Procedure mobile communication

A method of mobile communications for communication between a mobile station (UE) and a estacionbase radio (eNB) via a radio link using a certain key (KRRC_CIPH, KRRC_IP, KUP_CIPH), the method comprising the step of: ( a) transmitting (S1006, S2009, S3006, S4010), from the mobile station (UE) to the radio base (eNB) station, a request signal reset when detecting a failure of the radio link (S1004, S2007, S3004, S4008) and (B) performing a reconfiguration of the radio link between the mobile station (UE) and base stations (eNB) in response to the transmission request signal reset station; wherein in step (B), the radio base station transmits (S1007, S2010, S3007, S4011) the mobile station (UE) unasenal reset confirmation, including an index parameter to identify a second key (KeNB [ n]) for calculating a first key (KeNB [n + 1]) for generating a certain key to be used in the estacionbase radio (eNB) after a reset procedure, and the mobile station (UE) calculates the primeraclave ( KeNB [n + 1]) to be stored in the mobile station using the second key (KeNB [n]) identified by elparametro index included in the confirmation signal received reset.