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CELL_PCHThe CELL_PCH state is characterized by: Neither an uplink nor a downlink dedicated physical channel is allocated to theUE The UE uses DRX for monitoring a PCH via an allocated PICH. No uplink activity is possible [note: if the UE wants to make an uplink access t autonomously shall enter the CELL_FACH state]. The UE is known on cell level according to the cell where the UE last made a cel update in CELL_FACH state.In this state, the UE shall monitor the paging occasions according to the DRX cycle and receive paging infomation on the PCH acquire system information on the BCH and use the measurement control informatin according to that system information when no dedicated measurement control information has been assigned to the UE perform cell reselection and upon selecting a new UTRA cell, enter the CELL_FACstate and initiate a cell update procedure upon selecting a new cell belonging to another radio access system than UTRA, eter idle mode and make an access to that system according to its specifications perform measurements according to the measurement control information when needed according to the measurement control information, enter CELL_FACH s

ate and transmit measurement reportsURA_PCHThe URA_PCH state is characterized by: Neither an uplink nor a downlink dedicated physical channel is allocated to theUE The UE uses DRX for monitoring a PCH via an allocated PICH. No uplink activity is possible [note: if the UE wants to make an uplink access t autonomously enters the CELL_FACH state]. The UE is known on URA level according to the URA assigned to the UE during thelast URA update in CELL_FACH state.

In this state, the UE shall monitor the paging occasions according to the DRX cycle and receive paging infomation on the PCH acquire system information on the BCH and use the measurement control informatin according to that system information when no dedicated measurement control information has been assigned to the UE perform cell reselection and upon selecting a new UTRA cell that does not matchthe URA assigned to the UE, enter the CELL_FACH state and initiate a URA updateprocedure upon selecting a new cell belonging to another radio access system than UTRA, eter idle mode and make an access to that system according to its specifications

(FFS) perform measurements according to the measurement control information when needed according to the measurement control information, enter CELL_FACH sate and transmit measurement reports

URA or UTRAN Registration Area is a collection of cells that are used for fast moving UE's in Connected mode when they are not transferring any data.

In this case the UE is in CELL_PCH state. Every time a fast moving UE in CELL_PC

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H state changes the cell, a CELL UPDATE needs to be performed to let the UTRAN know of the new position of the UE. This is done because in the connected mode (CELL_PCH), UE is known at cell level rather than UTRAN level as in IDLE state. Iftoo many CELL UPDATES are performed, it defeats the purpose of UE being in CELL

_PCH. Hence in this case the UE is put in URA_PCH state. Now the UE will performCELL UPDATE only when the URA is changed for a UE. The drawback is that when UEneeds to be paged the paging area is now extended to many cells belonging to the URA.

URA_PCH is similar to CELL_PCH except the RNC tracks the location of the UE on aper URA basis rather than on a per cell basis.

Also Note that the CELL_PCH state is actually a subset of the URA_PCH state. Itis possible to define overlapping URAs to be used in the URA_PCH state.

The URAs can be overlapping or even hierarchical. The same cell may belong to several different URAs, and the UEs in that cell may have been registered to different URAs. SIB 2 contains a list of URA identities indicating which URAs this cell belongs to. This arrangement is done to further reduce the amount of locationupdate signaling because now the UEs moving back and forth in the boundary areaof two URAs do not have to update their URA location information if the boundary cells do belong to both URAs.

In Cell-PCH , the UEs current cell is known to the RNC. If the RNC wants to exchange data with the UE, it only needs to page the UE there. If the UE changes thecell, it must perform a cell update. Also periodical cell updates can be requested by UTRAN. To perform updates, the UE must change to the CELL_FACH sub-state.

UE in CELL_PCH have a lower resource requirement than UE in CELL_FACH, but cannot transfer uplink data. Only downlink CBS and MBMS services are possible. The RNC tracks the location of the UE on a per cell basis and paging type 1 messages can be forwarded to individual cells using a DRX cycle.

Now, If the UE is in the CELL_PCH and moving fast, a lot of cell updates have tobe performed. URAs are a combination of one or several cells under one C-RNC. URAs may overlap, i.e. a cell may belong to several URAs. If UTRAN wants to transmit something to the UE, it must page the UE within the URA. The UE is responsible for URA updates when it changes the URA and periodic URA updates when required by UTRAN.

So in this way UTRAN doesn't need to keep cell level information on an UE.

Difference is the area type... in CELL_PCH the paging is SA based (Or cell)... in URA_PCH the paging is done in URA based area. That is the main difference...... CELL_PCH can save lot more capacity in a UE not moving or changing the paging

area, and the URA_PCH can save lot of signaling due to CELL_UPDATEs messages..... and more be more efficient than LA (LOCATION AREA)......