8.5.6 Radio link failure criteria and actions upon radio link failure

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

In CELL_DCH state, after receiving N313 consecutive "out of sync" indications from layer 1 for the established DPCCH or F-DPCH physical channel on the downlink frequency associated with the primary uplink frequency in FDD, and the physical channels associated with mapped DCCHs in TDD, the UE shall:

1> start timer T313;

1> upon receiving N315 successive "in sync" indications from layer 1 on the downlink frequency associated with the primary uplink frequency and upon change of UE state:

2> stop and reset timer T313.

1> if T313 expires:

2> consider it as a "Radio link failure".

Periods in time where neither "in sync" nor "out of sync" is reported by layer 1 on the downlink frequency associated with the primary uplink frequency do not affect the evaluation of the number of consecutive (resp. successive) "in sync" or "out of sync" indications.

For 1.28 Mcps TDD, when the variable E_DCH_TRANSMISSION is set to TRUE (see subclause 8.5.28) and the UE has stored the IE "E-RUCCH info", a "Radio link failure" shall be triggered as below:

1> if the E-RUCCH transmission counter is added greater than N_RUCCH, another hysteresis Timer with the value of N-RUCCH times of T-RUCCH period shall be started:

2> upon the hysteresis Timer expires and still no Grant has been received for the whole time duration since the last E-RUCCH transmission:

3> consider it as a "Radio link failure", refer to [59].

For FDD in CELL_DCH state and in TDD when a radio link failure occurs, the UE shall:

1> clear the dedicated physical channel configuration;

1> perform actions as specified for the ongoing procedure;

1> if no procedure is ongoing or no actions are specified for the ongoing procedure:

2> perform a cell update procedure according to subclause 8.3.1 using the cause "radio link failure".

For FDD, in CELL_FACH state and Idle mode, in conjunction with the Enhanced Uplink in CELL_FACH state, after receiving an indication from layer 1 that physical layer transmission stopped caused by an DL out-of-synchronisation, the UE shall:

1> consider it as a "Radio link failure".