Method and apparatus for cell update while in an enhanced Cell
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.
1. A method for performing a cell update while in a Cell_FACH state, the method comprising:
detecting a cell update triggering event while receiving a high speed downlink packet access (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 comprising at least one of a radio link failure or a radio link control (RLC) unrecoverable error,
clearing a radio network temporary identity (RNTI) received in a source cell,
reading system information in a target cell, and
based on common HS-DSCH system information included in the system information, resetting a high speed downlink shared channel (HS-DSCH) medium access control (MAC-ehs) entity, and enabling HS-DSCH reception by setting an HS-DSCH reception variable to TRUE.
2. The method of claim 1 , further comprising:
sending a CELL UPDATE message via a random access channel (RACH); and
setting up HSDPA communication based on the common HS-DSCH system information included in the system information.
3. The method of claim 1 , further comprising:
setting up a random access channel (RACH) communication.
4. A wireless transmit/receive unit (WTRU) for performing a cell update while in a Cell_FACH state, the WTRU comprising:
a controller configured to:
detect a cell update triggering event while receiving a high speed downlink packet access (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 comprising at least one of a radio link failure or a radio link control (RLC) unrecoverable error,
clear a radio network temporary identity (RNTI) received in a source cell,
read system information in a target cell, and
based on common HS-DSCH system information included in the system information, reset a high speed downlink shared channel (HS-DSCH) medium access control (MAC-ehs) entity, and enable HS-DSCH reception by setting an HS-DSCH reception variable to TRUE.
5. The WTRU of claim 4 , wherein the controller is further configured to:
send a CELL UPDATE message via a random access channel (RACH); and
set up HSDPA communication based on the common HS-DSCH system information included in the system information.
6. The WTRU of claim 4 , wherein the controller is further configured to set up random access channel (RACH) communication.
7. A method for performing cell reselection while in a Cell_FACH state, the method comprising:
receiving information from a source cell that supports Cell FACH;
selecting a target cell for the cell reselection, wherein the target cell supports Cell_FACH or fails to support Cell_FACH;
reading system information broadcast from the target cell;
determining, based on the system information from the target cell, whether the target cell supports Cell_FACH; and
receiving information from the target cell based on whether the target cell supports Cell_FACH or fails to support Cell_FACH.
8. The method of claim 7 , further comprising:
when the target cell supports Cell_FACH, performing at least one of the following:
clearing a high speed downlink shared channel (HS-DSCH) radio network temporary identity (H-RNTI) associated with the source cell,
clearing a cell radio network temporary identity (C-RNTI) associated with the source cell,
resetting an HS-DSCH medium access control (MAC-ehs) entity configured in the source cell,
configuring a MAC-ehs entity based on common HS-DSCH system information, or
receiving high speed downlink packet access (HSDPA) transmission in the target cell.
9. The method of claim 7 , further comprising:
when the target cell fails to support Cell_FACH, performing at least one of the following:
clearing a radio network temporary identity (RNTI) received in the source cell;
resetting a high speed downlink shared channel (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; and
receiving downlink transmission on an S-CCPCH.
10. A wireless transmit/receive unit (WTRU) for performing cell update while in a Cell_FACH state, the WTRU comprising:
a controller configured to:
receive information from a source cell that supports Cell_FACH;
select a target cell for cell reselection, wherein the target cell supports Cell_FACH or fails to support Cell_FACH;
read system information broadcast from the target cell;
determine, based on the system information from the target cell, whether the target cell supports Cell_FACH; and
receive information from the target cell based on whether the target cell supports Cell_FACH or fails to support Cell_FACH.
11. The WTRU of claim 10 , wherein the controller is further configured to:
when the target cell supports Cell_FACH, perform at least one of the following:
clear a high speed downlink shared channel (HS-DSCH) radio network temporary identity (H-RNTI) associated with the source cell,
clear a cell radio network temporary identity (C-RNTI) associated with the source cell,
reset an HS-DSCH medium access control (MAC-ehs) entity configured in the source cell,
configure a MAC-ehs entity based on common HS-DSCH system information, or receive high speed downlink packet access (HSDPA) transmission in the target cell.
12. The WTRU of claim 10 , wherein the controller is further configured to:
when the target cell fails to support Cell_FACH, perform at least one of the following:
clear a radio network temporary identity (RNTI) received in the source cell;
reset a high speed downlink shared channel (HS-DSCH) medium access control (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; and
receive downlink transmission on an S-CCPCH.