DCH’s exist in Uplink and Downlink Direction
This is the most important characteristics of the CELL_DCH-state. Dedicated
TrCH’s
are available in uplink and downlink direction and can be used for the exchange
of DCCH- and, if configured, DTCH-logical channel information. Note that in CELL_DCH-state,
common / shared TrCH’s may be configured in addition, e.g. for the use
by the DTCH’s.
DCCH’s are available and can be used; DTCH’s may be available
Another important characteristics of the CELL_DCH state is that DCCH’s
are configured. Configuration relates to the mapping between DCCH X to DCH Y.
DTCH’s may also be configured in addition.
If UTRAN receives a paging message for the UE from the core network, it will
use the PAG_TYPE2-message on DCCH (over DCH) to inform the UE. This is possible
when the UE has radio access bearers established to one core network domain (e.g.
circuit-switched) and UTRAN receives a paging from the other core network domain.
UTRAN knows the Location of the UE on Cell Level
The SRNC has allocated a U-RNTI to the UE and knows the location of the UE
on
cell level. The allocation of a C-RNTI is not required in CELL_DCH.
Handover Scenarios are Applicable
Only in CELL_DCH-state, soft and hard handover scenarios are applicable. Handover
relates to the switching of the dedicated channels to another cell which may
be a UTRAN-cell (FDD or TDD) or which may belong to another RAT (e.g. GSM).
UE performs no Cell Updates or URA Updates
In CELL_DCH-state the UE relies on the network to handover the UE to the best
possible serving cell. Accordingly, neither cell updates nor URA-updates are
applicable.
Exceptions:
1. In case of a radio link failure or RLC-AM unrecoverable error in CELL_DCH-state,
the UE shall initiate a cell update scenario with cause “radio link failure” and
the network shall consecutively initiate the release of the RRC-connection by
sending RRC_CONN_REL to the UE [3GTS 25.331 (8.3.1.2)].
2. In CELL_DCH-state, UTRAN may also initiate a cell change to a GERAN-cell by
sending a CELL_CHAN_UTRAN-message to the UE, if the UE has only radio bearers
established towards the packet-switched domain.
UE provides Measurement Reports to the RNC
Which measurements the UE performs depends on the setup information received
from the RNC (ó SIB 11 and 12 / MEAS_CTRL-message).
[3GTS 25.331 (7.2.2.3, Annex B.3.1)]