1. A terminal comprising a processor and that performs a random access (RA) procedure with a base station and is at least temporarily embodied by the processor, the terminal comprising:a generator configured to generate a preamble sequence using a first sequence corresponding to a first root index based on a preamble index that is randomly selected;
a determiner configured to determine a second root index using the preamble index as an input value of a root index function; and
a communicator configured to transmit a transmission sequence including the preamble sequence and the tag sequence to the base station through a physical random access channel (PRACH),
wherein the generator is configured to generate a tag sequence using a second sequence corresponding to the second root index based on a tag index that is randomly selected,
wherein the generator is configured to generate the preamble sequence by cyclically shifting the first Zadoff-Chu sequence corresponding to a 1-1-th root index in response to time alignment information of the terminal having a fixed value, and to generate the preamble sequence by cyclically shifting the first Zadoff-Chu sequence corresponding to a 1-2-th root index in response to the time alignment information of the terminal having a variable value,
wherein the base station is configured to calculate a second correlation value of a second Zadoff-Chu sequence corresponding to the second root index and the transmission sequence, and to extract at least one piece of time alignment information based on the calculated second correlation value, and to determine whether a preamble collision is present based on at least one piece of the time alignment information corresponding to the tag sequence when a plurality of terminals transmit an identical preamble sequence.