No DCH’s exist in Uplink and Downlink Direction
Like in CELL_FACH-state there are no dedicated resources allocated to the UE
in CELL_PCH-state.
DCCH’s (and DTCH’s) are configured but cannot be used in this State
The most important difference between CELL_FACH-state and CELL_PCH-state is
that
in CELL_PCH-state there are no DCCH’s nor DTCH’s available.
UE monitors PICH / PCH in Downlink (<=> DRX)
If the network needs to transmit information to the UE it needs to page it
through a PAG_TYPE1-message (in the cell and on PCCH / PCH) prior to sending
any useful
information. Accordingly, the UE shall monitor the PICH to detect paging on PCH
which are destined for that UE. The reception of a PAG_TYPE1-message will trigger
a cell update scenario (cause: paging response) as paging response.
Uplink Transmission requires State Change to CELL_FACH (<=> Cell Update)
If the UE needs to transmit uplink data or signaling information, it needs
to perform a cell update scenario (cause: uplink data transmission) prior to
any
data transfer.
No Soft or Hard Handover Scenarios are applicable
There are no handover scenarios possible, since the UE occupies no dedicated
transport channels. If the UTRAN wants to move the UE to another cell, it prior
needs to page it and move it to CELL_FACH-state.
UE performs Cell Updates but no URA Updates
In CELL_PCH-state, the UE will autonomously reselect the serving cell and perform
a cell update scenario consecutively. Cell updates will also performed periodically
(if configured) upon timer T305 expiry. However, no URA-Updates are applicable.
UTRAN knows the Location of the UE on Cell Level
Even in CELL_PCH-state, the SRNC (and possible another CRNC) knows the location
of the UE on cell level, because the UE performs cell update scenarios.
UE provides Measurement Reports to the RNC
Which measurements the UE performs depends on the setup information received
from the RNC (<=> SIB 11 and 12 / MEAS_CTRL-message). The transmission of
a MEAS_REP-message requires the previous state change to CELL_FACH and therefore
a cell update scenario.
[3GTS 25.331 (7.2.2.1, Annex B.3.3)]