RRC different status

When the signalling connection exists, there is an RRC connection and the UE is in UTRAN Connected mode. In the

UTRAN Connected mode, the location of UE is known either on UTRAN registration area (URA) level or on cell level.

UE leaves the UTRAN Connected mode and returns to Idle mode when the RRC connection is released or on RRC

connection failure.

When the UE position is known on cell level, it is either in CELL_DCH, CELL_FACH, or CELL_PCH state.

􀂾CELL_DCH state is characterized by the allocation of a dedicated transport channel to the UE.

􀂾In the CELL_FACH state the UE continually monitors a FACH. It is able to transmit uplink control signals and may

be small data packets via the RACH. When an inactivity timer expires, the UE state is changed to CELL_PCH in order

to decrease UE power consumption.

􀂾In CELL_PCH state the UE listens to the PCH transport channel. The DCCH logical channel cannot be used in this

sub-state. The only overhead in keeping a UE in the PCH state is the potential possibility of cell updating, when the

UE moves to other cells. To reduce this overhead, the UE is moved to URA_PCH state when low activity is observed.

•In URA_PCH state the location of a UE is known on URA level. The URA contains a set of cells. The mobility in this

state is handled by URA update procedures. In this state the UE listens to the PCH transport channel.

In URA_PCH state the location of the UE is known by the URA level. The URA contains a set of cells. There is no

dedicated channel allocated for the UE in URA_PCH state. The mobility in this state is handled by RRC: URA Update

procedure. In this state the UE uses discontinuous reception (DRX) and monitors paging messages from RNC. If the

network wants to initiate any downlink activity, it needs to make a paging request in all cells on the PCCH logical

channel within the URA where the location of the UE is known. Any Activity causes the UE to be transferred to the

Cell_FACH state, where the uplink access is performed on RACH.

Comparison between CELL_PCH and URA_PCH

•UE receives System Information in both states and can maintain inter- system mobility (cell reselection from

WCDMA to GSM).

•UE can be reached only via paging channel on both Cell/URA_PCH state.

•In serving RNC, UE is known on URA_PCH state in UTRAN Registration Area (URA) level instead Cell level in Cell_PCH

(Cell_DCH and Cell_FACH).

•In both Cell/URA_PCH states UE battery consumption is less than in Cell_FACH state, since the monitoring of the

paging channel includes DRX functionality.

•URA_PCH state is very similar to Cell_PCH, except that UE does not execute Cell Update after each cell reselection

(Cell_PCH), but instead reads URA-identities from the broadcast channel.

•To perform Cell/URA update procedure, UE autonomously enters the Cell_FACH state to execute the procedure

and then reverts to Cell/URA_PCH state.

•If the UE is moving fast it is forced to URA_PCH when the inactivity supervision timer expires and “Fast Moving

UE” information is valid