UM-SAP
• Dedicated Control Function Entity (DCFE)
  - Handles all functions specific to one UE
  - Used to deliver RRC services required at DC-SAP and uses lower layer services of UM/AM-SAP and Tr-SAP depending on message to be sent and on current UE service state
• Shared Control Function Entity (SCFE)
  - Assists in TDD mode the DCFE
  - Location in the C-RNC controlling allocation of PDSCH and PUSCH using lower layers services of UM-SAP and Tr-SAP
• Transfer Mode Entity (TME)
  - Handles mapping between different entities inside RRC layer and SAPs of RLC

Functions

• Broadcast of information provided by non-access stratum (Core Network)
  - FRRC layer performs system information broadcasting from network to all UEs
  - PSystem information is normally repeated on regular basis
  - RRC layer performs scheduling, segmentation and repetition
  - Supports broadcast of higher layer (above RRC) information (may be cell specific or not; for example Core Network location service area information related to some specific cells)
• Broadcast of information related to access stratum
  - RRC layer performs system information broadcasting from network to all UEs
  - System information is normally repeated on a regular basis
  - RRC layer performs scheduling, segmentation and repetition
  - Supports broadcast of typically cell-specific information
• Broadcast of ODMA relay node neighbor information
  - Performs probe information broadcasting to allow ODMA routing information to be collected
• Establishment, re-establishment, maintenance, and release of an RRC connection between UE and UTRAN
  - Establishment of RRC connection is initiated by request from higher layers at UE side to establish first Signaling Connection for the UE
  - Establishment of RRC connection includes optional cell re-selection, admission control and layer 2 signaling link establishment
  - Release of RRC connection can be initiated by a request from higher layers to release last Signaling Connection for UE or by RRC layer itself in case of RRC connection failure 33
  - In case of connection loss, UE requests re-establishment of RRC connection
  - In case of RRC connection failure, RRC releases resources associated with RRC connection
• Collating ODMA neighbor list and gradient information
  - ODMA relay node neighbor lists and their respective gradient information will be maintained by RRC
• Maintenance of number of ODMA relay node neighbors
  - RRC will adjust broadcast powers used for probing messages to maintain desired number of neighbors
• Establishment, maintenance and release of a route between ODMA relay nodes
  - Establishment of ODMA route and RRC connection based upon routing algorithm
• Interworking between Gateway ODMA relay node and UTRAN
  - Control interworking with standard TDD or FDD communication link between Gateway ODMA relay node and UTRAN
• Establishment, reconfiguration and release of Radio Bearers
  - RRC layer, on request from higher layers, performs establishment, reconfiguration and release of Radio Bearers in user plane
  - A number of Radio Bearers can be established to UE at the same time
  - For establishment and reconfiguration, RRC layer performs admission control and selects parameters describing Radio Bearer processing in layer 2 and layer 1, based on information from higher layers
• Assignment, reconfiguration and release of radio resources for RRC connection
  - Handles the assignment of radio resources (for example codes and CPCH channels) needed for RRC connection including needs from both control and user plane
  - May reconfigure radio resources during an established RRC connection
  - Includes coordination of radio resource allocation between multiple radio bearers related to same RRC connection
  - Controls radio resources in uplink and downlink such that UE and UTRAN can communicate using unbalanced radio resources (asymmetric uplink and downlink) 35
  - RRC signals to UE to indicate resource allocations for purposes of handover to GSM or other radio systems
• RRC connection mobility functions
  - Performs evaluation, decision, and execution related to RRC connection mobility during an established RRC connection, such as handover, preparation of handover to GSM or other systems, cell re-selection, and cell/paging area update procedures, for example based on measurements done by UE
• Paging/notification
  - Broadcast paging information from network to selected UEs. Higher layers on network side can request paging and notification
  - Initiate paging during an established RRC connection
• Control of requested QoS
  - Ensure to meet requested QoS for Radio Bearers
  - Includes allocation of a sufficient number of radio resources
• UE measurement reporting and control of reporting
  - Measurements performed by UE are controlled by RRC layer, in terms of what, when, and how to measure and report, including both UMTS air interface and other systems
  - Performs reporting of measurements from UE to network
• Outer loop power control
  - Controls setting of target of closed loop power control
• Control of ciphering
  - Provides procedures for setting of ciphering (on/off) between UE and UTRAN
• Slow DCA
  - Allocation of preferred radio resources based on long-term decision criteria
  - Applicable only in TDD mode
• Arbitration of radio resources on uplink DCH
  - Controls allocation of radio resources on uplink DCH effectively
  - Uses broadcast channel to send control information to all involved users (Function is implemented in CRNC)
• Initial cell selection and re-selection in idle mode
  - Selection of most suitable cell based on idle mode measurements and cell selection criteria
• Integrity protection
  - Adds a Message Authentication Code (MAC-I) to RRC messages that are considered sensitive and/or contain sensitive information
• Initial Configuration for CBS
  - Performs initial configuration of BMC sublayer
• Allocation of radio resources for CBS
  - Allocates radio resources for CBS based on traffic volume requirements indicated by BMC
  - Radio resource allocation set by RRC (for example schedule for mapping of CTCH onto FACH/S-CCPCH) indicated to BMC to enable generation of schedule messages
  - Resource allocation for CBS is broadcast as system information
• Configuration for CBS discontinuous reception
  - Configures the lower layers (L1, L2) of UE when it listens to resources allocated for CBS based on scheduling information received from BMC
• Timing advance control
  - Controls operation of timing advance
  - Applicable only in TDD mode