CELL_DCH state
The CELL_DCH state features the following:
* A dedicated physical channel is allocated to the UE in both the uplink and the
downlink.
* RNC knows the cell where the UE camps on according the current active set of the
UE.
*The UE can use the dedicated transport channels, downlink/uplink shared
transport channels or the combination of these transport channels.
The UE enters the CELL_DCH state in one of the following two ways:
1) In the idle mode, the UE sets up the RRC connection on the dedicated channel,
thus shifting from the idle mode to the CELL_DCH state.
2) In the CELL_FACH state, the UE uses the common transport channel and then is
converted to the dedicated transport channel, thus shifting from the CELL_FACH
state to the CELL_DCH state.
2. CELL_FACH state
The CELL_FACH state features the following:
* No dedicated transport channel is allocated to the UE.
* The UE continuously monitors a downlink FACH channel.
* A default uplink common channel (for example, RACH) or an uplink shared
transport channel is allocated to the UE for the UE to use at any time during the
access procedure.
* The cell-level location of the UE is known by the UTRAN, specifically, the cell
reported during the last cell update initiated by UE.
The UE performs the following operations in the CELL_FACH state:
* Monitors an FACH.
* Monitors the BCH channel of the current serving cell to decode the system
messages.
* Initiates a cell update procedure when the cell becomes another UTRA cell.
* Uses the C-RNTI allocated in the current cell as the UE identification on the
common transport channel unless a new cell is selected.
* Transmits uplink control signaling and small data packets on the RACH.
In the CELL_FACH state, if the data service is not activated in a certain time period, the
UE will enter the CELL_PCH state so as to save the power. In addition, if neither the UE
nor the network side has the data transport requirement after the UE temporarily exits
the CELL_PCH state and executes the cell update, the UE will return to the CELL_PCH
state.
3. CELL_PCH state
The CELL_PCH state features the following:
* No dedicated channel is allocated to the UE.
* The DRX (discontinuous reception) technology is adopted for the UE to monitor
the information transmitted on the PCH channel at a specific paging time slot.
* No uplink activity is allowed.
The cell-level location of the UE is known by the UTRAN, specifically, the cell reported
during the last cell update initiated by the UE in the CELL_FACH state.
The UE performs the following operations in the CELL_PCH state:
Monitors the paging time slot based on the DRX period and receives the paging
messages transmitted on the PCH.
Monitors the BCH channel of the current serving cell to decode the system messages.
Initiates the cell update procedure when the cell changes.
The DCCH logical channel cannot be used in this state. To initiate any activity, the
network needs to send a paging request via the PCCH logical channel of the cell where
the UE is.
The UE shifts to the CELL_FACH state in one of the following two ways: By paging from
the UTRAN and by any uplink access.
4. URA_PCH state
The URA_PCH state features the following:
* No dedicated channel is allocated to the UE.
* The DRX technology is adopted for the UE to monitor the information transmitted
on the PCH channel at a specific paging time slot.
* No uplink activity is allowed.
* The URA-level location of the UE is known by the UTRAN, specifically, the URA
reported during the last URA update initiated by the UE in the CELL_FACH state.
The UE performs the following operations in the URA_PCH state:
* Monitors the paging time slot based on the DRX period and receives the paging
messages transmitted on the PCH.
* Monitors the BCH channel of the current serving cell to decode the system
messages.
* Initiates the URA update procedure when the URA changes.
The DCCH logical channel cannot be used in this state. To initiate any activity, the
network needs to send a paging request via the PCCH logical channel of the URA
where the UE is.
No resource is allocated for data transport in the URA_PCH state. Therefore, if the UE
has the data transport requirement, it needs to first shift to the CELL_FACH state.
SOURCE FROM : basics principles of WCDMA system
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