A method and apparatus for cell update while in a Cell_FACH state are
disclosed. After selecting a target cell, system information is read from
the target cell including high speed downlink shared channel (HS-DSCH)
common system information. A radio network temporary identity (RNTI)
received in a source cell is cleared and a variable HS_DSCH_RECEPTION is
set to TRUE. An HS-DSCH medium access control (MAC-hs) entity is
configured based on the HS-DSCH common system information. High speed
downlink packet access (HSDPA) transmission is then received in the
target cell. A CELL UPDATE message is sent to notify of a cell change.
The HSDPA transmission may be received using a common H-RNTI broadcast in
the system information, a reserved H-RNTI as requested in a CELL UPDATE
message, or a temporary identity which is a subset of a U-RNTI. The
MAC-hs entity may be reset.