Method and apparatus for cell update while in an enhanced cell_fach state

A method for performing cell reselection while in a Cell_FACH state when only a source cell supports Enhanced Cell_FACH, the method comprising:

• selecting a target cell;
• reading system information from the target cell;
• clearing a radio network temporary identity (RNTI) received in a source cell;
• resetting an HS-DSCH medium access control (MAC-ehs) entity configured in the source cell;
• preventing HS-DSCH reception by setting an HS-DSCH reception variable to FALSE;
• setting up secondary common control physical channel (S-CCPCH) and random access channel (RACH) communication;
• sending a CELL UPDATE message;
• and
• receiving downlink transmission on an S-CCPCH.

A method for performing cell update while in a Cell_FACH state, the method comprising:

• detecting a cell update triggering event while receiving HSDPA transmission in a Cell_DCH state using a dedicated high speed downlink shared channel (HS-DSCH) radio network temporary identity (H-RNTI), the cell update triggering event being one of a radio link failure and a radio link control (RLC) unrecoverable error;
• reading system information in a target cell;
• clearing a radio network temporary identity (RNTI) received in a source cell;
• setting up random access channel (RACH) communication,
• sending a CELL UPDATE message via an RACH;
• enabling HS-DSCH reception by setting an HS-DSCH reception variable to TRUE, if it is determined from the system information that the target cell supports an enhanced Cell_FACH state;
• and
• receiving HSDPA transmission using the dedicated H-RNTI.

A wireless transmit/receive unit (WTRU) for performing cell reselection while in a Cell_FACH state, the WTRU comprising:

• a transceiver;
• a high speed downlink shared channel (HS-DSCH) medium access control (MAC-ehs) entity for high speed downlink packet access (HSDPA) communication;
• and
• a controller configured to, while in a Cell_FACH state, select a target cell, read system information from the target cell, clear a radio network temporary identity (RNTI) received in a source cell, the RNTI being at least one of an HS-DSCH RNTI (H-RNTI) and a cell RNTI (C-RNTI), reset the MAC-ehs entity configured in the source cell, set up random access channel (RACH) communication, send a CELL UPDAATE message, and configure HSDPA communication based on HS-DSCH common system information included in the system information.

A wireless transmit/receive unit (WTRU) for performing cell reselection while in a Cell_FACH state when only a source cell supports Enhanced Cell_FACH, the WTRU comprising:

• a transceiver;
• a high speed downlink shared channel (HS-DSCH) medium access control (MAC-ehs) entity for high speed downlink packet access (HSDPA) communication;
• and
• a controller configured to, while in a Cell_FACH state, select a target cell, read system information from the target cell, clear a radio network temporary identity (RNTI) received in a source cell, reset the MAC-ehs entity configured in the source cell, prevent HS-DSCH reception by setting an HS-DSCH reception variable to FALSE, set up secondary common control physical channel (S-CCPCH) and random access channel (RACH) communication, send a CELL UPDATE message, and configure the transceiver to receive downlink transmission on an S-CCPCH.

A wireless transmit/receive unit (WTRU) for performing cell update while in a Cell_FACH state, the WTRU comprising:

• a transceiver;
• a high speed downlink shared channel (HS-DSCH) medium access control (MAC-ehs) entity for high speed downlink packet access (HSDPA) communication;
• and
• a controller configured to, while in a Cell_FACH state, detect a cell update triggering event while receiving HSDPA transmission in a Cell_DCH state using a dedicated high speed downlink shared channel (HS-DSCH) radio network temporary identity (H-RNTI), the cell update triggering event being one of a radio link failure and a radio link control (RLC) unrecoverable error, read system information in a target cell, clear a radio network temporary identity (RNTI) received in a source cell, set up random access channel (RACH) communication, if it is determined from the system information that the target cell supports an enhanced Cell_FACH state, send a CELL UPDATE message via an RACH, enable HS-DSCH reception by setting an HS-DSCH reception variable to TRUE, and configure the MAC-ehs entity based on the common HS-DSCH system information included in the system information to receive HSDPA transmission in the target cell.