Patent ID: 7957298

Claim:
A method of detecting a random access channel (RACH) failure, the method comprising: selecting and transmitting, by a mobile terminal, a random access channel (RACH) preamble; checking, by the mobile terminal, whether a random access response (RAR), which includes information about the transmitted RACH preamble, is received within a specified time; if the RAR is not received within the specified time or if the information about the transmitted RACH preamble included in the RAR does not match the transmitted RACH preamble, incrementing, by the mobile terminal, a preamble transmission counter by 1; comparing, by the mobile terminal, a value of the preamble transmission counter and a maximum value of a preamble transmission; indicating, by the mobile terminal, to an upper layer that the value of the preamble transmission counter is larger than the maximum value of the preamble transmission; and applying, by the mobile terminal, a back-off time to delay a subsequent RACH preamble transmission; or if the RAR is received within the specified time and if the information about the transmitted RACH preamble included in the RAR matches the transmitted RACH preamble, transmitting, by the mobile terminal, a uplink data including a temporary C-RNTI according to a uplink grant value included in the received RAR, wherein the uplink data is transmitted by using C-RNTI MAC control element; monitoring, by the mobile terminal, a reception of a physical downlink control channel (PDCCH) including the temporary C-RNTI; if the PDCCH including the temporary C-RNTI is not received and contention resolution is considered unsuccessful, incrementing, by the mobile terminal, the preamble transmission counter by 1; comparing, by the mobile terminal, a value of the preamble transmission counter and the maximum value of the preamble transmission; indicating, by the mobile terminal, to an upper layer that the value of the preamble transmission counter is larger than the maximum value of the preamble transmission; and applying, by the mobile terminal, a back-off time to delay a subsequent RACH preamble transmission after indicating it.