【资料名称】：FACH 信道作用研究

【资料作者】：xx

【资料日期】：xx

【资料语言】：中文

【资料格式】：ppt

【资料目录和简介】：

Cell Update function
to update the current location of the UE when it is in CELL_FACH state and keep WCDMA RAN informed about its location in the radio network with the granularity of cell. Cell Update is also performed when a transition is done from dedicated channels (DCH) to common channels (FACH). The UE then tries to (re)select a (new) cell and performs a Cell Update.

Cell update can be initiated by
Re-entering service area: In CELL_FACH state, UE reenters service area after having been out of service area.
RLC unrecoverable error: The UE has detected an RLC unrecoverable error in an AM RLC entity
Cell Reselection: In CELL_FACH state, select a new cell (or reselect the old cell) when entering a new cell and/or the UE does not have a valid C-RNTI in the selected cell.
Periodic Cell Update: In CELL_FACH state, location update after a certain period (expiry of a timer) and the UE is "in service area".