Patent ID: 9124425
Filing Date: 2015-09-01
Classification: H04L,H04W

Abstract:
1. A method comprising: receiving, from an external source, a signal comprising a numeric value indicating a predefined number of failed resynchronization attempts; using a first set of one or more cipher input parameters to decipher ciphered data in a received protocol data unit (PDU) to generate a first set of deciphered data, wherein the ciphered data was ciphered using a second set of one or more cipher input parameters; comparing a first value of at least a portion of the first set of deciphered data to an expected value; determining, with decipher control circuitry, an occurrence of a ciphering error when the value of the at least a portion of the deciphered data is not equal to the expected value; initiating a ciphering resynchronization procedure in response to the determination that a ciphering error occurred so as to resynchronize at least one of the first set of cipher input parameters with at least one of the second set of cipher input parameters; and initiating a radio link control (RLC) resynchronization in response to a failure of the ciphering resynchronization procedure; wherein the ciphering resynchronization procedure comprises: selecting a most probable alternative value for at least one of the first set of cipher input parameter, said most probable alternative comprising an incremented value of a cipher input parameter when the cipher input parameter comprises a parameter that is incremented with each received PDU; deciphering data in one of the received PDU for which a ciphering error occurred or in a subsequently received PDU; comparing at least a portion of the deciphered data to the expected value; repeating the most probable alternative cipher parameter selection and deciphering until a number of repeat attempts exceeds the predefined number of failed resynchronization attempts; and determining that the ciphering resynchronization procedure has failed in response to the number of repeat attempts exceeding the predefined number of failed resynchronization attempts.