Method for detecting failures of random access procedures

A mobile terminal for detecting a failure of a random access procedure comprising:

• a transceiver configured to transmit a random access preamble;
• and
• a processor configured to control the transceiver and operate such that if a random access response (RAR) is not received within a random access response window or if information related to the random access preamble included in the RAR does not match with the transmitted random access preamble,
• incrementing a preamble transmission counter by 1;
• if a value of the preamble transmission counter is equal to a maximum value of the preamble transmission +1, indicating to an upper layer that there is a problem with the random access procedure;
• and
• applying a back-off time to delay a transmission of a subsequent random access preamble;
• or
• wherein the processor operates such that if the RAR is received within the random access response window and if the information related to the random access preamble included in the RAR matches with the transmitted random access preamble,
• transmitting a uplink data which is transmitted through uplink channel including a C-RNTI MAC CE (control element) or CCCH SDU;
• monitoring a reception of a physical downlink control channel (PDCCH) to check whether contention resolution is successful, the checking is based on whether the uplink data includes C-RNTI MAC CE or CCCH SDU, or a timer for the contention resolution expires;
• if the contention resolution is not successful, incrementing the preamble transmission counter by 1;
• if the value of the preamble transmission counter is equal to the maximum value of the preamble transmission +1, indicating to an upper layer that there is a problem with the random access procedure;
• and
• applying a back-off time to delay a transmission of a subsequent random access preamble.