ts_125331v120300p

3GPP TS 25.331 version 12.3.0 Release 12
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ETSI TS 125 331 V12.3.0 (2014-10)
5.2 RRC Services provided to upper layers
The RRC offers the following services to upper layers, a description and primitives of these services are provided in [2]
and [17].
- General Control;
- Notification;
- Dedicated control.
The RRC layer provides the UE-UTRAN portion of signalling connections to the upper layers to support the exchange
of upper layer's information flow. The signalling connection is used between the user equipment and the core network
to transfer upper layer information. For each core network domain, at most one signalling connection may exist at the
same time. The RRC layer maps the signalling connections for one UE on a single RRC connection. For the upper layer
data transfer on signalling connections, the RRC layer supports the discrimination between two different classes, named
"High priority" (corresponding to "SAPI 0" for a GSM-MAP based core network) and "Low priority" (corresponding to
"SAPI 3" for a GSM-MAP based core network).
5.3 Primitives between RRC and upper layers
The primitives between RRC and the upper layers are described in [17].
6 Services expected from lower layers
6.1 Services expected from Layer 2
The services provided by layer 2 are described in [2], [15] and [16].
6.2 Services expected from Layer 1
The services provided by layer 1 are described in [2].
6.3 Signalling Radio Bearers
The Radio Bearers (RB) available for transmission of RRC messages are defined as "signalling radio bearers" and are
specified in the following. The UE and UTRAN shall select the signalling radio bearers for RRC messages using RLC-
TM, RLC-UM or RLC-AM on the DCCH and CCCH, according to the following:
- Signalling radio bearer RB0 shall be used for all messages sent on the CCCH (UL: RLC-TM, DL: RLC-UM).
- Signalling radio bearer RB1 shall be used for all messages sent on the DCCH, when using RLC unacknowledged
mode (RLC-UM).
- Signalling radio bearer RB2 shall be used for all messages sent on the DCCH, when using RLC acknowledged
mode (RLC-AM), except for the RRC messages carrying higher layer (NAS) signalling.
- Signalling radio bearer RB3 and optionally Signalling radio bearer RB4 shall be used for the RRC messages
carrying higher layer (NAS) signalling and sent on the DCCH in RLC acknowledged mode (RLC-AM), as
specified in subclauses 8.1.8., 8.1.9 and 8.1.10.
- Signalling radio bearer RB4 shall be used for UE INFORMATION RESPONSE message carrying Logged
Measurement Reports.
- Additionally, RBs whose identities shall be set between 5 and 32 may be used as signalling radio bearer for the
RRC messages on the DCCH sent in RLC transparent mode (RLC-TM).
ETSI