Cell Update Procedure and Causes to occur Cell Update in UMTS

Uplink data transmission:

For FDD, if the variable H_RNTI is not set, and for TDD:if the UE is in URA_PCH or CELL_PCH state; and UE has uplink RLC data PDU or uplink RLC control PDU on RB1 or upwards to transmit: perform cell update using the cause *"uplink data transmission"*.

Paging response:

if the criteria for performing cell update with the cause specified above. are not met; and if the UE in URA_PCH or CELL_PCH state, receives a PAGING TYPE 1 .message fulfilling the conditions for initiating a cell update procedure.perform cell update using the cause *"paging response".*

Radio link failure:

if none of the criteria for performing cell update with the causes specified above in the current sub-clause is met: if the UE is in CELL_DCH state and the criteria for radio link failure are ,or if the transmission of the UE CAPABILITY INFORMATION message fails. perform cell update using the cause *"radio link failure".*

MBMS ptp RB request:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met; and if the UE is in URA_PCH, Cell_PCH or Cell_FACH state; and if the UE should perform cell update for MBMS ptp radio bearer request, perform cell update using the cause *"MBMS ptp RB request".*

Re-entering service area:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met; and if the UE is in CELL_FACH or CELL_PCH state; and 2> if the UE has been out of service area and re-enters service area before T307 or T317 expires: 3> perform cell update using the cause *"re-entering service area".*

RLC unrecoverable error:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met; and if the UE detects RLC unrecoverable error [16] in an AM RLC entity: perform cell update using the cause *"RLC unrecoverable error".*

Cell reselection:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met: if the UE is in CELL_FACH or CELL_PCH state and the UE performs cell re-selection; or if the UE is in CELL_FACH state and the variable C_RNTI is empty: perform cell update using the cause *"cell reselection".*

Periodical cell update:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met; and if the UE is in CELL_FACH or CELL_PCH state; and if the timer T305 expires; and if the criteria for "in service area" and if periodic updating has been configured by T305 in the IE "UE Timers and constants in connected mode" set to any other value than "infinity": perform cell update using the cause *"periodical cell update".*

MBMS reception:

if none of the criteria for performing cell update with the causes specified above in the current subclause is met; and if the UE is in URA_PCH, Cell_PCH or Cell_FACH state; and if the UE should perform cell update for MBMS counting , perform cell update using the cause *"MBMS reception".*